@article{gluck_fellner_mcleod_stuska_pratt-phillips_2023, title={An in-Vitro Model of the Equine Fecal Microbiome to Assess How Horse Population Affects Fermentation Following a Starch Challenge}, volume={101}, ISSN={["1525-3163"]}, url={http://dx.doi.org/10.1093/jas/skad068.048}, DOI={10.1093/jas/skad068.048}, abstractNote={
 The use of an in-vitro model of the equine microbiome is beneficial to assess how fermentation patterns differ based on a horse populations’ habitual diet. The purpose of this study was to determine the in-vitro fermentation patterns of the microbial community within different horse populations before and following a starch challenge. Fecal samples were taken from three different populations of horses: horses from the Shackleford Banks, a North Carolina feral horse population living on native grasses; horses from the NCSU Equine Educational Unit that are predominantly kept on cool season mixed pastures, though may be supplemented with hay and concentrates when warranted; and privately owned horses that were fed mixed diets consisting of grass hay, concentrates and some pasture. Horses were monitored and fecal samples were collected immediately following a void and were stored on dry ice and frozen until analysis. Fecal samples from individual horses were pooled to form a representative sample for each population and mixed with an anaerobic medium to prepare an inoculum. The inoculum was placed into bottles containing either a treatment substrate of alfalfa (A) or of alfalfa and starch (AS). Bottles were capped, purged with CO2 and placed in a water bath at 39°C to incubate for 0, 2, 4 or 24 hours. Culture samples were processed to measure methane and short chain fatty acids (SCFAs; acetate, propionate, butyrate and other isoacids) using gas chromatography. Results were analyzed using the Proc Mixed procedure in SAS to compare the effects of horse population, time and treatment. Methane was significantly greater after 24 hours within all populations with AS, as the inoculum compared with A alone (P = 0.03). Propionate was greater for AS (molar percentage, mean ± standard deviation; 2.21 ± 4.97%) versus the A treatment (11.95 ± 4.97%, P = 0.02). Acetate concentrations were significantly (P < 0.001) greater within the A treatment in the Shackleford and NCSU horses (60.31 ± 10.3% and 62.18 ± 11.47%, respectively) compared with the AS treatment (59.09 ± 11.21% and 59.77 ± 8.85%, respectively). Privately owned horses showed similar values of acetate concentration when comparing the treatment of A (63.42 ± 10.13%) versus AS (63.55 ± 10.77%). Butyrate concentrations were greater in the Shackleford Banks and NCSU horses (13.16 ± 1.92% and 2.64 ± 4.22%, respectively) compared with the privately owned horses (10.96 ± 2%). Isoacids were greater in the Shackleford Banks horses (10.19 ± 4.15%) than the NCSU horses (9.87 ± 3.98%) and the privately owned horses (9.52 ± 3.53%; P< 0.0001). It appears that fermentation of starch differs between these horse populations, likely due to their habitual diet.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Gluck, Cassandra R. and Fellner, Vivek and McLeod, Sarah and Stuska, Sue and Pratt-Phillips, Shannon E.}, year={2023}, month={May} }
 @article{spears_lloyd_siciliano_pratt-phillips_goertzen_mcleod_moore_krafka_hyda_rounds_2020, title={Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration}, volume={98}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skaa095}, abstractNote={Forty-eight Quarter Horse geldings (3 - 8 yr of age) were used to determine the effects of dietary chromium (Cr), in the form of Cr propionate (Cr Prop) on insulin sensitivity. Horses were blocked by age, body condition score, and glucose response to concentrate feeding on d 0, and randomly assigned to treatments. Treatments consisted of 0, 2, 4, or 8 mg Cr/d from Cr Prop. Horses were fed daily a concentrate mix at a rate of 0.2 kg/100 kg BW and grass hay at 1.75 to 2.0 kg/100 kg BW. All horses were fed the control diet for 7 d prior to initiation of the study. After an overnight fast, blood samples from the jugular vein were obtained at 0, 2, and 4 h after concentrate feeding on d 0 and 28 for determination of glucose, NEFA, and insulin. A glucose tolerance test (GTT) was conducted on d 42. Glucose was infused via jugular vein catheters, and blood samples were collected at various times relative to dosing for glucose and insulin determination. Plasma glucose on d 28 was affected (P < 0.05) by treatment, time, and treatment x time. Horses fed 4 mg Cr/d had lesser (P < 0.05) plasma glucose concentrations than those in the other treatments at 0 h. At 2 h post feeding glucose concentrations were greater (P < 0.05) in horses fed 0 or 8 mg Cr/d than in those given 4 mg Cr. Horses fed 2 mg Cr/d had lesser ( P < 0.05) plasma glucose at 4 h post feeding compared to those fed 0 or 8 mg Cr. Plasma glucose did not differ among horses receiving 2 or 4 mg Cr/d at 2 or 4 h. Serum insulin was affected (P < 0.05) by treatment, time, and treatment x time. Insulin concentrations were greater (P < 0.05) in horses fed 0 or 2 mg Cr/d than in those given 4 or 8 mg Cr at 0 h. At 4 h post feeding insulin concentrations were greater (P < 0.05) in horses given 0 or 8 mg Cr than in those fed 2 or 4 mg Cr/d. Plasma glucose was affected (P < 0.05) by treatment and time, but not by treatment x time following the GTT. Mean plasma glucose (across sampling times) were greater (P < 0.05) in controls than in horses fed 2 or 4 mg Cr/d. Glucose concentrations following the GTT did not differ among controls and horses given 8 mg Cr/d. Following glucose infusion, serum insulin concentrations were greater (P < 0.05) in horses fed 2 or 4 mg Cr and tended to be greater in those fed 8 mg Cr/d compared to controls. Results of this study indicate that 2 or 4 mg Cr/d from Cr Prop increased insulin sensitivity in adult horses following oral carbohydrate consumption.}, number={4}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Spears, Jerry W. and Lloyd, Karen E. and Siciliano, Paul and Pratt-Phillips, Shannon and Goertzen, Ellen W. and McLeod, Sarah J. and Moore, Jennifer and Krafka, Kristi and Hyda, Jill and Rounds, Whitney}, year={2020}, month={Apr} }
 @article{lloyd_fellner_mcleod_fry_krafka_lamptey_spears_2010, title={Effects of supplementing dairy cows with chromium propionate on milk and tissue chromium concentrations}, volume={93}, ISSN={["1525-3198"]}, DOI={10.3168/jds.2010-3198}, abstractNote={Eight primiparous and 8 multiparous Holstein cows were used to determine the effects of Cr supplementation, in the form of Cr propionate (Cr Prop), on milk and tissue Cr concentrations. Cows were randomly assigned by parity to one of 2 diets: 1) control diet or 2) 2 mg of supplemental Cr/kg of DM. The level of Cr Prop supplemented exceeded by 4-fold the concentration of 0.5 mg of Cr/kg permitted by the FDA. Experimental diets were fed from approximately 30 d prepartum until at least 91 d postpartum, resulting in a minimum of 121 d of exposure to supplemental Cr. The control prepartum and postpartum diets analyzed 0.48 and 0.38 mg of Cr/kg of DM, respectively. Milk samples were obtained from the a.m. milking on d 0 (colostrum), 7, 14, 21, 28, 42, 56, 77, and 90 and on the final day of the study for Cr analysis. Cows were harvested after lactating for a minimum of 91 d and samples of liver, kidney, semitendinosus muscle, and fat were obtained for Cr analysis. Chromium was measured using electrothermal atomic absorption spectrophotometry. Milk Cr concentration averaged 1.7 ng/mL and was affected by day of lactation but not by Cr or a Cr × day interaction. Supplementation of 2 mg of Cr/kg of DM increased kidney Cr by approximately 3-fold and liver Cr concentrations by approximately 2-fold. Chromium concentrations in muscle and fat were not affected by Cr supplementation. In summary, supplementation of Cr Prop at a level of 2 mg of Cr/kg of DM did not affect Cr concentration in milk, muscle, or fat, the major bovine products consumed by humans.}, number={10}, journal={JOURNAL OF DAIRY SCIENCE}, author={Lloyd, K. E. and Fellner, V. and McLeod, S. J. and Fry, R. S. and Krafka, K. and Lamptey, A. and Spears, J. W.}, year={2010}, month={Oct}, pages={4774–4780} }