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 کاملFactors Affecting Age at First Calving in Kankrej Cattle
The data of 35 years from 1980 to 2014 were analyzed to study the effect of genetic and non-genetic factors viz. period of calving, season of calving as fixed effect and sire as random effect on the reproduction trait (age at first calving) of Kankrej cattle maintained at Livestock Research Station, S.D. Agricultural University, Sardarkrushinagar, Gujarat. The least square mean of age at first ...
متن کاملG enetic relationships between calving date, calving interval, age at first calving and type traits in beef cattle
In this paper the genetic relationships between major reproductive traits in beef cattle (Calving Date, Calving Interval and Age at First Calving) and type traits have been estimated to evaluate the usefulness of type classification in predicting reproductive performance in beef cattle. We estimated favourable genetic correlations between Calving Interval and type traits ranging from 2 0.027 to...
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...
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 1980
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(80)82904-3