ABSTRACT
A study was conducted using 231 chicks (101 Normal feather, 56 frizzle and 74 Naked neck) to evaluate growth traits and semen quality characteristics using biochemical and IGF-1 as molecular marker on three genotypes (normal, frizzle and naked neck) of Nigeria indigenous chickens. Each of the genotypes comprised of twenty five hens and five roosters mated in the ratio of 1 rooster: 5 hens (1:5). Body weight (BW) and measurements of breast girth (BG), shank length (SL), body length (BL), wattle length (WL), wattle width (WW), comb length (CL), comb height (CH), wing span (WS) and shank diameter (SD) were taken at an interval of 4 weeks starting from 8 weeks of age. Semen quality characteristics (volume, colour, pH, concentration and live and dead ratio) and morphological defects (acrosoma swelling, detached head, mid piece drop, bent tail, curled tail and full tail) were evaluated thrice at 24, 28 and 32 weeks of age, respectively. Blood samples for the haematological, biochemical and molecular studies (IGF-1) were collected at 20 weeks of age. The data collected were subjected to General Linear Model procedure of SAS. The result showed that mean BW between 8 and 20 weeks ranged from 310.46g to 1117.80g and between 1096.80g and 1285.80g from 24 to 32 weeks with significant (P<0.05) differences with the normal feathered birds having the superior BW between 20 to 32 weeks of age. However, apart from BW and BL which were significant at all ages, other body linear measurements were not significantly (P>0.05) different at all the ages (8 to 32 weeks). The semen quality characteristics for the parameters were significantly (P<0.05) different except for semen colour and semen pH which were not significant (P>0.05) affected by the age of the birds. The morphological xviii defects showed that most of them were significantly (P<0.05) different for all the genotypes, but the mid piece was not significantly (P>0.05) different at 32 weeks. The results of the haematological and biochemical profile show that only Chloride in the biochemical parameter was significantly (P<0.05) different. The phenotypic correlation coefficients between traits show that some traits had positive correlation but not statistically significant (P>0.05) while others traits showed between moderate and high correlations amongst themselves. Two alleles; A and B and three genotypes: AA, AB and BB were observed with the A allele (0.72) being predominant and conforms to Hardy-Weinberg equilibrium. The relationship among IGF-1 marker, BW and semen quality was significant (P<0.05). The AA genotype was superior in body weight over the AB and BB genotypes at 28 and 32 weeks. Therefore, it is concluded that the normal feather genotype did better in terms of BW and body linear measurements (BLM). The semen characteristics revealed that as age increased the quality improved up to 28 weeks, while the IGF-1 gene had a positive relationship with BW and semen characteristics making it a good genetic marker for selection for growth traits (BW) and semen characteristics in the Nigerian indigenous chickens.
