Effects of Phenolic-Rich Onion (Allium cepa L.) Extract on the Growth Performance, Behavior, Intestinal Histology, Amino Acid Digestibility, Antioxidant Activity, and the Immune Status of Broiler Chickens

摘要

The effect of phenolic-rich onion extract (PROE), as a feed additive, was evaluated on the growth, carcass traits, behavior, welfare, intestinal histology, amino acid ileal digestibility “AID%” and the immune status of broiler chicks, for 35 days. A total number of 400, one-day-old broiler chicks (45.38 g ±1.35) were allocated to four different treatments with ten replicates each (100 chicks/treatment) consisting of; T1: basal diet without additives (control treatment) (PROE0); T2: basal diet onion extract (1 g/kg diet) (PROE1); T3: basal diet onion extract (2 g/kg diet) (PROE2); and T4: basal diet onion extract (3 g/kg diet) (PROE3). An increase in the final body weight “FBW”, bodyweight gain “BWG” and feed consumption was observed (P 0.05) at different PROE levels. Also, the thymus and bursa percentages were increased in the PROE2 and PROE3 treatments (P 0.05). The chicks fed on PROE supplemented diets had increased frequency of feeding, drinking, and showed comfortable behavior (P 0.05) with lesser aggression (P 0.05). Additionally, an increase was observed in the antioxidant enzyme activity, phagocytic %, phagocytic index, and lysozyme activity in PROE supplemented treatments, with the best outcome reported in the PROE3 treatment (P 0.01). IgM was increased in the birds fed with PROE2 and PROE3 diets (P 0.01). PROE supplementation increased the AID% of lysine and methionine (P 0.01), PROE3 treatment increased the AID% of threonine (P 0.05), and PROE2 and PROE3 treatments increased the AID% of leucine and isoleucine (P 0.05). Besides, PROE2 and PROE3 treatments increased the villus height and width, mucosal thickness, and goblet cell count from the duodena, jejuna, and ilea (P 0.05). Based on these results, we concluded that the dietary addition of phenolic-rich onion extracts can improve the growth rate of broiler chicken by improving the AID% of amino acids and intestinal histology. Also, it can improve the welfare, antioxidant enzymes, and immune status of the birds. Phenolic-rich onion extracts can be used as a natural growth promoter in the poultry feed to better their performance and health.