Influence of breed type and age on spermatological traits of Nigerian local chickens
This study evaluated semen quality traits of 36 roosters, comprising 18 roosters each of normal feather and naked neck Nigerian local chicken (NLC) breeds at different ages. The abdominal massage technique was used to collect semen samples from individual roosters at 28, 32, 36 and 40 weeks of age. Individual ejaculates were assessed for semen volume, sperm concentration, total sperm count/ejaculate, motility, morphology and viability. Results of the semen evaluation indicated that except for semen volume, breed of rooster did not statistically influence other spermatological traits studied. The normal feather had higher semen volume (0.13 mL) than the naked neck roosters. Semen volume, sperm concentration and total sperm count/ejaculate were influenced by age (p < 0.05). There was a 44.16% increase (p < 0.05) in semen volume between 28 and 36 weeks of age and 24.67% decrease by 40 weeks. Sperm concentration was highest at 28 weeks with a decrease of up to 1.32 × 109mL-1 at 40 weeks whereas total sperm count/ejaculate was highest at36 weeks of age. Sperm viability ranged from 70.60-80.00% and did not vary between the two breeds at different ages. It can be concluded that though there exist marginal variations in spermatological traits of the normal feather and naked neck roosters due to their genetic constitution and age, both breeds could still be used efficiently in planning artificial insemination/breeding programmes for genetic improvement of the Nigerian local chicken since the results obtained were within the accepted reference range for chickens.
Key words: artificial insemination, naked neck, Nigerian local chicken, normal feather, semen quality