ADDITIVE AND NON-ADDITIVE GENE EFFECTS ON LINEAR BODY TRAITS OF LOCAL TURKEYS REARED IN THE HUMID TROPICS OF NIGERIA

Abstract

Research reports on genetic evaluation of growth traits, general and specific combining ability effects in domestic turkeys are rare; hence the need for this study. Breeding programmes involve crossbreeding of various strains of turkey to improve the already existing breeds and to estimate specific and general combining abilities in the domestic turkey. General Combinig Ability (GCA) and Specific Combining Ability (SCA) were used to determine the influence of additive and non-additive genes effects on linear body traits, using a total of 215 1-day-old poults of three strains of local turkey crossbred in the humid tropics. A full diallel crossing experiment was conducted using three phenotypes of indigenous turkeys with the plumage colour: black, white and lavender (spotted). Randomized complete block design (RCBD) was also used to analyze the data with phenotypic class as a major factor and batch as block. Parameters measured includes: Body weight (BWT), Body length (BDL), Shank length (SL), Keel length (KL), Wing length (WL), Breast width (BW), Drumstick length (DL), Neck Length (NL). Data obtained were subjected to analysis of variance (ANOVA). The result obtained in the showed that GCA was significant for BL, WL, DS and SL and non-significant for BW, BRW, KL and NL with values ranging from – 0.34 to 0.640, respectively. SCA was also significant for BL, BW, BRW, KL and SL but non-significant for WL, DS and NL ranging from 2.981 to 8.324. It was concluded that the significance (P<0.05) differences observed for most LBMs and BW in different ages (weeks) for GCA and SCA indicates that non-additive effects of genes could be improved genetically through selection and crossbreeding of BxS, BxW and WxS genotypes to bring about genetic improvement for BW and LBMs and by improving the environment. The additive gene action governs BL, WL, DS and SL and not for the other traits which may be governed by genes with non-additive effect.