Aquatic animals have benefited from Bacillus subtilis-based probiotics over the past few decades.This study evaluated the effects of B.subtilis DSM 32315 probiotics as a feed additive on growth,immune response and res...Aquatic animals have benefited from Bacillus subtilis-based probiotics over the past few decades.This study evaluated the effects of B.subtilis DSM 32315 probiotics as a feed additive on growth,immune response and resistance to acute ammonia challenge in Nile tilapia.Specifically,four supplemental levels(0%,0.1%,0.2%,and 0.3%)of B.subtilis probiotics were tested under two dietary protein levels(32%and28%).Five replicate tanks were randomly allotted to each dietary treatment,with each tank containing 30Nile tilapia.After 8 weeks of feeding,Nile tilapia in each tank were exposed to 43.61 mg/L of total ammonia nitrogen for 48 h.The results revealed that reducing protein levels from 32%to 28%did not affect growth performance or antioxidant capacity.However,the low protein diet tended to induce an inflammatory effect shown by increased expressions of TGF-βand IFN-γgenes(P<0.05)in the liver.The impact was alleviated by the probiotic supplementation.Compared with the non-supplemented group,0.1%probiotic supplementation remarkably increased plasma lysozyme activity,total antioxidant capacity and complement C3 and interleukin-10 mRNA levels(P<0.05)in the 28%protein diet,while higher supplementation of probiotics(0.3%)was shown to be beneficial for the high protein diet(32%).In both the dietary protein levels,0.1%supplementation of probiotics promoted the antioxidant capacity of Nile tilapia before exposure to ammonia stress but higher probiotic supplementation(0.3%)proved to be necessary under ammonia stress as evidenced by higher fish survival rate.Results exhibited that supplementation with B.subtilis probiotics had a better effect on the intestinal morphology(villi height and width)regardless of protein levels.In conclusion,dietary supplementation of B.subtilis DSM 32315probiotics at 0.1%in the low protein diet and up to 0.3%in the high protein diet showed beneficial effects on the growth,immunity,and antioxidant capacity of Nile tilapia.Under ammonia stress conditions,the higher supplementation of B.subtilis DSM 32315 probiotics at 0.3%improves stress tolerance of Nile tilapia despite the two dietary protein levels(32%;28%).展开更多
基金supported by Project of Science and Technology of Guangdong Province(2021B0202050002)Project of Evonik Operations GmbH(Evonik Trial No.37.87.19004).
文摘Aquatic animals have benefited from Bacillus subtilis-based probiotics over the past few decades.This study evaluated the effects of B.subtilis DSM 32315 probiotics as a feed additive on growth,immune response and resistance to acute ammonia challenge in Nile tilapia.Specifically,four supplemental levels(0%,0.1%,0.2%,and 0.3%)of B.subtilis probiotics were tested under two dietary protein levels(32%and28%).Five replicate tanks were randomly allotted to each dietary treatment,with each tank containing 30Nile tilapia.After 8 weeks of feeding,Nile tilapia in each tank were exposed to 43.61 mg/L of total ammonia nitrogen for 48 h.The results revealed that reducing protein levels from 32%to 28%did not affect growth performance or antioxidant capacity.However,the low protein diet tended to induce an inflammatory effect shown by increased expressions of TGF-βand IFN-γgenes(P<0.05)in the liver.The impact was alleviated by the probiotic supplementation.Compared with the non-supplemented group,0.1%probiotic supplementation remarkably increased plasma lysozyme activity,total antioxidant capacity and complement C3 and interleukin-10 mRNA levels(P<0.05)in the 28%protein diet,while higher supplementation of probiotics(0.3%)was shown to be beneficial for the high protein diet(32%).In both the dietary protein levels,0.1%supplementation of probiotics promoted the antioxidant capacity of Nile tilapia before exposure to ammonia stress but higher probiotic supplementation(0.3%)proved to be necessary under ammonia stress as evidenced by higher fish survival rate.Results exhibited that supplementation with B.subtilis probiotics had a better effect on the intestinal morphology(villi height and width)regardless of protein levels.In conclusion,dietary supplementation of B.subtilis DSM 32315probiotics at 0.1%in the low protein diet and up to 0.3%in the high protein diet showed beneficial effects on the growth,immunity,and antioxidant capacity of Nile tilapia.Under ammonia stress conditions,the higher supplementation of B.subtilis DSM 32315 probiotics at 0.3%improves stress tolerance of Nile tilapia despite the two dietary protein levels(32%;28%).
