Effect of nutrition and active immunization against androstenedione on reproduction of SA Mutton Merino ewes:
Two groups of SA Mutton Merino ewes, consisting of forty ewes each, were used to determine the effect of nutritional level and immunization against and rostenedione on reproduction. The ewes of one group were immunized with polyandro-albumin (Fecundin R; Glaxo Animal Health, Coopers, Australia ). The effect of immunization was significant (P < 0,05) on ovulation rate (1,79 vs. 1,42) but non-significant (P > 0,05) on fecundity (1,53 vs. 1,42) and number of lambs born per ewes mated (1,22 vs. 1,34). Higher levels of nutrition acted complementary to the effect of immunization on ovulation rate. The immunization x nutritional level interaction was non-significant (P > 0,05). However, the nett result of immunization on fecundity and fertility was affected by nutritional levels.