Effects of a Compound Probiotics Combined with Chinese Herbal Medicine on Growth Performance, Intestinal Flora and Resistance to Diseases of GIFT Strain of Nile Tilapia (Oreochromis niloticus)

Abstract:

Here we studied the effects of four kinds of probiotics on the growth performance, intestinal flora, and resistance to diseases of GIFT strain of Nile tilapia (Oreochromis niloticus). Bacillus subtilis, Chinese herbal medicine compound Bacillus subtilis, compound probiotics, and Chinese herbal medicine compound probiotics were added into feed at the concentration of 2×107 CFU/g to form four treatment groups. The results were shown below: (1) All four probiotics obviously improved the weight gain rate of Nile tilapia (P<0.05). Probiotics also insignificantly promoted the survival rate and feed efficiency (P>0.05), and Chinese herbal medicine compound probiotics exhibited the best effect. (2) All four types of probiotics caused an increase in the total amounts of bacteria, bifidobacterium, lactobacillus, and bacillus in the guts of Nile tilapia (P<0.05), whereas the number of Escherichia coli was significantly reduced compared to the control group (P<0.05). These results indicated that all four probiotics in the feed could improve the structure of intestinal flora in Nile tilapia, and among them Chinese herbal medicine compound probiotics was the most effective. (3) After the Streptococcus agalactiae infection administered with artificial intraperitoneal injection, all the Nile tilapia in the control group died, but the infection was only fatal to some individuals in the treatment groups. Further tests confirmed streptococcus infection as the reason of death of Nile tilapia. The immune protection rates of the four probiotics were 51.42% (Group B), 58.62% (Group C), 58.62% (Group D) and 68.93% (Group E), again Chinese herbal medicine compound probiotics (Group E) showed the highest efficiency. In conclusion, adding a proper portion of Chinese herbal medicine compound probiotics into feed could effectively improve the growth index, the structure of intestinal flora, and the disease resistance of Nile tilapia.