|PYLES, MORGAN - University Of Kentucky|
|FOWLER, ASHLEY - University Of Kentucky|
|BILL, VERONICA - University Of Kentucky|
|HARLOW, BRITTANY - University Of Kentucky|
|CRUM, ANDREA - University Of Kentucky|
|HAYES, SUSAN - University Of Kentucky|
|LAWRENCE, LAURIE - University Of Kentucky|
Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2016
Publication Date: 7/21/2016
Citation: Pyles, M.B., Fowler, A.L., Bill, V., Harlow, B.E., Crum, A., Hayes, S.H., Flythe, M.D., Lawrence, L.M. 2016. Effect of starch source in pelleted concentrates on fecal bacterial communities in Thoroughbred mares. J. Anim. Sci Vol. 94, E-Suppl. 5/J. Dairy Sci. Vol. 99, E-Suppl. 1. Pgs. 383-384.
Technical Abstract: High starch concentrates are often added to equine diets to meet digestible energy requirements of some horses, such as broodmares. Starch source has been shown to affect fecal bacterial communities of horses when fed cereal grains with little to no processing. Others suggest that grain processing, such as pelleting, increases foregut starch digestibility, possibly mitigating the effects of starch source on bacterial communities. The aims were to: (i) determine the effect of starch source in pelleted concentrates on Lactobacillus spp., total starch utilizing bacteria (TSU), and cellulolytic bacteria in mares, and (ii) evaluate pre-and post-partum changes in fecal bacterial communities from 324 d of gestation to 28 d post-partum. Nineteen Thoroughbred mares were paired by last breeding date then randomly assigned to either an oat (OB) or corn and wheat middlings (CWB) based pelleted concentrate with ad libitum access to a mixed grass and alfalfa hay and cool season grass pasture. Beginning at 310 d of gestation, mares were fed 3.2 kg/d (DM) of assigned concentrate (OB or CWB). After parturition, concentrate intake gradually increased to 4.8 kg/d (DM). The concentrates provided the following nutrient concentrations: 38.0%, 36.2% starch, 6.6%, 8.8% WSC, and 5.4%, 7.5% ESC for OB and CWB, respectively. Fecal samples were collected at 324 d of gestation, before parturition, 24 h, 14 d, and 28 d post-partum. Fecal samples were collected immediately after defecation by catch or from the center of the pile into single use plastic bags and transported to the lab in an insulated cooler (37°C) under CO2. Samples were serially diluted 10-fold with phosphate buffered saline and the dilutions were used to inoculate selective media. Selective media was used for enumeration of Lactobacillus spp., total starch utilizing bacteria (TSU), and cellulolytic bacteria. Data were log transformed then analyzed with PROC MIXED (SAS 9.3) to test the main effects of treatment (OB or CWB), time of sample, and treatment by time interaction. Results were considered significant when P < 0.05. There were no treatment effects or interactions in enumerated bacterial communities (P > 0.05). These results suggest that pelleting concentrates may alter some of the effects of starch sources. There was no effect of time on TSU (P > 0.05), however Lactobacilli spp. and cellulolytic bacteria decreased 24 h post-partum (P < 0.05). Therefore, major physiological events, such as parturition, appear to alter the hindgut microbiota.