@article{benson_christensen_fairchild_davis_2009, title={The mRNA for zona pellucida proteins B1, C and D in two genetic lines of turkey hens that differ in fertility}, volume={111}, ISSN={["1873-2232"]}, DOI={10.1016/j.anireprosci.2008.02.013}, abstractNote={The avian inner perivitelline layer (IPVL) contains zona pellucida protein-B1 (ZPB1), zona pellucida protein-C (ZPC) and zona pellucida protein-D (ZPD). These three proteins may be involved in sperm binding to the IPVL. ZPB1 is produced by the liver and transported to the developing preovulatory follicle, while ZPC and ZPD are synthesized and secreted by the granulosa cells of the preovulatory follicle. The mRNA of ZPB1, ZPC, and ZPD was investigated in two lines of turkey hens selected for over 40 generations for either increased egg production (E line) or increased body weight (F line). Total RNA was extracted from the liver and from 1cm(2) sections of the granulosa layer around the germinal disc and a nongerminal disc area of the F(1) and F(2) follicles of hens from each genetic line. Northern analysis was performed using chicken cDNA probes for all three ZP proteins. Hepatic mRNA for ZPB1 was greater (P<0.05) in turkey hens from the E line than the F line. Although, there was no difference in ZPC mRNA between the germinal disc and nongerminal disc region of the two largest follicles in E line hens, ZPC mRNA was greater in the nongerminal disc region compared to the germinal disc region in the two largest follicles obtained from the F line hens. There were no differences in ZPD mRNA between the germinal disc and nongerminal disc regions of the F(1) and F(2) follicles for either genetic line. The results suggest that the greater rates of fertility previously observed in eggs from the E line hens compared with the F line of hens may be related to differential amounts of the potential sperm binding proteins ZPB1 and ZPC.}, number={2-4}, journal={ANIMAL REPRODUCTION SCIENCE}, author={Benson, A. P. and Christensen, V. L. and Fairchild, B. D. and Davis, A. J.}, year={2009}, month={Apr}, pages={149–159} }
 @article{wineland_christensen_yildrum_fairchild_mann_ort_2006, title={Incubator temperature and oxygen concentration at the plateau stage in oxygen consumption affects intestinal maturation of broiler chicks}, volume={5}, ISBN={1682-8356}, DOI={10.3923/ijps.2006.229.240}, abstractNote={Incubator temperature and oxygen concentrations were tested as factors determining the intestinal maturation of two lines of broiler chickens. One line was a Low G line selected because its eggs display low eggshell conductance. The second line was a High G line that grew at a reduced rate and its eggs show high eggshell conductance values. All eggs were incubated normally until the 18 day of development or the th beginning of the plateau stage in oxygen consumption. At that time the eggs were divided randomly and placed into experimental cabinets operating at 36, 37 38 or 39oC in experiment 1 or with 17, 19, 21 or 23% oxygen in experiment 2. In experiment 3, the best and worst conditions observed in experiments 1 and 2 were combined in a factorial arrangement. Body weight and intestinal maturation were measured by assaying for maltase and alkaline phosphatase activities in intestinal tissues. Increasing temperatures suppressed intestinal maturation whereas increasing oxygen concentrations enhanced intestinal maturation. When examined together in a factorial arrangement, it was clear that the effects of temperature and oxygen on the embryos were independent because they did not interact. The effects of temperature and oxygen were greater on Low G broiler embryos than they were on High G type embryos. It is concluded that incubator temperatures greater than 37o C, and oxygen concentrations less than 21% are detrimental to intestinal maturation in broiler chicks.}, number={3}, journal={International Journal of Poultry Science}, author={Wineland, M. W. and Christensen, V. L. and Yildrum, I. and Fairchild, B. D. and Mann, K. M. and Ort, D. T.}, year={2006}, pages={229} }
 @article{christensen_wineland_yildirum_fairchild_ort_mann_2005, title={Incubator temperature and oxygen concentrations during the plateau stage in oxygen uptake affect turkey embryo plasma T4 and T3 concentrations}, volume={4}, ISBN={1682-8356}, DOI={10.3923/ijps.2005.268.273}, abstractNote={Avian embryo thyroid responses to incubator temperature and oxygen concentrations during the plateau stage in oxygen consumption were measured. It was hypothesized that turkey embryo thyroid responds in a limited way at this critical time to environmental conditions to modulate basal metabolism. Turkey embryos were exposed to one of four incubator temperatures (36, 37, 38 or 39 C) beginning on the o 25 day of incubation at the onset of the plateau, a time when plasma thyroxine (T ) and triiodothyronine (T ) th 4 3 concentrations normally increase. Blood was collected and thyroid hormone concentrations were measured at pipping (27 day) and hatching (28 day). Elevated temperatures depressed T and T concentrations and th th 3 4 increased the T to T ratios. In a second experiment four oxygen concentrations (17, 19, 21 or 23% oxygen) 3 4 were provided to the embryos using identical procedures. The 21% treatment significantly reduced T and 3 T at pipping compared to all other treatments, but 23% oxygen increased plasma T and the T to T ratio 4 3 3 4 compared to all other treatments. The 17% oxygen treatment elevated T compared to all other treatments. 3 At hatching, 23% oxygen elevated T and T to T ratios compared to all other treatments. When temperature 3 3 4 and oxygen treatments were applied together in a factorial arrangement, temperature and oxygen affected T and T hormone concentrations independently but did not interact. Therefore, we conclude that 3 4 temperature and oxygen are independent stimuli of the avian embryonic thyroid gland during the plateau stage, and that incubator temperature and oxygen concentrations can modulate development of turke y embryos by changing plasma T and T concentrations. 3 4}, number={5}, journal={International Journal of Poultry Science}, author={Christensen, V. L. and Wineland, M. J. and Yildirum, I. and Fairchild, B. D. and Ort, D. T. and Mann, K. M.}, year={2005}, pages={268} }
 @article{christensen_fairchild_ort_2005, title={The relationship between sperm hydrolysis of the perivitelline layer and embryonic livability}, volume={14}, ISSN={["1056-6171"]}, DOI={10.1093/japr/14.1.60}, abstractNote={SUMMARY The hypothesis was proposed that altered sperm hydrolysis of the germinal disc area of the ovum affects embryonic survival. Genetics and damaged spermatozoa were the 2 factors tested. Both factors affect embryonic livability. The mechanism of sperm selection was proposed to be in the oviduct or at the ovum during fertilization. To test the hypothesis, sperm hydrolysis from the creation of holes in the perivitelline layer and embryonic mortality were compared in 3 lines of turkeys representing the past 50 yr of turkey genetics. In the newer lines compared with older, sperm hydrolysis decreased and embryo livability at the first week of embryonic development declined, but embryo livability during the fourth week improved. The same lines were inseminated with 0- or 24-h-stored semen. Although penetration of the perivitelline layer by fresh sperm cells declined in modern lines, penetration of 24-h-stored sperm cells did not. When inseminated with 24-h-stored semen, all 3 lines showed depressed embryo livability compared with fresh semen at wk 1 of embryo development but improved embryo livability at wk 4 of development. In experiment 2, specific comparisons of single-trait selected lines with unselected control lines indicated that selection for rapid growth has increased sperm hydrolysis of the perivitelline layer by 24-hstored sperm, but selection for increased egg production has not. In vitro sperm hydrolysis of the perivitelline layer was examined only for the growth-selected line in experiment 3. The in vitro technique was used to examine perivitelline layer hydrolysis without oviduct effects. The data indicated no differences in holes in the perivitelline layer for lines or sperm storage. Thus, the data suggest that a reduction in the penetration of sperm through the perivitelline layer results in improved embryo livability at wk 4 of development, but we saw no association with wk 1 embryo livability.}, number={1}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Christensen, VL and Fairchild, BD and Ort, DT}, year={2005}, pages={60–68} }
 @article{fairchild_christensen_grimes_wineland_bagley_2002, title={Hen age relationship with embryonic mortality and fertility in commercial turkeys}, volume={11}, ISSN={["1056-6171"]}, DOI={10.1093/japr/11.3.260}, abstractNote={Abstract The purpose of this study was to examine embryonic mortality in turkey eggs from hens of two ages and to report values that minimize the error of wrongly distinguishing between early embryonic mortality (EEM, Days 1 to 7 of incubation) and unfertilized eggs. Three hatch residue breakouts were performed at each of two commercial turkey hatcheries for a total of six hatches. Nicholas Large White turkey eggs from two hen age groups (32 to 35 and 44 to 50 wk of age) were set in the same incubator that operated under the incubation profile of each hatchery. The EEM was significantly greater (P ≤ 0.0001) in younger hens when compared to older hens. This was true for mortality prior to blood formation and mortality following blood formation. Hatchability, percentage internal pips, and live pips were not different between the two hen ages. Prepip mortality and percentage dead pips were significantly (P ≤ 0.0001) greater in older flocks. Fertility and EEM occurring after blood formation were negatively correlated in younger hens, whereas mortality occurring before blood formation did not correlate with fertility in eggs from either hen age. Eggs from young hens tended to experience embryonic mortality earlier in incubation than eggs from older hens. The results suggest that hen age influences embryonic mortality in modern commercial turkeys and could be used as an experimental model for further study of embryonic mortality.}, number={3}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Fairchild, BD and Christensen, VL and Grimes, JL and Wineland, MJ and Bagley, LG}, year={2002}, pages={260–265} }
 @article{christensen_fairchild_2002, title={Maternal and environmental influence on fertility and embryonic survival}, volume={13}, ISSN={["1470-2061"]}, DOI={10.3184/147020602783698584}, number={3}, journal={AVIAN AND POULTRY BIOLOGY REVIEWS}, author={Christensen, VL and Fairchild, BD}, year={2002}, pages={133–137} }