Genetic Studies On Semen Production In Jersey Crossbred And Holstein Friesian Crossbred Bulls
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Date
2014
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TANUVAS
Abstract
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
Description
Keywords
crossbred bulls, semen production, genetic parameters, Y-specific genes