Mass selection for 70-day body weight in rabbits

Area of Science:

• Animal Genetics and Breeding
• Quantitative Genetics
• Livestock Production

Background:

• Phenotypic mass selection is a common method for improving quantitative traits in livestock.
• Understanding genetic parameters is crucial for effective selection programs.
• Rabbit meat production relies on efficient growth and desirable carcass characteristics.

Purpose of the Study:

• To evaluate the effectiveness of five generations of phenotypic mass selection for increasing 70-d body weight (market age weight, MW) in rabbits.
• To estimate genetic parameters (heritability and correlations) for growth and carcass traits.
• To assess correlated responses in other traits due to selection for MW.

Main Methods:

• Five generations of phenotypic mass selection for MW in experimental rabbit lines (Select and Control).
• Measurement of growth traits (MW, 28-d weaning weight (WW), 28- to 70-d average daily gain (ADG)) and carcass traits (carcass yield percentage (CY), loin primal cut percentage (LP), lean-to-bone ratio in the loin primal cut (LBR)).
• Analysis using an animal model with Restricted Maximum Likelihood (REML) and regression procedures to estimate heritabilities and genetic correlations.

Main Results:

• Significant genetic trends for MW (29.1-29.4 g/generation) were observed.
• Heritability estimates for MW were .12 (observed) and .11 (realized).
• Positive and moderate to high genetic correlations were found between MW and WW/ADG (range .56-.98).
• Favorable correlated responses were noted for WW, ADG, and LBR, while other carcass traits showed inconclusive results.

Conclusions:

• Five generations of selection were effective in increasing rabbit market-age weight.
• Selection for MW had favorable correlated effects on some growth and carcass traits.
• The study provides valuable genetic parameter estimates for rabbit breeding programs.