Semen quality and sperm output of Yankasa rams at different ages.

Three groups of three Yankasa rams aged 1.4, 2.4, and 3.4 yr, weighing 32.8 +/- 0.8, 47.9 +/- 1.4, and 48.8 +/- 1.3 kg, and with scrotal circumferences measuring 26.8 +/- 0.9, 28.9 +/- 0.3, and 30.3 +/- 1.3 cm (mean +/- SEM), respectively, were used for this study. The rams were ejaculated once per day for 14 d using an artificial vagina and their semen quality and sperm output determined. For the three groups, ejaculate volume, sperm concentration, sperm motility, percentage of morphologically normal sperm, and total sperm output per ejaculate averaged 0.72 +/- 0.03, 0.90 +/- 0.04, and 0.88 +/- 0.03 ml; 3.421 +/- 0.133, 4.025 +/- 0.179, and 4.673 +/- 0.184 x 10(9)/ml; 83.2 +/- 2.3, 84.6 +/- 1.5, and 74.0 +/- 2.4%; 96.2 +/- 0.3, 96.0 +/- 0.4, and 95.4 +/- 0.4%; and 2.469 +/- 0.141, 3.663 +/- 0.237, and 4.163 +/- 0.247 x 10(9) sperm, respectively. Differences between groups were significant for all semen traits except for percentage of morphologically normal sperm. Total sperm output per ejaculate (Y; x 10(9)) was significantly correlated with scrotal circumference (X; cm) by the geometric regression equation Y = 0.000128 X(3.03) (r = 0.71; P < 0.05). Ejaculate characteristics were not influenced by day of collection except for percentage of morphologically normal sperm, which was significantly (P < 0.01) lower on the first day of collection.