Effect of Different Dietary Protein Levels and Age on Testicular Development and Ultrastructure in Karadi Ram Lambs

Abstract

This study was undertaken to investigate the effect of two dietary crude protein levels and age on testicular development and ultrastructure in Karadi ram lambs. Twenty five lambs [6 months old; 28.6±1.19kg (average body weight±SE)] were randomly assigned to one of the two experimental diets containing either 12% (n=12) or 16% (n=13) dietary crude protein. Two ram lambs were slaughtered from each dietary group at the beginning of the experiment at a monthly interval except for five animals, which were slaughtered when they attained 11 months of age. The right testicular tissue was then removed from each lamb and processed for histomorphometric analysis. The body weight, testicular measurements, and testicular histology was not significantly ( p >0.05) affected by the dietary protein levels. The body weight gain and testicular growth rate were increased ( p <0.05) linearly between 6 to 11 months of age. Most of the increase in the testicular weight (345%) was attained by lambs between 6 to 9 months of age. Greater and lower ( p <0.05) total seminiferous and spermatogenic cells were noticed in ram lambs at age of 11 and 6 months respectively. Moreover, the diameter of the seminiferous tubule and the height of the epithelial cells were increased by two folds ( p <0.01) in ram lambs at 11 months of age in comparison to those at 6 months of age. Sperm was observed in the lumen of the testicular seminiferous tubule for the first time when the old ram lambs were 6 months old. In conclusion, the testicular measurements and component weights of Karadi ram lambs were not affected by the dietary crude protein levels. However, the physiological puberty was attained approximately at the age of 10 months. This may enable the use of Karadi ram lambs for breeding purpose in early age, when they have attained physiological puberty as found in the study.