Chen J, Kok A, Remmelink G J, Gross J J, Bruckmaier R M, Kemp B, van Knegsel A T M
Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands; Animal Production Systems Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
J Dairy Sci. 2016 Nov;99(11):9287-9299. doi: 10.3168/jds.2016-11253. Epub 2016 Aug 24.
This study evaluated the effects of dry period (DP) length and dietary energy source on lactation curve characteristics over 2 subsequent lactations. It also evaluated the relationships of energy balance or metabolic status in early lactation with lactation curve characteristics in dairy cows. Holstein-Friesian dairy cows (n=167) were assigned randomly to 1 of 3 DP lengths (0-, 30-, or 60-d) and 1 of 2 early-lactation diets (glucogenic or lipogenic) for 2 subsequent lactations. In the second lactation following DP length treatments, 19 cows in the 0-d DP group were assigned to a 0→67-d DP group (actual days dry: 67±8d). Cows were allocated to this new group when they had a milk yield of <4kg/d at least 30d before their expected calving date. Fat- and protein-corrected milk (FPCM) was calculated weekly per cow in both lactations. Blood samples were taken weekly from calving to wk 4 after calving. A Wilmink lactation curve for each lactation was modeled based on FPCM yield records from calving through 305 DIM. During the first lactation following DP length treatments, cows with a 0- or 30-d DP had lower peak yield, later time of peak yield, and lower FPCM than cows with a 60-d DP. In the second lactation following DP length treatments, cows with a 0- or 30-d DP had lower peak yield than cows with a 60-d DP. In both lactations, lactation persistency was not affected by DP length and none of the lactation curve characteristics were affected by diet. In parity >2 cows, total FPCM yield and average daily FPCM yield throughout 2 lactations did not differ among DP lengths. In addition, average energy balance in the first 4wk after calving had a negative relationship with peak yield and FPCM, and a positive relationship with lactation persistency. Average plasma concentrations of free fatty acids and β-hydroxybutyrate had a positive relationship with peak yield and FPCM, and a negative relationship with lactation persistency. Shortening or omitting the DP affected lactation curve characteristics in both lactations after implementation of DP length treatments but did not compromise FPCM yield compared with a conventional DP of 60d in parity >2 cows. Severe negative energy balance and poor metabolic status were related to greater peak yield, FPCM, and lower lactation persistency.
本研究评估了干奶期（DP）长度和日粮能量来源对后续两胎泌乳曲线特征的影响。同时还评估了奶牛泌乳早期能量平衡或代谢状态与泌乳曲线特征之间的关系。将167头荷斯坦 - 弗里生奶牛随机分为3种干奶期长度（0天、30天或60天）中的1种和2种泌乳早期日粮（生糖日粮或生脂日粮）中的1种，进行后续两胎试验。在干奶期长度处理后的第二胎中，将0天干奶期组的19头奶牛分配到0→67天干奶期组（实际干奶天数：67±8天）。当奶牛在预期产犊日期前至少30天产奶量<4kg/d时，将其分配到这个新组。在两胎中每周计算每头奶牛的脂肪和蛋白质校正乳（FPCM）。从产犊到产后第4周每周采集血样。根据从产犊到305天泌乳天数（DIM）的FPCM产量记录，对每一胎建立Wilmink泌乳曲线模型。在干奶期长度处理后的第一胎中，0天或30天干奶期的奶牛比60天干奶期的奶牛峰值产量更低、峰值出现时间更晚且FPCM更低。在干奶期长度处理后的第二胎中，0天或30天干奶期的奶牛比60天干奶期的奶牛峰值产量更低。在两胎中，泌乳持久性不受干奶期长度影响，且日粮对任何泌乳曲线特征均无影响。在胎次>2的奶牛中，两胎期间的总FPCM产量和平均每日FPCM产量在不同干奶期长度之间没有差异。此外，产后前4周的平均能量平衡与峰值产量和FPCM呈负相关，与泌乳持久性呈正相关。游离脂肪酸和β - 羟基丁酸的平均血浆浓度与峰值产量和FPCM呈正相关，与泌乳持久性呈负相关。缩短或省略干奶期在实施干奶期长度处理后的两胎中均影响泌乳曲线特征，但与胎次>2的奶牛采用60天常规干奶期相比，并未影响FPCM产量。严重的负能量平衡和不良的代谢状态与更高的峰值产量、FPCM以及更低的泌乳持久性有关。
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