Genetic Studies On Semen Production In Jersey Crossbred And Holstein Friesian Crossbred Bulls
Sivaselvam, S.N.
2014
Ph.D
Data on 106197 ejaculates of crossbred Jersey (CBJY) bulls from 2002 to 2014 and 22442 ejaculates of crossbred Holstein Friesian (CBHF) bulls from 1996 to 2014 were analysed for semen production traits. The overall least-squares means for semen volume, sperm concentration, mass activity, initial sperm motility, post-thaw motility and number of doses per ejaculate were 4.03 ml, 1056.18 million per ml, 2.31, 67.08 per cent, 51.04 per cent and 172.58 doses respectively in CBJY bulls. The farm, ejaculate, period, season and age of the bulls were significant (P<0.01) sources of variation for sperm concentration, mass activity and initial sperm motility. Whereas, the semen volume, post-thaw motility and number of doses per ejaculate were significantly (P<0.01) influenced by farm, ejaculate, period and age of the bulls and not by season. The overall least-squares means for semen volume, sperm concentration, mass activity, initial sperm motility, post-thaw motility and number of doses per ejaculate were 4.53 ml, 1081.33 million per ml, 2.54, 70.00 per cent, 52.48 per cent and 221.82 doses respectively in CBHF bulls. The farm, period and age of the bulls were significant (P<0.01) sources of variation for all the semen production traits. Whereas, the order of ejaculate affected post-thaw motility and number of doses per ejaculate and the season influenced sperm concentration and initial sperm motility. The body weight and scrotal circumference of bulls significantly influenced all semen production traits except mass activity in CBJY bulls. Bulls having a body weight between 350 and 650 kg produced better quality semen and more number of frozen semen doses per ejaculate. When the scrotal circumference was >36 cm, majority of the semen traits showed better values. The8 CBHF bulls with a body weight of >450 kg and scrotal circumference of 36 to 38 cm produced better quality semen. The overall least-squares means for post-thaw incubation survival, hypo-osmotic swelling and acrosome integrity of spermatozoa were 50.55 at 0 h, 37.92 at 1 h, 24.80 at 2 h and 13.81 per cent at 3h; 59.52 per cent; and 81.94 per cent respectively in CBJY bulls. The corresponding values in CBHF bulls were 47.85 at 0 h, 37.12 at 1 h, 20.49 at 2 h and 11.45 per cent at 3 h; 58.13 per cent ; and 83.26 per cent respectively. The post-thaw incubation survival was affected by ejaculate, season and period; hypo- osmotic swelling by period; and acrosome integrity by ejaculate and period significantly in both CBJY and CBHF bulls. The overall least-squares mean age at first semen collection, semen production period, per bull lifetime production of frozen semen doses and estimated per bull annual production of frozen semen doses in CBJY and CBHF bulls were 736.87 and 683.61 days; 1795.38 and 1504.02 days; 83703.67 and 89164.51 doses; and 17016.92 and 21638.71 doses respectively. The repeatability estimates of semen volume, sperm concentration, mass activity, initial sperm motility, post-thaw sperm motility and number of doses per ejaculate were 0.32, 0.34, 0.29, 0.48, 0.29 and 0.39 respectively in CBJY bulls and 0.56, 0.14, 0.34, 0.42, 0.18 and 0.20 respectively in CBHF bulls. The heritability was estimated for these traits in CBJY bulls only and the values were 1.46, 0.16, 1.69, 0.26, 0.29 and 0.48 respectively. The genetic correlations were also estimated in CBJY bulls only and the correlation coefficients were -0.45 between semen volume and sperm concentration, -0.69 between semen volume and mass activity, -0.30 between semen volume and initial sperm motility, 0.95 between sperm concentration and mass activity, 0.18 between sperm concentration and initial sperm motility and 0.64 between mass activity and initial sperm motility. The rejection rate of semen before freezing was 29.72 per cent in CBJY and 9.80 per cent in CBHF bulls; it was 1.23 and 3.40 per cent after freezing. The major cause of disposal was poor semen quality in CBJY and CBHF bulls. SNP at 641 st position (G>T transversion) of SRY gene of Y-chromosome could be used as a candidate marker for selection bulls for semen volume and sperm concentration in CBJY bulls. Variation in expression of Y-specific SRY gene was positively correlated with semen volume and initial sperm motility. While variation in TSPY gene was negatively correlated and highly significant with semen volume, sperm concentration, initial sperm motility and post-thaw motility; and variation in USP9Y gene was negatively correlated with initial sperm motility and post-thaw motilit
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TANUVAS
Animal Genetics and Plant Breeding
Size 7.86 MB
TNV_PT_11002.pdf
Thesis