Characterization and evaluation of semen in growing Awassi ram lambs.

This study was conducted to determine when semen can be collected and to characterize and evaluate the semen collected from growing Awassi ram lambs. Semen was collected regularly once a week for 20 months, starting at 11 months of age, from 14 Awassi ram lambs of milk and meat lines that accepted the artificial vagina. After each collection, the semen was evaluated in terms of its appearance, ejaculate volume, progressive motility, spermatozoa concentration and density. There were significant effects (p < 0.01) for the age and weight of the lambs on ejaculate volume, progressive motility and spermatozoal concentration, while the types of birth and production line had no significant effects on these characteristics. Ejaculate volume and spermatozoal concentration increased significantly (p < 0.01) with age, despite monthly variations. Progressive motility was similar throughout the year. Average values for ejaculate volume, progressive motility and sperm concentration were 1.2 +/- 0.5 ml, 75 +/- 10% and (4.0 +/- 1.6) x 10(9) sperm/ml, respectively. The highest positive and significant correlations were found between the semen characteristics (r = 0.29-0.68). On the other hand, a negative and significant (p < 0.01) correlation (r = -0.66) was found between the spermiodensimeter readings and spermatozoal concentration, and the relationship could be represented by a linear equation Y = 7.85 - 0.07X +/- 0.37, where Y = expected concentration of sperm (units of 10(9) sperm/ml) and X = spermiodensimeter reading. However the modest correlation coefficient indicates that the accuracy and precision of the resulting predictions will not be high. It was concluded that semen can be collected with a good quality from growing Awassi ram lambs at 11 months of age.