The association between age at first calving and survival of first lactation heifers within dairy herds
نویسندگان
چکیده
منابع مشابه
Calving day and age at first calving in Angus heifers.
Because of difficulties in data collection and analysis, in most breeds there have been limited ways to evaluate fertility in females on a between-herd basis. The objective of this study was to determine the heritabilities (direct and maternal) for CD (calving day) and AFC (age at first calving) in American Angus heifers and to evaluate the potential for using these traits in genetic improvemen...
متن کاملAssociation between growth rates, age at first calving and subsequent fertility, milk production and survival in Holstein-Friesian heifers
Age at first calving (AFC) affects the profitability of dairy enterprises. This study examined the relationships between AFC and subsequent fertility, milk production and survival up to third calving in UK Holstein-Friesian heifers; Study 1 comprised 134 consecutively born heifers from the same herd (AFC 764 ± 8 days) and Study 2 contained 445 heifers born on 17 farms (AFC 796 ± 6 days). Growth...
متن کاملAssociation between the lactation curve shape and calving interval in Holstein dairy cows of Iran
This study was carried out to investigate the relationship between early lactation curve parameters andcalving interval in Holstein cows of Iran. In order to describe the lactation curve, the incomplete gammafunction was fitted to 5,754,428 test-day milk records corresponding to 766,108 lactations on 315,634 cowsin 2,448 herds. Cows with higher milk yield during early lactation had shorter calv...
متن کاملAssociation of LEPR gene Polymorphism with milk yield and age at first calv-ing in the Iranian Holstein dairy cows
The LEPR is a glycoprotein expressed mainly in hypothalamus, where it takes part in energy homeostasis and in regulation of the activity of the secretory organs. A transition mutation in this gene results in substitution of cytosine by thymine leading to the substitution of threonine by methionine in the intracellular domain of the LEPR-b isoform. This study investigated the impact of polymorph...
متن کاملLifetime production of beef heifers calving first at two vs three years of age.
Records of Angus, Hereford, Shorthorn, and first-cross cows born from 1960 to 1963 were used to study the effect of age at first calving and culling policy on cumulative survival (SU), number of breeding seasons (BS), pregnancies (PG), calves born (CB) and alive at 72 h (C72) and at weaning (CW), calf weaning weights (WW), and input/output efficiency, up to 12 yr of age. The 155 cows born in 19...
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ژورنال
عنوان ژورنال: Animal
سال: 2016
ISSN: 1751-7311
DOI: 10.1017/s1751731116000689