van Knegsel A T M, van den Brand H, Dijkstra J, Kemp B
Adaptation Physiology Group, Wageningen Institute of Animal Sciences, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
Theriogenology. 2007 Sep 1;68 Suppl 1:S274-80. doi: 10.1016/j.theriogenology.2007.04.043. Epub 2007 May 29.
This paper summarizes three recent studies by the same authors with the objective to study the effect of dietary energy source on the energy balance (EB) and risk for metabolic and reproductive disorders in dairy cows in early lactation. The first study, a literature survey, illustrated that feeding extra glucogenic nutrients relative to lipogenic nutrients, decreased milk fat and seems to decrease plasma non-esterified fatty acid (NEFA) and beta-hydroxybutyrate (BHBA) concentration. However studies are scarce and mostly confound the effect of energy source with level of energy intake, compromising eventual effects on EB and fertility. Therefore, in the second study, 16 dairy cows were either fed a glucogenic or a lipogenic diet (isocaloric) and EB was determined in climate-controlled respiration chambers from week 2 until 9 of lactation. Glucogenic diet decreased milk fat yield and milk energy and tended to decrease body fat mobilization compared with lipogenic diet. The objective of the third study was to study the effect of dietary energy source on EB, metabolites and reproduction variables. Dairy cows (n=111) were fed glucogenic, lipogenic or mixed diet from week 3 until week 9 relative to calving. Multiparous cows fed glucogenic diet had lower milk fat yield, higher calculated EB, and lower plasma NEFA, BHBA and liver triacylglyceride concentration and tended to have fewer days to first postpartum ovulation. In conclusion, increasing the glucogenic nutrient availability improved the EB and had potential to reduce the risk for metabolic disorders and to improve reproductive performance in dairy cows.
本文总结了同一批作者最近的三项研究，目的是研究日粮能量来源对泌乳早期奶牛能量平衡（EB）以及代谢和繁殖障碍风险的影响。第一项研究是一项文献调查，结果表明，相对于生脂营养素，饲喂额外的生糖营养素会降低乳脂，并且似乎会降低血浆非酯化脂肪酸（NEFA）和β-羟基丁酸（BHBA）的浓度。然而，相关研究较少，并且大多将能量来源的影响与能量摄入量水平混淆，从而影响了最终对能量平衡和繁殖力的影响。因此，在第二项研究中，16头奶牛被分别饲喂生糖或生脂日粮（等热量），并在气候控制的呼吸室内测定从泌乳第2周到第9周的能量平衡。与生脂日粮相比，生糖日粮降低了乳脂产量和乳能量，并倾向于减少体脂动员。第三项研究的目的是研究日粮能量来源对能量平衡、代谢物和繁殖变量的影响。从产犊后第3周到第9周，给111头奶牛饲喂生糖、生脂或混合日粮。饲喂生糖日粮的经产奶牛乳脂产量较低，计算出的能量平衡较高，血浆NEFA、BHBA和肝脏甘油三酯浓度较低，并且首次产后排卵的天数往往较少。总之，提高生糖营养素的供应量可改善能量平衡，并有可能降低奶牛代谢紊乱的风险，提高繁殖性能。
