Effects of feed form and feed particle size with dietary L-threonine supplementation on performance, carcass characteristics and blood biochemical parameters of broiler chickens

An experiment was conducted to evaluate the effect of form and particle size of feed supplemented with L-threonine on growth performance, carcass characteristic and blood biochemical parameters of broiler chickens. The experimental design was a $2{\times}2{\times}2$ factorial arrangement of treatments evaluating two feed forms (pellet or mash), two feed particle sizes (fine or course), and two inclusion rates of dietary L-threonine (with or without) which adopted from 7 to 42 days of age. In this experiment, 360 a day old chicks in two sexes were assigned in each treatment and each experimental unit was included 15 chicks. Feed consumption and weight gain were measured weekly. At 35 days of age, blood samples were taken to analysis blood biochemical parameters. At the end of the experimental period, two birds were slaughtered in each treatment and carcass analysis was carried out. The results showed that the effect of feed form on body weight gain and feed intake in whole of experimental period was significant (P < 0.05). Broilers fed pelleted diets had more weight gain than the mash group. Growth performance parameters were not affected by feed particle size and dietary L-threonine supplementation in whole of experimental period (P > 0.05). The results of carcass analysis showed that liver and gizzard relative weights were influenced by feed form (P < 0.05). However, pancreas and liver relative weights were affected by feed particle size and dietary L-threonine supplementation, respectively (P < 0.05). Triglyceride and VLDL levels were affected by feed form and dietary L-threonine supplementation (P < 0.05). The effect of feed particle size on blood biochemical parameters was not significant (P > 0.05). In conclusion, the experimental results indicated that feed form increased feed consumption and weight gain in whole of experimental period (1 to 42 days of age) while feed particle size and dietary L-threonine had no effect on broiler performance.