Rabbit Lines Divergently Selected for Total Body Fat Content: Correlated Responses on Growth Performance and Carcass Traits

SIMPLE SUMMARY: The aim of this study was to examine the effectiveness of selection for total body fat content and its effect on productive and carcass traits. Growing rabbits were selected for high or low body fat content. The selection was effective, and the difference in fat reserves (perirenal fat and scapular fat content) increased with each generation. After four generations, the feed conversion rate improved, and the ratios of fore and hind parts increased in lean rabbits. Selection for lower total body fat content could be useful for customers who want to buy animals and meat with lower fat content; while selection for higher fat content could be advantageous for rabbit does because they have more fat (energy) deposits which are in positive connection with maternal ability and a longer lifespan. ABSTRACT: The aim of this experiment was to study the effect of divergently selected rabbits for total body fat content (fat index) on growth performance and carcass traits. The fat index was determined at 10 weeks of age by computed tomography and lasted for four consecutive generations. The rabbits with the lowest fat index belonged to the lean line and those of the highest values belonged to the fat line. At generation four, 60 rabbits/line were housed in wire-mesh cages and fed with commercial pellet ad libitum from weaning (5 w of age) to slaughtering (11 w of age). Growth performance, dressing out percentage and carcass adiposity were measured. The lean line showed a better feed conversion ratio (p < 0.001) than the fat line. Furthermore, the carcass of the lean rabbits had the highest proportion of fore (p < 0.020) and hind (p < 0.006) parts. On the contrary, rabbits of the fat line had the highest carcass adiposity (p < 0.001). The divergent selection for total body fat content showed to be effective for both lean and fat lines. Selection for lower total body fat content could be useful for terminal male lines, while the selection for higher total body fat content could be an advantage for rabbit does in providing fat (energy) reserves.