الفهرس 
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Abstract
Tow factorial experiment (4×3) was conducted to evaluate the productive performance of laying hens fed diets containing four plant protein sources [soybean meal (SBM), sunflower meal (SFM), rocket seed meal (RSM) and their combination] supplemented with no feed additive, probiotics (Nutri-Bio Plus, 0.5 g/kg) or enzyme preparation (Natuzyme, 0.5g/kg). One hundred and eighty, 20-week-old Hy-Line W-36 hens were randomly assigned to 12 equal experimental groups on each experiment, each with five replications. All birds were kept in community battery cages (3 birds per cage), set up in an open-sided laying house, and exposed to a daily photoperiod of 16 hr and managed similarly. Twelve mash experimental diets were formulated to contain metabolizable energy of about 2800 kcal/kg and crude protein of about 19 % on experiment one and 17% on experiment tow. Feed and water were provided ad libitum throughout the experimental period (20-44 weeks of age). The performance criteria included body weight, productivity (daily feed intake, egg production, egg weight, daily egg mass, feed conversion and economic efficiency), some egg quality traits, nutrient digestibility and certain blood parameters (total lipids, total protein, albumin, globulin, total calcium and inorganic P and activity of alanine aminotransferase and aspartate aminotransferase) of laying hens. The most important results can be summarized as follows: Apart from the effect of feed additive, feeding the SFM- and combined plant protein produced positive effects on egg production rate, feed conversion, economic efficiency from 20 to 42 weeks of age. Hens fed the SFM, RSM and combined plant protein-diets consumed significantly less feed but exhibited superior means of body weight gain, yolk index, yolk color score and shell thickness as compared to their control counterparts; other criteria were not affected. Also, significantly higher means of digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), crude fiber (CF) and nitrogen-free extract (NFE) were observed for cockerels in response to feeding the SFM, RSM and combined plant protein-diets compared with those of the control group. Although hens fed the probiotics and enzyme-supplemented diets consumed significantly less feed they achieved superior means of body weight gain egg production rate, egg weight, feed conversion, economic efficiency, shell thickness, shell weight per unit surface area, yolk color score and Haught units as compared to the control group, regardless of the effect of dietary protein source; other parameters were not affected. Also, cockerels fed the probiotics and enzyme-supplemented diets achieved superior means of digestibility of DM, OM, CP, EE, CF and NFE as compared to their control counterparts. There were significant interactions between dietary protein source and feed additive for body weight gain, shell thickness and shell weight per unit surface area but protein source by feed additive interaction had no effects on other criteria of response. Based on these results, it could be concluded that sunflower meal and rocket seed meal can be used as safe feed ingredients in laying hens diets (at levels of 14-15% or SFM plus RSM at a weight ratio of 1:1), with or without enzyme or probiotics addition. Taking the economic aspect into account, the priority of choosing plant protein sources that can be used as a partial substitute of diet protein is to the two protein sources (i.e. SFM plus RSM), followed by SFM and then RSM.