Genetic and phenotypic relationships among milk yield and somatic cell count before and after clinical mastitis
Genetic and phenotypic relationships among milk yield and somatic cell count before and after clinical mastitis
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DOI：
10.3168/jds.s0022-0302(05)72747-8
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发表时间：
2005-02-01
影响因子：
3.5
通讯作者：
Serenius, T
中科院分区：
文献类型：
--
作者：
Koivula, M;Mäntysaari, EA;Serenius, T
本文研究了体细胞数(SCC)较低的奶牛是否比体细胞数较高的奶牛更易患临床型乳房炎(CM)，并评价了CM、SCC与产奶量之间的相关性。数据摘自芬兰国家牛奶记录数据库和健康记录系统。研究对象包括1998年1月至2000年12月间87,861头艾尔夏奶牛的第一次和第二次哺乳记录。研究的指标是CM的发生率、试验日体细胞癌和试验日产奶量。遗传参数的估计使用多性状REML和SIRE模型。结果并不表明，遗传低SCC的奶牛更容易感染CM。第一次哺乳和第二次哺乳的CM之间的遗传相关性相当高(0.73)，这表明不同哺乳期对乳房炎的易感性仍然相似。CM与产奶量性状的遗传相关为正相关(0.38~0.56)，证实了产奶量与乳房健康性状之间存在遗传拮抗作用。体细胞数与乳汁的遗传相关在第一次哺乳时为正相关，在第二次哺乳时为负相关或接近于零。这表明，选育体细胞系数较低的奶牛可能不会影响后期的产奶量。这项研究的结果支持使用SCC作为乳房炎的指标和选择乳房炎抵抗力的工具。
This paper studies whether cows with originally lower somatic cell count (SCC) are more susceptible to clinical mastitis ( CM) than cows with higher somatic cell count, and evaluates the correlations between CM, SCC, and milk yield. Data were extracted from the Finnish national milk-recording database and from the health recording system. First and second lactation records of 87,861 Ayrshire cows calving between January 1998 and December 2000 were included. Traits studied were incidence of CM, test-day SCC, and test-day milk yield before and following CM. Genetic parameters were estimated using multitrait REML with a sire model. Results did not indicate that cows with genetically low SCC would be more susceptible to CM. The genetic correlation between CM in the first and second lactation was reasonably high (0.73), suggesting that susceptibility to mastitis remains similar across lactations. The genetic correlation between CM and milk yield traits was positive ( from 0.38 to 0.56), confirming the genetic antagonism between production and udder health traits. The genetic correlation between SCC and milk was positive in the first lactation, but negative, or near zero in the second lactation. This indicates that breeding for lower SCC might not affect milk production in later lactations. The results of this study support the use of SCC as an indicator of mastitis and a tool for selection for mastitis resistance.