Effect of esophageal gavage of anti-enterococcus bacteriophage on productive performance, ileal microbial population, and nutrient digestibility of laying hens

Bacteria of the intestinal tract may have a profound impact on lipids' digestion and utilization. The proposed mechanism for reduced lipids digestibility is the de-conjugation of bile salts, via bacterial bile salt hydrolase (BSH) enzyme activity. The activity of BSH is well recognized in some genera of lactic acid bacteria like Enterococci. Bacteriophages are recognized as bacteria-eating viruses, which are host specific in contrast to antibiotics. We find bacteriophages that lysis the laying hen's intestinal Enterococci. It is expected that oral administration of bacteriophage lessens the negative impact of Enterococci BSH activity on lipids digestion.

A total of 240 high-line W-36 laying hens aged 50 weeks were tested in six treatments with five replications and eight pieces in each replication for eight weeks in a completely randomized design. Treatments include, 1) control (basal diet without additives), 2) basal diet + antibiotic (virginiamycin), 3) basal diet + lipid-lowering drug (atorvastatin), 4) basal diet + bile salt powder, 5) basal diet + oral gavage of Enterococcus bacteria, and 6) basal diet + oral gavage of bacteriophage against Enterococcus.

The results showed that the group receiving the lipid-lowering drug (atorvastatin) had significantly the lowest percentage of egg production, the lowest egg mass, and the highest feed conversion rate (P<0.05). Enterococcus bacteria and atorvastatin had the same performance, although Enterococcus bacteria did not increase the feed conversion rate as much as the lipid- atorvastatin, it performed poorly compared to the bacteriophage. The use of phage in poultry improved performance. No significant effect among treatments was observed in albumin, glucose, uric acid, calcium, and phosphorus. The level of cholesterol, triglyceride, total protein, and globulin in the atorvastatin group was lower compared to the antibiotic and bile salt groups (P<0.05). Cholesterol and triglyceride levels were higher in the antibiotic, bacteriophage, and bile salt powder treatments than in the other treatments (P<0.05). The lowest concentration of uric acid was observed in the control group and the highest percentage of hematocrit was observed in the bacteriophage and control groups. The role of antibiotic and bile salt in the rest of the reports was the same as bacteriophage but regarding the increase of hematocrit in bacteriophage treatment, phages showed their superiority in this field (P<0.05). The total number of aerobic bacteria, lactic acid bacteria, enterococcus, and coliforms in the bacteriophage group was less than in the bacteria group (P<0.05). However, the digestibility of crude protein was not significantly different between bacteriophage and bacteria groups (P<0.05). The total population of aerobic bacteria was lower in antibiotic and bacteriophage treatments. This study demonstrated the ability to use bacteriophage to reduce the population of specific bacteria. The population of lactic acid bacteria was higher than other treatments in bacteria treatment. Bacteriophage had been more effective to reduce the population of Enterococcus bacteria than other treatments. A close competition between antibiotics and bacteriophage was observed. Regarding the reduction of the E.coli bacteria population, it showed the appropriate ability of bacteriophage to replace the antibiotics. The digestibility of ether extract and dry matter in the bacteriophage was higher than in the bacteria group. The dry matter digestibility in antibiotic and bacteriophage is similar, but bile salt powder was not similar to bacteriophage in this case, and the dry matter in bile salt powder was the lowest (P<0.05).

Based on the results, oral bacteriophage could improve dry matter digestibility and reduce the Enterococcus bacteria population without a significant impact on production performance in laying hens.