Effects of genotype and plane of nutrition on performance, carcass composition, meat quality traits and nutrient content of guinea fowl (Numida meleagris) broilers raised in the tropics

Genetic selection of guinea stocks has improved production efficiency however studies directed to evaluate the nutritional requirements of new genotypes are limited. A total of 675 guinea keets from three (3) genotypes diverging in their genetic background a native genotype (NG) and two commercial genotypes (CG1, CG2) selected for rapid growth were raised under three feeding regimes to market age. Three experimental diets were formulated to provide a low (LPN), intermediate (IPN), and a high (HPN) plane of nutrition based on the crude protein and metabolizable energy of diets. Birds and feed were weighed at the end of the starter (35 d), grower (63 d), and finisher (84 d) periods to obtain body weight (BW), feed intake (FI), and feed conversion (FC). At 84 d, 35 birds per treatment were randomly selected and processed to evaluate carcass composition. The weights of New York dressed (NYD), ready to cook (RTC), and fat pad (FP) were obtained and yields calculated as a percentage from live BW. Carcasses were cut into major retail parts, weights were obtained and yields calculated as a percentage from live BW. Breast and thigh muscles were evaluated for pH, color, and water holding capacity (WHC). Breast fillets were also evaluated for cook loss and tenderness. Two carcasses per treatment were grounded to evaluate protein, ash, and fat content.Performance. A significant main effect of genotype for BW was found at 35, 63, and 84 d where birds of both CG had significantly heavier weights compared to NG. At 35 d, birds under IPN and LPN diets had significantly lower weights compared to birds under HPN diet. No significant differences were observed for FI. At 35, 63, and 84 d a significant effect of genotype was found for FC where both CG obtained similar but significantly lower FC compared to NG. Guineas of the NG had significantly lower percentage of FP weight and yield than the CG evaluated. Birds fed IPN and HPN diets obtained higher FP yields than guineas raised under a LPN regime.Meat quality. No significant differences were found for thigh pH among genotypes. However, CG2 breast fillets had significantly higher pH values than the NG. Thigh muscles of both CG had similar but higher WHC than the NG. No differences among genotypes were found for WHC of breast muscles. Thigh L* and a* values were significantly higher in both CG. A significant genotype and plane of nutrition interaction was found where birds of NG fed LPN diets obtained significantly lower breast L* values than the other treatments. The NG obtained significantly higher a* values than both CG. No significant differences were found for breast meat tenderness.Nutrient content. A significant main effect of genotype was determined were CG1 obtained significantly lower percentage of total, saturated, unsaturated, mono-unsaturated, and poly-unsaturated fat than birds from the CG2 and NG. Birds from CG1 also obtained levels of Omega 3 and Omega 6 significantly lower than the other genotypes.This investigation confirms that genetic selection has made significant improvements on live performance and carcass traits of guinea broilers. Heavier weights of commercially important carcass parts, breast, tender, and thigh are obtained when CG are grown. Guinea carcasses have a low content of fat and cholesterol with acceptable amounts of omega 3 and 6 fatty acids.