Efficacy of Butyric and Valeric Acid Esters in a Necrotic Enteritis Challenge Model.

Restrictions on the use of antibiotics in poultry production have increased interest in nonantibiotic alternatives to control necrotic enteritis (NE). Volatile fatty acids, and in particular butyric acid preparations, have shown potential as aids in controlling NE. Valeric acid compounds may be a new additional alternative. This series of three trials compared the effects of tributyrin, monovalerin, which is an organic acid mixture, and bacitracin in a NE challenge model consisting of challenge with coccidiosis followed by Clostridium perfringens. Trial 1 was a pen trial comparing tributyrin at 0.5 kg/metric ton continuously in the feed, a proprietary organic acid blend at 1 kg per 1000 L as a metaphylactic treatment in the water, and bacitracin in the feed at 55 g/metric ton. Tributyrin and the organic acid mixture were at least as effective as bacitracin in controlling the growth- and efficiency-suppressing effects of the NE challenge, and the organic acid mixture reduced NE lesion scores. None of the treatments reduced mortality. Trial 2 was a battery study comparing monovalerin at 1.5 kg/metric ton and bacitracin in the feed. Both interventions provided significant control of both clinical and subclinical NE, with bacitracin being slightly superior to monovalerin. Trial 3 was a pen trial comparing monovalerin at 1 kg or 1.5 kg/metric ton continuously, or 0.5 kg/metric ton from 0 to 14 days and 0.25 kg/metric ton from 14 to 42 days (variable dose), to tributyrin at the same variable-dose schedule. The higher dose of monovalerin appeared to suppress feed intake and weight gain prechallenge but also produced the lowest NE mortality and the lowest total mortality of the challenged groups. All of the treatments except the variable-dose monovalerin treatment demonstrated reductions in NE lesion scores compared with the positive challenge control group; however, they did not control mortality and had fewer effects on the performance effects of subclinical NE. Results of these studies indicate that the organic acid products monovalerin and tributyrin may be useful adjuncts to reduce NE in antibiotic-free broiler production.

Research Note: Effect of butyric acid glycerol esters on ileal and cecal mucosal and luminal microbiota in chickens challenged with Eimeria maxima.

Coccidiosis is one of the most prevalent diseases seen in the poultry industry leading to excessive economic losses. The aim of this study was to investigate the effect of butyric acid glycerol esters (BE) on the ileal and cecal microbiota in birds challenged with Eimeria maxima (EM). Ross 708 male broilers were fed a diet supplemented with 0 (control) or 0.25% BE from day 1. On day 21, half of the birds were infected with 103 EM oocysts. For determing microbiota, ileal and cecal contents and epithelial scrapings were collected at 7 and 10 D postinfection (PI). Alpha diversity of bacterial communities was mostly affected (P < 0.05) by time PI and EM infection. The richness of luminal bacterial populations in the ileum and ceca was affected (P < 0.05) by addition of BE and by time PI × EM × BE interaction, respectively. In the ileal and cecal luminal and mucosal bacterial communities, permutational multivariate analysis of variance (PERMANOVA, unweighted UniFrac) showed significant (P < 0.05) differences because of time PI and interaction between time PI, EM, and BE. Significant (P < 0.05) differences in taxonomic composition at the family level were observed in microbiota of luminal and mucosal populations of the ileum and ceca owing to time PI, EM, BE, and their interactions. The bacterial community present in the cecal lumen was characterized by the lowest number of differential bacteria, whereas the cecal mucosal community was characterized by the highest number of differentially abundant bacteria. In conclusion, our results show that EM infection and time PI has the biggest impact on microbial diversity in the chicken gut. The presence of BE in the diet had a limited effect on gut microbiota.