The effect of litter size before weaning on subsequent body development, feed intake, and reproductive performance of...

An experiment was performed to study the effect of litter size before weaning on subsequent body development and composition, feed intake, and reproductive performance of young rabbit does with the objective to improve reproductive performance. Litter size (LS) before weaning (treatment) was 6, 9, or 12 kits. After weaning (30 d), 58 female kits per treatment (in two successive replicates) were reared and fed for ad libitum intake to 14.5 wk of age (end of rearing). At 14.5 wk of age, receptive does were inseminated. Nonreceptive and nonpregnant does were inseminated at 17.5 wk of age. The experiment ended when the second litter was weaned. Part of the animals was slaughtered to determine body composition at the end of the experiment (replicate one) and at the end of rearing (replicate two). At weaning, BW differed among treatments (P < 0.05; 855, 773, and 664 +/- 15 g for LS6, 9, and 12, respectively). Compensatory growth was observed. At the end of rearing, LS12 does were smaller (P < 0.05) than LS9 and LS6 does (3,524, 3,778, and 3,850 +/- 48 g, respectively). After first lactation, no difference in BW among treatments was found. Compared with LS6, empty body weight (BW minus gut, bladder, and uterus content) of LS12 contained more (P < 0.05) nitrogen (32.5 vs 31.1 +/- 0.3 g/kg), more (P < 0.05) ash (30.7 vs 28.3 +/- 0.6 g/kg), and less (P < 0.05) fat (168.6 vs 200.2 +/- 8.6 g/kg). No differences in body composition among treatments were found at the end of the experiment. During rearing, LS12 had the lowest (P < 0.05) daily feed intake (152, 164, and 169 +/- 2 g/d for LS12, 9, and 6, respectively). During the reproductive period, no differences in feed intake among treatments were found. Kindling rate (the number of kindlings per number of inseminations) was not influenced by treatment. In the first parity, total litter size (number of alive and stillborn kits) was lower (P < 0.10) for LS12 than for LS9 (6.4 vs 8.6 +/- 0.5, respectively). When first mating was delayed by 3 wk, an increased (P < 0.05) total litter size was found regardless of treatment (7.5 and 9.4 +/- 0.3 for 14.5, and 17.5 wk, respectively). Decreasing litter size before weaning from nine to six kits did not alter future reproductive performance. Based on results of this study, it seems advisable to perform a limited standardization level (at nine kits) after kindling and postpone first mating to an older age (17.5 wk) to improve reproductive performance.