COMPARATIVE ASSESSMENT OF FERTILITY, HATCHABILITY AND SURVIVABILITY OF BOVAN NERA AND ISA BROWN BREEDER COCKS UNDER HUMID TROPICAL CONDITIONS OF NIGERIA
Keywords:Breed, Batch, Age, Fertility, Hatchability
The determination to identify a more, viable, adaptative and efficient breed of breeder cocks between two genotypes commonly used in the poultry industry to produce colour-sexed black and brown pullets necessitated this research work. There is the problem of productivity and viability with our commercial layers which could be a direct result of their parents inability to adapt to the prevailing hot weather conditions. The two genotypes are: Isa Brown (IB) and Bovan Nera (BN). The number of breeder cocks evaluated in three separate batches per breed between 2002 and 2005 were 1690 and 1333 for IB and BN respectively. Performance records, in terms of fertility, hatchability and survivability were assessed in order to identify the more productive and viable breed for the zone. The observed general means for fertility and hatchability of 83.86% and 69.18% respectively. Breed had a highly significant (P<0.001) effect on fertility and hatchability. BN cocks recorded higher percent fertility and hatchability of 83.86% and 73.25% respectively, while IB cocks had fertility and hatchability values of 81.57% and 63.97% respectively. Batch has no significant (P>0.05) effect on fertility but positive influence (P<0.001) was indicated for hatchability with Batch 1 having the highest percent fertility of 70.50% while Batches 2 and 3 recorded mean values of 68.39% and 66.93% respectively. Breed and batch had a highly significant (P<0.001) effect on survivability (P<0.01). BN cocks had lower mortality of 18% when compared to their IB cocks which recorded 27%. Age of cocks also had a highly significant (P<0.001) effect on fertility, hatchability and survivability. Percent fertility (84.70%) was highest in the 45 to 54 weeks age category, while hatchability (74.50%) peaked at 35 to 44 weeks age category. There was a significant interaction of breed and age effects on these reproductive traits (P<0.01), implying that both traits were breed and age dependent. IB genotype recorded better results at 45 to 74 weeks. BN cocks recorded lower mortality rate throughout the age subdivisions than IB. Bn cocks appeared hardier, productive and adapted to hot and humid climatic conditions. This breed showed genetic superiority in all the reproductive traits considered over IB genotype.