Response of two broiler genotypes to diets with varying levels of inclusion of palm kernel oil residue (PKOR)

An experiment was carried out to evaluate the effects of strain of broilers and different levels of inclusion of palm kernel oil residue (PKOR) diets on the growth and carcass characteristics of two commercial broiler strains. A total of 450 birds were evaluated in a 2 x 3 factorial experiment involving two broiler strains (Cobb and Ross) and three dietary treatments with 0%, 10% and 20% levels of inclusion of PKOR. For each of the broiler strains, a total of 225 birds were randomly assigned to each of the three diets with each dietary treatment having 75 birds with three replications with 25 birds in each replicate group. The experiment was done using 3-week old broiler chicks and fed over a period of 5 weeks in 18 partitioned deep litter pens (2.5m x 2.1m; floor space of 0.21m2 /bird). Both feed and water were supplied ad libitum, under a 24-hour lighting regime. Growth parameters were taken from week three to week eight. At the end of the experimental period, 4 birds from each replicate group were randomly selected and slaughtered for carcass evaluation. Data obtained were subjected to a two-way Analysis of Variance (ANOVA) with strain of broilers and dietary treatments as fixed factors using the general analysis of variance procedure of GenStat. Where differences in means occurred, the means were separated using the least significant difference (LSD) test at 5% level of significance. The results showed no significant effect of genotype on growth performance. There were, however, significant difference in growth performance with the different levels of inclusion of the PKOR, with the birds on the control diets (0% PKOR) being superior in terms of final live weights as compared to the birds fed 10 and 20% levels of inclusion of the PKOR diets. Interestingly, birds fed 0% and 20% levels of inclusion of PKOR were able to significantly convert feed to meat better (better FCR) than their counterparts on the 10% level of inclusion. There were no significant genotype × diet interaction effects on all performance parameters assessed. Furthermore, the results obtained showed no significant (p>0.05) effect of genotype on carcass characteristics. On the other hand, birds on 0% PKOR recorded significantly (p<0.05) higher warm carcass weight and warm dressing percentage than birds fed 10% and 20% PKOR; chilled carcass traits assessed were, however, similar (p>0.05) for all dietary treatments. The effects of genotype x diet interactions on all carcass traits assessed were not significant (p>0.05). The outcome of this work showed that the inclusion of PKOR at 10% and 20% led to a reduction in feeding cost/kg weight gain of US$0.34 and US$0.45 respectively; this can increase the profit margin of farmers.