Feed Supplementation with Red Seaweeds, Chondrus crispus and Sarcodiotheca gaudichaudii , Reduce Salmonella Enteritidis in Laying Hens

Enteritidis is vertically transmitted to eggs from laying hens through infected ovaries and oviducts. Enteritidis can also penetrate the eggshell from contaminated feces. Reducing Enteritidis in laying hens is vital to provide safer eggs and minimize the spread of salmonellosis to humans. Antibiotics have been widely used to control bacterial diseases in broilers and laying hens. However, there is a major concern that the use of antibiotics leads to the development of antibiotic resistance and adverse effects on microbiota of the treated birds. Thus, there is an interest in developing alternatives to antibiotics, such as dietary prebiotics. In the present study, feed supplemented with the red seaweeds: (CC) or (SG), was offered to laying hens late in production to control Enteritidis. Diets contained one of the following; 2% or 4% (CC2, and CC4, respectively) or (SG2 and SG4, respectively). Chlortetracycline was used in the positive control diet. During week-4, 48 birds were orally challenged with 2 × 10 CFU/mL of Enteritidis. Eggs and fecal samples were collected 1, 3, 5, and 7 days' post inoculation. Birds were euthanized and organs (ceca, ovary, liver, and spleen) were sampled and analyzed for the presence of Enteritidis, 7 days' post inoculation. Results showed that seaweed reduced the negative effect on body weight and egg production in Enteritidis-challenged laying hens. Analysis of fecal samples showed that the antibiotic (CTC) reduced Enteritidis in the intestinal tract and fecal samples, 3 days' post inoculation. Fecal samples from Chlortetracycline and CC4 supplemented birds tested negative for Enteritidis on days 5 and 7 post inoculation (lowest detection limit = 10 ). Enteritidis colonization in the ceca was also significantly reduced in birds fed CC (4%) and Chlortetracycline. Blood serum profiles revealed that there were no significant differences in serum aspartate aminotransferase (AST) and sodium. However, the level of serum immunoglobulin (IgA) was higher in the CC4 treatment. The relative abundance of was significantly higher in CC4 while, the abundance of the pathogenic bacteria, and Enteritidis were reduced compared to control. Results indicate that feed supplemented with 4% CC is effective in providing protection against Enteritidis colonization in laying hens.