Resumen de Effect of mother-litter separation and PMSG on the fertility of lactating does and the performance of their litter.
Two batches of 80 does each were inseminated (Al) 11 d post parturition during 10 months in arder to judge the effect of oestrus synchronisation of lactating does. Three different methods were comparad with the not treated control: a separation motheryoung during 40 h before Al, a 4 d. flushing prior to the Al with an energetic diet and a PMSG treatment (20 IU, 2 days before Al). A total of 991 inseminations, exclusively of lactating does, were analysed. After a 40 h separation, both receptivity and fertility (78.8 and 78.0%, respectively) were signlficantly higher (P<0.01) than the control (40.8 and 66.9%) and comparable with the PMSG treatment (75.1 and 76.7%, respectively). Effects were most pronounced for primiparous and does in their second lactation. However, the separation reduced (P<0.01) weaning weight of the young (40 - 47g). Flushing with the concentrated diet had a negativa effect on fertility (54. 7 vs 66.9% for controls). This was probably due to the low palatability of the experimental diet. In fact, the daily energy intake during the flushlng period was lower (-0.15 MJ ME/day) than in the control group. From this experiment it can be concluded that the bio-stimulation method applied is a real alternativa to hormonal treatments for inducing oestrus synchronisation. However, further research is necessary to better define the optimal mother-litter separation time by taking into account also considerations on animal welfare.
