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Reproductive performance of Holstein dairy cows in Iran

机译：荷斯坦奶牛在伊朗的生殖性能

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摘要

The objectives of the present study were to describe the current reproductive parameters of Holstein dairy cows in Iran and to determine factors which have a significant effect on reproductive performance with emphasis on high-producing dairy cows. Five large Holstein dairy herds from the major milk production areas of Iran were selected for this study. Reproduction data including parity of dam, calving date, days to first service, days open, number of services, dry period, and occurrence of diseases for cows that calved from 2004 to 2007 were collected from the herds' databases. To determine the effects of year and season of calving, disease status, level of milk production, and parity of dam on reproductive parameters, the proc-mixed procedure in SAS software was used. Overall, data about 8,204 lactation were collected for the study. Results showed that mean (plSD) days open, calving interval, and days to first service for study herds were 134 (pl89), 403 (pl86), and 67 (pl38) days, respectively. Conception rates at the first service and the overall service-conception rate were 41.6% and 41%, respectively. The level of milk production and diseases had significant negative effects on days open and service per conception (P<0.05); statistical analysis showed that for every 100-kg increase in milk yield, days open will increase by about 0.3 days. However, no significant effect of level of productivity was observed on days to first service. The results of this study indicate that high milk production is a risk factor for decreasing fertility in Iran, like many other parts of the world.
机译：本研究的目的是描述伊朗荷斯坦奶牛的当前生殖参数，并确定对生殖性能有重要影响的因素，重点是高产奶牛。这项研究选择了来自伊朗主要牛奶生产地区的五个大型荷斯坦奶牛群。从牛群数据库中收集了繁殖数据，包括大坝的均价，产犊日期，首次服务天数，营业天数，服务次数，干旱期以及2004年至2007年产犊的母牛的疾病发生率。为了确定产犊的年月和季节，疾病状况，产奶量和水坝平价对生殖参数的影响，使用了SAS软件中的混合过程。总体而言，该研究收集了约8,204次泌乳的数据。结果显示，研究组的平均（plSD）天，产犊间隔和首次服务天数分别为134天（pl89），403天（pl86）和67天（pl38）。首次服务的受孕率和总体服务受孕率分别为41.6％和41％。牛奶产量和疾病水平对每个受孕天数和服务天数有显着负面影响（P <0.05）;统计分析表明，牛奶产量每增加100千克，开放天数就会增加约0.3天。然而，在首次服务的几天中，没有观察到生产率水平的显着影响。这项研究的结果表明，与世界上许多其他地区一样，高产奶是降低伊朗生育力的危险因素。

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