The present research was carried out to evaluate the effect of Saccharomyces cerevisiae and Bacillus subtilis strain (QST 713) on broiler growth performance through the evaluation of live body weight gain, feed intake and feed conversion rate, mortality rate and weight of immune organs in chicks. The experiment consisted of a total number of 180 one day-old
cobb chicks were brought from a commercial hatchery and distributed randomly into three groups of 60 chicken in each . Subsequently, the chicks in each group were distributed into 2 replicates with 30 chicks in each and were housed in separate pens in 6 battery cages. They were placed on one of the three dietary treatments. The afore-mentioned treatments
were a basal diet (T1 control group). Two other diets composed of basal diet supplemented with probiotic as Bacillus subtilis spores strain (QST 713). To provide the concentration 10 10CFU /g feed and added by 100 gram per ton feed in the second group (T2 group). Saccharomyces cerevisiae by concentration 10 9CFU/g feed was added by 1000 gram per ton
in the last group (T3 group). All the chicks were allowed to have free access to starter diet during (1-21 day old) and then to a grower diet from 22 day old to the end of experiment at 42 day of age. Body weight gain, feed intake (FI), feed conversion rate (FCR) and mortality rates were recorded. At the end of the study, nine birds from each group were slaughtered for
collection of intestinal and cecal contents for determination of intestinal microbial population. Then remove immediately the immune organs (bursa of fabrics, spleen) then record their weight. Our results showed increased body weight gain, feed intake in groups supplemented by Saccharomyces cerevisiae and Bacillus subtilis respectively as compared with control.
Feed conversion rate was similar in probiotic supplemented groups at 42 day of age but both treated groups had FCR higher than that in broiler fed basal diet .bursa weight in probiotic added groups was affected and show heavier than it's similarity in control group . Three experimented groups did not show any change in spleen weight during all experimental period .Therefore,our results support the addition of both types of probiotics firstly Saccharomyces cerevisiae then Bacillus subtilis , respectively which showed low mortality rate, increased body weight gain ,increase feed intake, feed conversion rate improvement , increase Lactobacillus population in broiler intestine and inhibit enteric pathogenic bacteria. Finally,
the probiotics had a positive effect on broiler immune system by stimulate bursa weight, which might be attributed to improve bacterial populations.