High energy intake in the dry period has reportedly had adverse effects on mobilization of body reserves, DMI, and productivity of dairy cows. We investigated whether grass silage (GS) fed ad libitum (HEI; 141% of daily metabolizable energy requirements) in an 8-wk dry period affects metabolic adaptation—specifically, peripheral insulin resistance—compared with a total mixed ration consisting of GS, wheat straw, and rapeseed meal (55/40/5%; CEI; 108% of metabolizable energy/d) fed ad libitum. Multiparous Ayrshire dairy cows (n = 16) were used in a randomized complete block design until 8 wk after parturition. Commercial concentrates were fed 1 and 2 kg/d during the last 10 to 6 and 5 to 0 d before the expected calving date, respectively. Postpartum, a similar lactation diet with ad libitum access to GS and increasing concentrate allowance (maximum of 16 kg/d) was offered to all. The HEI group gained more body weight and had higher plasma insulin, glucose, and β-hydroxybutyrate concentrations than the CEI group prepartum. Postpartal plasma glucose tended to be higher and milk yield was greater from wk 5 onward for HEI compared with CEI cows. Intravenous glucose tolerance test (IVGTT) was performed at −13 ± 5 d and 9 ± 1 d relative to calving. The HEI cows had greater insulin response to glucose load and smaller area under the response curve for glucose than CEI cows in prepartal IVGTT. Thus, compensatory insulin secretion adapted to changes in insulin sensitivity of the peripheral tissues, preserving glucose tolerance of HEI cows. Higher insulin levels were needed in HEI cows than in CEI cows to elicit a similar decrement of nonesterified fatty acid concentration in prepartal IVGTT, suggesting reduced inhibition of lipolysis by insulin in HEI cows before parturition. In conclusion, high energy intake of moderately digestible GS with low concentrate feeding in the close-up dry period did not have adverse effects on metabolic adaptation, insulin sensitivity, and body mobilization after parturition. Instead, this feeding regimen was more beneficial to early-lactation performance than GS-based total mixed ration diluted with wheat straw.

据报道，干旱时期的高能量摄入对奶牛的身体储备，DMI和生产力产生了不利影响。我们调查了在8周干旱期间随意饲喂的青贮青贮饲料（GS）（HEI；每日代谢能量需求的141％）是否会影响代谢适应性-特别是外周胰岛素抵抗-与由GS和小麦组成的总混合日粮相比随意喂食稻草和菜籽粉（55/40/5％； CEI； 108％的可代谢能量/天）。在分娩后8周前，将多头Ayrshire奶牛（n = 16）用于随机的完全区组设计。在预期产犊日期之前的最后10到6天和5到0 d内分别喂入1和2 kg / d的商业浓缩物。产后 向所有人提供了类似的泌乳饮食，可随意获得GS和增加的浓缩物津贴（最高16公斤/天）。与CEI组相比，HEI组体重增加，血浆胰岛素，葡萄糖和β-羟基丁酸酯的浓度更高。与CEI奶牛相比，HEI从5周起产后血浆葡萄糖趋于更高，产奶量更高。相对于产犊，静脉葡萄糖耐量试验（IVGTT）在-13±5 d和9±1 d进行。与产前IVGTT中的CEI奶牛相比，HEI奶牛对葡萄糖负荷的胰岛素反应更大，并且在葡萄糖的反应曲线下面积较小。因此，代偿性胰岛素分泌适应于周围组织的胰岛素敏感性变化，从而保持了HEI牛的葡萄糖耐量。HEI奶牛需要比CEI奶牛更高的胰岛素水平，才能引起分娩前IVGTT中非酯化脂肪酸浓度的类似下降，这表明分娩前HEI奶牛胰岛素对脂解的抑制作用降低。总之，在接近干燥的高摄入量的高消化率的中等消化率的GS和低浓缩饲料对分娩后的代谢适应，胰岛素敏感性和身体动员没有不利影响。取而代之的是，这种饲喂方案比用小麦秸秆稀释的基于GS的总混合日粮更有利于早期泌乳性能。在接近干燥的阶段，高能量摄入的中等消化率的GS和低浓缩饲料的摄入对分娩后的代谢适应，胰岛素敏感性和身体动员没有不利影响。取而代之的是，这种饲喂方案比用小麦秸秆稀释的基于GS的总混合日粮更有利于早期泌乳性能。在接近干燥的阶段，高能量摄入的中等消化率的GS和低浓缩饲料的摄入对分娩后的代谢适应，胰岛素敏感性和身体动员没有不利影响。取而代之的是，这种饲喂方案比用小麦秸秆稀释的基于GS的总混合日粮更有利于早期泌乳性能。