Effect of somatic cell count on milk and protein yields and female fertility in Tunisian Holstein dairy cows
Effect of somatic cell count on milk and protein yields and female fertility in Tunisian Holstein dairy cows
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DOI：
10.1016/j.livsci.2007.11.001
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发表时间：
2008-07
影响因子：
1.8
通讯作者：
B. Rekik;N. Ajili;H. Belhani;A. Gara;H. Rouissi
中科院分区：
文献类型：
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作者：
B. Rekik;N. Ajili;H. Belhani;A. Gara;H. Rouissi
研究了试验日体细胞评分（SCS）变化对突尼斯荷斯坦奶牛产奶量和蛋白质产量、产犊至首胎期和产犊至受胎期的影响。第一胎、第二胎和第三胎奶牛的测试日生产记录分别为34129、25700和18077。记录是1996年到2004年间160个奶牛群的产犊情况。体细胞评分、产奶量和蛋白质产量使用线性模型进行分析，该模型包括畜群测试日日期和畜群年份的相互作用、产犊季节、产犊年龄和产犊至受孕间隔。繁殖性状模型包括群年相互作用、产犊季节、产犊年龄和授精月份。研究了SCS对产奶量和蛋白质产量的影响，将当前试验日产奶量回归到相应试验日产奶量和之前试验日产奶量，将产犊至初产期和产犊至受胎期分别回归到经环境和管理因素校正的实际产奶量的SCS，研究了SCS对育性性状的影响。一头奶牛每天的产奶量约为19.0 kg （SD=8.0 kg）和0.6 kg (SD=0.3 kg)，前三次泌乳的平均产奶量为3.8 （SD=2.1）。在所有哺乳期中，SCS与群试日和群年的相互作用一致（p<0.05）。泌乳天数、产犊日龄和产犊至受胎间隔都是主要发生在第一胎和第二胎SCS的重要变异源（p<0.05）。测试日的牛奶和蛋白质产量受到同一测试日记录的高SCS的不利影响，而在最近的测试日观察到的SCS的影响程度较小。增加的SCS减少的牛奶和蛋白质产量分别从0.23到1.76公斤和6到75克不等。同样，每增加一个单位的SCS，将产犊至首次服务（平均间隔=94.9天，SD=49.1天）和产犊至受胎（平均间隔=161天，SD=69.6天）的间隔延长1.3至2.0天。除乳性状外，利用SCS作为选择精液的标准，并改善兽医护理，应能提高牛奶和蛋白质产量，并取得令人满意的生育措施。
The effects of test-day somatic cell scores (SCS) variations on milk and protein yields, and calving to first service and calving to conception intervals were studied in Tunisian Holsteins. There were 34,129, 25,700, and 18,077 test-day production records collected on first, second, and third parity cows, respectively. Records were of cows calving between 1996 and 2004 in 160 herds. Somatic cell scores and milk and protein yields were analysed using a linear model that included herd-test-day date and herd–year interactions, calving season, calving age, and calving to conception interval. Reproductive trait model included herd–year interaction, calving season, calving age, and month of insemination. Effects of SCS on milk and protein yields were studied by regressing current test-day yields on corresponding and preceding test-day SCS, while effects of SCS on fertility traits were investigated by separately regressing calving to first service and calving to conception intervals corrected for environmental and management factors on SCS corrected for actual milk yield. A cow produced around 19.0 kg (SD=8.0 kg) and 0.6 kg (SD=0.3 kg) milk and protein yields on a daily basis and had an average of 3.8 (SD=2.1) SCS in the first three lactations. SCS varied consistently (p<0.05) with herd-test-day date and herd–year interactions in all lactations. Days in milk, calving age, and calving to conception interval were all together important sources of variation (p<0.05) for SCS mainly in the first and second parities. Test-day milk and protein yields were unfavourably affected by high SCS recorded in the same test-day and with a lesser degree by SCS observed in the nearest preceding test-day. Reduction in milk and protein productions from increased SCS varied from 0.23 to 1.76 kg and from 6 to 75 g, respectively. Likewise, increased test-day SCS lengthened both calving to first service (mean interval=94.9 days; SD=49.1 days) and calving to conception (mean interval=161 days; SD=69.6 days) intervals by 1.3 to 2.0 days for each unit increase in SCS. Using SCS in addition to milk traits as a criterion to select semen and improving veterinary care should result in increased milk and protein yields and in satisfactory fertility measures.