COMBINING ABILITY AND GENE ACTION OF VARIOUS STRAINS OF BROILER PARENTS 2. FEED CONVERSION

An experiment was carried out to estimate the combining ability and gone action of feed conversion. A total of 960 dam chicks and 200 sire chicks day old from broiler breeder strains (Fawbro, FB; IPA 2000, IP; Lohmann, LH; Hybro, HB) with 240 dam chicks and 50 sire chicks for each were used. At 24 wk of age, 160 dams and 46 sires from each strain were selected to be parents. They were mated a full 4 x 4 dialled cross, which resulted in a number og genetic groups equal to square of parents number (16 genetic groups). The comparisons among genetic groups were after obtaining hatching eggs (100 eggs combination) from parent dams at 50 wk of age. These hatching eggs were incubated to obtain the genetic groups thus used in this study. A total of 50 broiler chicks per strain crosses (800 chicks for all genetic combinations) were reared in floor house with 32 pens. They were assigned after wing-banded on the experimental replications with two replicates per combination (25-chicks replicate). There were significant differences on food conversion from 0-28, 29-49 and 0-49 days of age. The hybrids LHxHB exhibited better feed conversion ratio from 0-28 and 0-49 days of age. There were siginificant differences on htis trait from 0-28, 29-49 and 0-49 days of age. The hybrids LBxHB exhibited better feed conversion ratio from 0-28 and 0-49 days of age. The parents of FB and IP exhibited positive significant general combining ability (GCA). While, parents of LH and HB exhibited negative significant GCA only from 0-49 days of age. The hybrids LHxHB at 0-28 days of age and hybrids FBxIP and IPxLB at 29-49 days of age axhibited significant specific combining ability (SCA) on this trait. Reciprocal hybrids LHxHB exhibited positive significant reciprocal effect (RCA) at 0-28 days of age and negative RCA at 29-29 days of age. The degree of dominance was greater than 1.0 for of hybrids and less than 1.0 for reciprocals at 0-28 and 29-49 dats of age, which refer o partial dominance. While, it was zero at 0-49 days of age. This results refers to the role of additive genes effects.