Evaluation of Increasing Levels of Acacia mearnsii Tannins on Growth Performance and Intestinal Morphometrics of Broiler Chickens Undergoing a Salmonella Heidelberg Challenge

Phytogenic additives such as tannins are characterized as polyphenolic compounds known for their antimicrobial, anti-inflammatory, antioxidant, and immunostimulatory properties that have been used to enhance the performance, intestinal health, and meat quality of broiler chickens. The objective of this experiment was to evaluate the effects of increasing dietary supplementation of tannins from Acacia mearnsii on the intestinal morphometrics, litter moisture, and growth performance of broiler chickens. A total of 1400 Cobb 500 one-day-old male chicks were randomly distributed into five dietary treatments with eight replicates (35 birds/pen) until 42 days of age. The treatments consisted of Salmonella Heidelberg-challenged groups supplemented with 0, 300, 500, 700, or 900 mg/kg tannin from Acacia mearnsii. A four-phase feeding program was used with pre-starter, starter, grower, and finisher feeds. At 3 days of age, birds were orally gavaged with an S. Heidelberg culture. Feed intake, body weight gain (BWG), and feed conversion ratio (FCR) were evaluated until day 42. The morphometry of duodenum, jejunum, and ileum was measured at 7 and 42 days of age. From 1 to 28, 1 to 35, and 1 to 42 days of age, tannin supplementation for broilers under S. Heidelberg challenge led to quadratic increases (p < 0.05) in BWG, with optimal responses at 265, 412, and 456 mg/kg, respectively. No effects of tannin were observed on FCR in all periods. Villus height was similar in all segments on day 7 (p > 0.05); however, on day 42, tannin supplementation that improved villus height of the ileum was 600 mg/kg (p = 0.0100). In conclusion, tannins from Acacia mearnsii were able to improve body weight gain and intestinal morphometry of broiler chickens under an imposed challenge of S. Heidelberg.