Comparative evaluation of seven quality of the Norwegian (N), Tanzania local (l) and N X L cross bred bucks
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Date
1986
Authors
Journal Title
Journal ISSN
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Publisher
Sokoine University of Agriculture.
Abstract
The Tanzanian local (L) bucks were compared with the Norwegian (N)
and Norwegian half - cross (N x L) bucks for
their semen characteristics
and for seasonal influences on variation in semen quality.
The bucks
were divided into two age groups (Group 1, n = 8, Group II, n = 24).
For group I bucks observations were made for the period of six months
(Jan. - June) falling in two seasons of three months each ( SI =
Jan. - March & SII = April - June) while group II bucks were observed for
three months only (SII).
Ejaculates were collected from the bucks
by the use of electro - ejaculator once per week and twice on each day of
collection.
Positive correlations (59.4% and 41.1%) between semen volume and
respectively liveweight and testicular circumference were observed.
Semen volume increased from 0.42 ml and 0.32 ml by approximately 0.02 ml
and 0.03 ml respectively per each kilogram increase in liveweight and
each centimeter increase in testicular circumference.
Liveweight accounted
for 35% of all variation in semen volume among individual bucks.
Signifi
cant variation among bucks was observed for semen density (P < 0.01),
semen volume (P < 0.01);. wave - motion score (P < 0.01) and total number
of livespermatozoa per ejaculate (P < 0.01).
Norwegian bucks in group II exhibited significantly (P < 0.05) higher
semen volume (1.06 + 0.17 ml) than both the locals (0.67 + 0.03 ml) and
the crossbreds (0.84 + 0.03 ml).
In group I breed effect was non - signi
ficant with respect to semen volume but local bucks were significantly.V
superior in semen density
7
x 10 /ml (350.83 + 46.43 vs. 244.89 + 18.8)
wave - motion score (2.56 + 0.38 vs. 1.98 + 0.6 ) total number of
spermatozoa /ejaculate x 10? (410.99 + 56.05 vs. 311.38 + 13.13)
and total number of livespermatozoa/ejaculate x 10? (275.23 + 54.4 vs.
201.48 + 10.48).
Semen density, Z livespermatozoa and wave - motion score showed
significant monthly variations in all breed groups.
Higher values of
Z livespermatozoa were recorded in March (75.05 + 5.6Z) for local bucks
and in January (79.06 + 3.5Z) for Norwegian bucks.
Monthly variation in
semen volume among the 3 breeds were incosistent and insignificant.
Lowest volumes were recorded in May (0.93 ml for local and 1.10 ml for
Norwegian bucks) whereas highest values were recorded between February
and March in both breeds (1.2 ml and 1.56 for local and Norwegian bucks
respectively).
Body weight and testicular measurements can serve as indicators
of sperm producing capacity in bucks.
It is suggested that these parameters
should provide basis for setting appropriate male : female ratios in
planned matings.
From the observations on monthly and seasonal
variations in the semen attributes, it is concluded that annual rythms in
spermatogenic activity do exist in all the three breeds.
This however.
does not exclude the possibility of using males from any of three breeds
to serve throughout the year.
Description
MASTERS DISSERTATION
Keywords
Comparative evaluation, Norwegian, Crossbred, Bucks, Semen