INFLUENCE OF PROGESTERONE SUPPLEMENTATION ON FETAL SURVIVAL IN CONCURRENTLY PREGNANT AND LACTATING DOES

An experiment was conducted to assess the influence of progesterone le vels on late foetal mortality (second half of gestation) in concurrent ly pregnant and lactating does. All the females were mated within 12 h of parturition (d 0), and slaughtered on d 28 to study reproductive p erformance and body composition. Females were allowed to lactate 10 yo ung and received either 2 progesterone implants (group P, n = 29) or 2 empty implants (group C, n = 29) on d 7. The feed intake, the live-we ight variations of females during gestation, the growth of suckling li tters, as well as the foetal weight and body composition of the does a t slaughter, were similar in both groups. The concentration of progest erone was higher in group P than in C on d 16 and 25 (P < 0.01). The o vulation rate and late foetal mortality were similar in both groups bu t the early mortality was lower (12.3 vs 21.2%; P < 0.05) and the tota l number of foetuses on d 28 (live + resorbed + dead) was higher (9.8 vs 8.7; P < 0.05) in group P. These results indicate that progesterone supplementation improves early foetal survival but cannot increase la te foetal survival in concurrently pregnant and lactating does.