L-THREONINE SUPPLEMENTATION IN LOW CRUDE PROTEIN DIET OF BROILER STARTER CHICKEN

Résumé

This study was conducted to determine the effect of threonine (Thr) supplementation to low protein diet (LPD) on performance and nitrogen utilization of growing broilers (1 to 21 old). A total of 200, one-day-old unsex broiler chicks were randomly allocated to five treatments with four replicates of 10 birds each. Five isocaloric diets were formulated; diet 1 served as a positive control with 23% CP level, diet 2 served as the low protein diet (LPD, negative control) with 20% CP level while diet 2, 3 and 4 contained Thr supplementation to diet 2 at 0.2, 0.4 and 0.6%, respectively. The result showed that average daily feed intake, average daily gain, feed conversion ratio and all the nitrogen utilization parameters except nitrogen intake were significantly (P < 0.05) influenced by Thr supplementation. Daily feed intake was lower (P<0.05) in birds fed control and 0.6% Thr diet compared to other treatment diets. Improved (P<0.05) daily weight gain and feed conversion ratio was observed in birds fed the control diet and did differ from those fed 0.4 and 0.6% Thr diets compared with those on LPD and 0.2% Thr diets. A significant (P < 0.05) increase in nitrogen retention with corresponding decrease in nitrogen excretion was observed in birds fed 0.4% and 0.6% Thr diets. In conclusion, this study demonstrates that with a minimum level of 0.4% Thr supplementation, feeding a low CP diet of 20% in broiler starter chickens is possible without any adverse effect on performance and nitrogen utilization efficiency.