Effects of crossbreeding on rabbit production I. Growth characteristics of rabbits from weaning to sexual maturity

Postweaning growth characteristics of 115 rabbits were studied for 12 weeks period. Rabbits were classified into 4 breed groups namely Thai native (N), New Zealand White (NZW) originated from New Zealand and 2 reciprocal crosses between these two breeds (NxNZW and NZWxN). They were reared under uniform environment in individual feeding units with automatic waterer at the Department of Animal Husbandry Rabbit colony, Nakorn Pathom. All rabbits were fed 14% protein diet and freshly cut paragrass ad lib. Weights and amount of feed consumed were recorded biweekly. Total and daily feed consumed, gain and average daily gain as well as feed conversion ratio were calculated at the end of the experiment. Least squares analyses of variance revealed significant breed group effects on weaning weight, weight at 10 and 12 weeks of the experiment, gain (P .05), average daily gain and feed conversion (P .01) Sex differences were found in weight at 12 weeks of the experiment (P .01), total and daily feed consumed, gain and average daily gain (P .05). Breed group by sex interaction was important in weights at 10 and 12 weeks of the experiment, gain and average daily gain (P .05). Least squares means and breed group comparisons were presented. Breed group contrast between purebreds revealed that NZW rabbits were smaller than N rabbits at weaning and no significant differences were observed after that except for weight at 10 weeks of the experiment. NZW rabbits were more efficient in feed conversion than N rabbits, NxNZW and NZWxN reciprocal crosses were similar in all growth traits. Crossbree-purebred contrasts showed adventages of crossbred over purebred rabbits in gain, average daily gain and feed efficiency (P .05). Heterosis of all traits studied were low which is normal for growth characteristics since they are moderately to highly heritable.