The aim of this work is to study the effects of cereal type (corn or wheat–based diets), and multi-carbohydrase enzyme supplementation to broiler diets containing recommended, intermediate (-100) or low (-150) Kcal/kg ME energy levels and their interactions on broiler performance, protein and energy efficiency ratios, nutrient digestibility, carcass traits and some blood measurements.
A total of 480, seven day-old unsexed Cobb500 broiler chicks of 160 g average body weight were randomly divided into eight experimental treatments and three replicates per treatment group. The experiment consisted of 3 growing phases {starter (7-14 d), grower (15 – 28 d) and finisher (29 – 42 d)}. Diets were formulated to contain 21, 19 and 18 % protein levels and 2988, 3083 and 3176 kcal/kg ME during the starter, grower and finisher phases, respectively. During each growing phase, each group was fed on one of the following experimental diets: corn–soybean based diet without supplementation(C), wheat–soybean based diet without supplementation (W), corn–soybean based diet supplemented with enzymes cocktail at level of 50 g/ 100 kg diet (C+), wheat–soybean based diet supplemented with enzymes cocktail at level of 50 g/ 100 kg diet (W+), low energy (100 kcal) corn–soybean based diet supplemented with enzymes cocktail at level of 50 g /100 kg diet (LC100+), low energy (-100 kcal) wheat–soybean based diet supplemented with enzymes cocktail at level of 50 g /100 kg diet (LW100+), low energy (150 kcal) corn – soybean based diet supplemented with enzymes cocktail at level of 50 g /100 kg diet (LC150+) or low energy (-150 kcal) wheat–soybean based diet supplemented with enzymes cocktail at level of 50 g /100 kg diet (LW150+). The carbohydrase enzymes cocktail supplement supplied per 1 g, 3000 U α – galactosidase, 5000 U β- mannanase 2500 U xylanase, 1500 U β- glucanase and 1000U cellulose.
The obtained results could be summarized as follows: birds fed the corn-based diets had overall superior weight gain, feed consumption, feed conversion ratio, nutrient digestibility and protein and energy conversion ratio compared with those fed the wheat-based diets. Enzyme cocktail supplementation to corn or wheat based diets improved all tested parameter cited above. No significant differences were found between the low ME enzymes supplemented diets (L100+ and L150+) and their respective control groups for body weight gain during the overall period. Enzymes supplementation to low energy diets compensate for lowering energy level by increasing feed consumption.
Birds fed corn based diets or enzyme supplemented diets, irrespective of cereal type, had significantly high blood plasma glucose level. On the other hand, neither cereal type nor enzyme supplementation had a significant effect on blood plasma total proteins and total lipids. Chicks fed corn based diet improved EPEI (European production efficiency index) by 18.21 % compared to those fed wheat based diet and enzyme supplementation to corn or wheat based diets improved significantly EPEI and the improvement was more pronounced for wheat based diet compared to corn based diet (13.03 vs. 5.03). No significant differences in EPEI were detected when enzyme cocktail was added to low AME diets based on corn or wheat.