Abstract:
The aim of the present study was to investigate the effect of breed on some weaning and post-weaning
performance traits as well as estimation of heterosis and combining ability for these traits. Two bucks and five does
from each of New Zealand White, Californian and Gray Giant Flander breeds were used as parents to produce 183
progeny. Significant differences were observed among different progeny genotypes for body weight, average daily gain
(ADG) and relative growth rate (RGR) at weaning and post-weaning growing period. New Zealand White x Flander
rabbits recorded the heaviest weaning weight (668.18 g). On the other hand, Californian x New Zealand White
recorded the heaviest market weight at 12th week of age (2278.52 g) and the highest ADG at the age periods from 4-
6 weeks (45.29 g) and 10-12 weeks (24.01 g). New Zealand White x Californian recorded the highest RGR at the
age period of 4-6 weeks (72.50%). Californian x New Zealand White rabbits recorded the highest positive estimates
of heterosis for body weight at all ages studied (22.69, 17.60, 6.76, 4.50 and 7.60 % for weaning, 6th , 8th , 10th , and
12th week of age; respectively), also the highest positive estimates for ADG at the age period from 4-6 weeks (12.77
%), while Californian x Flander rabbits recorded the highest positive estimates at 10-12 weeks of age (42.27 %). In
general, effect of general combining ability (GCA) was non-significant (p>0.05) on body weight, ADG and RGR at
most of ages studied, while effect of specific combining ability (SCA) were highly significant (p<0.01) on body
weights at most of ages studied, but non-significant on ADG and RGR at most of age intervals studied. In
conclusion, we recommended the use of Californian as a sire breed to improve body weights and body weight gains
of fryer rabbits and crossing of Californian males with New Zealand White females will improve body weights and
body weight gain due to heterotic effect. Gray Giant Flander does is better mothers than Californian and New
Zealand White which is reflected by higher weaning weights of progeny of Gray Giant Flander does. Moreover, Gray
Giant Flander breed and specifically, crossing of New Zealand White with Californian are the best to improve body
weights of fryer rabbits during weaning and post-weaning period
