van Hoeij R J, Dijkstra J, Bruckmaier R M, Gross J J, Lam T J G M, Remmelink G J, Kemp B, van Knegsel A T M
Adaptation Physiology Group, Department of Animal Sciences, Wageningen University and Research, PO Box 338, 6700 AH, Wageningen, the Netherlands.
Animal Nutrition Group, Department of Animal Sciences, Wageningen University and Research, PO Box 338, 6700 AH, Wageningen, the Netherlands.
J Dairy Sci. 2017 Jul;100(7):5863-5879. doi: 10.3168/jds.2016-11703. Epub 2017 Apr 27.
Shortening or omitting the dry period (DP) improves energy balance (EB) in early lactation because of a reduction in milk yield. Lower milk yield results in lower energy demands and requires less energy intake. The aim of this study was to evaluate the effects of DP length and concentrate level postpartum on milk yield, feed intake, EB, and plasma metabolites between wk -4 and 7 relative to calving of cows of second parity or higher. Holstein-Friesian dairy cows (n = 123) were assigned randomly to 1 of 2 DP lengths: 0-d DP (n = 81) or 30-d DP (n = 42). Prepartum, cows with a 0-d DP received a lactation ration based on grass silage and corn silage (6.4 MJ of net energy for lactation/kg of dry matter). Cows with a 30-d DP received a dry cow ration based on grass silage, corn silage, and straw (5.4 MJ of net energy for lactation/kg of dry matter). Postpartum, all cows received the same basal lactation ration as provided to lactating cows prepartum. Cows with a 0-d DP were fed a low level of concentrate up to 6.7 kg/d based on the requirement for their expected milk yield (0-d DP-L; n = 40) or the standard level of concentrate up to 8.5 kg/d (0-d DP-S; n = 41), which was equal to the concentrate level for cows with a 30-d DP (30-d DP-S; n = 42) based on requirements for their expected milk yield. Prepartum dry matter intake, concentrate intake, basal ration intake, energy intake, plasma β-hydroxybutyrate (BHB), and insulin concentrations were greater and plasma free fatty acids (FFA) and glucose concentrations were lower, but EB was not different in cows with a 0-d DP compared with cows with a 30-d DP. During wk 1 to 3 postpartum, milk fat yield and plasma BHB concentration were lower and dry matter intake and concentrate intake were greater in cows with a 0-d DP compared with cows with a 30-d DP. During wk 4 to 7 postpartum, fat- and protein-corrected milk (FPCM), lactose content, and lactose and fat yield were lower in 0-d DP-L or 0-d DP-S cows compared with 30-d DP-S cows. Basal ration intake, EB, body weight, plasma glucose, and insulin and insulin-like growth factor-1 concentrations were greater and plasma FFA and BHB concentrations were lower in 0-d DP-L and 0-d DP-S cows compared with 30-d DP-S cows. Concentrate and energy intake were lower in 0-d DP-L cows than in 0-d DP-S or 30-d DP-S cows. Milk yield and concentrations of plasma metabolites did not differ in wk 4 to 7, although EB was lower in wk 6 and 7 postpartum in 0-d DP-L cows than in 0-d DP-S cows. In conclusion, a 0-d DP reduced milk yield and improved EB and metabolic status of cows in early lactation compared with a 30-d DP. Reducing the postpartum level of concentrate of cows with a 0-d DP did not affect fat- and protein-corrected milk yield or plasma FFA and BHB concentrations in early lactation but did reduce EB in wk 6 and 7 postpartum.
缩短或省略干奶期(DP)可改善泌乳早期的能量平衡(EB),因为产奶量会降低。较低的产奶量导致能量需求降低,所需的能量摄入量也减少。本研究的目的是评估第二胎及以上母牛产犊后第-4周至第7周期间,干奶期长度和产后精料水平对产奶量、采食量、能量平衡和血浆代谢物的影响。将123头荷斯坦-弗里生奶牛随机分为2种干奶期长度中的1种:0天干奶期(n = 81)或30天干奶期(n = 42)。产前,0天干奶期的奶牛采食基于青贮牧草和玉米青贮的泌乳日粮(每千克干物质含6.4兆焦泌乳净能)。30天干奶期的奶牛采食基于青贮牧草、玉米青贮和稻草的干奶牛日粮(每千克干物质含5.4兆焦泌乳净能)。产后,所有奶牛采食与产前泌乳奶牛相同的基础泌乳日粮。0天干奶期的奶牛根据预期产奶量的需求,饲喂低水平精料,最高达6.7千克/天(0天干奶期-低精料组;n = 40)或标准水平精料,最高达8.5千克/天(0天干奶期-标准精料组;n = 41),后者等于30天干奶期奶牛(30天干奶期-标准精料组;n = 42)根据预期产奶量需求的精料水平。与30天干奶期的奶牛相比,0天干奶期的奶牛产前干物质采食量、精料采食量、基础日粮采食量、能量摄入量、血浆β-羟基丁酸(BHB)和胰岛素浓度更高,而血浆游离脂肪酸(FFA)和葡萄糖浓度更低,但能量平衡无差异。产后第1至3周,与30天干奶期的奶牛相比,0天干奶期的奶牛乳脂产量和血浆BHB浓度更低,干物质采食量和精料采食量更高。产后第4至7周,与30天干奶期-标准精料组奶牛相比,0天干奶期-低精料组或0天干奶期-标准精料组奶牛的脂肪和蛋白质校正乳(FPCM)、乳糖含量以及乳糖和脂肪产量更低。与30天干奶期-标准精料组奶牛相比,0天干奶期-低精料组和0天干奶期-标准精料组奶牛的基础日粮采食量、能量平衡、体重、血浆葡萄糖、胰岛素和胰岛素样生长因子-1浓度更高,而血浆FFA和BHB浓度更低。0天干奶期-低精料组奶牛的精料和能量摄入量低于0天干奶期-标准精料组或30天干奶期-标准精料组奶牛。尽管产后第6周和第7周0天干奶期-低精料组奶牛的能量平衡低于0天干奶期-标准精料组奶牛,但第4至7周的产奶量和血浆代谢物浓度无差异。总之,与30天干奶期相比,0天干奶期降低了产奶量,改善了泌乳早期奶牛的能量平衡和代谢状态。降低0天干奶期奶牛产后精料水平对泌乳早期的脂肪和蛋白质校正乳产量或血浆FFA和BHB浓度无影响,但在产后第6周和第7周确实降低了能量平衡。