Effect of Bacillus-direct-fed microbial on leaky gut, serum peptide YY concentration, bone mineralization, and ammonia excretion in neonatal female turkey poults fed with a rye-based diet

Abstract

Rye is high in nonstarch polysaccharides (NSP), a complex carbohydrate which cannot be digested by poultry as they lack the endogenous enzymes to do so. Exogenous carbohydrases must therefore be supplemented to avoid the antinutritional effects associated with a high NSP diet. The objectives of the present study were to evaluate the effects of a rye-based diet with and without supplementation of a Bacillus direct-fed microbial (DFM) on body weight, bone mineralization, and leaky gut, as well as its role on influencing serum concentrations of peptide YY (PPY) and the ammonia concentration in turkey manure. Two independent trials were conducted. In each experiment, day-of-hatch female turkey poults were neck tagged and randomly assigned to either a control rye-based diet or a rye-based diet supplemented with the DFM (n = 25 birds/group). At 10 days-of-age, poults in both groups were administered with an appropriate dose of fluorescein isothiocyanate-dextran (FITC-d) by oral gavage. One hour later, all poults were euthanized. Blood was collected to evaluate serum FITC-d and PPY concentrations. Furthermore, in Trial 2 only, both tibias were removed for assessment of bone parameters, and turkey manure was collected to evaluate physicochemical analysis. In both trials, poults treated with the DFM showed a significant increase (P < 0.05) in body weight and body weight gain as compared with control nontreated poults. Poults that received the DFM also had a significant reduction in serum levels of PPY and FITC-d when compared with control nontreated poults. In Trial 2, turkeys treated with the DFM had a substantial increase in tibia strength, tibia diameter, total ash, calcium, and phosphorus when compared with control nontreated turkeys. Their manure was also shown to have a significant reduction in the concentration of ammonia. This is the first report of a commercial DFM reducing the concentration of this compound in turkey manure. In summary, the results of the present study confirm that turkeys fed with a rye-based diet have a significant increase in gut permeability, a reduced body weight, and decreased bone mineralization when compared with turkeys fed with the DFM. Turkeys that received the rye-based diet supplemented with the Bacillus-DFM also had a significant reduction in the serum concentration of PPY when compared with control turkeys. This finding suggests a possible prebiotic effect of rye, warranting future studies to test this effect. Further studies to evaluate the microbiota diversity, as well as the concentration of ceca short-chain fatty acids, are also necessary to confirm the reliability of PPY as a potential metabolomic biomarker in poultry.

Keywords: Bacillus-DFM; ammonia; bone mineralization; leaky gut; peptide YY.