EFFECTS OF NATURAL ANTIOXIDANT EXTRACTS SUPPLEMENTATION ON GROWTH PERFORMANCE, CARCASS TRAITS, MEAT QUALITY AND SHELF-LIFE OF BROILER CHICKENS

Abstract

Five experiments were conducted to evaluate the effect of three natural antioxidants: sweet orange peel extracts (SOPE); shaddock peel extracts (SHPE) and lemon peel extracts (LMPE) on performance, carcass traits, meat quality and lipid oxidation of broiler chickens. The peels of ripe sweet orange, shaddock and lemon fruits were oven-dried and extracted using standard methods. The qualitative and quantitative phytochemical contents and diphenyl 2- picrylhydrazyl (DPPH) abilities of SOPE, SHPE and LMPE, were also evaluated. Steroids, flavonoids, coumarins triterpenes and alkaloids were the phenolic compounds found in SOPE, SHPE and LMPE. While phlobatanin, anthocyanin and amino acid were not detected. SOPE contains significantly higher steroids (34.43 mg/100g), flavonoids (161.82 mg/100g), terpenoids (17.09 mg/100g), triterpenes (128.27μg/100g) and alkaloids (32.44 mg/100g) than SHPE and LMPE. SHPE contains significantly higher phenolics (26.76 mg/100g) than SOPE and LMPE. While LMPE contains significantly higher tannins (1.74 mg/100g), coumarins (18.15 μg/100g) than SOPE and SHPE. Three hundred Abhor acre- day old broiler chicks were assigned into 5 treatments (T) and 3 replicates each in a completely randomised design. The feeding trial was for 8 weeks period each. The birds were fed starter diets (23 % CP and 2879 Kcal/kg ME) for the first 4 weeks and finisher diets (20 % CP and 3000 Kcal/kg ME) for the remaining 4 weeks. The first feeding trial was based as follows; T1 (butylated hydroxy anisole BHA, 0.02 % per litre of water, + control), T2 (water OW as – control) and T3 (SOPE), T4 (SHPE), T5 (LMPE), 0.02 % per litre of water respectively. While in the second feeding trial, the supplementation was T1 (BHA as control), T2 T3, T4 and T5 (SOPE 0.02, 0.04, 0.06, 0.08 and 0.10 %) per litre of water respectively. In the first feeding trial, LMPE had better weight gain (WG) and FCR compared to other treatments. Treatment OW was significantly higher (p<0.05) in white blood cell (WBC) than other treatments. Whereas, red blood cell (RBC) of both SHPE and LMPE treatments were higher (p<0.05) than other treatments. Total protein (TP) and cholesterol (TC) were significantly higher (p<0.05) in OW and SOPE treatments. Treatment LMPE had a higher (p<0.05) carcass weight compared to other treatments. Sensory parameters of SOPE treatment were significantly higher (p<0.05) than other treatments. Thiobarbituric acid reactive substance (TBARS) value at day 0; for cooked meat in SHPE treatment and raw meat in OW and SOPE treatments were significantly lower (p>0.05) than other treatments. In storage day 2; the TBARS value in SHPE cooked meat was significantly lower (p>0.05) than other treatments. Whereas, for raw meat storage day 2, the TBARS values were similar in BHA, SOPE, SHPE and LMPE treatments but significantly lower (p>0.05) to OW treatment. In the second feeding trial, the WG and feed intake were significantly higher (p<0.05) in SOPE (0.04 %) compared to other treatments. Whereas, there were similarities in the FCR of BHA, SOPE (0.04 and 0.10 %) treatments and were significantly lower (p>0.05) to SOPE (0.06 and 0.08 %) treatments. Treatment SOPE (0.10 %) was significantly higher (p<0.05) in WBC compared to other treatments. Whereas, the RBC of SOPE (0.08 %) treatment was higher (p<0.05) than other treatments. Total cholesterol (TC) was significantly higher (p<0.05) in SOPE (0.06 %) treatment. Treatment SOPE (0.04 %) had a higher (p<0.05) carcass weight compared to other treatments. Sensory parameters of SOPE (0.10 %) treatment were significantly higher (p<0.05) compared to other treatments. TBARS value at day 0; for both cooked and raw meat in BHA, SOPE (0.04, and 0.08 %) with the exception of cooked meat of treatment SOPE (0.06 %), were significantly lower (p>0.05) than other treatments. It was concluded that SOPE had significant effect in most of the parameters of interest with better performance recorded in birds fed higher doses (0.04, 0.06 and 0.10 %) of SOPE in the second experimental feeding trial.