Department of Veterinary Preventive Medicine, The Ohio State University, Columbus 43210.
Department of Animal Sciences, The Ohio State University, Wooster 44691.
J Dairy Sci. 2019 Apr;102(4):3362-3375. doi: 10.3168/jds.2018-15387. Epub 2019 Feb 22.
The objectives were to evaluate the associations of lying time (LT) during the first 14 d in milk (DIM) with milk yield, cyclicity (CYC), culling within 60 DIM (CULL), and reproductive performance of lactating dairy cows. A total of 1,052 Holstein cattle (401 nulliparous heifers and 651 parous cows) from 3 commercial dairy farms had electronic data loggers (IceQube, IceRobotics, Edinburgh, UK) placed on a hind leg 14 ± 3 d before the expected parturition date and removed at 14 ± 3 DIM to assess their LT. Serum concentrations of β-hydroxybutyrate were determined at 7 ± 3 and 14 ± 3 DIM. Cases of retained placenta, metritis, mastitis, pneumonia, and digestive disorders within 30 DIM were recorded and lactating cows were categorized into 1 of 4 groups: (1) nondiseased (ND, n = 613; cows without ketosis or any other diagnosed health condition); (2) cows with only ketosis (KET, n = 152); (3) sick cows experiencing ≥1 health conditions but without ketosis (SICK, n = 198); or (4) cows with ketosis plus ≥1 health condition (KET+, n = 61). Ultrasound was performed at 28 ± 3 and 42 ± 3 DIM to assess ovarian cyclicity (presence or absence of corpus luteum). Milk yield at first Dairy Herd Improvement Association test was not associated with LT during the first 14 DIM, but it was negatively correlated with the coefficient of variation of LT during the first 14 DIM. Lactating dairy cows experiencing KET+ had the lowest milk yield compared with ND, regardless of parity. Parity, health status, and season were significantly associated with CYC and CULL. Lying time had a significantly linear association with the risk of being culled: for every 1-h increment of LT during 0 to 14 DIM, the risk of culling within 60 DIM increased by 1 percentage point. Lying time had a negative quadratic association with cyclicity at 42 DIM. Multiparous cows with a LT of 9 to 13 h/d had a significantly greater probability of pregnancy up to 300 DIM compared with cows with a LT >13 h/d. Regardless of parity, KET+ cows had significantly higher proportion of culling within 60 DIM and decreased probability of pregnancy up to 300 DIM compared with ND cows. These findings suggest that there is an optimum daily LT range for early postpartum cows housed in freestall barns, different from that reported for mid-lactation cows, with the potential for improved survival, health, and the overall performance (milk yield and reproduction).
本研究旨在评估奶牛产后第 14 天（DIM）内的躺卧时间（LT）与产奶量、周期性（CYC）、产后 60 天内淘汰（CULL）和泌乳奶牛繁殖性能的关系。共有 3 个商业奶牛场的 1052 头荷斯坦奶牛（401 头初产奶牛和 651 头经产奶牛）在预计分娩日期前 14 ± 3 天在后腿上放置电子数据记录器（IceQube、IceRobotics、Edinburgh、UK），并在产后 14 ± 3 DIM 时取下，以评估其 LT。在产后第 7 ± 3 和 14 ± 3 DIM 时测定血清β-羟丁酸浓度。产后 30 天内记录了胎衣不下、子宫内膜炎、乳腺炎、肺炎和消化障碍病例，并将泌乳奶牛分为 4 组之一：（1）非疾病（ND，无酮病或任何其他诊断性健康状况的奶牛；（2）只有酮病（KET）的奶牛；（3）患有≥1 种健康状况但无酮病（SICK）的奶牛；或（4）有酮病和≥1 种健康状况的奶牛（KET+）。在产后第 28 ± 3 和 42 ± 3 DIM 时进行超声检查以评估卵巢周期性（黄体存在或不存在）。首次奶牛群改良协会（DHI）测试的产奶量与产后第 14 天的 LT 无关，但与产后第 14 天 LT 的变异系数呈负相关。与 ND 相比，患有 KET+的泌乳奶牛的产奶量最低，无论胎次如何。胎次、健康状况和季节与 CYC 和 CULL 显著相关。躺卧时间与淘汰风险呈显著线性关系：产后第 0 至 14 天内 LT 每增加 1 小时，产后 60 天内淘汰的风险增加 1 个百分点。躺卧时间与产后第 42 天的周期性呈负二次关系。产次为 9 至 13 小时/d 的多产奶牛与产次>13 小时/d 的奶牛相比，至 300 天的妊娠概率显著增加。无论胎次如何，KET+奶牛产后 60 天内淘汰的比例显著较高，至 300 天的妊娠概率显著降低。这些发现表明，与中泌乳奶牛报道的范围不同，产后期奶牛在厩舍中存在一个最佳的每日 LT 范围，这可能会提高奶牛的生存、健康和整体性能（产奶量和繁殖性能）。
