Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
J Dairy Sci. 2020 Jan;103(1):954-964. doi: 10.3168/jds.2019-17051. Epub 2019 Oct 16.
The aim of this observational study was to identify the influence of key nongenetic factors such as month of kidding, parity, and litter size on milk yield and composition of Australian dairy goats throughout lactation. The study was conducted over 4 consecutive kidding seasons from June 2016 to March 2017. Data from 940 lactations of Saanen goats from a commercial herd were used to observe the effects of month of kidding, parity number, and litter size on total milk yield (L/goat) in early lactation (kidding to 90 d in milk; DIM), mid lactation (91-180 DIM), and late lactation (181-270 DIM), cumulative milk yield (from kidding to 270 DIM; CMY), average lactation length, proportion (%) of does reaching their target lactation length (270 DIM), somatic cell count (SCC), and percentages of milk fat and protein in early lactation. The mean herd responses throughout the entire study were as follows: CMY = 519 L/goat; lactation length = 233 d, with 70% of does reaching 270 DIM; milk fat = 4.2%; milk protein = 2.9%; and SCC = 6.2 × 10 cells/mL. Average milk production peaked in February and was lowest in June (2.4 vs. 1.8 L/goat per day, respectively). Milk yield was affected by month of kidding, parity number, and litter size in all phases of lactation. November kidders had the greatest CMY, and March kidders had the lowest CMY. March kidders had the shortest lactation length and the lowest proportion of does reaching 270 DIM. June kidders had the longest lactation length, whereas September kidders had the highest proportion of does reaching 270 DIM. Maximum milk yield was attained in third parity. Goats in fourth or greater parity had the shortest lactation length, the lowest proportion of does reaching 270 DIM, and the highest SCC. Goats delivering single kids had lower CMY, lower SCC, and higher percentages of fat and protein than does delivering multiple kids. Our findings indicate that milk yield was primarily influenced by month of kidding, and the effects of month of kidding on milk yield were accentuated during mid lactation. However, the effects of month of kidding on milk yield varied significantly among parities.
本观察性研究旨在确定关键非遗传因素（如产羔月份、胎次和产羔数）对澳大利亚奶山羊泌乳期内产奶量和乳汁成分的影响。该研究于 2016 年 6 月至 2017 年 3 月连续进行了 4 个产羔季。使用来自一个商业羊群的 940 次泌乳数据，观察产羔月份、胎次数和产羔数对早期泌乳（产羔至泌乳 90 天；DIM）、中期泌乳（91-180 DIM）和晚期泌乳（181-270 DIM）、总产奶量（产羔至 270 DIM；CMY）、平均泌乳长度、达到目标泌乳长度（270 DIM）的母羊比例（%）、体细胞计数（SCC）以及早期泌乳中乳脂和乳蛋白的百分比的影响。整个研究期间的平均群体反应如下：CMY=519 L/羊；泌乳期长度=233 d，70%的母羊达到 270 DIM；乳脂=4.2%；乳蛋白=2.9%；SCC=6.2×10 个细胞/ml。平均产奶量在 2 月最高，6 月最低（分别为 2.4 和 1.8 L/羊/天）。产羔月份、胎次数和产羔数在泌乳各阶段均影响产奶量。11 月产羔的 CMY 最大，3 月产羔的 CMY 最小。3 月产羔的泌乳期最短，达到 270 DIM 的母羊比例最低。6 月产羔的泌乳期最长，而 9 月产羔的达到 270 DIM 的母羊比例最高。第三胎次的最大产奶量。第四胎次或更高胎次的羊泌乳期最短，达到 270 DIM 的母羊比例最低，SCC 最高。产单羔的羊的 CMY、SCC 较低，乳脂和乳蛋白百分比较高。我们的研究结果表明，产奶量主要受产羔月份的影响，产羔月份对产奶量的影响在泌乳中期更为明显。然而，产羔月份对产奶量的影响在胎次间有显著差异。
