Effects Of Bacillus Subtilis (PB6) On Growth Performance Of Broilers

Spore bacteria, as probiotic, have been widely used in livestock production, but the mechanism of spore bacteria is not consistent. In this study, the thermal stability of bacillus subtilis (PB6) in feed-making pellet, the effects of bacillus subtilis on the performance and development of immune organs in AA broiler were studied to provide scientific theory in the application of the probiotics. Chapter one:The thermal stability of bacillus subtilis (PB6) in feed-making pellet100g of bacillus subtilis (PB6,2×1011cfu/kg) were added in each ton of feed. Samples of the mixed feed were collected before being granulated (control group) and after82℃(experiment group I) and being granulated at85℃(experiment group Ⅱ). Three replications were taken in each group. All samples were cultured with nutrient agar medium at37℃for48h and the spores of bacillus subtilis was calculated. Result:Spores of bacillus subtilis was1.92×104in control group. Spores of bacillus subtilis was1.87×104and1.53×104in group I and group Ⅱ, respectively. The results showed that no significant difference (P>0.05) was obtained between control group and group I, but there was significant difference (P<0.05) between control group and group Ⅱ.Chapter2:Effects of bacillus subtilis (PB6) on production performance of AA Broiler 900AA broiler chickens at one day old were randomly divided into3groups. They were control group, fed with based diet; group Ⅰ fed by based diet with spicy treasure at the dose of100g/t and group Ⅱ fed by based diet with bacillus subtilis (PB6) at the dose of100g/t. Three replications were taken in each group and there were100chickens in each replication. The differences of initial body weights of chickens between each group were not significant. Duration of this study was lasted for42days. Average daily gain (ADG) and feed conversion efficiency were determined at the21th and42th of this study. Results: Compared with control, average daily gain in group Ⅱ and group I is higher than the control (P<0.05, P>0.05); average feed intake in group Ⅱis the lowest among the three groups (P<0.05), and it is higher in group Ⅰ than control(P<0.05); feed conversion rate in group Ⅱ is higher than group Ⅰ and control (P<0.05), and it is higher in group Ⅰ than control (P<0.05); average weight gain in group Ⅱ and group Ⅰ is higher than that of control, it is significant difference in the former (P<0.05) but it is no significant difference in the latter (P>0.05). The results showed that the PB6can keep intestinal health and improve the feed conversion rate.Test three:Effects of bacillus subtilis (PB6) on the development of immune organs in AA broilers18broilers were slaughtered in the21th day and another18broilers were slaughtered in the42th day. Bursa of fabricius and spleen of each bird was weighed. Results:weight of bursa of fabricius and spleen in group Ⅱ was significantly higher than that of control (P<0.05). It is also higher in group I than in control, but no significant difference was obtained (P>0.05). Results show that PB6may stimulate the development of immune organs of broiler and improve the immune function.ConclusionIn this study, it is verified that the bacillus subtilis (PB6) has a thermal stability under the condition of82℃when the feed was granulated; it is cleared that bacillus subtilis (PB6) as a feed additives can improve the growth performance and stimulate the development of immune organ of AA chicken.