EFFECT OF DIFFERENT PERIODS OF FLUSHING AND SYNCHRONIZED MATING ON BODY-WEIGHT, BLOOD-GLUCOSE AND REPRODUCTIVE-PERFORMANCE IN SPRING-MATED EWES

One hundred and sixty Merino ewes were allocated to four flushing (600 g/ewe/d of an alkali-ionophore-treated maize) groups; the aim being t o determine the effect of flushing for different intervals (2 to 4 wee ks), prior to and following synchronization, on the reproductive perfo rmance. Parameters monitored included body weight, blood glucose conce ntrations, ovulation rate and reproductive performance. No significant difference in body weight was recorded between groups following treat ment. Following the onset of flushing, significantly (P < 0.01) higher blood glucose levels were immediately recorded in the group receiving flushing from sponge withdrawal fora 2-week interval (3.0 vs. 3.9 mmo l/l) and the group receiving flushing from a week prior to sponge with drawal for an interval of 3 weeks (3.2 vs. 3.9 mmol/l). Flushing did n ot significantly affect duration of induced oestrus. Ovulation rate fo llowing 3 weeks of flushing was significantly higher (P < 0.01) than i n controls and other groups (1.33 vs. 0.5). Fecundity (123%) was also significantly (P < 0.05) higher in this group. No significant differen ce in conception and lambing rate between the different treatment grou ps was recorded. Flushing had a beneficial effect on the overall repro ductive performance, and in this trial flushing from a week before spo nge withdrawal for a total period of 3 weeks gave best results (lambin g rate of 95%). Whether this improved fecundity and lambing rate obtai ned is economically viable remains speculative.