Genetic improvement of growth traits, disease resistance and docility of four varieties of local guinea fowl in Ghana

Abstract

The goal of this work was to improve productivity of indigenous Guinea fowl varieties in Ghana. The objectives were to: (1) estimate average values of traits and verify sex and seasonal effects on traits; (2) determine disease resistance in local Guinea fowls using using SRBC as an indicator trait; (3) measure DOC in local Guinea fowls by the use of cage score and heterophil/lymphocyte ratio; (4) estimate phenotypic and genetic parameters and (5) estimate genetic gain of 3rd generation birds for body weight, disease resistance and DOC. The study was conducted at the Animal farm of the Department of Animal Science Education, University of Education, Winneba, Mampong-Ashanti campus, Ghana. Data used was obtained from four varieties of indigenous Guinea fowls which were randomly picked from a large population and reared from 2015-2018. Data was analyzed using General Linear Model (GLM) procedure of Statistical Analysis System (SAS for Windows, version 7). Pearl Guinea fowls had better (p<0.05) body weight, body weight gain, EGGWT and HDEP relative to the other varieties. Keets hatched in the minor rainy and dry seasons had better (p<0.05) HWT. Body weight was higher (p<0.05) during the major rainy season at 8, 16, 24 and 32. Daily weight gain was higher (p<0.05) in the dry season at 8-16 weeks of age and was better (p<0.05) in the major and minor rainy seasons at 16-24 weeks. Lavender varieties laid their first eggs earlier (p<0.05) than their other counterparts. FERT was higher (p<0.05) in the Pearls than in the other varieties. Black strain showed the best (p<0.05) HATCH potentials. Lavender, White and Black strains produced more (p<0.05) protein in the meat compared to the Pearl. The White strain had the best (p<0.05) DRESSP. Lavender was the most (p<0.05) docile strain. Pre-brooding survival was higher (p<0.05) in the Pearls and lower (p˃0.05) in the Black. Post-brooding survival was higher (p<0.05) in males than in females. FCR was better (p<0.05) for bids hatched during the dry season. University of Education,Winneba http://ir.uew.edu.gh xxii The Pearl genotype had the highest (p<0.05) immune competence. Antibody response to SRBC antigen was better (p<0.05) in females than in males. Intravenous injection was more effective (p<0.05) in presenting SRBC antigen to immunocompetent cells than the intramuscular injection. Body weight and EMWTG showed the highest (p<0.05) additive genetic variation. Direct heritability estimates in the Guinea fowls were high for HWT, 2 and 4 months body weight, moderate at 6 and 8 in both males and females. The heritability estimates of body weight gains were moderate at month 2 and 6 but low at month 4 and 8 in the males whereas in the female counterparts the estimates were moderate at month 2 and 4 and low at 6 and 8. Heritability estimates for SVV, DRESSP and FI were all low in the males and females apart from FI which was medium in the females. DOC and FCR heritability estimates were moderate in both males and females. Estimates of heritability of EGGWT and HDEP were high, moderate at ATFE and low for FERT and HATCH. Genetic and phenotypic correlations among HWT, TMWT, FMWT, SMWT, EMWT, TMWTG, FMWTG, SMWTG, EMWT, FI, FCR, DRESSP, SVV, DOC, ATFE, HDEP and EGGWT were moderate to high and positive.The mean response for each trait improved in the positive direction over the three generations of selection. ATFE, egg numbers and weight, growth traits and docility were affected to a very large extent by additive genetic effect and genetic selection can be used to improve them. Moderate to high positive genetic correlation existing in the SMWT, DOC and SVV is an indication that these traits could be exploited in multiple trait selection using the selection index.