Scholarly Works, Large Animal Clinical Sciences

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https://hdl.handle.net/10919/24343
Research articles, presentations, and other scholarship

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Browsing Scholarly Works, Large Animal Clinical Sciences by Department "School of Plant and Environmental Sciences"

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    Evaluating digestibility and toxicity of native warm-season grasses for equines
    Ghajar, Shayan; McKenzie, H. C.; Fike, John H.; McIntosh, B.; Tracy, B. F. (2021-01)
    Introduced cool-season grasses are dominant in Virginia's grasslands, but their high digestible energy and nonstructural carbohydrate (NSC) levels pose a risk for horses prone to obesity and laminitis. Native warm-season grasses (NWSGs) have lower digestible energy and NSC levels that may be more suitable for horses susceptible to laminitis. Although NWSGs have desirable characteristics, they are novel forages for horses. Little is known about NWSG intake or potential toxicity to horses or how grazing by horses may affect NWSG swards. The overall objectives of this research were to 1) assess voluntary intake, toxicological response, and apparent digestibility of NWSG hays fed to horses; and 2) evaluate the characteristics of three NWSG species under equine grazing. For the first objective, a hay feeding trial using indiangrass (IG) (Sorghastrum nutans) and big bluestem (BB) (Andropogon gerardii) was conducted with nine Thoroughbred geldings in a replicated 3 x 3 Latin square design. Voluntary dry matter intake of IG and BB hays by horses were 1.3% and 1.1% of BW/d, lower than orchardgrass (Dactylis glomerata), an introduced cool-season grass, at 1.7% of BW/d (P = 0.0020). Biomarkers for hepatotoxicity remained within acceptable ranges for all treatments. Apparent dry matter digestibility (DMD) did not differ among hays, ranging from 39% to 43%. NSC levels ranged from 4.4% to 5.4%, below maximum recommended concentrations for horses susceptible to laminitis. For the second objective, a grazing trial was conducted comparing IG, BB, and eastern gamagrass (EG) (Tripsacum dactyloides) yields, forage losses, changes in vegetative composition, and effects on equine bodyweight. Nine, 0.1-ha plots were seeded with one of the three native grass treatments, and each plot was grazed by one Thoroughbred gelding in two grazing bouts, one in July and another in September 2019. IG had the greatest available forage, at 4,340 kg/ha, compared with 3,590 kg/ha from BB (P < 0.0001). EG plots established poorly, and had only 650 kg/ha available forage during the experiment. Grazing reduced standing cover of native grasses in IG and BB treatments by about 30%. Horses lost 0.5-1.5 kg BW/d on all treatments. Findings suggest IG and BB merit further consideration as forages for horses susceptible to obesity and pasture-associated laminitis.
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    Quantification of zearalenone and α-zearalenol in swine liver and reproductive tissues using GC-MS
    Pack, Erica; Stewart, Jacob; Rhoads, Michelle; Knight, James W.; De Vita, Raffaella; Clark-Deener, Sherrie; Schmale, David G. III (Elsevier, 2020-12-01)
    The mycotoxin zearalenone (ZEN) is a common contaminant of swine feed which has been related to a wide range of reproductive anomalies in swine, such as pelvic organ prolapse, anestrous, and pseudopregnancy. New information is needed to understand how ZEN and related metabolites accumulate in swine reproductive tissues. We conducted a feeding study to track ZEN and the metabolite α-zearalenol (α-ZEL) in swine liver and reproductive tissues. Thirty pubertal gilts were randomly assigned one of three treatments, with ten pigs in each treatment group: (1) base feed with solvent for 21 days, (2) ZEN-spiked feed for seven days followed by base feed with solvent for 14 days, and (3) ZEN-spiked feed for 21 days. At the end of the trial, liver, anterior vagina, posterior vagina, cervix, uterus, ovaries, and broad ligament were collected from pigs. ZEN was found in the anterior vagina, posterior vagina, cervix, and ovaries, with significantly higher concentrations in the cervix relative to other reproductive tissues. ZEN and α-ZEL were found in liver tissue from pigs in each treatment group. Our results show that ZEN accumulates more in the cervix than other reproductive tissues. The presence of ZEN in reproductive tissues may be indicative of ZEN-related reproductive symptoms. Future work could examine how ZEN concentrations vary in reproductive tissues as a factor of the pigs age, weight, sex, or parity, to establish parameters that make pig more sensitive to ZEN.