Adaptation Physiology Group, Wageningen University and Research, NL-6700 AH Wageningen, the Netherlands.
Wageningen Livestock Research, Wageningen University and Research, NL-6700 AH Wageningen, the Netherlands.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skad194.
An extended calving interval (CInt) by extending the voluntary waiting period (VWP) could be associated with altered metabolism in dairy cows. The aim of this study was first to evaluate the effects of VWP on metabolism and body condition during the first 305 d after the first calving in the experiment (calving 1), around the end of the VWP, and during pregnancy (280 d before calving 2). Second, the effects of the VWP on metabolism were determined from 2 wk before until 6 wk after calving 2. Third, individual cow characteristics were used to predict milk production and body condition of cows after different VWP. Holstein-Friesian cows (N = 154, 41 primiparous [PP], 113 multiparous [MP]) were blocked for parity, milk production, and lactation persistency, randomly assigned to a VWP of 50, 125, or 200 d (VWP50, VWP125, or VWP200) and followed from calving 1 until 6 wk after calving 2. In the first 6 wk after calving 1 and from 2 wk before until 6 wk after calving 2, weekly plasma samples were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate, glucose, insulin, and insulin-like growth factor 1 (IGF-1). From wk 7 after calving 1 until 2 wk before calving 2, insulin and IGF-1 were analyzed every 2 wk. Fat- and protein-corrected milk (FPCM) and body weight (BW) gain were measured weekly. Cows were divided in two parity classes based on calving 1 (PP and MP) and remained in these classes after calving 2. During pregnancy, MP cows in VWP200 had greater plasma insulin and IGF-1 concentration and lower FPCM compared with MP cows in VWP125 (insulin: 18.5 vs. 13.9 µU/mL, CI 13.0-19.7, P < 0.01; IGF-1: 198.5 vs. 175.3 ng/mL ± 5.3, P = 0.04; FPCM: 22.6 vs. 30.0 kg/d ± 0.8, P < 0.01) or VWP50 (insulin: 15.8 µU/mL, P < 0.01; IGF-1: 178.2 ng/mL, P < 0.01; FPCM: 26.6 kg/d, P < 0.01) and had a greater daily BW gain compared with cows in VWP50 (3.6 vs. 2.5 kg/d ± 0.2; P < 0.01). After calving 2, MP cows in VWP200 had greater plasma NEFA concentration (0.41 mmol/liter) compared with MP cows in VWP125 (0.30 mmol/liter, P = 0.04) or VWP50 (0.26 mmol/liter, P < 0.01). For PP cows, the VWP did not affect FPCM or body condition during the first lactation in the experiment, or metabolism after calving 2. Independent of the VWP, higher milk production and lower body condition before insemination were associated with higher milk production and lower body condition at the end of the lactation. Variation in these characteristics among cows could call for an individual approach for an extended VWP.
延长自愿等待期（VWP）的产犊间隔（CInt）可能与奶牛代谢发生变化有关。本研究的目的首先是评估 VWP 对首次产犊后 305 天（产犊 1 ）、VWP 结束时和妊娠期间（产犊 2 前 280 天）奶牛代谢和体况的影响。其次，从产犊 2 前 2 周开始到产犊后 6 周，确定 VWP 对代谢的影响。第三，利用个体牛的特征来预测不同 VWP 下奶牛的产奶量和体况。将荷斯坦弗里生奶牛（N = 154，41 头初产 [PP]，113 头经产 [MP]）按胎次、产奶量和泌乳持久性进行分组，随机分配到 50、125 或 200 d 的 VWP（VWP50、VWP125 或 VWP200）中，并从产犊 1 一直跟踪到产犊 2 后 6 周。在产犊后 1 的前 6 周和产犊前 2 周至产犊后 6 周期间，每周分析血浆样本中非酯化脂肪酸（NEFA）、β-羟丁酸、葡萄糖、胰岛素和胰岛素样生长因子 1（IGF-1）。从产犊后 1 的第 7 周直到产犊前 2 周，每 2 周分析胰岛素和 IGF-1。每周测量产奶量和体重（BW）。根据产犊 1 （PP 和 MP）将奶牛分为两个胎次类别，在产犊 2 后仍保留在这些类别中。在妊娠期间，VWP200 下的 MP 奶牛的血浆胰岛素和 IGF-1 浓度更高，FPCM 更低，与 VWP125（胰岛素：18.5 vs. 13.9 µU/mL，CI 13.0-19.7，P < 0.01；IGF-1：198.5 vs. 175.3 ng/mL ± 5.3，P = 0.04；FPCM：22.6 vs. 30.0 kg/d ± 0.8，P < 0.01）或 VWP50（胰岛素：15.8 µU/mL，P < 0.01；IGF-1：178.2 ng/mL，P < 0.01；FPCM：26.6 kg/d，P < 0.01）相比，VWP50 的奶牛的 BW 日增重更大（3.6 比 2.5 kg/d ± 0.2；P < 0.01）。在产犊 2 后，VWP200 下的 MP 奶牛的血浆 NEFA 浓度（0.41 mmol/liter）高于 VWP125（0.30 mmol/liter，P = 0.04）或 VWP50（0.26 mmol/liter，P < 0.01）下的奶牛。对于 PP 奶牛，VWP 在实验的首次泌乳期间以及产犊后 2 时的产奶量和体况或代谢均不受影响。独立于 VWP，发情前产奶量较高和体况较低与泌乳期末产奶量较高和体况较低相关。奶牛这些特征的变化可能需要采用个性化方法来延长 VWP。
