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.

Development of testicular dimensions and size, and their relationship to age, body weight and parental size in growing Awassi ram lambs.

Ninety-six Awassi ram lambs, aged 2-3 months, raised and managed under a semi intensive system were used to measure development of testicular length, width, circumference and volume, and their association with development of body growth. The effects of parental size, age and body weight of lambs, production line (dairy or meat), type of birth and weight at birth and weaning on development of the four testicular parameters from weaning at 2-17 months of age were investigated. No significant differences were observed between measurements of the left and right testis. The highest increase in testicular parameters occurred between 7 and 10 months of age at 34.6kg live body weight. Only parental size, age and body weight affected testicular growth (P<0.05). Measurements of testes were correlated (P<0.01) with each other (r=0.68-0.97). They increased progressively and were correlated with body weight more than with age.

Effects of liner composition, cooling profile and time of glycerolization on survival of bovine spermatozoa.

Bovine spermatozoa from five bulls (158 ejaculates) were collected into one-piece combination liner-collection cones in an artificial vagina. Spermatozoal motility and differential staining were evaluated at each sequential step of semen processing. Linear 30-min and nonlinear 150-min cooling profiles resulted in equivalent postthaw spermatozoan survival rates. Preglycerolation holding times of 60 and 150 min, after 30-min linear cooling, were associated with increased, but nonsignificant, postthaw survival rates for bovine spermatozoa collected in polyethylene liner-collection cones. Highly significant differences (P<0.0001) were found to be associated with the composition of the liner-collection cones used. Motility estimates made at collection and after thawing from liquid nitrogen storage indicated that at least 50% of motile spermatozoa collected in polyethylene liner-collection cones survived; whereas, not more than 30% of the cells survived when they had been collected in rubber liner-collection cones.