Effect of creatine monohydrate supplementation in diets containing different protein levels on the performance, carcass characteristics and hematological parameters of the broiler chickens

This experiment was conducted to investigate the effect of graded creatine monohydrate levels on diets at different levels of protein on carcass characteristics and hematological parameters. A total of 320 Ross 308 one-day-old broilers were in the form of 2*4 factorials, with four levels of creatine (zero, 0.1, 0.3, 0.5%), and two levels of protein (requirements of Ross 308 and 10% higher), with four replicates, were used. Blood sampling was performed at 35 days of age. To investigate the carcass characteristics, at the end of the experiment two birds at each replicate were randomly selected, weighed and slaughtered. 10% higher protein requirement increased daily weight gain, live weight, carcass yield, relative liver, and breast weight, and decreased feed conversion ratio and abdominal fat (P<0.05). Adding 0.3% and 0.5% creatine monohydrate to the diet increased live weight, carcass yield and relative weight of breast and thigh compared to other groups (P<0.05). Protein and creatine levels had no effect on immune cells and Newcastle titer; however, the data indicated a numerical increase in lymphocyte, monocyte and Newcastle titer and a decrease in heterophil. Creatinine concentration in the blood of birds fed with 0.3 and 0.5% creatine monohydrate was higher than broilers fed with 0.1% creatine monohydrate and control group (P<0.05). The results showed that moreover the beneficial effects of creatine at high levels and 10% higher protein requirements on growth performance and carcass traits, blood creatinine concentrations should be increased which could potentially improve immune system function.