The effect of nutritional fetal programming on post-pubertal male reproduction in sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies at Massey University, Palmerston North, New Zealand

Abstract

There is evidence that the in utero environment affects or programmes postnatal development and performance of offspring. Previous investigations have been conducted to establish the effects of dam nutrition on the development and reproductive performance of rams following various nutritional regimes of the ewe during pregnancy. This study further examines the effect of nutritional treatments of ewes during pregnancy on post-pubertal male reproductive performance. Sixty-two ram offspring, obtained from twin-bearing ewes that were fed at one of three different nutritional treatments in early pregnancy (Day 21-50, Low (LD21-50) vx. Maintenance (MD21-50) vs. High (HD21-50)), and one of two different nutritional treatments in mid to late pregnancy (Day 51-140), Maintenance (MD51-140) vs. High (HD51-140), were utilised in this study. Reproductive performance was measured using the accepted indicators of scrotal circumference, and semen quality and quantity (visual density, motility, quantitative sperm density and morphology) to establish if there was any effect of maternal nutrition on these parameters. The influence of seasonality was also investigated. Ewe nutrition during D 21-50 or D 51-140 had no effect on scrotal circumference, semen quality nor quantity. The rams in this study generally conformed to previously described seasonal patterns of reproductive activity. In conclusion, the present study demonstrates that under these conditions, post-pubertal male reproductive function and capacity and therefore fertility appear to be unaffected by prenatal maternal nutrition, and that rams maintain their cyclical reproductive response to seasonal cues.