Browsing by Author "Aboud Ali A.O."

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Comparative evaluation of seven quality of the Norwegian (N), Tanzania local (l) and N X L cross bred bucks
(Sokoine University of Agriculture., 1986) Aboud Ali A.O.
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.