@article{lin_flowers_knauer_lin_2024, title={Estimation of genotype by environmental interaction for litter traits by reaction norm model in Taiwan Landrace sows}, volume={102}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skae189}, abstractNote={Abstract The negative effects of heat stress on swine reproduction have been well documented and the recent global warming trend caused by climate change is leading to more days with high temperatures every year. This has caused a reduction in litter trait performance of Landrace sows in Taiwan, a country extending across tropical and subtropical oceanic zones. Therefore, this study developed a modified model to determine which stages of pregnancy, before, early, middle, and late, had the largest impacts of heat stress on litter traits. A reaction norm model (RNM) was used to identify sows with high resilience to heat stress for litter traits followed by analysis of the modified model. Data from Landrace sows were collected from two farms in Taiwan between 2008 and 2021. A total of 11,059 records were collected for total number born (TNB), number born alive (NBA), and stillborn rate (STBR). The results showed that the heritabilities of TNB, NBA, and STBR were 0.170, 0.115, and 0.077, respectively. These results were similar between the conventional model and the modified model. In the modified model, the before and early stages of sow pregnancy were the significant periods for TNB and NBA (p<0.05), while the early and middle stages were significant for STBR (p<0.05). According to the RNM results, the heritability estimates for TNB, NBA, and STBR were 0.23–0.11, 0.18–0.08, and 0.10–0.04, respectively, showing a decrease from low temperature-humidity index (THI) to high THI. The minimum genetic correlations between the highest and the lowest THI for TNB, NBA, and STBR were 0.85, 0.64, and 0.80, respectively. The results of the RNM for breeding value showed re-ranking across THI values. In conclusion, similar results were obtained for heritability when the model was modified for heat stress estimation. Yet re-ranking of breeding values across THI could help farmers to select not only for improved litter trait performance but also for heat stress resilience of Landrace sows in Taiwan}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Lin, Kai-Hsiang and Flowers, Billy and Knauer, Mark and Lin, En-Chung}, year={2024}, month={Aug} }
 @article{vier_dritz_orlando_diaz_camp_cast_lu_canavate_hamilton_knauer_et al._2024, title={Relationship between sow caliper measurements with sow reproductive performance and longevity in the herd}, volume={102}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skae102.198}, abstractNote={Abstract Ideal conditioned sows are desired because they maximize herd performance, improve female well-being, and optimize financial outcomes. Sow productivity has increased, and body composition of females has changed, with sows being leaner and having less adipose tissue compared with their predecessors. Our objective was to determine the relationship between sow caliper measurements with sow reproductive performance and longevity in the herd. Data collected in four different production systems located in the US and Brazil were used, with 3,083, 356, 7,456, and 26,773 individual PIC Camborough observations represented within each of these databases. Caliper measurements were collected at due to farrow and weaned sows and were recorded in units, standardized to an ideal range of 12 to 15 units. Caliper change in lactation was determined as the caliper units at weaning minus the caliper units pre-farrowing. Response variables included proportion of born alive and stillborn piglets, lactation feed intake, as well as removal and mortality risk for all causes, or specifically for reproductive and pelvic organ prolapse (POP) causes. Data were analyzed using generalized linear mixed models, hazard ratio analysis, and survival models with the lmer, glmer, and surv functions of R. Sow served as the experimental unit. Caliper measurements at farrowing had curvilinear associations (P < 0.05) with percentage born alive piglets and percentage stillborn piglets. Increasing caliper units at farrowing resulted in linear reduction (P < 0.05) in lactation average daily feed intake and in linear increase (P < 0.05) in caliper losses during lactation. Sows losing 1 to 2, 3 to 4, or 5 and greater caliper units in lactation had 1.5, 1.8, and 2.4 times, respectively, greater risk (P < 0.05) of being removed from the herd in the next cycle compared with sows that gained 0 or more units. Reduced caliper units in due-to-farrow sows resulted in reduced probability (P < 0.05) of survival in the next cycle considering prolapse removal reasons. Sows with due to farrow caliper units of 12 to 15 had 1 to 1.6 times (95% Odd Ratio Confidence Interval), 9 to 11 had 1.2 to 2.1 times, and less than 9 caliper units 3.1 to 3.2 times greater risk of death or being removed from the herd due to POP compared with those with >15 units. Reduced caliper units in due-to-farrow sows resulted in reduced probability of survival in the next cycle considering all removal and mortality causes. Specifically, sows with less than 9 caliper units at farrowing had 2.0 times greater risk (P < 0.05) of removal and 4.4 times greater risk (P < 0.05) of mortality compared with sows with over 15 caliper units. In summary, both under and over-conditioned sows have reduced productivity. Underconditioned sows are at greater risk for mortality and for POP related removal.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Vier, Carine M. and Dritz, Steve and Orlando, Weasley A. and Diaz, Julia A. Calderon and Camp, Jordi and Cast, Wayne R. and Lu, Ning and Canavate, Sergio and Hamilton, Dan and Knauer, Mark and et al.}, year={2024}, month={May}, pages={179–180} }
 @article{lin_flowers_jiang_knauer_lin_2024, title={The effect of temperature-humidity index in different pregnancy stages on litter traits in Taiwan Landrace sows}, volume={102}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skae102.025}, abstractNote={Abstract Because of climate change, annual average temperatures are gradually rising. Hence, increasing heat stress can impair the litter traits of Taiwanese sows located in tropical and subtropical zones. However, some pregnancy stages may be impacted more by heat stress than other periods. Thus, the purpose of this study was to demonstrate the effect of temperature-humidity index (THI) in different pregnancy stages on total number born (TNB), number born alive (NBA), and stillborn rate (STB). Data were collected in two Taiwanese farms from 2008 to 2021 for TNB, NBA, and STB, while weather data were collected from the closest respective weather station. There were 4,247 and 6,812 pure line Landrace record from farm 1 and farm 2, respectively. Pregnancy stages included 28 d before mating (BEFORE), mating to 30 d of pregnancy (EARLY), 31 to 70 d of pregnancy (MIDDLE), and 71 d of pregnancy to farrowing (LATE). Average THI was calculated in each pregnancy stage and regression coefficients were estimated by linear mixed models within ASReml. A two-trait analysis was used to estimate regression coefficients and genetic correlations among TNB, NBA, and STB. Results showed THI impacted (P < 0.05) TNB and NBA BEFORE and EARLY, while THI influenced (P < 0.05) STB EARLY and MIDDLE. Regression coefficients for TNB were -0.0069 and -0.0228 for BEFORE and EARLY, respectively. For NBA, regression coefficients were 0.0106 and -0.0391 for BEFORE and EARLY, respectively. Regression coefficients for STB were -0.0651 and 0.1332 for EARLY and MIDDLE, respectively. Heritability estimates for TNB, NBA, and STB were 0.168, 0.113, and 0.069, respectively. Genetic correlations between TNB with NBA and STB were 0.913 and 0.539, respectively. While the genetic correlation between NBA and STB was 0.158. In conclusion, THI impacted BEFORE and EARLY stages for TNB and NBA, while the stages of EARLY and MIDDLE were impacted by THI for STB. Hence, control of the environments in these specific stages for sows could improve the performance of litter traits.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Lin, Kai-Hsiang and Flowers, Billy and Jiang, Jicai and Knauer, Mark and Lin, En-Chung}, year={2024}, month={May}, pages={20–20} }
 @article{kittle_leonard_knauer_almond_2024, title={Water quality analysis and flow rate comparison between wean-finish swine barns}, volume={102}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skae102.033}, abstractNote={Abstract Water is an essential nutrient to sustain life and a vital component of biological functioning, impacting regulation of pig body temperature along with transporting nutrients to the body. Drinker availability, position, design, water flow rate and pressure, and water quality are major components of pig water intake. The ideal water flow rate for wean-to-finish pigs is 1 L m-1. Excessive flow rates could limit pig water intake and increase humidity in the barn, while too little water flow can lead to a decrease in water intake and biological functioning of the pig. Water should not contain harmful substances and should be readily accessible to pigs. Compounds in water are highly variable depending on region, water source, and pH. Quality of water influences feed consumption along with pig health. Water can contain a variety of microorganisms such as bacteria, viruses, algae, and protozoa; while not all microorganisms are harmful a highly contaminated water analysis is an index of poor water quality. In this study water quality and water flow rates were analyzed across five wean-finish sites comprising 16 barns for three turns of finishing pigs. Water flow rates were measured twice per turn, wk 1 and wk 17. Each barn contained 36 pens and flow rate measurements were collected in 8 pens evenly distributed within the barn. One suspended water source was available per pen, with two nipple drinkers per water source. Water flow rates were averaged over each turn within barns. Average water flow rates were 1.42 L m-1 with standard deviation of 0.44 L m-1. Overall barn water flow rates ranged from 0.78 to 2.19 L m-1. Barn flow rates were compared over time to evaluate performance and maintenance of facilities. Water quality samples were also collected and submitted for standard water analysis. Results will provide information on management strategies to assess water quality and water flow rates in wean-finish facilities.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Kittle, Olivia C. S. and Leonard, Suzanne M. and Knauer, Mark and Almond, Glen}, year={2024}, month={May}, pages={27–27} }
 @article{kittle_leonard_knauer_almond_2023, title={Comparison of Ammonia Concentrations Between Flush and Pull-Plug Waste Management Systems in Wean-Finish Swine Barns.}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad068.139}, abstractNote={Abstract
               Pig manure contains a wide variety of corrosion-inducing chemicals such as ammonia. Ammonia production and its release are influenced by temperature and moisture in the barn environment. Increased concentrations of ammonia can negatively affect pig health and growth, as well as pose a risk to human health. Additionally, even at decreased concentrations, ammonia reacts with humidity and causes premature corrosion of barn equipment and is a threat to the structural integrity of livestock buildings. In this study, ammonia concentrations were monitored and compared between two 880 head wean-finish swine facilities with different types of waste management systems. Both facilities had shallow manure pits, one containing a flush system and one containing a pull plug system to remove manure from the barns into the lagoon. Ammonia, dry-bulb air temperature, and relative humidity levels were measured every0 min for an entire wean-finish cycle (approximately 20 weeks). Data will be compared between the facilities to evaluate the impact of the waste management systems on indoor air quality conditions. Potential implications for pig health and growth and facility maintenance will be explored. Results will provide information on best management strategies for swine facilities.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Kittle, J. and Leonard, Suzanne M. and Knauer, Mark and Almond, Glen}, year={2023}, month={May} }
 @article{knauer_2023, title={Dead Sows do not Rear Piglets}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad341.214}, abstractNote={Abstract
               Increasing sow mortality continues to challenge pig producers in the U.S. Sow mortality is an animal well-being, economic and sustainability concern. The majority of sow death loss occurs during late gestation and lactation. Unborn piglets are not able to survive when a sow dies in late gestation. During lactation, sow death (depending on stage of lactation) reduces the availability of colostrum, milk and number of functional teats available to a batch of piglets. Hence sow mortality impedes reproductive throughput. The author characterized sow mortality and evaluated nutritional interventions at a 2,600 animal commercial sow farm in eastern North Carolina over a 27-week period. Sows were housed in individual stalls during gestation. Sow mortality was specifically evaluated between day 95 of gestation and 30 days post-farrowing. Females were evaluated at day 95 of gestation for body condition using the Knauer sow body condition caliper. Sows were further evaluated for abnormalities (e.g., structural conformation, overgrown toes and dew claws, perineal swelling, behavior). Farm recorded sow mortality codes included difficult farrow (7%), lameness (32%), prolapse (21%) and unknown (40%). Of the 3,340 sows evaluated, 190 (5.7%) died between day 95 of gestation and 30 days post-farrow. Abnormalities were more likely (P < 0.01) to be recorded for sows that subsequently died when compared with sows that lived (15.3 vs. 4.5%). Sow mortality was associated (P < 0.05) with both parity and sow body condition. First litter females and heavier conditioned sows were more likely to survive. Yet these two factors combined explained less than 2% of the variation in sow mortality. Few nutritional interventions have been scientifically evaluated in relation to sow mortality. The author will report on five pilot studies, conducted at the commercial sow farm in eastern North Carolina, evaluating the impact of different nutritional strategies to enhance sow livability. Pilot studies consisted of vitamin supplementation experiments (n = 3) in late gestation or the transition period, soybean meal supplementation in late gestation and increased feeding levels in late gestation. Supplementing a combination of vitamins E and C, in late gestation, showed promise in enhancing sow livability. Results challenge the author’s paradigm that poor stockmanship and structural conformation are largely related to the sow U.S. sow mortality dilemma. Hence it is recommended that the swine industry work to better understand the micro and macro nutrient requirements of modern sow genotypes under commercial environments.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark}, year={2023}, month={Oct}, pages={193–194} }
 @article{peppmeier_leonard_knauer_2023, title={Effect of Temperature and Humidity on Daily Feeding Behavior in Swine}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad068.010}, abstractNote={Abstract
               Heat stress has negative impacts on pork production, particularly during the grow-finish phase. During heat stress events, swine alter feeding behavior to reduce heat production, which can negatively affect performance. Recent technology advancements in feed management systems allow for individualized data recording of feeding behavior for group housed pigs during the finishing phase. The objective of this study was to utilize an RFID-based feed management system to determine feeding behavior patterns of finishing pigs during heat stress conditions and identify changes in behavior due to heat stress events. Data included one pen of 29 Duroc boars reared in a mechanically ventilated facility in north central North Carolina. Feed Intake Recording Equipment (FIRE) pig feeders (n = 3; Osborne Technologies) fed individual pigs in the group housed setting using RFID technology and recorded the number of visits, feed intake of each visit, visit duration, and body weight of each pig during each visit. Feeders were calibrated once per week to ensure accuracy of feed intake and body weight measurements. On day 1 of the study, pigs were placed in the experimental pen and body weights were recorded (37.4 kg ± 4.9 kg) using the FIRE feeders. Air temperature, humidity, and dew point data were collected continuously every 5 minutes from day 13 until the end of the finishing period. Pigs exited finishing (134.5 ± 8.6 kg) on day 83. Feeding behavior traits (number of visits and feed intake) were summarized by day. Temperature, humidity, and heat index were summarized by a maximum, minimum, and mean value for each day. Average temperature, humidity, feeder visits a day, and average daily feed intake across the trial was 26.3 ± 1.6 º C, 75.8 ± 6.7%, 6.1 ± 1.0 visits, 2.66 ± 0.39 kg. Models were used to associate feeding behavior traits with the quadratic effects of day and the linear effects of average temperature and humidity and the interaction of temperature and humidity. Temperature and humidity were associated (P < 0.01) number of feeder visits and average daily intake per day. Further, there was an interaction (P < 0.01) between temperature and humidity in relation to number of feeder visits and average daily feed intake. Results suggest substantial variation in feeding behaviors can be explained by temperature and humidity.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Peppmeier, Zack and Leonard, Suzanne M. and Knauer, Mark}, year={2023}, month={May} }
 @article{peppmeier_howard_knauer_leonard_2023, title={Estimating backfat depth, loin depth, and intramuscular fat percentage from ultrasound images in swine}, volume={17}, ISSN={["1751-732X"]}, url={https://doi.org/10.1016/j.animal.2023.100969}, DOI={10.1016/j.animal.2023.100969}, abstractNote={Fast, accurate, and reliable estimates of backfat depth, loin depth, and intramuscular fat percentage in swine breeding stock are used to increase genetic improvement and farm profitability. The objective of this study was to develop an equation-based model for the estimation of swine backfat depth, loin depth, and intramuscular fat percentage estimates obtained from longitudinal ultrasound images. Images were collected from purebred Duroc (n = 230), purebred Large White (n = 154), and commercial (n = 190) pigs born in January 2021 at three farms located in North Carolina. An Exapad ultrasound machine captured longitudinal images across the 10th to 13th ribs at 182 (±12.8 SD) days of pig age. The total number of images processed for Duroc, Large White, and commercial pigs was 1 385, 928, and 1 168 images, respectively. To establish a standard measurement for model comparison, trained personnel following standard company procedures using the BioSoft Toolbox (v4.0.1.2; Biotronics Inc., Ames, IA) obtained backfat and loin depth measurements from the images. Longissimus muscle intramuscular fat percentage was predicted using near-infrared spectroscopy at approximately 22 h postmortem. Backfat and loin depth estimation were conducted only for commercial pigs (n = 190) while intramuscular fat estimation was conducted on all pigs (n = 574). Average backfat depth, loin depth, and intramuscular fat percentage were 14.6 (±2.6 SD) mm, 63.7 (±5.5 SD) mm, and 2.21 (±0.82 SD) %. Image analysis and estimation model development were conducted in MATLAB R2021a. Edge detection via the image gradient was applied to segment ultrasound images into backfat, loin, and rib regions. Segmented images were used to estimate backfat depth, loin depth, and loin intramuscular fat percentage. After image quality control and filtering, the image inclusion rate for each breed-trait combination ranged from 76 to 97%. All Duroc and commercial pigs and 97% of Large White pigs were represented by at least one image for trait estimation. Coefficient of determination of models for the estimation of backfat depth, loin depth, and intramuscular fat percentage were 0.58, 0.57, and 0.56, respectively. Root mean square error of backfat depth, loin depth, and intramuscular fat estimation were 1.65 mm, 3.58 mm, and 0.54%, respectively. Results demonstrate the feasibility of using ultrasound image gradient and an equation-based approach to estimate swine backfat and loin depth, and intramuscular fat percentage. This equation-based approach to estimate carcass traits in live swine can enhance genetic improvement.}, number={10}, journal={ANIMAL}, author={Peppmeier, Z. C. and Howard, J. T. and Knauer, M. T. and Leonard, S. M.}, year={2023}, month={Oct} }
 @article{earnhardt-san_gray_knauer_2023, title={Genetic Parameter Estimates for Teat and Mammary Traits in Commercial Sows}, volume={13}, ISSN={["2076-2615"]}, DOI={10.3390/ani13152400}, abstractNote={The objective was to evaluate the genetics of sow teat and mammary traits at farrowing and at weaning. Data were recorded on 3099 Landrace × Large White F1 sows. Underline traits included the total teat number (TT), the functional teat number (FT), the non-functional teat number (NFT), the damaged teat number (DT), and the number of functional mammary glands (FMG). Variance components were estimated using AIREMLF90. Means for TT, FT, and NFT at farrowing were 14.93, 13.90, and 1.03, respectively. Heritability estimates for TT, FT, and NFT ranged from 0.18 to 0.37, 0.16 to 0.28, and 0.14 to 0.18, respectively. Estimates of heritability for DT and FMG at weaning were 0.03 and 0.06, respectively. Estimated genetic correlations between FT with TT and NFT were 0.68 to 0.78 and −0.19 to −0.57, respectively. Genetic correlation estimates between TT, FT, and NFT with the number weaned were 0.25, 0.50, and −0.38, respectively. An increase of one TT and FT enhanced (p < 0.05) the number weaned by 0.14 to 0.16 and 0.18 to 0.27 piglets, respectively. The results suggest that genetically increasing the number of functional teats on a sow at farrowing would improve the number of piglets at weaning.}, number={15}, journal={ANIMALS}, author={Earnhardt-San, Audrey L. and Gray, Kent A. and Knauer, Mark T.}, year={2023}, month={Aug} }
 @article{knauer_peppmeier_purvis_2023, title={Impact of Prefarrow Fat Supplementation on Piglet Survival and Subsequent Reproduction}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad341.344}, abstractNote={Abstract
               Past research (40+ years ago) suggests feeding fat to sows before parturition and during lactation improves piglet energy stores, sow colostrum fat percentage, sow milk fat percentage and piglet survival. Therefore, the objective was to evaluate the impact of sow fat feeding on piglet survival and throughput in a modern production system. Data were collected from 1,866 sows at a 3,600 sow commercial farm in eastern North Carolina between May and August. Sows were randomly assigned to one of four treatments from day 108 of gestation until farrowing (no supplementation; Control), supplemented with 227g or 454g of soybean oil per day, or supplemented with 227g of coconut oil per day. Oil sources were top dressed daily with 2.27kg of lactation diet. After farrowing, sows had ad libitum access to the lactation diet. At birth, piglets received a colored ear tag corresponding to prefarrow diet. Traits recorded included total number of piglets born, stillborns, crossfosters, number weaned, piglet survival (number weaned ÷ total number born), litter weaning weight, lactation length, whether a sow farrowed a subsequent litter, subsequent total number born, subsequent number born alive, subsequent stillborns, Knauer sow body condition caliper score prefarrow and sow caliper score at weaning. Linear models were used in statistical analysis. Fixed effects included sow prefarrow diet, parity, contemporary group and location of the sow within the farrowing room. Covariates were included when applicable. Results are shown in Table 1. Stillborns and stillborn percentage did not differ (P > 0.05) between dietary treatments. Yet sows supplemented with soybean oil tended (P = 0.10) to have fewer stillborn piglets (0.06 piglets) than Control sows. No differences (P > 0.05) in piglet survival across dietary treatments were observed. Sows supplemented with soybean or coconut oil prefarrow had greater (P < 0.05) subsequent total number born (13.71 vs. 13.31 piglets) and tended (P = 0.07) to have greater subsequent number born alive (13.07 vs. 12.72 piglets) than Control fed sows. Accordingly, sows supplemented with soybean oil tended (P = 0.08) to have more subsequent total number born (13.69 vs. 13.31 piglets) and tended (P = 0.09) to have greater subsequent number born alive (13.07 vs. 12.72 piglets) than Control fed sows. No differences (P > 0.05) in sow body condition loss during lactation were observed between dietary treatments. In summary, prefarrow fat supplementation did not impact piglet survival but did enhance subsequent litter size. The authors would like to thank the United Soybean Board for funding projects designed to enhance pig farmer profit.
               }, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Peppmeier, Zack and Purvis, Jerry}, year={2023}, month={Oct}, pages={302–303} }
 @article{knauer_2023, title={Impact of Vitamins C and E on Sow Mortality and Stillborn Rate}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad341.400}, abstractNote={Abstract
               The objective of the study was to evaluate late gestation supplementation of vitamins C and E on sow mortality and percentage of stillborn piglets. Sows (n = 466), housed in stalls at a commercial sow farm in eastern North Carolina, were randomly allocated to either receive 35g of a top-dress containing vitamins C and E or no top-dress (Control). The 35g top-dress contained 1.05g of vitamin C (from STAY-C 35), 500 IU of vitamin E (from ROVIMIX E50) and ground corn as a carrier. Vitamins C and E were top-dressed twice per week, from day 87 of gestation until farrowing. At the start of vitamin supplementation, sow body condition was measured using a Knauer sow body condition caliper (Knauer scale: < 12 = “thin”, 12 to 15 = “ideal”, >15 = “fat”). The gestation and lactation diets on the farm were formulated to contain no vitamin C and 66 IU/kg of vitamin E. Sow mortality was evaluated from day 95 of gestation through day 30 post-farrow. Mortality codes recorded by farm technicians included sudden death, lameness, prolapse and farrowing difficulty. Sow mortality traits were analyzed using a Chi-square analysis and percentage of stillborn piglets [stillborns ÷ (number born alive + stillborns)] was analyzed using linear regression. Of the 466 sows, 29 (6.2%) died or were euthanized between day 95 of gestation and 30 days post-farrow. Sows that died had less (P < 0.01) body condition (15.3 vs. 16.4 sow caliper score) and were greater (P < 0.01) parity (2.8 vs. 1.9) than sows that survived. Sows supplemented with vitamins C and E tended (P = 0.11) to die less from sudden death and prolapse when compared with Control sows (6.0 vs. 3.0%). Vitamin C and E supplementation tended (P = 0.08) to reduce the number of sows that died at or before farrowing. There was no difference (P=0.33) in percentage of stillborn piglets between sows supplemented with vitamins C and E when compared with Control sows (6.4 vs. 5.5%, respectively). Yet there was an interaction (P < 0.01) between sow body condition caliper score and vitamin supplementation in relation to percentage of stillborn piglets. Thin and ideal sows supplemented with vitamins C and E, thin and ideal Control sows, fat sows supplemented with vitamins C and E, and fat Control sows had stillborn rates of 8.3, 4.8, 4.4 and 6.1%, respectively. For each additional piglet born, percentage of stillborn piglets increased (P < 0.01) by 0.38%. Results suggest supplementation of vitamins C and E in late gestation may be a strategy to enhance sow livability.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark}, year={2023}, month={Oct}, pages={352–353} }
 @article{knauer_peppmeier_leonard_2023, title={Sow Location Within Farrowing Room Impacts Reproduction During Heat Stress.}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad068.013}, abstractNote={Abstract
               The objective was to evaluate the impact of sow location, within farrowing room, on reproduction during periods of heat stress. Data were collected on 1,866 sows at a 3,600-sow commercial farm in eastern North Carolina from May to August 2021. In the farrowing buildings, evaporative cool cell pads cooled the air entering the hallway. Cooled air, from the hallway, then entered the farrowing rooms through inlets at the front of the room and was pulled through the room by fans in the back of the farrowing room. For data analysis, each farrowing room was divided into four zones. Zone 1 included the sows at the front of the farrowing room near the inlets letting in cooled air. Zone 4 included sows at the back of the room where air exited the building through fans embedded within the wall. Zones 2 and 3 were intermediate. Each farrowing room on the farm housed between 18 and 36 sows. After farrowing, sows had ad libitum access to the lactation diet. Traits included piglet survival (number weaned ÷ total number born) the percentage of sows conceiving by 7 days after weaning, subsequent total number born, subsequent number born alive, subsequent stillborns, sow caliper score prefarrow, sow caliper score at weaning and sow caliper lactation loss. Results are shown in Table 1. Piglet survival was greater (P < 0.05) for sows that farrowed at the front of the room near the cool air inlets. Similarly, litter weaning weight was heavier (P < 0.05) near the cool air inlets relative to the back part of the farrowing room. The percentage of sows that conceived by 7 days after weaning, and farrowed, was linearly associated (P < 0.05) with farrowing zone. Sows near the cool air inlets lost less (P < 0.05) body condition and farrowed more (P < 0.05) piglets in the subsequent litter relative to sows in the back of the farrowing room. Results showed sows that farrowed at the front of the farrowing room lost less body condition, had greater piglet survival, heavier litter weaning weights and were more likely to be rebred and conceive by 7 days after weaning relative to sows farrowing in the back of the farrowing room.
               }, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Peppmeier, Zack and Leonard, Suzanne M.}, year={2023}, month={May} }
 @article{knauer_bergstrom_hough_2023, title={Sow Supplementation with Vitamin C Enhances Pig Throughput}, volume={101}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skad341.076}, abstractNote={Abstract
               The objective was to evaluate the impact of vitamin C supplementation, during the transition phase, on sow reproduction and subsequent offspring performance. Landrace × Large White composite sows (n = 58), mated to Smithfield Premium Genetics Duroc boars, were housed at the NCDA Tidewater Research Station. Parity 1 and parity 2 sows were randomly assigned to one of three vitamin C (STAY-C35) levels (0, 250, or 500 mg/kg of diet). Diets were fed from day 107 of gestation through day 7 of lactation. A common lactation diet was then fed from day 8 of lactation until weaning. Sows were fed 2.27 kg per day pre-farrow and ad libitum after farrowing. Cross-fostering was minimized and performed within dietary treatment. Sow body condition was assessed on day 107 of gestation and at weaning (day 23 of lactation) using the Knauer sow body condition caliper. After weaning and 5 weeks in a nursery, offspring were transferred to a naturally ventilated, totally slatted grow-finish facility and housed at 0.62 m2 per pig. Offspring were individually reweighed at 124 days of age (88 ± 5.0 kg). All statistical models contained fixed effects of dietary vitamin C level and sow parity. Total number born was included as a covariate for average piglet birth weight (BWT), stillborn percentage, BWT CV, piglet survival [number weaned ÷ (number born alive + stillborns)], number of littermates at 124 days of age, average daily gain (ADG) from birth to 124 days and pig survival from birth to 124 days [number weighed ÷ (number born alive + stillborns)]. Weaning age and number weaned were included as covariates for average piglet weaning weight (WWT) and WWT CV. Sow and litter was the experimental unit. Results (LSMEANS) are shown in Table 1. Percentage of stillborn piglets did not differ (P > 0.05) between dietary treatments. Sows fed 500 mg/kg of vitamin C had lighter (P < 0.05) piglet BWT CV compared with Control sows. Supplementing 500 mg/kg of vitamin C increased (P < 0.05) both average piglet birth weight and average piglet weaning weight compared with Control sows. Piglet survival did not differ (P > 0.05) between treatments. Average daily gain from birth to 124 days of age tended (P = 0.06) to be greater for pigs from sows fed vitamin C when compared with pigs from Control sows (707 vs. 688 g). Offspring survival from birth to 124 days of age did not differ (P > 0.05) between parity 1 and 2 sows (80.6 and 78.4%, respectively). Yet offspring from parity 2 sows had greater (P < 0.05) ADG from birth to 124 days of age when compared with parity 1 sows (713 vs. 688 g). In summary, supplementing sows with vitamin C increased throughput by enhancing piglet birth weight, piglet weaning weight and offspring growth performance.
               }, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Bergstrom, Jon R. and Hough, Sara D.}, year={2023}, month={Oct}, pages={68–69} }
 @article{obermier_howard_gray_knauer_2023, title={The impact of functional teat number on reproductive throughput in swine}, volume={7}, ISSN={["2573-2102"]}, DOI={10.1093/tas/txad100}, abstractNote={Abstract
               The objective was to evaluate the impact of functional teat number on reproductive throughput in swine. Data included 735 multiparous Landrace × Large White F1 females. Sow underlined traits consisted of total teat number (TT), functional teat number (FT), nonfunctional teat number (NFT), and number of functional mammary glands (FMG). Weaning traits were calculated for both the biological and the nurse dam. For the biological dam, litter size at weaning (LSW) included a sow’s biological piglets regardless of cross-fostering. For nurse dam, number weaned (NW) included the piglets a sow weaned. For the biological dam, piglet survival (PS) was calculated as litter size at weaning / (total number born × 100). Linear regression estimates were calculated in RStudio v. 1.1.456 and variance components were estimated using GIBBS3F90. Average total number born, number born alive, TT, FT, NFT, and FMG were 14.22, 13.12, 14.43, 13.96, 0.42, and 10.7, respectively. An increase in one FT enhanced (P < 0.05) LSW by 0.32 piglets and NW by 0.33 piglets. Similarly, an increase in one FT improved (P < 0.05) PS by 1.63% and reduced (P < 0.05) preweaning mortality by 2.73%. However, an increase in one FT reduced (P < 0.05) average piglet weaning weight (WW) for biological and nurse dams by 35 and 94 g, respectively. Yet an increase in one FT enhanced (P < 0.05) litter weaning weight (LWW) for biological and nurse dams by 1.3 and 1.5 kg, respectively. Heritability estimates for TT, FT, NFT, FMG, WW, LWW, LSW, and PS were 0.25, 0.22, 0.53, 0.18, 0.21, 0.22, 0.16, and 0.18, respectively. Genetic correlation estimates between FT with TT, NFT, and FMG were 0.79, 0.09, and 0.28, respectively. Estimated genetic correlations between TT with WW, LWW, LSW, and PS were 0.37, 0.38, 0.11, and −0.19, respectively. Genetic correlation estimates between FT with WW, LWW, LSW, and PS were 0.44, 0.49, 0.39, and 0.35, respectively. Results suggest increasing functional teat number would enhance both piglet survival and reproductive throughput.}, number={1}, journal={TRANSLATIONAL ANIMAL SCIENCE}, author={Obermier, Dalton R. and Howard, Jeremy Thomas and Gray, Kent A. and Knauer, Mark T.}, year={2023}, month={Jan} }
 @article{nguyen_holt_knauer_abner_lobaton_young_2023, title={Towards rapid weight assessment of finishing pigs using a handheld, mobile RGB-D camera}, volume={226}, ISSN={["1537-5129"]}, url={https://doi.org/10.1016/j.biosystemseng.2023.01.005}, DOI={10.1016/j.biosystemseng.2023.01.005}, abstractNote={Pig weight measurement is essential for monitoring performance, welfare, and production value. Weight measurement using a scale provides the most accurate results; however, it is time consuming and may increase animal stress. Subjective visual evaluations, even when conducted by an experienced caretaker, lack consistency and accuracy. Optical sensing systems provide alternative methods for estimating pig weight, but studies examining these systems only focus on images taken from stationary cameras. This study fills a gap in existing technology through examining a handheld, portable RGB-D imaging system for estimating pig weight. An Intel RealSense camera collected RGB-D data from finishing pigs at various market weights. 3D point clouds were computed for each pig, and latent features from a 3D generative model were used to predict pig weights using three regression models (SVR, MLP and AdaBoost). These models were compared to two baseline models: median prediction and linear regression using body dimension measurements as predictor variables. Using 10-fold cross validation mean absolute error (MAE) and root-mean-square error (RMSE), all three latent feature models performed better than the median prediction model (MAE = 12.3 kg, RMSE = 16.0 kg) but did not outperform linear regression between weight and girth measurements (MAE = 4.06 kg, RMSE = 4.94 kg). Of the models under consideration, SVR performed best (MAE = 9.25 kg, RMSE = 12.3 kg, mean absolute percentage error = 7.54%) when tested on unseen data. This research is an important step towards developing rapid pig body weight estimation methods from a handheld, portable imaging system by leveraging deep learning feature outputs and depth imaging technology.}, journal={BIOSYSTEMS ENGINEERING}, author={Nguyen, Anh H. and Holt, Jonathan P. and Knauer, Mark T. and Abner, Victoria A. and Lobaton, Edgar J. and Young, Sierra N.}, year={2023}, month={Feb}, pages={155–168} }
 @article{wiegert_knauer_shah_2022, title={EVAPORATIVE PAD COOLING IMPACTS ON BARN ENVIRONMENT AND FINISHING PIG PERFORMANCE}, volume={38}, ISSN={["1943-7838"]}, DOI={10.13031/aea.14810}, abstractNote={HighlightsFirst study to evaluate evaporative cool cell pad impacts on finishing pig performance in commercial barnsThe cool cell pad reduced air temperature from 31.5°C by 3.9°C with a cooling efficiency of 52%Cool cell pads improved pig well-being by providing more cooling than sprinklers but pig performance was unaffectedTunnel ventilation (cool cells or sprinklers) improved daily weight gain over natural ventilation with sprinklersAbstract. Since heat stress reduces pig growth, cooling is required to optimize barn environment to maintain performance of modern lean-type swine. Hence, summertime barn environment and finisher pig performance were compared between tunnel ventilated barns with sprinklers (TUNNEL; n=3) and tunnel ventilated barns with evaporative cool cell pads (COOLCELL; n=2). Pig performance was also measured in naturally-ventilated barns with sprinklers and mixing fans (NATURAL; n=4). Evaporative cool cell pad performance was also quantified. Barns with identical dimensions and fully slatted flooring were located at the same commercial production site in eastern North Carolina and were monitored from 2014 to 2016. Barn temperature, relative humidity (RH), temperature-humidity index (THI), and thermal images to assess pig temperature were compared between the COOLCELL and TUNNEL treatments. Average daily gain (ADG), feed conversion ratio (FCR), pig survival, culls, and medication costs were compared across all three barn types and seasons (SUMMER vs. NON-SUMMER) on 72 batches of pigs (46,459 total pigs). Between 12 noon and 1 p.m., the evaporative cool cell pads reduced temperature by 3.9°C and had a cooling efficiency of 52%. COOLCELL barn temperature and THI were significantly lower and RH was significantly higher than TUNNEL. There were no significant differences in pig performance or pig temperature between TUNNEL and COOLCELL. Pig ADG was significantly higher in TUNNEL and COOLCELL vs. NATURAL. SUMMER FCR and medication cost were significantly improved vs. NON-SUMMER. Despite lack of treatment effect on pig performance, COOLCELL improved thermal comfort vs. TUNNEL. Keywords: Growth, Heat stress, Pig, Temperature-humidity-index.}, number={2}, journal={APPLIED ENGINEERING IN AGRICULTURE}, author={Wiegert, Jeffery and Knauer, Mark and Shah, Sanjay B.}, year={2022}, pages={351–359} }
 @article{yu_shah_knauer_boyette_stikeleather_2021, title={Comprehensive Evaluation of a Landscape Fabric Based Solar Air Heater in a Pig Nursery}, volume={14}, ISSN={["1996-1073"]}, url={https://doi.org/10.3390/en14217258}, DOI={10.3390/en14217258}, abstractNote={Supplementing fossil fuels with solar air tempering for brooding young livestock could reduce energy use and improve indoor air quality. Metal transpired solar collectors (TSC) are effective but too expensive for heating livestock buildings. An inexpensive 12.7 m2 dark grey landscape-fabric-based transpired solar collector (fTSC) was evaluated in a swine nursery with two herds of pigs. A fraction of the fTSC area was underlain with phase change material (PCM) to store excess heat. The Test room with the fTSC was compared with an adjacent identical Control room, each with 120 piglets. The fTSC provided supplemental heating, e.g., with a suction velocity (Vs) of 0.027 m/s during a 9 h period, air temperature was increased by 11.6 °C (mean irradiance of 592 W/m2). Between 4 pm and 9 pm that same day, the PCM increased air temperature by 3.9 °C. The fTSC did not reduce propane use or improve pig performance. Higher Vs, operational changes and controller modifications could improve system performance and reduce cost. Modeling could be used to optimize PCM use. Hence, this very low-cost fabric-based solar air heater offers potential for considerable reduction in heat energy use in livestock barns.}, number={21}, journal={ENERGIES}, author={Yu, Li and Shah, Sanjay B. and Knauer, Mark T. and Boyette, Michael D. and Stikeleather, Larry F.}, year={2021}, month={Nov} }
 @article{knauer_peppmeier_2021, title={Effect of Substandard Teats on Piglet and Sow Performance}, volume={99}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skab054.225}, abstractNote={Abstract
               The objective of the study was to evaluate sow teat quality in relation to subsequent reproductive throughput. Data included one cohort of 42 Landrace × Large White second parity maternal line sows at the Tidewater Research Station (Plymouth, NC). Functional teats (FUNCTIONAL) were classified pre-farrow as acceptable (ACCEPTABLE) or substandard (SUBSTANDARD). Teats were categorized as SUBSTANDARD when teat size was ≤75% of ACCEPTABLE. At day 20 of lactation, ACCEPTABLE and SUBSTANDARD were assessed for the presence of a swollen mammary gland and piglets observed nursing SUBSTANDARD were recorded (24 piglets from 15 litters). Means for FUNCTIONAL, ACCEPTABLE and SUBSTANDARD were 15.07, 13.59 and 1.48 teats, respectively. Biological dam traits included birth weight (BWT), total number born (TNB), litter size at weaning (LSW) and piglet survival (LSW/TNB). Weaning weight (WWT) was considered a trait of the nurse dam. Means for TNB, LSW, litter BWT and litter WWT were 13.4, 10.9, 17.8 kg and 57.8 kg, respectively. Data was analyzed using a chi-square test for binary traits and linear mixed models for continuous traits. At weaning, a greater (P < 0.01) proportion of ACCEPTABLE had a functional mammary gland when compared to SUBSTANDARD (76 vs. 47%). Within litters, piglets nursing SUBSTANDARD tended (em>P = 0.09) to be 158 grams lighter at weaning in comparison to ACCEPTABLE. Yet BWT of SUBSTANDARD piglets did not differ (em>P = 0.60) from piglets nursing ACCEPTABLE. Across litters, an increase in one SUBSTANDARD tended (em>P = 0.07) to reduce litter WWT by 1.74 kilograms. An increase in one SUBSTANDARD tended (em>P < 0.07) to increase piglet survival by 3.5%. Results suggest substandard teats, identified pre-farrow, are less likely to have a functional mammary gland at weaning, impair piglet quality yet may enhance piglet survival.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Peppmeier, Zack}, year={2021}, month={May}, pages={133–133} }
 @article{knauer_mani_marsteller_iseri_kremer_2021, title={Evaluating the Performance of Grow-finish Pigs Supplemented with Butipearl (R) Z and Kemtrace (R) Chromium During Natural Heat Stress Exposure}, volume={99}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skab054.294}, abstractNote={Abstract
               Heat stress (HS) severely impacts swine leading to compromised barrier integrity, diminished intestinal health and decreased performance. ButiPEARL® Z (BPZ) is an encapsulated formulation of zinc and butyrate shown to alleviate the impact of HS by improving intestinal health. KemTRACE® Chromium (KTCr) is an organic trace mineral shown to decrease the impact of stress and improve glucose utilization, leading to muscle growth and improved performance. To test the efficacy of BPZ and KTCr on mitigating stress from natural heat exposure, a grow-finish trial was conducted from June-September. There were four treatments: negative control (NC), NC+.45kg BPZ, NC+.91kg BPZ and NC+1.82kg BPZ. Three BPZ treatments were also supplemented with 200ppb KTCr. Pigs (n=480) were randomly assigned to 96 pens at 22.5kg. Performance was measured at d0, 28, 56 and at marketing. From d56 to market, ADFI was greater (P< 0.05) for 0.45kg and 0.91kg BPZ when compared to NC and 1.82kg BPZ (3.40 and 3.35 vs. 3.26 and 3.27kg, respectively). Therefore, relationships between ADFI day 56 to market and ADFI day 0 to market with BPZ level were curvilinear (P< 0.05). Both market weight and overall ADG tended (P< 0.10) to have curvilinear relationships with BPZ level. While not different, 0.45kg and .91kg BPZ supplemented pigs were .97kg and 1.25kg heavier, respectively, on marketing day compared to control. No differences (P >0.10) were observed for Feed:Gain. Part of the negative effects of HS include decrease in feed intake which contributes to intestinal damage and decreased performance. Data from this study show that both treatment combinations were able to improve feed intake and decrease stress which might have led to the improved weight gain at the end. The data provides evidence that the combination of BPZ and KTCr may alleviate the negative effects of HS and help with the performance of grow-finish pigs during heat stress.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Mani, Venkatesh and Marsteller, Tom and Iseri, Vanessa and Kremer, Brian}, year={2021}, month={May}, pages={174–174} }
 @article{harlow_renwick_shuping_sommer_lents_knauer_nestor_2021, title={Evidence that pubertal status impacts kisspeptin/neurokinin B/dynorphin neurons in the gilt(dagger)}, volume={105}, ISSN={["1529-7268"]}, DOI={10.1093/biolre/ioab189}, abstractNote={Abstract
               Puberty onset is a complex physiological process, which enables the capacity for reproduction through increased gonadotropin-releasing hormone and subsequently luteinizing hormone secretion. While cells that coexpress kisspeptin, neurokinin B (NKB), and dynorphin in the hypothalamic arcuate nucleus are believed to govern the timing of puberty, the degree to which kisspeptin/NKB/dynorphin (KNDy) neurons exist and are regulated by pubertal status remains to be determined in the gilt. Hypothalamic tissue from prepubertal and postpubertal, early follicular phase gilts was used to determine the expression of kisspeptin, NKB, and dynorphin within the arcuate nucleus. Fluorescent in situ hybridization revealed that the majority (>74%) of arcuate nucleus neurons that express mRNA for kisspeptin coexpressed mRNA for NKB and dynorphin. There were fewer arcuate nucleus cells that expressed mRNA for dynorphin in postpubertal gilts compared to prepubertal gilts (P < 0.05), but the number of arcuate nucleus cells expressing mRNA for kisspeptin or NKB was not different between groups. Within KNDy neurons, mRNA abundance for kisspeptin, NKB, and dynorphin of postpubertal gilts was the same as, less than, and greater than, respectively, prepubertal gilts. Immunostaining for kisspeptin did not differ between prepubertal and postpubertal gilts, but there were fewer NKB immunoreactive fibers in postpubertal gilts compared to prepubertal gilts (P < 0.05). Together, these data reveal novel information about KNDy neurons in gilts and support the idea that NKB and dynorphin play a role in puberty onset in the female pig.}, number={6}, journal={BIOLOGY OF REPRODUCTION}, author={Harlow, KaLynn and Renwick, Allison N. and Shuping, Sydney L. and Sommer, Jeffrey R. and Lents, Clay A. and Knauer, Mark T. and Nestor, Casey C.}, year={2021}, month={Dec}, pages={1533–1544} }
 @article{harlow_renwick_shuping_sommer_knauer_nestor_2020, title={Effects of genetic selection for early puberty on the hypothalamic-pituitary-ovarian axis in gilts}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa054.368}, abstractNote={Abstract
               Puberty onset in gilts is an awakening of the hypothalamic-pituitary-ovarian axis that is the result of reduced estradiol-negative feedback at the level of the hypothalamus which yields elevated gonadotropin secretion from the anterior pituitary. Given the importance of hypothalamic kisspeptin and neurokinin B (NKB) signaling for the onset of puberty in other species, the objective of this study was to determine if gilts selected for early pubertal onset (SELECT) would display measurable differences within the hypothalamus (i.e. increased expression of kisspeptin and NKB) and within the ovary (i.e. increased ovarian mass) compared to age-matched and weight-matched gilts (CONTROL) that achieve puberty 20 days later than SELECT gilts. Gilts were sacrificed at three timepoints: Timepoint A, both groups were determined to be prepubertal (n=6/group), Timepoint B, SELECT gilts were determined to be pubertal and CONTROL gilts were determined to be prepubertal (n=6/group), and Timepoint C, both groups were determined to be pubertal (n=6/group). All animals were euthanized, heads were perfused with 8 L of 4% paraformaldehyde, and ovaries were harvested. Brain tissue was removed post-fixation, submerged in fixative for 24 hrs followed by 20% sucrose until sectioned for immunohistochemistry. Ovarian mass tended (p≤0.10) to be greater for SELECT gilts on the right ovary (4.34 vs. 3.67 g) and the left ovary (4.49 vs. 3.68 g) when compared to CONTROL (Timepoints A and C), and at Timepoint B right ovary mass from SELECT gilts was heavier than CONTROL gilts (p< 0.05; 7.22 vs. 4.65 g). Hypothalamic immunohistochemistry for kisspeptin and NKB revealed differences in neuronal fiber density between both groups at various timepoints. Therefore, we conclude that gilts genetically selected for early puberty do so via changes within the hypothalamus that increase gonadotropin secretion and, in turn, stimulate ovarian growth to ultimately advance the timing of puberty onset.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Harlow, KaLynn and Renwick, Allison and Shuping, Sydney and Sommer, Jeff and Knauer, Mark and Nestor, Casey}, year={2020}, month={Nov}, pages={212–212} }
 @article{knauer_purvis_lu_orlando_vier_cast_2020, title={Evaluation of the NRC (2012) model in estimating standard maintenance metabolizable energy requirement of PIC sows during midgestation}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa054.170}, abstractNote={Abstract
               The objective was to evaluate the NRC (2012) model in predicting standard maintenance metabolizable energy (MEm) of PIC sows during mid-gestation. A total of 201 PIC Camborough sows (parity 1 to 10) were randomly assigned to 1 of 4 treatments in a complete randomized design between day 36 and 46 post-breeding. Treatments consisted of feeding sows with daily feed allowances to meet 80, 90, 100 or 110% of MEm calculated as MEm, kcal/day = 100 × (body weight)0.75. A common corn-soybean meal-based diet with 3,302 kcal of ME/kg and 0.61% standardized ileal digestible lysine was fed for 28 days. Sow body weight (BW) and sow body condition caliper score (CS) were captured at day 0, 14 and 28. Data were analyzed with PROC GLM of SAS with sow as experimental unit. Average sow parity and feed allowance were 4.2 and 1.79 kg/day, respectively. Average sow BW and sow CS at day 0, 14 and 28 were 234, 233 and 242 kg and 14.9, 14.9 and 14.8, respectively. Increasing feed allowances to meet 80 to 110% of MEm requirement increased (linear, P< 0.01) average daily gain (ADG; 0.100, 0.259, 0.417 and 0.440 kg/d, respectively). The estimated regression equation was ADG, kg/day = -0.83 + 1.193 × MEm, estimating the MEm to maintain BW was below 80% of NRC (2012) estimate. Caliper score change (CSC) increased (linear, P< 0.01) with increasing feed allowances to meet 80 to 110% of MEm requirement (-0.78, -0.26, 0.13, and 0.35, respectively). The estimated regression equation was CSC = -3.73 + 3.78 × MEm, estimating the MEm to maintain CS at 98.7% of NRC (2012) estimate. In summary, results showed that the MEm to maintain BW and CS for PIC sows during mid-gestation was below 80% and at 98.7%, respectively, of NRC (2012) estimated requirement.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Knauer, Mark and Purvis, Jerry and Lu, Ning and Orlando, Uislei and Vier, Carine and Cast, Wayne}, year={2020}, month={Nov}, pages={98–98} }
 @article{see_knauer_2019, title={Associations with four generations of divergent selection for age at puberty in swine}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz129}, abstractNote={The objective was to evaluate 4 generations of divergent selection for age at puberty (young age at puberty = YOUNG; old age at puberty = OLD) in swine. Composite Landrace × Large White animals (n = 4,941) were reared at the North Carolina Department of Agriculture Tidewater Research Station. At 130 d of age, gilts were exposed to mature boars for 7 min daily. Estrous detection continued for 90 d. Puberty was defined as first observed standing reflex in the presence of a boar. Reproductive and performance traits included: age at puberty (AGEPUB), probability of a gilt reaching puberty by 220 d of age (PUB), puberty weight (PUBWT), pubertal estrus (LEN1), length of second estrus (LEN2), vulva width at puberty (VW1), vulva width at second estrus (VW2), gilt birth weight (BWT), gilt weaning weight (WWT), loin eye area (LEA), backfat depth (BF), and weight (WT178) were measured at 178 d of age on average. Variance components were estimated utilizing an animal model in ASReml 4.1. Models included fixed effects of generation and sex, a random common litter effect, and a random animal genetic effect. Covariates were fit for reproductive traits (age at boar exposure), LEA and BF (WT178) and WT178 (age weighed). In generation 4, YOUNG and OLD gilts had on average a PUB of 87% and 64%, respectively, and AGEPUB of 163 and 183 d, respectively. Heritability estimates for AGEPUB, PUB, PUBWT, LEN1, LEN2, VW1, VW2, BWT, WWT, LEA, BF, and WT178 were 0.40, 0.07, 0.39, 0.19, 0.17, 0.36, 0.48, 0.20, 0.12, 0.42, 0.43, and 0.37, respectively. Common litter effect estimates for AGEPUB, PUB, PUBWT, LEN1, LEN2, VW1, VW2, BWT, WWT, LEA, BF, and WT178 were 0.08, 0.14, 0.03, 0.00, 0.01, 0.05, 0.00, 0.03, 0.29, 0.02, 0.10, and 0.11, respectively. Genetic correlations between AGEPUB with PUBWT, LEN1, LEN2, VW1, VW2, BWT, WWT, LEA, BF, and WT178 were 0.83, -0.22, -0.31, 0.25, 0.19, -0.08, -0.29, 0.15, -0.21, and -0.43, respectively. Results suggest selection for reduced AGEPUB in swine would decrease AGEPUB and increase PUB.}, number={6}, journal={JOURNAL OF ANIMAL SCIENCE}, author={See, Garrett M. and Knauer, Mark T.}, year={2019}, month={Jun}, pages={2320–2328} }
 @article{quick_knauer_2019, title={Effect of gilt feeding level and length of increased feeding level in late gestation on piglet birth weight.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz122.410}, abstractNote={Abstract
               The objective of the study was to evaluate the impact of increasing gilt feeding level in late gestation, for different durations, on piglet quality. Gilts (n = 472) were allocated to one of five dietary treatments in a 2 × 2 factorial + control design at a commercial farm in eastern North Carolina. Hence gilts were fed 1.82 kg of feeding until farrowing (Control) or feeding level was increased by either 0.68 or 1.36 kg at either day 93 (d93) or 100 (d100) of gestation. Treatments were randomly assigned by pen (5 to 6 gilts per pen). The gestation diet contained 2,979 Kcal/kg ME and 0.58% SID lysine. Gilt body condition score was captured at day 93 of gestation using a sow body condition caliper (thin = < 12, ideal = 12 to 15, fat = > 15). Piglet birth weights were captured within 24 h of farrowing and piglets were ear notched by treatment prior to cross-fostering. Data were analyzed using PROC GLM with fixed effects of dietary treatment, contemporary group and covariates of litter size and sow functional teat number when applicable. Average gilt caliper score at d 93 of gestation was 17.0. Gilt caliper score did not differ (P > 0.05) across dietary treatments. Mean piglet birth weight did not differ (P > 0.05) between the five dietary treatments or the main effects of feeding level or length of feeding level. A one piglet increase in litter size reduced (P < 0.01) mean piglet birth weight by 30 g. An increase of one functional sow teat increased (P < 0.05) litter size at weaning of the biological sow by 0.28 piglets. Results suggest increasing gilt feeding level in late gestation does not impact mean piglet birth weight when gilts are over conditioned.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Quick, James K. and Knauer, Mark}, year={2019}, month={Jul}, pages={233–233} }
 @article{wiegert_knauer_2019, title={Meta-analysis of increasing lysine and energy in late gestation on piglet growth, colostrum composition and piglet throughput.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz122.367}, abstractNote={Abstract
               A meta-analysis of four late gestation sow nutrition studies (n = 298 sows) was conducted to evaluate the effects of sow feeding level and diet composition on colostrum composition and sow productivity. In all experiments, sows were fed either a gestation diet (2,979 Kcal/kg ME, 0.58% SID lysine) or lactation diet (3,322 Kcal/kg ME, 0.99% SID lysine, 2.5% added fat). The timing of transition from the gestation to the lactation diet varied between day 93 and 107 of gestation. Feeding levels ranged from 1.5 to 4.5 kg. Total lysine (LYS) and total added fat (FAT) intake from day 93 of gestation to farrowing were calculated. Data was analyzed using PROC GLM in SAS with fixed effects of experiment, parity, litter size and day of diet transition. Sow was the experimental unit. Average total number born and mean piglet colostrum intake (CI) were 13.2 and 470 g, respectively. Increasing piglet CI increased (P < 0.05) number of piglets weaned by the biological dam (LSW) and average piglet weaning weight (WWT). A 1 g increase in added fat during late gestation increased piglet CI by 0.03 g (P < 0.01). A 1 g increase in LYS intake increased (P < 0.05) piglet CI by 0.12 g and WWT by 1.2 g. Feeding level did not impact (P > 0.05) piglet CI, LSW or WWT. Feeding level, LYS and FAT did not impact (P > 0.05) colostrum composition. A one nipple increase in functional teat number was associated with a 260 g increase (P < 0.01) in litter CI and a 0.30 piglet increase (P < 0.05) in LSW. Results suggest increasing LYS and FAT in late gestation, above what is typically fed on commercial sow farms, may improve sow reproduction. However a cost benefit analysis should be conducted before increasing feed cost. Strategies to increase sow functional teat number should be evaluated.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Wiegert, Jeffrey and Knauer, Mark}, year={2019}, month={Jul}, pages={208–208} }
 @article{peppmeier_obermier_knauer_2019, title={Production trait differences between show pig and commerical genetic lines.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz122.297}, abstractNote={Abstract
               The objective was to compare growth and body composition of pigs sired by boars from the show pig industry to those sired by modern commercial genetic lines. Data included one group of 174 male pigs from 16 sires and 50 dams. Pigs were sired by Large White (LW) show pig sires (SHOW) or one of two maternal LW commercial genetic lines (W or P). Dams of all pigs evaluated were from line P. Pigs were weaned at 27 d of age and placed into a mechanically ventilated nursery (0.23 m2 per pig). After 35 d in the nursery, pigs moved to a naturally ventilated finisher (0.74 m2 per pig) with fully slatted floors. Weight, 10th rib backfat, and loin eye area (LEA) were collected at 156 d of age (backfat and LEA adjusted to 114 kg). Data was analyzed using PROC GLM with a fixed effect of genetic line and covariates of weaning age and birth weight. A one day increase in weaning age increased (P < 0.01) 156 d weight by 658 g. Nursery average daily gain (ADG) was greater (P < 0.01) for pigs sired by SHOW and W when compared to P (414 and 397 vs. 351 g, respectively) yet finishing ADG did not differ (P > 0.05) (821 and 817 vs. 797 g, respectively). Backfat was thicker (P < 0.01) for SHOW when compared to W or P (16.7 vs. 14.7 and 14.7 mm, respectively) and LEA was larger (P < 0.05) for SHOW when compared to W or P (47.3 vs. 44.8 and 44.0 cm2, respectively). Finishing lean gain per day was greater (P < 0.05) for SHOW and W when compared to P (323 and 322 vs. 309 g per d, respectively). Results suggest pigs sired by LW SHOW are fatter, heavier muscled, and have comparable lean growth to those sired by commercial LW genetic lines.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Peppmeier, Zack and Obermier, Dalton R. and Knauer, Mark}, year={2019}, month={Jul}, pages={168–168} }
 @article{obermier_peppmeier_knauer_2019, title={Structural conformation differences between show pigs and commercial genetic lines.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz122.070}, abstractNote={Abstract
               Structural conformation differences between show pig and commercial genetic linesD.R. Obermier, Z.C. Peppmeier, M.T. Knauer North Carolina State University, Raleigh.The objective was to compare the structural conformation of pigs sired by boars from the show pig industry to those sired by modern commercial genetic lines. Data included 174 male pigs from 16 sires and 50 dams. Pigs were sired by Large White (LW) show pig sires (SHOW) or one of two maternal LW commercial genetic lines (W or P). Dams of all pigs evaluated were from line P. Pigs were reared in barns (0.74 m2 per pig) with natural ventilation and totally slatted concrete flooring. Two technicians visually evaluated pigs at five months of age for front leg side view (FSIDEVIEW), rear pastern angle (RPASTERN), rib width (RIB) and locomotion (LOCO). The traits FSIDEVIEW and RPASTERN were scored on a seven point scale where one was soft pasterns, four was normal and seven was buck-kneed and straight pasterns, respectively. Rib width was scored on a five point scale with five being wide ribbed. Locomotion was scored on a seven point scale where one was ideal. Correlations between technicians for FSIDEVIEW, RPASTERN, RIB and LOCO were 0.54, 0.66, 0.77 and 0.72, respectively. Males sired by SHOW had lower (P < 0.01) FSIDEVIEW scores than those sired by W or P (2.2 vs. 3.3 and 3.6, respectively) and softer (P < 0.05) RPASTERN (3.4 vs. 3.8 and 4.2, respectively). Rib width was wider (P < 0.01) for SHOW when compared to W or P (3.7 vs. 2.6 and 2.4, respectively) Locomotion was superior (P < 0.01) for SHOW when compared to W or P (2.6 vs. 3.4 and 3.6, respectively). Line W had lower (P < 0.05) FSIDEVIEW and RPASTERN than P. Yet RIB and LOCO did not differ (P > 0.05) between W and P. Results suggest pigs sired by SHOW had softer pasterns, greater rib width and superior locomotion when compared to those sired by commercial genetic lines.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Obermier, Dalton R. and Peppmeier, Zack and Knauer, Mark}, year={2019}, month={Jul}, pages={39–39} }
 @article{obermier_knauer_graham_frobose_2019, title={The effects of lift crates on sow performance and litter survival.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz122.411}, abstractNote={Abstract
               In modern sow farms, pre-weaning mortality (PWM) remains a key barrier to achieving peak productivity and optimizing piglet welfare. Therefore, a total of 270 sows (PIC 1050, 3.6 average parity) were used (May to July 2018) to determine the effect of lift crates in farrowing on sow and piglet performance and litter survival in a commercial setting in southwestern Ontario, Canada. Lift crates are driven by postural changes in the sow which activate a hydraulic lift system (Balance Frame; NOOYEN, Deurne, NL) which temporarily raises a movable sow slat 25 cm above the crate floor. Sows were randomly assigned to 2.44 m × 1.83 m farrowing crates that were 1) conventional or 2) lift crates. Within rooms, litters were standardized to 13 or 14 pigs within 24 h after parturition. Daily sow feed intake was measured using electronic lactation feeders (Gestal SOLO; JYGA Technologies, Inc.). Data were analyzed using the MIXED procedure of SAS (Cary, NC). Sow was the experimental unit. No differences (P > 0.22) were observed for number born alive, stillbirths or mummified fetuses. Sow backfat loss (2.2 vs. 2.5 mm), average daily feed intake (5.67 vs. 5.74 kg) and wean-to-estrus interval (5.27 vs. 5.62 d) were similar (P > 0.16) between conventional and lift crate treatments. However, from birth to cross-fostering, lift crates reduced (P < 0.01) piglet deaths by 55% when compared to conventional crates (0.58 vs. 0.32 piglets). Piglet deaths from cross-fostering to weaning did not differ (P = 0.18, 0.68 vs. 0.54 piglets). Number of pigs weaned (12.62 vs. 12.87) and suckled litter weaning weight (75.7 vs. 75.6 kg) did not differ (P > 0.11) across treatments. These results provide evidence that lift crates can reduce the number of piglet deaths and may improve PWM in sow farms.Keywords: crate, piglet, survival}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Obermier, Dalton R. and Knauer, Mark and Graham, Amanda and Frobose, Hyatt}, year={2019}, month={Jul}, pages={233–233} }
 @article{putz_tiezzi_maltecca_gray_knauer_2018, title={A comparison of accuracy validation methods for genomic and pedigree-based predictions of swine litter size traits using Large White and simulated data}, volume={135}, ISSN={["1439-0388"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85040771964&partnerID=MN8TOARS}, DOI={10.1111/jbg.12302}, abstractNote={SummaryThe objective of this study was to compare and determine the optimal validation method when comparing accuracy from single‐step GBLUP (ssGBLUP) to traditional pedigree‐based BLUP. Field data included six litter size traits. Simulated data included ten replicates designed to mimic the field data in order to determine the method that was closest to the true accuracy. Data were split into training and validation sets. The methods used were as follows: (i) theoretical accuracy derived from the prediction error variance (PEV) of the direct inverse (iLHS), (ii) approximated accuracies from the accf90(GS) program in the BLUPF90 family of programs (Approx), (iii) correlation between predictions and the single‐step GEBVs from the full data set (GEBVFull), (iv) correlation between predictions and the corrected phenotypes of females from the full data set (Yc), (v) correlation from method iv divided by the square root of the heritability (Ych) and (vi) correlation between sire predictions and the average of their daughters' corrected phenotypes (Ycs). Accuracies from iLHS increased from 0.27 to 0.37 (37%) in the Large White. Approximation accuracies were very consistent and close in absolute value (0.41 to 0.43). Both iLHS and Approx were much less variable than the corrected phenotype methods (ranging from 0.04 to 0.27). On average, simulated data showed an increase in accuracy from 0.34 to 0.44 (29%) using ssGBLUP. Both iLHS and Ych approximated the increase well, 0.30 to 0.46 and 0.36 to 0.45, respectively. GEBVFull performed poorly in both data sets and is not recommended. Results suggest that for within‐breed selection, theoretical accuracy using PEV was consistent and accurate. When direct inversion is infeasible to get the PEV, correlating predictions to the corrected phenotypes divided by the square root of heritability is adequate given a large enough validation data set.}, number={1}, journal={JOURNAL OF ANIMAL BREEDING AND GENETICS}, author={Putz, A. M. and Tiezzi, F. and Maltecca, C. and Gray, K. A. and Knauer, M. T.}, year={2018}, month={Feb}, pages={5–13} }
 @article{lu_jiao_tiezzi_knauer_huang_gray_maltecca_2017, title={The relationship between different measures of feed efficiency and feeding behavior traits in Duroc pigs}, volume={95}, DOI={10.2527/jas2017.1509}, number={8}, journal={Journal of Animal Science}, author={Lu, D. and Jiao, S. and Tiezzi, F. and Knauer, M. and Huang, Y. and Gray, K. A. and maltecca}, year={2017}, pages={3370–3380} }
 @article{knauer_baitinger_2015, title={The sow body condition caliper}, volume={31}, DOI={10.13031/aea.31.10632}, abstractNote={Abstract. Sows throughout the world are commonly fed to a subjective body condition target. Therefore, the objective of the study was to develop a fast and accurate, objective tool to measure sow body condition. A prototype caliper was developed to quantify the angularity from the spinous process to the transverse process of a sow’s back. The sow caliper technology is based on the premise that as a sow loses weight, fat and muscle her back becomes more angular. The arms of the caliper were 3.8 cm tall and could be adjusted to 16.5, 21.6, 26.7, or 31.8 cm wide. Landrace A— Large White gilts and multiparous sows (n = 315) were utilized to associate the caliper with weight, backfat, muscling, and visual body condition at commercial sow farms in eastern North Carolina. The caliper was evaluated at locations on the sow’s back: behind the shoulder, middle of the back, and at the last rib. Sow weight was estimated and parity recorded. Backfat (BF) and loin depth (LD) were measured using an Aloka 500V SSD ultrasound machine. Visual body condition (BCS) was scored using a scale of 1 (thin) to 5 (over conditioned). Weight, BF, LD, and BCS explained 51% to 71% of the variation in caliper measures. Results suggest the optimal sow caliper width was 26.7 cm and measurements should be taken at the last rib. The sow body condition caliper is an objective tool that can be used by farmers to standardize sow body condition.}, number={2}, journal={Applied Engineering in Agriculture}, author={Knauer, M. T. and Baitinger, D. J.}, year={2015}, pages={175–178} }
 @article{putz_tiezzi_maltecca_gray_knauer_2015, title={Variance component estimates for alternative litter size traits in swine}, volume={93}, ISSN={["1525-3163"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84975508749&partnerID=MN8TOARS}, DOI={10.2527/jas.2015-9416}, abstractNote={Litter size at d 5 (LS5) has been shown to be an effective trait to increase total number born (TNB) while simultaneously decreasing preweaning mortality. The objective of this study was to determine the optimal litter size day for selection (i.e., other than d 5). Traits included TNB, number born alive (NBA), litter size at d 2, 5, 10, 30 (LS2, LS5, LS10, LS30, respectively), litter size at weaning (LSW), number weaned (NW), piglet mortality at d 30 (MortD30), and average piglet birth weight (BirthWt). Litter size traits were assigned to biological litters and treated as a trait of the sow. In contrast, NW was the number of piglets weaned by the nurse dam. Bivariate animal models included farm, year-season, and parity as fixed effects. Number born alive was fit as a covariate for BirthWt. Random effects included additive genetics and the permanent environment of the sow. Variance components were plotted for TNB, NBA, and LS2 to LS30 using univariate animal models to determine how variances changed over time. Additive genetic variance was minimized at d 7 in Large White and at d 14 in Landrace pigs. Total phenotypic variance for litter size traits decreased over the first 10 d and then stabilized. Heritability estimates increased between TNB and LS30. Genetic correlations between TNB, NBA, and LS2 to LS29 with LS30 plateaued within the first 10 d. A genetic correlation with LS30 of 0.95 was reached at d 4 for Large White and at d 8 for Landrace pigs. Heritability estimates ranged from 0.07 to 0.13 for litter size traits and MortD30. Birth weight had an h of 0.24 and 0.26 for Large White and Landrace pigs, respectively. Genetic correlations among LS30, LSW, and NW ranged from 0.97 to 1.00. In the Large White breed, genetic correlations between MortD30 with TNB and LS30 were 0.23 and -0.64, respectively. These correlations were 0.10 and -0.61 in the Landrace breed. A high genetic correlation of 0.98 and 0.97 was observed between LS10 and NW for Large White and Landrace breeds, respectively. This would indicate that NW could possibly be used as an effective maternal trait, given a low level of cross-fostering, to avoid back calculating litter size traits from piglet records. Litter size at d 10 would be a compromise between gain in litter size at weaning and minimizing the potentially negative effects of the nurse dam and direct additive genetics of the piglets, as they are expected to increase throughout lactation.}, number={11}, journal={JOURNAL OF ANIMAL SCIENCE}, publisher={American Society of Animal Science}, author={Putz, A. M. and Tiezzi, F. and Maltecca, C. and Gray, K. A. and Knauer, M. T.}, year={2015}, month={Nov}, pages={5153–5163} }
 @article{knauer_hostetler_2013, title={US swine industry productivity analysis, 2005 to 2010}, volume={21}, number={5}, journal={Journal of Swine Health and Production}, author={Knauer, M. T. and Hostetler, C. E.}, year={2013}, pages={248–252} }
 @article{knauer_cassady_newcom_see_2012, title={Gilt development traits associated with genetic line, diet and fertility}, volume={148}, ISSN={["1871-1413"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863775012&partnerID=MN8TOARS}, DOI={10.1016/j.livsci.2012.05.024}, abstractNote={The objective was to associate gilt development traits with genetic line, diet and fertility group (FG). Gilts (n=1225) were reared from 162 to 265 days of age at a gilt development unit (GDU) and sent to sow farms. Females were Landrace (L), Large White (LW), L and LW F1 or L and LW composite. Estrous traits included age at puberty (AGEPUB), length of estrus (LOE), maximum strength of standing reflex with (MSRBOAR) or without (MSRNOBOAR) a boar present, total strength of standing reflex with (TSRBOAR) or without (TSRNOBOAR) a boar present, vulva redness (VR), strength of vulva reddening and swelling (VISUAL VULVA) and vulva width (VW). Growth and body composition traits were puberty weight, days to 114 kg and 10th rib backfat (BF) and loin muscle area (LMA) at 114 kg and puberty. Structural conformation traits included muscle mass, rib width, front leg side view, rear leg side view, front legs front view, rear legs rear view and locomotion (LOC). Sow farm entry traits were age, weight, BF and LMA. Sow traits included whether or not a gilt farrowed (STAY), age at first farrowing and total number born (TNB). Fertility groups were; FG0=did not reach puberty at the GDU (NOPUB), did not farrow (DNF); FG1=reached puberty at the GDU (YESPUB), DNF; FG2=NOPUB, farrowed; FG3=YESPUB, farrowed. Genetic lines differed (P<0.05) for estrous traits LOE, TSRBOAR, MSRNOBOAR, TSRNOBOAR, VR, VISUAL VULVA and VW. Females fed restrictively vs. ad libitum had a longer (P<0.05) LOE (2.18 vs. 2.03 d), higher (P<0.05) TSRBOAR (15.4 vs. 14.0) and younger (P<0.05) AGEPUB (219 vs. 225 d). Fertility groups 0, 1, 2 and 3 contained 45 (4%), 255 (24%), 66 (6%) and 698 (66%) gilts, respectively. Gilts from FG3 in comparison to FG1 had a longer (P<0.05) LOE (2.16 vs. 2.06 d), greater (P<0.05) MSRBOAR (7.6 vs. 7.4) and greater (P<0.05) TSRBOAR (15.4 vs. 14.6). Fertility group 0 had less (P<0.05) BF, poorer (P<0.05) LOC and was narrower (P<0.05) ribbed compared with the other FG's. Based on these results it was concluded that gilts with LOE ≤1 day or weak standing reflexes were less likely to farrow a litter.}, number={1-2}, journal={LIVESTOCK SCIENCE}, author={Knauer, M. T. and Cassady, J. P. and Newcom, D. W. and See, M. T.}, year={2012}, month={Sep}, pages={159–167} }
 @article{layman_knauer_stalder_karriker_mckean_serenius_baas_johnson_2009, title={Characterization of Lesions in U.S. Cull Sows}, volume={12}, ISSN={1088-8705 1532-7604}, url={http://dx.doi.org/10.1080/10888700902720359}, DOI={10.1080/10888700902720359}, abstractNote={Physical and reproductive conditions of 3,158 cull sows from 2 U.S. Midwestern harvest facilities were assessed. Body condition, feet, shoulders, teeth, lungs, and reproductive tracts were visually evaluated for gross lesions at harvest. Based on the observations of this study, body condition score (BCS) was associated with several abnormal conditions of sows. Foot-related lesions (overgrown toes, foot pad lesions) represented the most frequently documented lesions. Temporal associations of the interactions between lesions and BCS are unknown. Even though causal relations were not established by this study, the strong associations observed suggest that sows who do not respond to increased feeding with improved BCS could reasonably be expected to have additional lesions that may impact performance and welfare. On-farm management practices may be related to 1 or more lesions (including foot lesions) that had a high prevalence in this study. Farm management practices and nonhuman animal welfare could not be evaluated with this study so no extrapolation can be given to the type of animal housing or the antemortem behavior of these sows.}, number={2}, journal={Journal of Applied Animal Welfare Science}, publisher={Informa UK Limited}, author={Layman, Lori and Knauer, Mark and Stalder, Ken J. and Karriker, Locke A. and McKean, James and Serenius, Timo and Baas, Tom and Johnson, Colin}, year={2009}, month={Mar}, pages={152–152} }
 @article{knauer_stalder_karriker_baas_johnson_serenius_layman_mckean_2007, title={A descriptive survey of lesions from cull sows harvested at two Midwestern U.S. facilities}, volume={82}, ISSN={0167-5877}, url={http://dx.doi.org/10.1016/j.prevetmed.2007.05.017}, DOI={10.1016/j.prevetmed.2007.05.017}, abstractNote={Physical and reproductive conditions of cull sows (3158) from two U.S. Midwestern harvest plants were assessed. Body condition, feet, shoulders, teeth, lungs, and reproductive tracts were visually evaluated for gross lesions on harvested sows. PROC FREQ (SAS, Cary, NC) was used to calculate the frequency of each binary trait event. Pearson chi-square tests were used to test the alternative hypothesis that a linear association existed between binary traits and body condition score (BCS). The most common foot lesions observed were rear (n = 2064, 67.5%) and front (n = 1024, 32.9%) heel lesions. Cracked hooves were found on the front feet of 703 (22.6%) and rear feet of 552 (18.1%) sows. Rear digital overgrowth was observed in 644 (21.1%) sows. The most common reproductive gross lesion observed among harvested cull sows was acyclic ovaries (n = 277, 9.0%). Presence of acyclic ovaries increased (p < 0.01) as BCS decreased. Cystic ovaries were found in 192 (6.3%) sows, which increased (p < 0.01) as BCS increased. Pneumonia was observed in 298 (9.7%) sows, and increased in frequency as BCS decreased (p < 0.01). The most frequently observed shoulder lesion among harvested cull sows was shoulder abrasions (n = 394, 12.5%). The presence of shoulder abrasions increased (p < 0.01) as BCS decreased. The prevalence of reproductive lesions detected in the present study was less than the reported percentage of sows culled for reproductive failure from previous studies based on record keeping summaries.}, number={3-4}, journal={Preventive Veterinary Medicine}, publisher={Elsevier BV}, author={Knauer, M. and Stalder, K.J. and Karriker, L. and Baas, T.J. and Johnson, C. and Serenius, T. and Layman, L. and McKean, J.D.}, year={2007}, month={Dec}, pages={198–212} }