Alternative to antimicrobial growth promoters in the diets of broilers challenged with subclinical necrotic enteritis

Necrotic enteritis (NE) is a disease of worldwide distribution, which affects young broilers and causes economic losses on a scale of 6 billion dollars per year. For decades, NE was controlled in poultry flocks by dietary administration of low doses of antimicrobial growth promoters (AGPs). However, an increase in NE incidence was noted after the AGP ban. This study aimed to compare the effect of an antibiotic (Enramycin) diet to a combination of sodium butyrate, hydrolyzed yeast, and zinc proteinate (ViligenTM) on broiler diets regarding performance, blood parameters, intestinal permeability, morphology and lesions, and carcass yield of broilers challenged with Eimeria spp. and Clostridium perfringens to simulate subclinical necrotic enteritis. A total of 1,150 one-day-old male broiler chickens with an initial average weight of 43.9 ± 0.65 g were allocated to 50 experimental pens. Animals were divided into five groups: Negative control (NC) without additives; Positive control (PC) with 0.12 g ton-1 of Enramycin (8%); V500, V1000, and V1500 with the addition of 500, 1.000, and 1.500 g ton-1 of ViligenTM, respectively. All animals were challenged by Eimeria spp. at 7 days of age and by C. perfringens at 17, 18, and 19 days for induction of subclinical NE. The broilers fed with all concentrations of ViligenTM showed similar performance, blood parameters, intestinal permeability, and carcass yield compared to PC broilers. However, NC broilers showed higher FCR compared to PC broilers from 1 to 33 days (1.42 vs. 1.39) (P = 0.048) and from 1 to 42 days (1.51 vs. 1.49) (P < 0.001). V1500 broilers had fewer intestinal lesions at 28 days when compared to the PC treatment (P < 0.05) and showed that higher ViligenTM inclusion resulted in lower intestinal damage. At 21 days, the V500 group showed higher intestinal morphology characteristics (VH:VD 4.9 vs 3.5) compared to the PC treatment (P<0.001). Thus, in this study, the dietary addition of ViligenTM to broilers challenged by an experimental model of subclinical NE resulted in lower intestinal damage and similar performance to that obtained by the addition of Enramycin.