EFFECT OF DIETARY GLUTAMIC ACID ON PRODUCTIVE PERFORMANCE AND CARCASS TRAITS OF GROWING APRI RABBITS

Abstract

This study aimed to find out the effect of supplementing two sources of dietary glutamic acid (artificial and natural) in rabbit diets on productive performance and carcass traits of growing APRI rabbits. The basal diet was formulated to meet nutrients recommendations. A total number of 150 APRI rabbit kids were weaned at five weeks of age with an average body weight of 667.48±3g. The rabbits were distributed according to body weight to five equal groups (G, n = 30 each, from weaning to 16 weeks of age). The five groups were assigned at random to five dietary treatments. The control (G1) was fed ad-libitum on a basal commercial pellet diet; diets of G2 and G3 were supplemented with artificial source of glutamic acid at a rate of 0.125 and 0.25%, respectively. While part of rations of G4 and G5 were substituted with a natural glutamic acid using tomato by-products at a rate of 5 and 10% (contained natural glutamic acid, 0.125 and 0.25%), respectively. At the end of the experimental period (16 weeks of age), digestibility trials were carried out to determine the digestibility of feed nutrients and feeding value of the experimental diets. In addition, four rabbits were slaughtered from each group to study the carcass traits and some blood parameters. Results showed that body weight tended to be higher in G3 and G5 during the period from 5-12 and 5-16 weeks of age, than that in G1, G2 and G4, respectively. The highest weight gain values from 5-12 and 5-16 weeks were observed with G3 and G5. Feed intake was significantly affected by the diets. Lowest average feed intake from weaning to slaughter (5-16 weeks of age) was recorded for G4. Better feed conversion and performance index (%) were for G3 and G5 than in the other groups, in all ages. No significant differences of digestibility coefficients of nutrients among studied groups were observed. The maximum mortality rate was recorded in G1 and G4, respectively. The empty carcass (%) was significantly higher in G5. Dressing % and carcass cuts were higher for G5. The lowest values of AST and ALT (U/I) were recorded in rabbit of G2 and G3 than the other groups. Rabbits fed diet G3 recorded the lowest values of plasma urea and creatinine (mg/dl) followed by G4 and G5, while the highest value was shown with G1. In conclusion, natural source of glutamic acid (tomato by-products) could be valid feed ingredient due to its good content of glutamic acid could be included in rabbit diets in levels up to 10% for better productive performance, carcass traits, physiological function and economic revenue.