Pomegranate peel extract for broiler chickens under heat stress: Its influence on growth performance, carcass traits, blood metabolites, immunity, jejunalmorphology, and meat quality

Abstract

This study was conducted to evaluate the effects of dietary pomegranate peel extract (PPE) on growth performance, carcass characteristics, serum metabolites, immune response, jejunal morphology, and meat quality of broiler chickens reared under heat stress (HS). Two hundred 1-d-old male broiler chickens were randomly assigned to 4 treatments with 5 replicates of 10 broiler chickens each. The dietary treatments consisted of basal diets supplemented with PPE at levels of 0 (control), 250, 450, and 650 mg PPE/kg. The broiler chickens were subjected to HS (37 ± 1 °C for 7 h/d and 21 ± 1°C for 17 h/d) from d 25 to 42. Dietary PPE supplementation linearly increased the body weight gain during the starter (P = 0.004) and overall experimental (P = 0.033) periods. Dietary supplementation of PPE quadratically decreased the feed intake during the starter period (P = 0.033). Furthermore, PPE supplementation linearly improved the feed conversion ratio during the finisher (P = 0.035) and overall experimental (P = 0.046) periods. Dietary PPE addition did not affect the relative weights of carcass, breast, thigh, abdominal fat, liver, pancreas, gallbladder, heart, gizzard, bursa of Fabricius, and spleen. Dietary supplementation with PPE linearly reduced the plasma triglycerides (P = 0.049) and alanine aminotransferase (P = 0.005) concentrations, but linearly increased the plasma concentration of high-density lipoprotein at d 24 (P = 0.044). Dietary PPE addition linearly reduced the plasma concentrations of cholesterol (P = 0.035), low-density lipoprotein (P = 0.032), alkaline phosphatase (P = 0.001), and alanine aminotransferase (P = 0.025) at d 42. The primary total anti- sheep RBC titer linearly increased with dietary PPE addition (P = 0.006). It also linearly enhanced the secondary total (P = 0.024) and Ig G (P = 0.045) anti-SRBC titers. The dietary treatments did not affect the jejunal villus height, villus width, and villus height / crypt depth ratio. Dietary PPE supplementation linearly reduced the malondialdehyde concentration in breast muscle during refrigerated storage (P < 0.05); however, linearly increased water holding capacity of breast meat during refrigerated storage (P < 0.05). It is concluded that dietary supplementation with PPE, at levels up to 650 mg/kg, improved the growth performance and plasma lipid profile of broiler chickens reared under HS. Furthermore, dietary PPE addition also preserved the quality of meat during refrigerated storage.