Use of Early Lactation Days Open Records for Genetic Evaluation of Cow Fertility
نویسندگان
چکیده
منابع مشابه
Use of early lactation days open records for genetic evaluation of cow fertility.
National genetic evaluations for cow fertility were introduced by the USDA in February, 2003. These evaluations, reported as daughter pregnancy rate, are based on days open. One requirement of the evaluation system is that lactations be at least 250 d in milk (DIM) to be included for analysis. The objective of this research was to develop a predictor of days open, usable in genetic evaluation, ...
متن کاملDevelopment of a national genetic evaluation for cow fertility.
A national fertility evaluation was developed based on pregnancy rate, which measures the percentage of nonpregnant cows becoming pregnant within each 21-d opportunity period. Data for evaluation are days open, which are calculated as date pregnant minus previous calving date. Date pregnant is determined from last reported breeding or from subsequent calving minus expected gestation length. Suc...
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a data file containing 607662 (317608) milk (open days) records belonging 294417 (177838) holstein cows that were calved from 1983 to 2008 was used. the bivariate repeatability model was used for data analyzing so that herd, calving year, calving month, days in milk (only for milk trait) and calving age for each parity, were assumed as fixed effects and additive genetics and permanent environme...
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Effects of twinning on lactation and days open in Holsteins were studied from calving records compiled by member surveys of Eastern Artificial Insemination Cooperative. Records of cows with 305-day mature-equivalent records from the Northeast Dairy Records Processing Laboratory were grouped according to whether the twin calving was associated with dystocia. Records of each cow that had a twin c...
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 2004
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(04)70048-x