Hooper Kathryn J, Bobe Gerd, Vorachek William R, Bishop-Stewart Janell K, Mosher Wayne D, Pirelli Gene J, Kent Michael L, Hall Jean A
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Dryden Hall 206, Corvallis, OR, 97331-4802, USA.
Biol Trace Elem Res. 2014 Dec;161(3):308-17. doi: 10.1007/s12011-014-0134-1. Epub 2014 Sep 26.
Gastrointestinal parasites cause substantial economic losses in pasture-based sheep production systems. Supranutritional organic selenium (Se) supplementation may be beneficial because it improves immune responses to pathogens. To evaluate the effect of Se-yeast supplementation on gastrointestinal parasite load, 30 ewes per treatment group were drenched weekly with no Se, 4.9 mg Se/week as Se yeast (maximum FDA-allowed concentration), or supranutritional concentrations of Se yeast (14.7 and 24.5 mg Se/week) starting early fall for 85 weeks. Fecal samples were collected at weeks 63, 66, 78, and 84 and counted for total trichostrongyle-type eggs and Haemonchus contortus eggs (in samples with ≥200 trichostrongyle eggs/g feces). During breeding season (fall), ewes were kept on pasture; ewes receiving 24.5 mg Se/week had lower fecal trichostrongyle egg counts (93 ± 40 eggs/g feces) compared with ewes receiving no Se (537 ± 257 eggs/g feces; P = 0.007) or ewes receiving 4.9 mg Se/week as Se yeast (398 ± 208 eggs/g feces; P = 0.03). In winter, fecal trichostrongyle egg counts decreased, and group differences were not apparent. During lambing season (spring), ewes were kept in the barn and fecal trichostrongyle egg counts increased, although no group differences were observed. However, none of the ewes receiving supranutritional Se yeast, and with trichostrongyle egg counts ≥200 eggs/g of feces, but four of the ewes receiving lower Se dosages had H. contortus egg counts ≥1,000 eggs/g feces (P = 0.04). Our results suggest that supranutritional Se-yeast supplementation may enhance resistance to naturally occurring H. contortus gastrointestinal parasitism in sheep.
胃肠道寄生虫在以牧场为基础的绵羊生产系统中造成巨大经济损失。超营养水平补充有机硒（Se）可能有益，因为它能改善对病原体的免疫反应。为评估补充硒酵母对胃肠道寄生虫负荷的影响，每个处理组30只母羊从初秋开始，每周分别灌服不添加硒、4.9毫克硒/周的硒酵母（美国食品药品监督管理局允许的最大浓度）或超营养水平的硒酵母（14.7和24.5毫克硒/周），持续85周。在第63、66、78和84周采集粪便样本，计数总毛圆线虫型虫卵和捻转血矛线虫虫卵（粪便中毛圆线虫虫卵≥200个/克的样本）。在繁殖季节（秋季），母羊饲养在牧场；与未补充硒的母羊（537±257个虫卵/克粪便；P = 0.007）或接受4.9毫克硒/周硒酵母补充的母羊（398±208个虫卵/克粪便；P = 0.03）相比，接受24.5毫克硒/周的母羊粪便中毛圆线虫虫卵计数较低（93±40个虫卵/克粪便）。冬季，粪便中毛圆线虫虫卵计数下降，组间差异不明显。在产羔季节（春季），母羊饲养在羊舍，粪便中毛圆线虫虫卵计数增加，尽管未观察到组间差异。然而，接受超营养水平硒酵母补充且毛圆线虫虫卵计数≥200个/克粪便的母羊中，没有一只捻转血矛线虫虫卵计数≥1000个/克粪便，但接受较低硒剂量的母羊中有四只捻转血矛线虫虫卵计数≥1000个/克粪便（P = 0.04）。我们的结果表明，超营养水平补充硒酵母可能增强绵羊对自然发生的捻转血矛线虫胃肠道寄生虫感染的抵抗力。
