Relationship between Growth Pattern, Age at First Calving and Next Reproduction in Holstein Heifers

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...

Association 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...

Genetic Relationship between Milk Production, Calving Ease and Days Open at First Parity in Holstein Cows

Data containing 14,188 lactation and reproductive records of Korean Holstein cows at first parity distributed across 3,734 herd-year-season groups were analyzed to get genetic (co)variance estimates for milk yield, fat yield, calving ease, and days open. Milk and Fat yields were adjusted to 305 d. Heritabilities and genetic correlations were estimated in two different animal models on which wer...

The Relationship of Milk Somatic Cell Count to Milk Yields for Holstein Heifers After First Calving

The contribution of a dilution effect to the relationship between milk yield and milk SCC was investigated using data from 24 Holsteins during the first 75 d after first calving. Bucket and quarter milk SCC were collected at weekly intervals. Individual milk weights were obtained at milking, and samples were obtained for determination of SCC. The milk weights at the corresponding a.m. milking o...

Relationship between serum total cholesterol levels before calving and occurrence rate of diseases after calving in Holstein heifers and cows.