The Effect of Probiotic and Enzyme Mixture Containing Phytase on Growth Performance, Carcass Characteristics, Meat Quality and Biochemical Constituents of Plasma of Broiler Chicks Fed Different Protein Levels

Abstract

The influence of dietary protein levels and two types of pro-nutrients e.g. enzyme mixture containing phytase or probiotics on growth performance, carcass characteristics, meat quality and plasma biochemical constituents of broiler chicks was studied herein as means of improving protein utilization and decreasing feed cost. A complete randomized factorial design was conducted including two levels of crude protein 22 and 20% CP in the starting and 20 and 18% CP in the growingfinishing periods. Each CP level was fed either without or with enzyme mixture containing phytase or probiotics. Thus, there were 6 dietary experimental treatments, each one was fed to 24 one d-old unsexed broiler chicks divided equally among four replicates of 6 chicks each housed in a battery (30×35×40 cm). At the end of the experiment, 3 chicks of each treatment were slaughtered to determine carcass characteristics and meat quality traits. Furthermore, four plasma blood samples of each treatment were collected to determine some biochemical constituents. Also, nutrients digestibility and economic efficiency of treatments were also calculated.Increasing protein level significantly increased growth, decreased feed intake thus improved feed conversion ratio (FCR), protein conversion ratio (PCR) and economic efficiency. Pro-nutrients supplementation significantly increased growth, decreased feed intake and improved FCR, PCR and economic efficiency, with probiotics being more efficiently than enzyme mixture containing phytase, and this was clear in each protein level. Enzyme mixture containing phytase or probiotics significantly improved digestibility of dry matter and crude fibre. Increasing protein level significantly increased front part and decreased hind part, meanwhile protein level and /or pro-nutrients did not significantly affect chemical composition and physical characteristics of meat.Enzyme mixture containing phytase increased plasma Ca and inorganic phosphorus (iP), the later was significantly increased by probiotics supplementation, too. Plasma ALT was significantly decreased due to probiotics supplementation, showing the improvement in liver functions.In conclusion, low crude protein diet e.g. 20 and 18% in the starter and growerfinisher diets, respectively could be fed to broiler chicks when supplemented with probiotics cocktail containing Bacillus subtillis fermentation extract, Brewers yeast extract, lactic acid, citric acid, calcium propionate, sodium aluminosilicate and DLmethionine without adverse effects on growth performance and carcass quality, moreover it improved economic efficiency.