Postnatal development of testis and epididymis, semen characteristics and fertility of brown- swiss crossbred bulls
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Date
1981
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Department of Animal Reproduction and Gyneacology, College of Veterinary and Animal Sciences, Mannuthy
Abstract
A systematic investigation involving the use of 24 Brown Swiss crossbred bull
calves and 7 adult bulls with 62.5% exotic inheritance varying in age from 0-
360 days and 22-40 months respectively, resred and maintained at Indo-Swiss
Project, Mattupatty, Kerala, was carried out in order to
(a)
trace the postnatal growth and development of the testis and epididymis
and (b) assess the semen characteristics such as volume, initial motility, sperm
concentration, live sperm count and incidence of abnormal sperms; As a
corrolary to and as an integral part of this comprehensive study, 6679 semen
collection particulars from the records maintained at the Indo-Swiss Project,
Mattupatty and 7586 insemination data at the Crossbreeding
Research
Centre, Muvathuphza werecritically scrutinised to deduce freezability/discard
rate
of the ejaculates and the fertility potenoy of the bulls, respectively. The
materials used, the salient observations made and the valid inferences drawn
aare given below:
Twenty four pairs of testis and epididymis collected from the bull calves were
processed to study the postnatal growth and development. The pattern of
growth of testis and of the epididymis was found to be curvilinear. The
testicularand epididymal weights were observed to be significantly (p<0.01)
correlated with the age, and body weight of the animals. A highly significant
(p<0.01) correlation between epididymal weight and testicular weight was also
observed. The growth rate of the seminiferous tubules appeared to be of
sigmoid type. Formation of lumen in the seminiferous cords was initiated at
150 days and completed, at 180 days of age. The transformation of gonocytes
to spermatogonia occurred at 150 days of age. The formation of primary
spermatocytes, spermatid and spermatozoa cocurred at the age of 150 days,
300 days and 300-360 days, respectively. The process of transformation of
supporting cells was initiated at 120 days and completed at 180 days of age.
The transformation of immature Leydig cells to mature cells was initiated at
150 days and completed, by 180 days of age. There were distinct regional
differences between the caput, the corpus and the cauda epididymis in respect
of the diameter of the tubules, height of the epithelium and the degree of
transformation of
Epithelial lining from simple columnar to pseudostratified type. The distal
part of the ductus epididymis seemed to have attained the adult size at an
earlier age than the proximal. Sperms were seen in all the three regions at
about 300 days.
The mean values of ejaculate volume, initial motility, sperm concentration, live
sperm count, sperm head abnormalities, tail abnormalities and proximal
protoplasmic droplets were found to be 2.65 ± 0.84 ml, 66.24 ± 0.87%, 1599.64
± 55.371 milions per ml of semen, 72.55 ± 1.310%, 4.91 ± 0.439%, 0.65 ±
0.045%, 6.47 ± 0.775% and 1.20 ± 0.143%, respectively. Significant (p<0.01)
variations between bulls were observed in respect of sperm head
abnormalities, tail abnormalities and proximal protoplasmic droplets and
between months, in respect of ejaculate volume, sperm head abnormalities,
free loose head, tail abnormalities and proximal protoplasmic droplets.
Seasonal variation (p<0.05), however, was evident only in the incidence of tail
abnormalities. Variations due to age of bulls were found to be significant
(p<0.01) in the casse of ejaculate volume, sperm concentration, free loose head,
middle piece abnormalities and tail abnormalities.
The freezability of sperms expressed in terms of per cent of post-thawing
motility was found to be 36.86. There was no seasonal effect on the freezability
of sperms. The freezability rate increased significantly (p<0.01) with
advancement of age of bulls.
The overall rejection rate of the ejaculates was noted to be 39.80%. Most of the
rejection (71.75%) was done before freezing. The pre-freezing rejection was
found to be 28.55% of the total ejaculate. The post-freezing discard to be
15.74% of the frozen samples. The rejection rates of the ejaculates differed
significantly (p<0.01) between months/seasons/age of the bulls. The rate of
rejection was found to decrease with advancing age.
The overall fertility rate of the bulls was found to be 56.06%. There were
significant (p<0.01) differences in the fertility rate between months/seasons of
insemination and between age of the bulls. As between bulls also, there was a
significant variation (p<0.01) in the fertility rate.
The significance of the observations inferences indicated above and their
relevance to the implementation of cross breeding programme in Kerala were
discussed briefly.
Description
PhD
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Citation
170101