Valldecabres A, Lopes R B, Lago A, Blanc C, Silva-Del-Río N
Veterinary Medicine Teaching and Research Center, University of California, Davis, Tulare 93274; Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616.
DairyExperts Inc., Tulare, CA 93274.
J Dairy Sci. 2022 Jan;105(1):595-608. doi: 10.3168/jds.2021-20590. Epub 2021 Oct 14.
The effects of postpartum milking strategy on plasma mineral concentrations, blood β-hydroxybutyrate (BHB) concentration, and colostrum, transition milk, and first monthly test milk yield and composition were evaluated in 90 multiparous Jersey and Jersey × Holstein crossbreed cows from a commercial farm. Before first postpartum milking, cows were randomly assigned to the following milking strategies, implemented during the first 2 d postpartum: twice-a-day milking (M2, standard industry practice, milking every 12 h; n = 22), once-a-day milking (M1, milking every 24 h; n = 24), restricted milking (MR, 3-L milking every 12 h; n = 21), and delayed milking (MD, no milking for the first 24 h, and milking every 12 h afterward; n = 23). Blood samples for total plasma Ca, P, and Mg determination were collected from enrollment every 4 h up to 48 h, and at 3 d in milk. Blood BHB concentration was determined at 3 and 11 d in milk. Colostrum and transition milk yields were recorded, and samples were collected at each study milking for IgG and somatic cell count (SCC) determinations. Information for first monthly test milk yield and composition was obtained from the Dairy Herd Improvement Association. Statistical analyses were conducted using generalized multiple linear and Poisson regressions with Dunnett adjustment and M2 as reference group for mean comparisons. Overall, plasma Ca concentration within 48 h after enrollment was higher for MD (2.17 mmol/L), tended to be higher for MR (2.15 mmol/L), and was similar for M1 (2.09 mmol/L) compared with M2 cows (2.06 mmol/L). No statistically significant differences compared with M2 cows were observed for plasma P and Mg concentrations. Colostrum and transition milk and total Ca harvested within 48 h after enrollment were lower for M1, MR, and MD compared with M2 cows. The MD strategy prevented harvesting colostrum with >50 g of IgG/L. No statistically significant effects were detected on plasma mineral concentrations at 3 DIM, blood BHB concentration, colostrum and transition milk SCC within 48 h after enrollment, or milk yield, energy-corrected milk yield, and SCC at first monthly test. Our results suggest that postpartum plasma Ca concentration may be influenced by postpartum milking strategy, without interfering with future milk yield and udder health. Further studies should evaluate whether the proposed milking strategies in early postpartum affect production, reproduction, or health.
在一家商业农场的90头经产泽西牛和泽西×荷斯坦杂交奶牛中，评估了产后挤奶策略对血浆矿物质浓度、血液β-羟基丁酸（BHB）浓度、初乳、过渡乳以及首次月度检测乳产量和成分的影响。在首次产后挤奶前，将奶牛随机分配到以下产后前2天实施的挤奶策略中：一天两次挤奶（M2，行业标准做法，每12小时挤奶一次；n = 22）、一天一次挤奶（M1，每24小时挤奶一次；n = 24）、限量挤奶（MR，每12小时挤奶3升；n = 21）和延迟挤奶（MD，前24小时不挤奶，之后每12小时挤奶一次；n = 23）。从入组开始，每4小时采集一次血样用于测定血浆总钙、磷和镁，直至48小时，并在产奶3天时采集。在产奶3天和11天时测定血液BHB浓度。记录初乳和过渡乳产量，并在每次研究挤奶时采集样本用于测定免疫球蛋白G（IgG）和体细胞计数（SCC）。首次月度检测乳产量和成分的信息来自奶牛群改良协会。使用广义多元线性和泊松回归进行统计分析，并采用Dunnett校正，以M2作为均值比较的参照组。总体而言，与M2组奶牛（2.06 mmol/L）相比，MD组（2.17 mmol/L）入组后48小时内的血浆钙浓度更高，MR组（2.15 mmol/L）趋于更高，M1组（2.09 mmol/L）相似。与M2组奶牛相比，血浆磷和镁浓度未观察到统计学上的显著差异。与M2组奶牛相比，M1组、MR组和MD组入组后48小时内的初乳、过渡乳以及总钙收获量更低。MD策略可防止收获IgG含量>50 g/L的初乳。在产奶3天时的血浆矿物质浓度、入组后48小时内的血液BHB浓度、初乳和过渡乳SCC或首次月度检测时的产奶量、能量校正产奶量和SCC方面，未检测到统计学上的显著影响。我们的结果表明，产后挤奶策略可能会影响产后血浆钙浓度，而不会干扰未来的产奶量和乳房健康。进一步的研究应评估产后早期提出的挤奶策略是否会影响生产、繁殖或健康。
