Effect of genotype and seasons on semen characteristics of three indigenous cock types in the semi arid zone of Nigeria

The effects of seasons and genotype on semen characteristics of three indigenous cocks types in semi arid zone of Nigeria were assessed. Fifteen (15) local breeder cocks at maturity comprising three strains of indigenous cocks (5 Frizzled, 5 Normal feathered and 5 Naked Neck) were obtained from local farmers in the study area and were used for the study. This employed a 3x4 factorial in a completely randomized design. Semen sample were collected from September 2016 to August 2017 by abdominal massage method, and were assessed for semen colour, semen volume, semen pH, and by routine laboratory methods for semen concentration, sperm motility, sperm abnormality, percent dead sperm cells. The highest mean value of semen volume (0.45ml) was obtained in frizzle feathered cocks while the lowest mean value of (0.31ml) was obtained in the naked neck cock. Coefficient of variability was highest in semen volume and ranged from 29.77% in the normal feathered to 43.69% in the frizzle feathered cock. The lowest variable semen characteristics were pH which showed percentage variability that ranged from 4.25% in the naked neck to 6.13% in the normal feathered cock. Coefficient of variation for percent dead sperm cells, semen concentration and percent abnormality values ranges between 12.67 and 15.60%. Genotype had a significant (p<0.05) effect on semen volume with frizzle feathered having the highest value of 0.48±0.02 ml followed by the normal and naked neck cock with corresponding values of 0.33±0.01ml and 0.30 ±0.01 ml. Semen colour, pH, motility, concentration, percent dead sperm cells and abnormality were not significantly (p>0.05) affected by genotype of bird. Season of year significantly (p < 0.05) affected all the semen characteristics. The results indicated that for semen volume, early dry season had the highest mean value which is significantly different from the mean values obtained in the late dry, early rainy and late rainy season, which are statistically similar. The semen colour showed no significant (p> 0.05) difference in the early dry, late dry and early rainy season but these seasons were significantly (p<0.05) higher in colour intensity than the late rainy season. The intensity of semen colour decrease with the rains. Semen pH was nearly neutral in all the season except early rainy season which tended towards acidity and was significantly different from the other seasons. There were no statistically significant (p> 0.05) interaction effects on almost all semen characteristics except semen volume. Semen volume was the same in late dry and late rainy seasons which was significantly different (p< 0.05) for early dry and early rainy in the normal feathered and naked neck genotype. The combined effects of season and genotype had no significant effect on semen volume in the frizzled feathered cock. The non-significant (p> 0.05) effect of the combined factors of season and genotype on the semen volume of the frizzled cock demonstrates the robostness or stability of the frizzle cock in terms of ejaculates volume all year round. From the results of this study, it is recommended that the frizzle feathered cock should be the genotype of choice for genetic upgrading in the region because of its stability in semen characteristics in all the seasons of the year.