Sheep - AgRIS

collection frequencies per day in 3 successive weeks from adult Bikaneri rams revealed that
highly significant difference between weeks and rams in all the seminal attributes examined
(Volume, motility, conc./ml., conc./ejaculate and live spermatozoa). Although with increased
frequencies, sperm concentration is successive ejaculates declined, there was a net increase in
either attributes when compared to only one collection per day. It was noted that there was no
substantial advantage in increasing the frequency of collection from 2 and 3 per day. Based on
the requirement of 100 million spermatozoa for obtaining optimum fertility in ewe, it has been
concluded that an average 700-800 ewes can be inseminated when semen is collected once
daily for a period of 20 days from one ram.
Tiwari and Sahni (1970) have examined the various seminal attributes of Rambouillet and
cross-bred rams through out the year. It was concluded that Rambouillet rams did not donate
good quality semen during hotter part of the year. Semen of excellent quality was obtained
from the Rambouillet rams during the months from October to February when the indigenous
sheep are not bred norrnally. Semen quality was moderate in April and it started deteriorating
from May onward till it was watery with almost azoesperimic condition in the month of June to
August. The semen quality did not show any deterioration due to season in half-bred (50%)
rams. No azospermia was noted in 75% corss-bred rams; however, a slight deterioration in
semen quality was observed during the hotter part of the year.
The studies on extention rates indicted that Rambouillet semen froze well to give optimum
level of cryosurvival and motility, whereas 3/4 exotic semen showed very poor post thaw
survival in both the lconcentrations and replicates (Mathur et al., 1989).
ii) Season
Marked seasonal variations in density, percentage of abnormal sperms and glycolysis in
semen of rams was observed by Comstock et al., (1945). Poor quality of semen was recorded
during summer and early autum months i.e. July to September. Bell (1945) observed slight
seasonal variations in Rambouillet rams in which semen quality was poor in spring (March-
April). It improved in summer (MayJuly). Koger (1951) found that in autumn, ram semen has
higher motility and longer viability on storage than in the semen collected in spring. Maqsood
(1951) on his observations on young Suffolk rams reported that during the non-breeding seaon,
there is a marked decrease in the libido, volume and spermatozoal density and increase in the
number of abnormal sperms. Poor libido is believed to be due to interference with the
production of androgens by the interstitial cells. Histological examination of testes of the young
ram carried during spring and summer revealed arrested spermatogenesis in the majority of the
seminiferous tubules. Waston (1952) observed that Merino rams show higher fertility in the
autumn but there is uncertainty in the spring. Wiggins et al. (1953) found a significant
correlation between libido and fertility in the range rams. Volcani (1953) observed seasonal
variations in spermatogenesis in Awassi sheep in Israel. In July and August when days are long
and hot, histological examination of testes in rams indicated active spermatogenesis. Whereas
from September to December, degenerative changes were noticeable. He considered that the
temperature was not the causative factor and implicated availability of grazing facility.
Shuklaand Bhattacharya (1952) observedthatthe reaction time, differed significantly
between rams, but there was no seasonal trend and non relationship to quality of semen.
Significant seasonal variations inthe volume of semen, pH, sperm concentration, motility and
percentage of abnormal sperrnatozoa were observed. Variations between months and within
seaons were also significant. The quality of semen was poorest in autumn and best in spring.
Hafez et al. (1955) observed that the quality of semen of Ausimi and Rahmani rams in
Egypt was very good during spring and autumn than in summer and winter. Hulet et al. (1956)
found that ram fertility was 42.8% before September due to poor quality of semen and
thereafter the fertility improved to 67.6%.
Sahni and Roy (1967b) observed in their studies on Romney Marsh rams brought in Uttar
Pradesh (India) for improving the indigenous sheep, that in the month of January, the abnormal
sperm count was 3.8% but during the months of February, as the climate begins to get warmer,
the percentage of abnormal spermatozoa increased to 27.5%. The signs of seminal degeneration
gradually developed, thereafter as the summer advanced the initial motility became poor, sperm
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