Regression of Mature-Equivalent Production on Age at Calving
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...
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The time between birth and first calving represents a period in which replacement heifers are not generating income. Instead this rearing period requires considerable capital expenditures including feed, housing, and veterinary expenses. These expenses constitute 15 to 20% of the total expenses related to milk production (Heinrichs, 1993). A basic approach to reducing this cost is to reduce the...
متن کاملAnalysis of milk production, age at first calving, calving interval and economic parameters in dairy cattle management
The objective of this study was to evaluate main indicators of milk production on total 60 commercial dairy herds from the Czech Republic during a 9-yr period (2006-2014). Breakeven points and sensitivity analysis were used and associations of age at first calving (AFC), milk yield (MY) and calving interval (CI) were analyzed. Lowest AFC≤749 d showed the highest fertility, the lowest death rate...
متن کاملeconomic aspects of mature body weight and age at first calving in holstein dairy cattle of iran
the aim followed in the present study was to investigate the economic aspects of , and to derive economic weights (ews) for mature body weight (mbw) as well as for age at first calving (afc) in holstein dairy cattle of iran. economic values (evs) for traits were estimated using trait-by-trait bio-economic models. absolute evs were rls -16400 and -17900 per cow per year for mbw and afc, respecti...
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: Journal of Dairy Science
سال: 1970
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(70)86230-0