Influence of solid feed intake and age at weaning on caecal content characteristics and post-weaning performance
This study examined the effects of the feed/milk ratio at weaning time on caecal content characteristics at weaning and on post-weaning performances. Twenty-seven primiparous NewZealand White does were used in this study involving with standardized litters of 8 kits at birth and a mínimum of 7 kits alive at weaning. During lactation, all does were mated and fertilized 12 days after kindling. Litters were caged separately from their mother and fed according to the following scheme: Group A (n = 8), litters fed ad libitum and weaned at 35 days; Group B (n = 10) litters fed 60% ad libitum and weaned at 35 days; Group C (n = 9) litters fed ad libitum and weaned at 30 days. At weaning one animal per litter was slaughtered to study caecum characteristics, while 50 other rabbits per group were raised during 5 weeks in cages of 2 rabbits in order to evaluate post-weaning performance. At weaning, litters of Group A, besides weighing more (6141, 4693 and 4729 g in Groups A, B and C, respectively), showed as expected the highest feed/milk intake ratio (8.35, 4.05 and 1.53; P < 0.01, in Groups A, B and C, respectively). At weaning, caecal content of Group A rabbits recorded a lower pH (5.67, 6.40 and 5.97, P < 0.01, in Groups A, B and C, respectively), a lower concentration of ammonia (7.3, 10.1 and 9.5 mMol/I in Groups A, B and C, respectively) and a lower C3 proportion in VFA (5.8, 9.5 and 10.2% in Groups A, B and C, respectively). Group A also, had the highest levels of total volatile fatty acids (57.4, 51.2 and 46.0 mMol/I in the A, B and C Groups, respectively). During the fattening period, rabbits of Group A showed a higher feed intake (127, 115 and 100 g/d, P < 0.01, in Groups A, B and C, respectively) and a poorer food conversion ratio (3.50, 3.12 and 2.78 in Groups A, B and C, respectively). Weaning age also exerted sorne specific effects, for example, on caecal content weight or post-weaning daily growth rate (36.5 g/d for C rabbits weaned at 30 days and 38.2 for B rabbits weaned with the same live weight but at 35 days; P<0.05). In conclusion, the feed/milk inlake ratio al weaning influenced some characteristics of caecal contents and some post-weaning performances of rabbits.
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