Dietary Propels as an Alternative to Antibiotic Growth Promoters: Effects on Performance, Immunity, Gut Morphology, and Antioxidant Status in Broilers
Abstract
The ban and restriction of antibiotic growth promoters (AGPs) in poultry production has intensified the search for natural alternatives. This study evaluated the efficacy of dietary ethanolic extract of propels (EEP) as a substitute for AGPs in broiler chickens over a 42-day trial. A total of 240, 1-day-old unsexed commercial broiler chicks (Ross 308) were randomly assigned to four dietary treatments in a completely randomized design (3 replicate floor pens per treatment, 20 birds per replicate): Control (basal diet without additives), AGP (basal diet + oxy-tetracycline at 100 mg/kg), Propels-L (basal diet + propels at 100 mg/kg), and Propels-H (basal diet + propels at 200 mg/kg). Propels supplementation significantly improved growth metrics (p < 0.05); final body weight (BW) and body weight gain (BWG) reached 2600 +_ 60 g and 2550 +_ 58 g in Propels-H compared to 2450 +_50 g and 2400 +_ 48 g in AGP, and 2150+_ 45 g and 2100 +_ 40 g in Control. Feed conversion ratio (FCR) was lowest in Propels-H (1.46 +- 0.02), followed by Propels-L (1.49+_ 0.02), AGP (1.54 +_ 0.02), and Control (1.74 +_ 0.03). Intestinal histology revealed higher jejunal villus height (1200 mum) and villus height to crypt depth (VH:CD) ratio (7.50) in Propels-H compared to Control (920 mu4.38). Humoral immunity against Newcastle Disease Virus (NDV titers) increased from 3.2 \2 (Control) to 4.9 \2 (Propels-H). Propels reduced serum cholesterol (140 dL vs. 180 dL in Control) and lowered ALT (30 U/L}) and AST (75 U/L. Antioxidant enzyme activities were significantly upregulated in Propels-H: Superoxide dismutase (SOD: 185.4 U/mL vs. 112.1 U/mL Control), Glutathione peroxidase (GPx: 245.2U/mL vs. 155.0U/mL Control), and Catalase (CAT: 68.2 U/mL vs. 41.5U/mL Control). Cecal Lactobacillus counts increased while Escherichia coli were markedly suppressed. In conclusion, dietary propels at 100–200 mg/kg represents an effective natural replacement for AGPs in broiler diets.