Analysis of the growth curve in broiler chickens fed diets containing a commercial probiotic (Bio-Poul®)

This experiment was conducted to determine the nutritional effects of dietary inclusion of a commercial local-produced probiotic (Bio-Poul®) on parameters of broiler growth curve. In this way, the fitting and prediction abilities of three models including the Gompertz, Logistic and Richards were compared. A total of 280 one day-old Ross chicks were used in a completely randomized design with four treatments and five replicates each (pens with 14 birds of both sexes male and female in equal numbers). Four dietary treatments containing 0, 100, 200, and 300 grams of Bio-Poul® probiotic per ton of feed were fed. To estimate the growth characteristics of birds, the weekly body weight of chickens from 0 to 42 days of age was recorded and fitted to the three growth models. Prediction abilities of the models in describing the growth of chickens were tested using goodness of fit indexes such as coefficient of determination (R2), root mean square error (RMSE), bias and a standard F test. Based on calculated indexes values, it was found that the Richards model had better prediction in compared with Gompertz and Logistic models with R2 value of 0.9998, RMSE of 9.16 g and bias of 0.52 g. In addition, the results of the pairwise comparison by F test showed that the Richards model was also more accurate in predicting growth of birds. In conclusion, the results showed that the diet containing 200 grams of Bio-Poul® probiotic may help to obtain optimum growth response and improve growth rate in broiler chickens.