The impact of adding phytase to plant protein concentration in broiler diets

Abstract

The objective of this study was to evaluate the nutritional value of phytase supplementation to plant protein diet on broiler performances. A total number of 200 un-sexed one-day old Ross commercial broilers were distributed randomly and divided equally into four treatment groups nearly equal in average live body weight. Each treatment was represented by 50 chicks in five replicates of 10 chicks each and kept under similar hygienic, environmental and management conditions in flour pens. Two different basal diets were formulated, the first was containing fish and meat meal (animal diet, AD) and fed to the first treatment (D1), another one was containing soybean and corn gluten meal as a source of protein (plant diet, PD) and fed to the second treatment group (D2). The third and fourth treatment groups (D3 and D4) were fed the second diet (plant diet) with phytase (Citrobacter phytase) addition (500 and 1000 FTU/kg, for each treatment, PD+Ph1 and PD+Ph2, respectively). The experimental period lasted forty two days. All diets were formulated to be isocaloric and isonitrogenous in each of the experimental periods (starting, growing and finishing periods) according to the strain catalog recommendation. The Results of this study clearly indicated that, at the end of starting period (21 d of age), both levels of phytase addition to PD increased (P≤0.01) broiler (BW) and (BWG) for both (D3 and D4 than those fed (D2) or fed (D1). However, at the end of the experiment periods (42 d of age), chicks fed (D4) recorded the highest BW and BWG (2123.89 and 2070.04 g, respectively) comparing with the other treatments. Supplementation broiler plant protein diets (D3 and D4) with phytase during growing and finishing periods (22-42 d of age) and for all excremental periods (0 -42 d of age), improved (P≤0.01) (FCR) comparing with those fed PD. The addition of both levels of photos to PD (P≤0.01) increase relative weights of eviscerated carcass, bursa of Fabricius, spleen and pancreas. Relative weights of abdominal fat dissected were (P≤0.01) decreased for the broiler fed (D3 and D4) comparing with those fed (D1 and D2). Chemical composition of chicks meat indicated that phytase supplementation to PD (D3 and D4) (P≤0.01) decreased ether extract percentages comparing with those fed AD or PD while, the crude protein percentages had the opposite trend. Addition of phytase to broiler PD (P≤0.01) decreases plasma total cholesterol, total lipid concentrations and broiler meat total cholesterol. Supplementation of phytase to PD (P≤0.01) increased digestibility coefficient values of crude protein, ether extract, crude fiber and nitrogen free extract compared with the digestibility values for the broiler fed PD. In conclusion, the investigation clearly indicated that phytase supplementation to broiler plant diets has important role in improving broiler performances, nutrient digestibility and blood lipid profiles.