Effects of Acacia mearnsii tannins on growth performance, footpad dermatitis, nutrient digestibility, intestinal permeability, and meat quality of broiler chickens

An experiment was conducted to evaluate the effects of increasing dietary supplementation of tannins from Acacia mearnsii on broiler growth performance, footpad dermatitis, litter moisture, and ileal digestibility as well as on intestinal permeability, jejunal morphometric, and lipid oxidation measurements. A total of 1620 Cobb 500 one-day-old male chicks were fed 6 experimental diets with 10 replicate pens of 27 birds each in a 4-phase feeding program. Dietary treatments were as follow: non-challenged control, challenged control, and challenged supplemented with 300, 500, 700, or 900 mg/kg tannin from Acacia mearnsii. All birds on challenged groups were challenged with Eimeria spp. on day 1 and Clostridium perfringens on days 11, 12, and 13. Performance was evaluated weekly until day 43. On day 21, blood samples were collected for biochemistry analyses and the intestinal permeability was evaluated using FITC-d as marker. Ileal digestibility and jejunal morphometric were also determined on day 21. Footpad dermatitis, litter moisture, and litter pH were evaluated on days 28, 35, and 43. On day 44, carcass and commercial cuts weights were evaluated and thigh samples were collected for lipid oxidation (TBARS) through a 6 months storage period. Broilers under intestinal challenge had lower growth performance, higher intestinal permeability, and lower serum albumin, cholesterol, glucose, and triglycerides compared to non-challenged birds (P < 0.05). From day 1 to 43, increasing tannin supplementation for broilers under intestinal challenge led to quadratic increases (P < 0.05) in body weight gain, with optimal supplementation at 310 mg/kg as well as optimized estimations for feed conversion ratio at 444 mg/kg tannin. Dietary tannin supplementation that reduced intestinal permeability at 21 days was 466 mg/kg (P < 0.05). Tannin supplementation that improved protein and energy digestibility were at 374 and 294 mg/kg, respectively (P < 0.05). No effects of tannin were observed on blood biochemistry, crypt depth, litter pH, carcass measurements, and lipid oxidation until the storage day 60. However, increasing levels of tannin supplementation led to a linear (P < 0.05) decrease on lipid oxidation of broiler meat after 90 days of storage. In conclusion, low levels of supplemental tannins from Acacia mearnsii improved growth performance, nutrient digestibility, and intestinal permeability in broilers under an intestinal challenge.