In order to study the effect of dietary fat source in the feed of broiler chickens, an experiment had been taken place with completely randomized design with five treatments and each is including four replications on two hundred Ross 308 broiler chicks. Experimental treatments were the first treatment with 4% animal fat of tallow, the second treatment with 4% fat plant of canola oil, the third treatment with 4% plant fat of sunflower oil, the fourth treatment with 2% animal fat of tallow + 2% plant fat of canola oil and the fifth treatment with 2% animal fat of tallow and 2% plant fat of sunflower oil. The results showed that adding plant and animal fat had no statistically significant effect on microbial bacteria of total bacteria, and microbial population of Lactic acid bacteria (P>0.05), but addition of fat sources on microbial populations of Lactobacillus bacteria was statistically significant effect (P<0.05).
