GENETIC EVALUATION OF SEMEN PRODUCTION AND FERTILITY TRAITS IN EXOTIC, CROSSBRED AND INDIGENOUS CATTLE AND BUFFALOES
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Date
2021
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Abstract
The records of 736 bulls comprised of 2,69,795; 9,662 and 2,239 ejaculates of semen production, semen quality and sperm abnormality data respectively, while, 5,76,870 artificial inseminations on different genetic groups were broadly classified into five categories viz. Holstein Friesian, Jersey, crossbreds of Holstein Friesian and Jersey, indigenous cattle and buffaloes.
The effect of genetic and non-genetic effects on semen production, semen quality, sperm abnormality, and fertility traits were tested using linear mixed model. The effect of genetic and non-genetic factors on lifetime semen production performances were analysed using general linear model. The variance components were estimated by REML method using the animal repeatability model (univariate and multivariate) while, the breeding values were estimated using BLUP method.
The order of ejaculate, collection interval, time of collection, breed × age at collection, semen collector × year of collection and month × year of collection had a significant influence (P<0.01) on ejaculate volume, sperm concentration, total sperm, mass activity (only for buffaloes), initial motility, total motile sperm, post-thaw motility, and total motile sperm after thawing in both cattle and buffaloes. In case of sperm abnormality traits, level exotic inheritance, age at collection, had no effect (P>0.05) on Jersey crossbred bulls, while, the age at semen collection had a significant (P<0.05) effect on only mid-piece abnormality, total abnormal sperm, and total normal sperm of Holstein Friesian crossbred bulls. The breed and age at semen collection had a significant effect (P<0.05) on semen quality traits involving acrosome integrity of neat and frozen semen, hypo-osmotic swelling test and incubation tests in cattle. While, the breed and age at semen collection were mostly non-significantly influenced semen quality traits in buffaloes. However, season × year of collection significantly (P<0.01) affected (P<0.01) both sperm abnormality and semen quality traits. The fertility trait was significantly affected (P<0.05) by body condition score, stage of heat and order of parity etc. on different genetic groups.