Selection on Litter Size at Birth and Correlated Responses in Pre-weaning Litter Traits of Heterogeneous Rabbits in Southern Nigeria

Mass selection to improve litter size at birth in rabbits will contribute to bridging the protein deficiency gap and improve income for rabbit farmers. The study investigated the effect of mass selection on litter size at birth and the correlated responses in pre-weaning litter traits in mongrel rabbits. One hundred and five female rabbits form a total of one hundred and ninety-six (196) progeny (91 males and 105 females) generated from a mating scheme involving eighteen (18) bucks and forty-eight (48) dams constituted experimental animals for the study. The selection criterion was litter size at birth (LSB). Animals were housed in three-tier hutches and fed with concentrate diet containing 15.81% protein, 2480 kcal energy and 8.22% fiber in the morning and green forages in the evening. Mass selection was performed on the criterion within three generations (FS, F1 and F2). The experiment employed a nested design where dams were nested within sires. Pre-weaning litter traits studied with the criterion of selection were litter birth weight (LBW), kits birth weight (KBW) and number of kits born alive (NBA). Results revealed that LSB did not significantly (p>0.05) evolve with selection, although numerical improvements were observed. Sire and dam effects were not significant for the criterion. Values noted for LSB were 4.46±0.14, 4.48±0.15, 4.50±0.11 and 4.51±0.18 kits in FS, F1, F2 and F3 respectively. Realized selection responses per generation were 0.02, 0.02 and 0.01 in FS, F1 and F2 respectively. Responses were less than expected in F2 and F3 generations of selection but similar in F1. The correlated changes in pre-weaning traits were non- significant (p>0.05) but with numerical improvements of 193.82±2.03, 193.38±2.27, 203.79±3.88 and 203.81±3.88 g for LBW and 4.09±0.16, 4.11±0.13, 4.20±0.09 and 4.21±0.17 for NBA but reduction of 43.56±1.16, 43.36±1.41, 42.99±0.65 g for KBW in the three generations respectively. It is concluded from this study that mass selection on litter size at birth (LSB) neither significantly improved the trait nor the pre-weaning traits that were correlated with it. Litter size at birth in heterogeneous rabbits could be genetically improved using other improvement strategies such as cross breeding.