SalmoFree® Phage Additive Proves Its Safety for Laying Hens.

Background: The avian pathogen Salmonella Gallinarum causes avian typhosis in laying hens, leading to high mortality rates among adult birds, which poses a significant problem in the poultry industry. Various products, such as vaccines, antibiotics, probiotics, and disinfectants, are commonly used to prevent and control the disease on farms. An alternative to these products is the use of bacteriophages, which may effectively prevent the colonization of S. Gallinarum.

Materials and methods: This study evaluated the safety of SalmoFree^®, a bacteriophage cocktail, administered to 276 laying hens from the first week of age until the 28th week. The hens were divided into two groups: a control group (138 birds) and a treatment group (138 birds). Over the 28-week period, eight doses of SalmoFree^® (∼10¹⁰ UFP per bird) were administered via drinking water in a controlled environment.

Results: The results indicate that the consumption of SalmoFree^® has no adverse effects on bird health or zootechnical parameters. Additionally, there is a trend toward improving weight homogeneity (up to 19%), feed conversion (up to 68%), and egg weight (up to 2.7%). The detection of phages by PCR in cloacal swabs suggests that they persist in birds for 2 to 8 weeks post-ingestion. Furthermore, phages were detected in organs and eggshells, indicating that they provide protection beyond the gut.

Conclusion: The study demonstrates that SalmoFree^® is safe for use in laying hens and may offer additional benefits, such as improved zootechnical parameters and extended protection against S. Gallinarum through the persistence of bacteriophages in the birds.