Effect of fulvic acid inclusion in broiler diets on growth performance, physiological and meat quality parameters

Abstract

The use of non-conventional feed sources in poultry farming has a beneficial impact on sustainably improving nutrient supply in poor communities in South Africa. Fulvic acid (FA) is one of the feed resources which can promote animal performance by improving growth rate, immunity, feed efficiency and reducing the risk of infections, but its utility in broilers has not been fully assessed. This study was therefore, undertaken to investigate the effect of FA inclusion in broiler diets on growth performance, physiological and meat quality parameters. For six weeks, chickens were fed five isonitrogenous and isoenergetic experimental diets formulated as follows: negCON (T1): commercial diets without antibiotics, posCON (T2): commercial diet with antibiotics, FA1 (T3) commercial diet + 1% FA1, FA2 (T4): commercial diet + 2% FA and FA3 (T5): commercial diet with 3% FA. The feeding trial was conducted over 3 feeding phases, Starter (day 1-14); Grower (15-28) and Finisher ration (day 28-42). Birds fed the posCON diet had the highest (P < 0.05) ADFI (93.33 g) followed by those fed the FA2 (90.66 g) diet. Dietary inclusion on cumulative weight gain (CWG) in the final week revealed that birds fed the FA2 (1897.34 g) diet gained at the same level as those fed the posCON (1932.74 g) diets and birds in both treatments achieved similar final weights at the end of the feeding trial. Dietary inclusion treatments significantly influenced protein utilization and growth efficiency parameters in all the three growth phases apart from the protein efficiency ratio (PER) in the grower phase, the protein consumed (PC) and the specific growth rate (SPR) at the finisher phase. Chickens offered the negCON (44.05) diet had the highest platelet count, while broilers offered the FA3 diet had the lowest platelet count values. Birds fed the posCON, FA1 and FA2 diets had statistically similar values for platelet counts with FA3 having the least value. Dietary treatments significantly (P <0.05) affected the glucose concentration, symmetric dimethylarginine (SDMA), alanine transaminase (ALT), alkaline phosphatase (ALP), phosphorus and lipase concentration. The SDMA was observed to decline III with increasing levels of FA inclusion in diet with the birds fed the FA3 (6.87 μg/dL) diet having the lowest levels of SDMA compared with all other diets. Diet had a significant effect (P <0.05) on all measured carcass characteristic parameters apart from the dressing percentage, chilling loss percentage and the thigh index. Chickens fed the posCON diet (1959.27 g) obtained the highest slaughter weights, followed by those offered the FA2 diet (1942.10 g), while broilers offered the negCON diet had the lowest (1789.25 g) value. Chickens offered posCON (42.61) diet had statistically similar values for lightness as with those fed FA1 (42.62) and FA3 (42.54) diets. However, the birds fed the FA2 (41.90) diets appeared to have darker breast muscle compared to all other treatments. Findings from this study illustrate that the experimental diets cooperated with FA inclusion revealed an increase in total PUFA/SFA ratio compared to the control diets. However, diets consisting of FA reduced the total n-3/n-6 ratio in all the FA treatments with FA2 having a ratio of 5 in the n-3PUFA, resulting in a beneficial impact on the important fatty acid needed for human and animal health maintenance. Results showed that diet had no effect on latency to lie, feather and gait scoring test. The highest latency to lie was observed in broilers fed the positive control diet with the highest standing persistence observed in broilers fed FA2 followed by FA3. Diet showed no dietary influence on all micro and macro minerals apart from phosphorus, iron and molybdenum. Serum calcium levels were higher in all the diets containing FA compared to the control. FA inclusion in diets also increased calcium levels and ash concentration with increment levels. Overall, the inclusion of FA in broiler diets did not compromise the nutrient utilization efficiency, broiler performance, health status, meat quality traits, internal organs, carcass traits and bone development of broiler diets. Collectively, findings from this study may be useful in developing low-cost feed formulas that will benefit customers and enhance future chicken farming systems for growth performance, health status, carcass features, meat quality.