This study was conducted to compare the effects of feeding graded levels of untreated and cellulase and pectinase hydrolyzed corncob based diets on growth, nutrient digestibility, carcass yield, haematological and biochemical parameters of broiler chickens. Three hundred and fifteen day-old broiler chicks with an average initial body weight of 60g were used for the study. Seven dietary treatments were formulated such that Diet 1 was a control. Diets 2, 3 and 4 contained 5%, 10%, and 15% levels of untreated corncob, while diets 5, 6 and 7 contained cellulase and pectinase hydrolyzed corncob at 5%, 10% and 15% levels respectively. The birds were randomly distributed into seven treatment groups in three replicates and each replicate had fifteen birds. Crushed corncobs were pretreated with NaOH to remove the lignin contents and later subjected to locally produced cellulase and pectinase enzymes for the degradation of non-starch polysaccharides (NSPs) for five days. Proximate analyses of untreated corncobs, cellulase and pectinase hydrolyzed corncob, standard diet, diets containing untreated corncobs and diets containing cellulase and pectinase treated corncobs were carried out to determine the nutrient composition of the ingredients and feeds. Data obtained from Growth performance, nutrient digestibility, haematological and serum biochemical profile as well as carcass yield were determined in a 2x4 factorial arrangement. Feeding regime was twice daily for all the treatment groups while diets and water were supplied to birds ad libitum. The results showed that at the end of week eight when the experiment was terminated, the broilers placed on untreated corncob diets consumed higher quantities (2497.28 g) of feed than birds placed on enzyme treated diets (2142.94 g) and conversely recorded lower performance indices in all parameters measured. The result also showed that as the levels of untreated corncob diets increased, the final body weight of birds (1450.00 g) significantly (P<0.05) reduced when compared to 2385.33g obtained for enzyme treated birds. The result equally showed that broilers fed hydrolyzed corncob diets had significantly higher (P<0.05) and better performance in terms of feed conversion efficiency (0.67 as compared to 0.50) in the untreated birds, protein efficiency ratio (4.17 as compared to 1.69) in the untreated birds, feed conversion ratio (1.21 as compared to 2.70) in the untreated birds, nutrient digestibility, final body weight, dressed carcass percentage (80.22 as compared to 73.93%) in the untreated birds and carcass cuts when compared to broilers fed untreated corncob diets. Enzyme treated corncob diets significantly (P< 0.05) lowered the blood cholesterol levels (1.85 g/dL as compared to 2.15 g/dL) in the untreated birds and also improved other haematological indices measured in the birds compared to the control broilers. Generally, broilers fed enzyme hydrolyzed corncob diets performed better with birds fed 15.00% enzyme treated corncob diets having the highest and the best performance record which could be attributed to better utilization of nutrients since the enzymes have hydrolyzed the nutrient releasing monomers and hence are better metabolized. It is concluded that feeding broilers with enzyme hydrolyzed corn cob at the levels 5 to15.0 % improved performance and carcass values. In addition, it elevated 99 albumin, globulin, total protein, Aspartate amino transaminase (AST) and Alanine amino transaminase (ALT) levels in the blood.
Cafeteria-Type Feeding of Chickens Indicates a Preference for Insect (Tenebrio molitor) Larvae Meal