Calving interval genetic parameters and trends for dairy breeds in South Africa
نویسندگان
چکیده
منابع مشابه
Trends in calving ages and calving intervals for dairy cattle breeds in the United States.
Trends since 1980 for calving age and calving interval, 2 factors that influence herd life, were examined by parity for 5 breeds of US dairy cattle. Calving data were from cows with records that passed edits for USDA genetic evaluations and were in herds that remained on Dairy Herd Improvement test. First-calf heifers calved at progressively younger ages over time, but the age decline was less ...
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The objective of the present study was to estimate genetic trends for lactation milk yield, persistency of milk yield, somatic cell count and interval between first and second calving in Holstein dairy cows of Iran. The dataset consisted of 210,625 test day and 25,883 first parity cows with milk yield recorded from July 2002 to September 2007 comprising 97 herds in Iran. Breeding values of anim...
متن کاملEstimation of Genetic and Phonotypic Trends for Age at First Calving, Calving Interval, Days Open and Number of Insemination to Conception for Isfahan Holstein Cows
For the current research the records of 62 farms in Isfahan province were available. To estimate genetic and phonotypic trends of reproductive traits such as age at first calving, calving interval, days open and number of insemination to conception rate the records of 63,866 cows including 167793 reproductive records were employed. Farms were covered by Vahdat industrial Agriculturists and Dair...
متن کاملEstimation of Genetic and Phonotypic Trends for Age at First Calving, Calving Interval, Days Open and Number of Insemination to Conception for Isfahan Holstein Cows
For the current research the records of 62 farms in Isfahan province were available. To estimate genetic and phonotypic trends of reproductive traits such as age at first calving, calving interval, days open and number of insemination to conception rate the records of 63,866 cows including 167793 reproductive records were employed. Farms were covered by Vahdat industrial Agriculturists and Dair...
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...
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ژورنال
عنوان ژورنال: South African Journal of Animal Science
سال: 2010
ISSN: 2221-4062,0375-1589
DOI: 10.4314/sajas.v40i2.57288