Department of Primary Industries, Future Farming Systems Research, Kyabram Centre, 120 Cooma Road, Kyabram, Victoria 3620, Australia.
J Dairy Sci. 2011 Jan;94(1):262-72. doi: 10.3168/jds.2010-3590.
Seventy multiparous Holstein-Friesian cows were fed different amounts of pasture and concentrates, or a total mixed ration (TMR), for 42 d in mid-lactation to test the hypothesis that the concentration of Se in milk would depend on the amount of Se consumed, when the Se is primarily organic in nature, regardless of the diet of the cows. Of the 70 cows, 60 grazed irrigated perennial pasture at daily allowances of either 20 or 40 kg of dry matter (DM)/cow. These cows received 1 of 3 amounts of concentrates, either 1, 3, or 6 kg of DM/cow per day of pellets, and at each level of concentrate feeding, the pellets were formulated to provide 1 of 2 quantities of Se from Se yeast, either about 16 or 32 mg of Se/d. The other 10 cows were included in 2 additional treatments where a TMR diet was supplemented with 1 kg of DM/d of pellets formulated to include 1 of the 2 quantities of supplemental Se. Total Se intakes ranged from 14.5 to 35.9 mg/d, and of this, the Se-enriched pellets provided 93, 91, and 72% of the Se for cows allocated 20 and 40 kg of pasture DM/d or the TMR, respectively. No effects of the amount of Se consumed on any milk production variable, or on somatic cell count, body weight, and body condition score, for either the pasture-fed or TMR-fed cows were found. Milk Se concentrations responded quickly to the commencement of Se supplementation, reaching 89% of steady state levels at d 5. When milk Se concentrations were at steady state (d 12 to 40), each 1mg of Se eaten increased the Se concentration of milk by 5.0 μg/kg (R(2)=0.97), and this response did not seem to be affected by the diet of the cows or their milk production. The concentration of Se in whole blood was more variable than that in milk, and took much longer to respond to change in Se status, but it was not affected by diet at any time either. For the on-farm production of Se-enriched milk, it is important to be able to predict milk Se concentration from Se input. In our study, type of diet did not affect this relationship.
70 头泌乳中期的荷斯坦弗里生奶牛被喂食不同量的牧场和浓缩物，或全混合日粮（TMR），持续 42 天，以检验以下假设：当硒主要以有机形式存在时，无论奶牛的饮食如何，牛奶中的硒浓度都将取决于所消耗的硒量。在这 70 头奶牛中，有 60 头每天以 20 或 40 公斤干物质（DM）/头的限量放牧灌溉多年生牧场。这些奶牛接受 3 种浓缩物中的 1 种，每天 1 、 3 或 6 公斤 DM/头的颗粒，并且在每个浓缩物喂养水平下，颗粒均由酵母硒提供 2 种硒量中的 1 种，每天约 16 或 32 毫克硒。其余 10 头奶牛被纳入另外 2 种处理中，其中 TMR 日粮补充了 1 公斤 DM/天的颗粒，这些颗粒中包含 2 种补充硒量中的 1 种。总硒摄入量从 14.5 到 35.9 毫克/天不等，其中，富硒颗粒为每天分配 20 和 40 公斤牧场 DM 的奶牛或 TMR 提供了 93 、 91 和 72%的硒。未发现硒摄入量对任何产奶变量、体细胞计数、体重和体况评分有任何影响，无论是牧场喂养还是 TMR 喂养的奶牛。牛奶中的硒浓度对硒补充的开始迅速做出反应，在第 5 天达到稳态水平的 89%。当牛奶中的硒浓度达到稳态（第 12 至 40 天）时，每消耗 1 毫克硒，牛奶中的硒浓度就会增加 5.0 微克/千克（R2=0.97），而且这种反应似乎不受奶牛的饮食或产奶量的影响。全血中的硒浓度比牛奶中的硒浓度变化更大，需要更长的时间才能对硒状况的变化做出反应，但在任何时候都不受饮食的影响。对于富硒牛奶的农场生产，能够从硒投入中预测牛奶中的硒浓度非常重要。在我们的研究中，饮食类型并没有影响这种关系。
