Effects of length of dry period on yields of milk fat and protein, fertility and milk somatic cell score in the subsequent lactation of dairy cows
Effects of length of dry period on yields of milk fat and protein, fertility and milk somatic cell score in the subsequent lactation of dairy cows
复制标题
干奶期长短对奶牛后续泌乳期乳脂、乳蛋白产量、受精率及乳体细胞评分的影响
DOI：
10.1017/s0022029905001597
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发表时间：
2006
影响因子：
2.1
通讯作者：
H. Norman
中科院分区：
文献类型：
--
作者：
M. Kuhn;Jana L Hutchison;H. Norman
目的是利用现代美国奶牛的数据来确定干奶天数对随后哺乳期脂肪和蛋白质产量、脂肪和蛋白质百分比、开放天数和体细胞评分的影响。 1997 年 1 月至 2003 年 12 月通过奶牛群改良协会收集的现场数据以及从动物改良计划实验室国家数据库中提取的数据用于分析。本研究使用了使用测试间隔方法根据测试日产量计算出的实际泌乳记录。分析模型包括产犊的牛群年份、产犊年份-州-月份、之前的哺乳记录、产犊年龄和干奶天数作为分类变量。在随后的哺乳期和 60 天的干奶期中，脂肪和蛋白质产量最大化。 20天或更短的干奶期会导致随后的哺乳期脂肪和蛋白质产量的大量损失。与产量相比，较短的干旱期有利于脂肪和蛋白质百分比。干奶期短也会导致随后的哺乳期开放天数减少；然而，这完全是由于干奶期缩短导致产奶量降低所致。当根据产奶量进行调整时，短暂的干奶期实际上会导致随后的哺乳期生育能力较差。长时间干燥可提高随后哺乳期的体细胞评分。患有乳腺炎问题的牛群在缩短干奶期时应谨慎，因为与 60 天干奶期相比，短干奶期会导致随后泌乳期的细胞得分更高。
The objective was to utilize data from modern US dairy cattle to determine the effect of days dry on fat and protein yield, fat and protein percentages, days open, and somatic cell score in the subsequent lactation. Field data collected through the dairy herd improvement association from January 1997 to December 2003 and extracted from the Animal Improvement Programs Laboratory national database were used for analysis. Actual lactation records calculated from test-day yields using the test-interval method were used in this study. The model for analyses included herd-year of calving, year-state-month of calving, previous lactation record, age at calving, and days dry as a categorical variable. Fat and protein yield was maximized in the subsequent lactation with a 60-d dry period. Dry periods of 20 d or less resulted in substantial losses in fat and protein yield in the subsequent lactation. In contrast to yields, a short dry period was beneficial for fat and protein percentages. Short dry periods also resulted in fewer days open in the subsequent lactation; however, this was entirely due to the lower milk yield associated with shortened dry period. When adjusted for milk yield, short dry periods actually resulted in poorer fertility in the subsequent lactation. Long days dry improved somatic cell score in the subsequent lactation. Herds with mastitis problems should be cautious in shortening days dry because short dry periods led to higher cell scores in the subsequent lactation compared with 60-d dry.