Performance of purebred and crossbred rabbits in Australia: doe reproductive and pre-weaning litter traits

TLDR: High phenotypic variances and coefficients of variation observed for traits NW and LWW indicate that good response could be realised through selection and selection methods, and Buck breed did not have any significant effect on any of the pre-weaning litter traits under study.

Abstract: Data from a rabbit breeding experiment were analysed to compare the doe reproductive and pre-weaning litter performance of 3 breeds of rabbits, namely New Zealand White (N), Californian (C), and Flemish Giant (F), and their crosses CN (C × N) and FN (F × N). The foundation stock of 152 rabbits was collected from 26 different sources in New South Wales, Australia. Data on reproductive traits, doe age at first successful mating (DA), doe weight at first successful mating (DW) arising from 104 does, conception rate (CR) from 808 matings, and kindling interval (KI) from 325 records of 119 does were analysed. Overall means for reproductive traits DA, DW, CR, and KI were 21 weeks, 3.6 kg, 0.75, and 7.4 weeks, respectively. DA, CR, and KI did not differ significantly among different breeds and their crosses. DW of C does was found to be significantly lighter than all other breed crosses in the study. Month-year of mating significantly affected DA, DW, and CR (P < 0.01), and as the parity number increased, there was a significant (P < 0.01) decrease in KI. As age of the doe at mating increased there was a significant increase in DW (P < 0.01), CR (P < 0.05), and KI (P < 0.01). Data from 436 litters of 157 does were included in the analysis of pre-weaning litter traits. The overall means for the pre-weaning litter traits were: number born per litter (NB, 8.1), number born alive per litter (NBA, 6.9), number weaned per litter (NW, 3.3), total litter birth weight (TLBW, 453.7 g), live litter birth weight (LLBW, 397.1 g), litter weaning weight (LWW, 2.8 kg), and average birth weight of kits per litter (ABW, 58.1 g). Doe breed significantly affected NW (P < 0.05), TLBW (P < 0.01), LLBW (P < 0.05), LWW, and ABW (P < 0.01). N does and crossbred does (CN and FN) performed better than purebred F and C does for NW and LWW. A significant heterosis of 41.9% and 40.8% was observed in CN does for traits NW and LWW, respectively. ABW of F does was significantly higher than that of all other breed crosses in the study. Buck breed did not have any significant effect on any of the pre-weaning litter traits under study. Parity significantly affected NW (P < 0.05), TLBW (P < 0.01), LLBW (P < 0.05), and ABW (P < 0.01). First parity does produced litters with significantly lighter birth weights. The month-year of birth effect was significant for NW, LWW (P < 0.01), and ABW (P < 0.05). The coefficients of variation for the doe reproductive traits and pre-weaning litter traits ranged between 12.1 and 59.5% and 16.1 and 93.3%, respectively. High phenotypic variances and coefficients of variation observed for traits NW and LWW indicate that good response could be realised through selection. Repeatability estimates for reproductive traits CR and KI were very low. Low to moderate repeatability estimates in the range 0.17-0.25 were observed for pre-weaning litter traits. Significant positive phenotypic correlations were observed between litter size and litter weight traits (0.30-0.97). A significant negative correlation was observed between ABW and NB (-0.56) and NBA (-0.36). Additional keywords: selection, repeatability, phenotypic variance, phenotypic correlation. Ae oAu K.a aa