| Summary: | A better understanding of genetic parameters is required to evaluate the combining abilities of different genotypes. The current experiment aimed to estimate crossbreeding parameters for body weight (BW), body weight gain (BWG), and feed conversion ratio (FCR) in genetic groups generated through reciprocal mating between Fayoumi (FM) and three other exotic breeds, namely, Koekoek (KK), Sasso (SS), and White Leghorn (WL) at different growth stages. Birds were weighed individually at hatch and every four weeks until 20 weeks, and BWG was determined. The FCR was estimated based on the feed intake of each genetic group. Purebred effect (PE), general combining ability (GCA), maternal effect (ME), specific combining ability (SCA), and heterosis were highly significant for BW, BWG, and FCR at different ages. Purebred SS had the highest PE and GCA for BW and BWG but the lowest estimate for FCR; in some instances, KK showed values slightly closer to SS's. Closely followed by KK, purebred SS had the highest ME for BW. Crosses of FM with WL and KK exhibited the highest SCA for BW and BWG and the lowest value for FCR, whereas reciprocal crosses between FM and KK had positive heterosis for BW and BWG but negative heterosis for FCR. The results generally suggest the importance of additive (PE, GCA, and ME) and non-additive (SCA and heterosis) genetic effects for the inheritance of growth and feed efficiency traits. In crossbreeding programs involving these genetic groups, synthetic breeds with different breed combinations could be developed using genotypes showing the highest additive effects (SS and KK) as male parents and those having the highest non-additive effects (FM x KK, KK x FM, and FM x WL) as female parents.
|
|---|