The effect of an elevated fat level and feed protein concentrate on nutrient utilization and carcass quality of broiler chickens

Ninety-six Hybro broiler chickens were fed diets with increasing protein and energy contents at a constant protein-to-energy ratio: with no added fat (I, control), with 5% added fat (II), 9% (starter) and 10% (grower) added fat (III), 6% (starter) and 8% (grower) added fat and instead of soyabean meal, fish meal and premix, 10% feed protein concentrate (FPC) made from a meat-and-bone meal (MBM) and supplemented with amino acids, vitamins, and minerals (IV).Increasing the protein and energy concentrations improved body weight gains by an average of 26.5% (P<0.01) and lowered feed intake per kilogram gain by 16.3% (P<0.01) in comparison with the performance of control chickens (I).The use of FPC (IV) reduced the final body weight of the chickens by 2.1% and increased feed consumption by 5.6% (P<0.05) in comparison with chickens fed diets with a similar protein and energy content (III).Both the apparent protein digestibility coefficient of the diet as well as nitrogen retention determined by the slaughter method were lower in group IV than in the other groups (P<0.05 in both instances).The protein content in the body of chickens fed diets containing FPC (IV) was lower (P<0.05)than in the remaining groups with a concomitant distinct tendency towards a higher fat content.The carcass dressing percentage of chickens fed fat-supplemented diets was higher than in control chickens (P<0.05).The use of FPC reduced breast muscle palatability (P<0.05).