Ovulation induction in doe rabbits and caffeine administration during pregnancy to increase litter performance

The present study was conducted to investigate the effect of caffeine administration during pregnancy period on some reproductive and productive traits of hormonally traited New Zealand White (NZW) rabbits - Three groups of 20 does each (average body weight 3350+/-83 g) were injected with saline solution (control) or with either 40 IU PMSG plus 50 IU HCG (group 2) or 40 IU PMSG plus 20 mu g GnRH (group 3). Each experimental group was divided into two sub-groups according to caffeine administration. The first sub-group was used without caffeine administration. The 2nd was administred with caffeine (500 mg/liter of drinking water) from day 1 until day 28 of pregnancy. The hormonally treated does were significantly (P< 0.01 or 0.05) higher in total litter size at birth and daily weight gain from birth to 21 days than the control. However, insignificant differences were detected in conception rate, gestation length, litter weight, milk yield, litter weight gain, bunny weight, pre-weaning mortality rate and plasma T-3 and T-4 concentrations among the experimental groups. Litter weight at birth and 21 days, milk yield at 3rd and 4 th week of lactation, daily weight gain from birth to 21 days of age and plasma T-4 concentration were increased significantly (P<0.01 or 0.05) by caffeine administration during pregnancy period. However, conception rate, litter size, litter weight gain, bunny weight, pre-wening mortality rate and plasma T-3 concentrations were not affected by caffeine administration.