Effect of using mannan-oligosaccharides and β-glucans as feed additives on growth, biochemical parameters, and immunity of Salmonella enterica serovar Enteritidis-challenged turkey.

This study aimed to detect the prevalence, antimicrobial susceptibility, and molecular characterization of some virulence determinants in Salmonella recovered from 100 diseased turkeys in Dakahlia Governorate, Egypt. Twelve Salmonella isolates were recovered from the diseased turkeys with an overall prevalence of 12%. The recovered isolates were serotyped into 4 serovars: (S. enterica serovar Enteritidis, S. enterica serovar Typhimurium, S. enterica serovar Infantis and S. enterica serovar Heidelberg). Additionally, a 21-d trial investigated the effects of dietary Mannan-oligosaccharides (MOS) and β-glucans as feed additives on growth performance parameters, intestinal morphology, and blood biochemical, immunological parameters, and fecal shedding of S. enterica serovar Enteritidis-challenged turkey. A total of 300 One-day-old turkey poults were allocated into five treatment groups (100 poults for each) in a completely randomized design: group 1: a negative control group (non-challenged, non-supplemented), group 2: a positive control group (S. enterica serovar Enteritidis-challenged at 7th day, non-supplemented), group 3 and 4: two challenged groups supplemented with a mixture of MOS and β-glucan at 1 & 2 g/kg diet, respectively, and T5: a challenged group and treated with Florfenicol antibiotic on the 8th day of the experiment at a dose of 1 ml /liter drinking water for five consecutive days. The in vivo experimental results showed that birds in the positive control group showed reduced growth performance compared with the negative control group. Supplementation with MOS and β-glucan, particularly at 2 g/kg ration, significantly improved body weight gain, and feed conversion ratio, in addition to reduced clinical signs and mortality compared with the positive control group. Overall, MOS and β-glucan at 2 g/kg restored growth performance close to negative control and showed better feed efficiency than the antibiotic-treated group. MOS and β-glucan supplementation, particularly at 2 g/kg, significantly increased globulin, thyroid hormones, and immunoglobulins (IgA, IgG, and IgM), and IL1β, and interferon-gamma (IFN-γ) compared with the control groups. Histopathological examination revealed normal liver and spleen structures in the negative control group, while the positive control group showed marked degenerative and inflammatory changes in the liver and lymphoid depletion in the spleen. Supplementation with MOS and β-glucan, particularly at 2 g/kg, markedly improved hepatic and splenic histological structures with mild inflammatory changes, approaching the normal architecture. The antibiotic-treated group also exhibited nearly normal histological features. Bacteriological examinations revealed lower Salmonella shedding in the MOS and β-glucans 2 g/kg group in comparison with the positive control and the MOS and β-glucans 1 g/kg groups. In conclusion, dietary addition of MOS and β-glucans 2 g/kg in turkey diets improved growth performance, immune status, and hepatic and splenic histological structures in addition to lowering Salmonella fecal shedding.