Response to Selection of Indigenous Chicken in Rwanda Using Within-Breed Selection Strategy

Abstract

The study evaluated response to selection from within-breed selection strategy for conventional (<I>CBS</I>) and genomic (<I>GBS</I>) breeding schemes. These breeding schemes were evaluated in both high-health environments (nucleus) and smallholder farms (commercial). Breeding goal was to develop a dual-purpose IC for both eggs and meat through selective breeding. Breeding objectives were body weight (BW), egg weight (EW), egg number (EN) and resistance to Newcastle disease (AbR). A deterministic simulation was performed to evaluate rates of genetic gain and inbreeding. Base population in the nucleus was made up of 40 cockerels and 200 pullets. Selection pressure was 4% and 20% in the males and the females, respectively. The impact of nucleus size and selection pressure on rates of genetic gain and inbreeding of the breeding program was investigated through sensitivity analysis. SelAction software was used to predict rates of genetic gain and inbreeding. Results showed that using <I>CBS</I> in the nucleus, the breeding goal was 340.41\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\$ and 1.13 times higher than that in the commercial flock. Inbreeding rate per generation of selected chicken in the nucleus was 1.45% and lower by 1.32 times compared to their offspring under smallholder farms. Genetic gains per generation in the nucleus for BW and EN traits were 141.10 g and 1.07 eggs and 1.12 and 1.10 times greater than those in smallholder farms, respectively. With <I>GBS</I>, the breeding goal was increased by 3.00 times whereas inbreeding rate was reduced by 3.15 times. Besides, using <I>GBS</I>, the selected birds in the nucleus were relatively similar to those in a commercial environment. Finally, the study revealed that the nucleus size and mating ratio influence the rates of genetic gain and inbreeding in both <I>GBS</I> and <I>CBS.</I> This study shows that IC in Rwanda have the potential to be improved through within-breed selection strategy using either <I>CBS</I> or <I>GBS</I>.