Nutrition and reproduction in the ewe

Abstract

1. A preliminary trial involving forty-six ewes demonstrated that when ewes in store condition were flushed for different periods, there was a marked increase in ovulation rate after 1 month with no further increase after 2 or 3 months. Flushing did not lead to ovulation rates higher than in ewes maintained in fat condition. 2. When similar ewes in fat condition were fed submaintenance diets there was no decline in ovulation rate while the animals had good body reserves, but as the period of submaintenance feeding was extended there was a gradual fall in ovulation rate. 3. In the main experiment forty-eight ewes were allocated to four groups of twelve ewes each. One group was fed a submaintenance diet till they were in moderately poor condition (submaintenance group). The other three groups were reduced to store condition and were then flushed on good pasture for 5–8 days, one oestrous cycle and two oestrous cycles, respectively. All ewes were slaughtered 2–5 days post-oestrus and half the ewes of each group were injected subcutaneously with 600 i.u. of P.m.s. on the twelfth or thirteenth day of the oestrous cycle prior to slaughter.