TESTICULAR SIZE AND SPERM OUTPUT IN HOLSTEIN-FRIESIAN AND N'DAMA BULLS

Résumé

Records collected over a period of four months from October 1978 to January 1979 from four Holstein-Friesian and four N'dama hulls, were used to study the relationship between testicular size and sperm output. Semen samples were collected from the bulls twice a week using the artificial vagina and non-oestrous female teasers. The means (± s.e.) of testicular measurements for Holstein-Friesian and N'danta, respectively, were 35.6 ± 1.8 and 7.9 ± 0.3cm. for scrotal cir­cumference, 12.6 ± 0.3 and 7.7 ± 0.8cm for testis length, 6.7 ± 0.3 and 3.7 ± 0.2em for testis diameter. Calculated mean testicular volumes were 296.8 I 22.2 and 57.4 ± 10.1m1 respectively for Holstein-Friesian and N'dama bulls. T^-he mean total sperm per ejaculate were 8.80 t 3.045 x 10⁹ for (be Holstein-Friesian and 3.03 ± 0.905 x 10⁹ for the N'dama bulls. Simple correla­tions for Holstein-Friesian and N'damn in the same order, were between body weight and scrotal dr. rumference 0.49 and 0.66, body weight and sperm output/einculate 0.48 and 0.88, scrotal cir­cumference and testicular volume 0.74 and 0.60. scrotal circumference and sperm outpuilejactilete 0.18 and 0.69, and testicular volume and sperm out­put/ejaculate —.45 and 0.84. Regression equations for predicting sperm oat­put/ejaculate from testicular volume are given as Y = .13.458 — .031 X and Y' = - .650 + 0,038 x respectively, for holstein-Friesian and N'dania bulls.