The effects of selenium (Se) yeast supplementation on performance, blood biochemical and antioxidant parameters, and milk Se content and speciation were evaluated. Thirty-six mid-lactation Holstein dairy cows were randomly assigned to 1 of 3 treatments: 1) control (basal diet containing Se at 0.11 mg/kg DM), 2) basal diet + 0.5 mg supplemental Se/kg DM (SY-0.5), and 3) basal diet + 5 mg supplemental Se/kg DM (SY-5). Selenium was supplemented as Se yeast. The trial consisted of a 1-week pretrial period and an 8-week experimental period. Milk somatic cell score decreased with SY-5 supplementation (P < 0.05), but other performance parameters were not affected (P > 0.05). The serum Se concentration increased with the increasing levels of Se yeast supplementation (P < 0.05), however, blood biochemical parameters showed few treatment effects. The antioxidant capacity of dairy cows was improved with Se yeast supplementation reflected in increased serum glutathione peroxidase activity (P < 0.05) and total antioxidant capacity (P = 0.08), and decreased malondialdehyde concentration (P < 0.05). Milk total Se concentration increased with Se dose (P < 0.05). Also, the selenomethionine concentration increased with Se dose from 13.0 ± 0.7 μg/kg in control to 33.1 ± 2.1 μg/kg in SY-0.5 and 530.4 ± 17.5 μg/kg in SY-5 cows (P < 0.05). Similarly, selenocystine concentration increased from 15.6 ± 0.9 μg/kg in control and 18.9 ± 1.1 μg/kg in SY-0.5 to 22.2 ± 1.5 μg/kg in SY-5 cows (P < 0.05). In conclusion, Se yeast is a good organic Se source to produce Se-enriched cow milk with increased Se species including selenomethionine and selenocystine. The results can provide useful information on milk Se species when a high dose Se yeast was supplemented in the cow diet.

评估了酵母补充硒 (Se) 对性能、血液生化和抗氧化参数以及牛奶硒含量和形态的影响。 36 头泌乳中期荷斯坦奶牛被随机分配到 3 个处理中的 1 个：1）对照（基础日粮中含硒量为 0.11 mg/kg DM），2）基础日粮 + 0.5 mg 补充硒/kg DM (SY-0.5) )，以及 3) 基础饮食 + 5 mg 补充硒/kg DM (SY-5)。硒以硒酵母的形式补充。该试验包括1周的预试验期和8周的实验期。添加SY-5后，乳汁体细胞评分降低（ P <0.05），但其他性能参数未受影响（ P >0.05）。随着硒酵母添加量的增加，血清硒浓度升高（ P < 0.05），但血液生化指标治疗效果较差。补充硒酵母提高了奶牛的抗氧化能力，表现为血清谷胱甘肽过氧化物酶活性增加（ P <0.05）和总抗氧化能力（ P =0.08），丙二醛浓度降低（ P <0.05）。牛奶总硒浓度随硒剂量的增加而增加（ P < 0.05）。此外，硒代蛋氨酸浓度随着硒剂量的增加而增加，从对照组的 13.0 ± 0.7 μg/kg 增加到 SY-0.5 奶牛的 33.1 ± 2.1 μg/kg 和 SY-5 奶牛的 530.4 ± 17.5 μg/kg（ P < 0.05）。同样，硒代胱氨酸浓度从对照组的 15.6 ± 0.9 μg/kg 和 SY-0.5 的 18.9 ± 1.1 μg/kg 增加到 SY-5 奶牛的 22.2 ± 1.5 μg/kg（ P < 0.05）。总之，硒酵母是生产富硒牛奶的良好有机硒源，其硒种类增加，包括硒代蛋氨酸和硒代胱氨酸。 当在奶牛日粮中添加高剂量硒酵母时，结果可以提供有关牛奶硒种类的有用信息。