Effect of genotype on semen quality traits of main and reciprocal crossbred chickens
Semen quality of cocks is of utmost importance in reproduction. Breeding method, breed, strain and genetic constitution are the major components of the genetic factors capable of affecting the semen quality of cocks. This research seeks to determine the effect of genotype on the semen quality traits of 272 F crossbred cocks produced at day-old by main and 1 reciprocal crossbreeding of 69 Isa Brown and local frizzle feathered, naked neck and normal feathered chickens. The genotypes of the cocks were Isa Brow x frizzle feathered main cross (IBxF), Isa Brown x naked neck main cross (IBxNa), Isa Brown x normal feathered main cross (IBxN), frizzle feathered x Isa Brown reciprocal cross (FxIB), naked neck x Isa Brown reciprocal cross (NaxIB) and normal feathered x Isa Brown reciprocal cross (NxIB). At 36- 40 weeks of age, semen was extracted from the cocks by abdominal massage technique and used to evaluate semen volume (SV), sperm motility (SM), sperm concentration (SC) and live sperm (LS) at weekly intervals. Data obtained from the evaluation were subjected to analysis of variance and tested at 5% level of probability. Genotypes differed significantly (P <0.05) in SC at 37-40 weeks and in SM and LS at all ages. There was no significant difference (P >0.05) in SV. Regardless of genotype and age, the mean SV, SM, SC and LS ranged from 0.31±0.02 to 0.24±0.01ml, 71.84±1.33 to 58.75±2.16 %, 3.22±0.02 to2.92±0.02 x109/ml and 71.91±1.37 %, respectively. The NxIB and IBxNa genotypes produced largest numerical semen volume at 37 and 39 weeks of age respectively. Whereas SC and LS were significantly highest for IBxF and IBxN respectively at week 37, SM was so for IBxN at all ages. Further, the LS of IBxN genotype was significantly highest at 36-38 and 40 weeks of age. The exotic Isa Brown and normal feathered main cross cocks exhibited the best semen quality traits among all genotypes studied and should be selected for improvement of the reproductive characteristics of cocks.
Keywords: Chicken, crossbreeding, crosses, reproductive traits.