Genetic and phenotypic trends of fertility traits for Holstein dairy population in warm and temperate climate
Rahbar, RabieAminafshar, MehdiAbdullahpour, RohullahChamani, Mohammad
The main objective of this study was to investigate genetic and phenotypic trends for fertility traits in Holstein dairy population under warm and temperate climate. Fertility traits were: success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open. The edited data set included up to 23,402 records from 9,486 cows. The mean and standard deviation for fertility traits were 0.32 ± 0.003, 278.2 ± 5.58, 2.73 ± 1.94,0.31 ± 0.001, 415.99 ± 79.62, 40.4 ± 6.08 and 140.36 ± 76.16 for success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open, respectively. In general, there were decreasing genetic trends for all traits over the years. On the other hand, there were decreasing phenotypic trend for days open, calving interval, gestation length, number of inseminations and calving birth weight, but estimates of phenotypic trends were positive for success in first service and insemination outcome over the years. It was concluded decreased trend for days open, calving interval, gestation length, number of inseminations and calving birth weight and increased trend for success in first service and insemination outcome traits over time indicated that Holstein dairy producers in warm and temperate climate were successful in managing and improving in nutrition during 1999 to 2013> (AU)
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