Maize-based diets are more conducive to crude protein reductions than wheat-based diets for broiler chickens

Abstract

The hypothesis that maize-based diets for broiler chickens are more conducive to crude protein reductions than wheat-based diets was examined. A total of 324 male, off-sex (parent line) Ross 308 chicks were offered nine experimental diets from 7 to 35 days post-hatch as a 3 × 3 factorial array of dietary treatments. The design included three levels of dietary crude protein (CP) of 222, 193 and 165 g/kg and three feed grains: maize, ground wheat, and whole wheat (150 g/kg added post-pelleting). The determined parameters included growth performance, relative gizzard and abdominal fat-pad weights, nutrient utilisation, water and feed intakes over the total collection period and excreta dry matter, apparent ileal digestibility coefficients and disappearance rates of starch, protein (N) and amino acids (n = 15), concentrations of free amino acids (n = 20) in systemic plasma, and Pearson correlations between apparent ileal digestibility coefficients of neutral amino acids. The growth performance of birds offered the 165 g/kg CP maize-based diet was very acceptable relative to their 222 g/kg CP counterparts with significant advantages of 7.05 % in weight gain (2370 versus 2214 g/bird), 8.51 % in feed intake (3481 versus 3208 g/bird) and a numerical disadvantage of 1.38 % (1.473 versus 1.453) in FCR. In contrast, 165 g/kg CP ground wheat-based diets supported highly unsatisfactory growth performances. In comparison to 222 g/kg CP wheat-based diets, there were pronounced disadvantages of 35.5 % (1549 versus 2403 g/bird) in weight gain, 18.5 % (2843 versus 3487 g/bird) in feed intake and 26.6 % (1.840 versus 1.453) in FCR. Thus, the hypothesis that maize-based diets are more conducive to CP reductions than wheat-based diets was unequivocally established. While it is not straightforward, the genesis of the inferiority of wheat relative to maize in this context is considered against the background of the observations recorded in the present study.