الفهرس 
Live body weight and weight gainOnly 14 pages are availabe for public view
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Abstract
Two feeding trials were done at a private farm under the supervision of Faculty of Agriculture, Tanta University, Egypt. The first trial was performed during the winter season from December to March while the second one was carried out in summer season from June to September 2017. The aim of this study was to investigate the effects of three dietary levels of crude protein (CP) in absence or presence of phytase or protease addition and their interaction on growth performance, carcass traits, nutrient digestibility and some blood parameters of growing Japanese quail under Egyptian conditions. In each experiment, a total number of four hundred and five Japanese quail chicks were randomly distributed into 9 treatments, each contained 45 chicks. Each treatment included three equal replications. Chicks of each replication were kept in a battery cage of the dimensions of 50×50×25 cm and fed their respective experimental diet. Birds had free access to feed and water and managed similarly. Three basal diets containing graded levels of CP (24, 21 and 18%) were formulated. Within each level of dietary protein, 3 levels of exogenous enzymes were added (0.0, 0.1 g/kg phytase and 0.5 g/kg protease), thus nine experimental diets were formulated and used from hatching to 6 weeks of age. Criteria of response: In both experiments, growth performance of quail chicks was evaluated in terms of live body weight (LBW), body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), protein efficiency ratio (PER), and economic efficiency of feeding (EEF). Nutrient digestibility was also determined in Japanese quail at 5 weeks old. Carcass characteristics and certain blood parameters of Japanese quail were also measured at the end of a completely randomized design in a factorial arrangement of treatments (3×3) was used in this study; three levels of dietary protein (24, 21 and 18%) and three levels of enzyme supplementation (0.0, 0.1 g/kg phytase and 0.5 g/kg protease). Data were statistically analyzed using twoway analysis of variance by the SPSS Program (SPSS, 1996). The most important results could be summarized as follows: Summer experiment: • Apart from dietary enzyme addition, dietary protein level had no significant effect on final LBW of quail at 42 days of age. • There were no significant differences in BWG, FI or FCR during the total period of study (0-6 weeks of age), nutrient digestibility or carcass traits of quail due to dietary protein level. • The PER and EEF were improved by decreasing dietary protein level, independently from the effect of dietary enzyme addition. • Dietary enzyme supplementation was not effective in improving LBW, BWG, FI, FCR, PER, EEF, nutrient digestibility or carcass traits of Japanese quail. • Dietary phytase supplementation significantly improved the relative weights of gizzard and total edible parts compared with other treatments. • The effects of interactions between dietary protein and enzyme supplementation were not significant on most criteria of growth performance, nutrient digestibility and carcass traits of Japanese quail. Winter experiment: • Dietary protein level had no significant effect on final LBW of quail at 42 days of age, irrespective of dietary enzyme addition. • There were no significant differences in BWG, FI or FCR, nutrient digestibility or most carcass traits of quail chicks due to dietary protein level. • The PER and EEF were improved by decreasing dietary protein level, irrespective of the effect of dietary enzyme addition. • Feeding the enzyme-supplemented diets exhibited no positive effect on final LBW at 42 days of old, BWG, FI, FCR, PER, EEF, nutrient digestibility or carcass traits of quail chicks, regardless of dietary CP level. • There were no significant interactions between dietary protein level and added dietary enzymes on most growth performance criteria, nutrient digestibility or carcass traits of Japanese quail.