Impact of changes in organic nutrient metabolism on feeding the transition dairy cow.
Impact of changes in organic nutrient metabolism on feeding the transition dairy cow.
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DOI：
10.2527/1995.7392820x
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发表时间：
1995-09
影响因子：
3.3
通讯作者：
R. Grummer
中科院分区：
文献类型：
--
作者：
R. Grummer
妊娠、妊娠后期采食量减少、泌乳和分娩对产奶前3wk至产后3wk过渡期间奶牛的代谢有显著影响。血浆NEFA的增加发生在产犊前10天，可能先于采食量的减少。血浆NEFA浓度在产犊时最高，产后迅速下降。血糖浓度在过渡期内下降，但与产犊相关的一过性升高除外。在过渡期，肝糖原减少，血脂增加。在准备阶段的最后3周，采食量通常会减少30%到35%，但能量和蛋白质的负平衡并不像分娩后的一周那样严重。产前采食量与产后采食量呈正相关；因此，应在产犊前开始努力最大限度地增加采食量。过度饲养的奶牛可能更容易受到产前采食量下降的影响。在过渡期增加日粮的营养密度可能会增加采食量。在产前过渡期饲喂更多的可发酵碳水化合物可以使微生物种群适应哺乳饲料，促进瘤胃乳头的发育，增加瘤胃上皮的吸收能力，并通过向肝脏输送更多的生糖前体和提高血液胰岛素来减少脂肪分解。在过渡饮食中补充脂肪似乎并不能缓解与负能量平衡相关的健康问题。提高奶牛产前对氨基酸的吸收可能会改善哺乳性能和健康，尽管其作用机制尚未确定。
Pregnancy, decreased feed intake during late gestation, lactogenesis, and parturition have dramatic effects on metabolism in dairy cows during the transition period from 3 wk before calving to 3 wk after calving. Increases in plasma NEFA occur during the 10 d before calving and may precede the decrease in feed intake. Plasma NEFA concentrations are highest at calving and decrease rapidly after calving. Plasma glucose concentration decreases during the transition period except for a transient increase associated with calving. Hepatic glycogen is reduced and lipid is increased during the transition period. Feed intake is usually decreased 30 to 35% during the final 3 wk prepartum, but negative energy and protein balances are not as severe as during the week following parturition. Prepartum feed intake is positively correlated to postpartum feed intake; therefore, efforts to maximize feed intake should begin before calving. Overconditioned cows may be more susceptible to a prepartum decrease in feed intake. Increasing nutrient density of the diet during the transition period may enhance feed intake. Feeding more fermentable carbohydrate during the prepartum transition period may acclimate the microbial population to lactation diets, promote development of ruminal papillae, increase absorptive capacity of the rumen epithelium, and reduce lipolysis by delivering more glucogenic precursor to the liver and enhancing blood insulin. Supplementing fat to transition diets does not seem to alleviate health problems associated with negative energy balance. Enhancing amino acid absorption by the prepartum cow may improve lactation performance and health, although mechanisms of action have not been identified.