This experiment was carried out at Poultry ReseachFarm. belonging to Animal Production Department,Facultyof Agriculture. Zagazig University. Benha branch.Two experiments were oonduoted :1. The first was designed to find out the possibilityof improving any undesirable effect resulting fromlowering the dietary protein level by usingconvenient level of calcium and vito 0 which areassumed to improve the protein utilization.2. The second was carried out to improve the meatplatability by sub~tituting a part of animalprotein in diet with single cell protein (yeast).A total number of 630 and 210 day-old Hubbardhybrid chicks were used in first and second experiment.respectively.All chicks were wing banded at hatch, weighed.vaccinated and kept under similar and standardconditions of management.nutrition.Chicks of the first experiment were divided intothree major groups each of 210 chicks fed dietsenvironment. hygein andcontaining 20. 22. and 24~ total protein respectively,from hatch to the 21st day of age, lowered to 18, 20173and 22% respectively therafter.Chicks of each major group were divided into threemajor subgroups each of 70 chicks receiving 1.0%. 1.3%and 1.9% dietary Calcium levels. respectively. Chicksof each calcium level were Provided with either 2200 or5120 I.U. vitamin D (each of 35 chicks).Chicks of the second experiment were grouped intotwo main groups each of 105. receiving diet containing23:20% and 23~18% total dietary protein, respectively.Each group was then subdivided into three subgroups in chicks fed 24. dietaryprotein followed by those fed 22 (3.28>. Analysis ofvariance for data showed significant .ffect due todietary protein content on plasma total protein level.d - Birds fed 1.3~ dietary calcium had the highesttotal protein level (3.33 ml/l00 ml), followed by thosefed 1.9. dietary calcium (3.29 mg/l00 ml).e Chicks fed 5120 I.U./kg ration vit.D hadrelatively the hi.her average of plas.a total protein(3.33 mg/l00 ml) followed by those fed 2200 I.U••However, analysis of variance showed insignificanteffect of either dietary calcfu. content and vit. D.supplementation.f - No significant variation in serum albumen contentwere found due to any factor studied or due to theinteraction between them on this trait.VII - Parameteers of calcium absorption rats:a - Ileum had always the higher average of bothtotal calcium absorption. calcium absorption/emlength/hr or per gm dry matter.b Dietary protein level showed significanteffect on the total calcium absorption only.On the other hand. dietary calcium level showedsignificant effect on the absorbed amount/cm length/hronly.c - Vit.D supplementation showed no .ilnifioanteffact in aJ I parameters of calcium absorption rate.b - Values of the correlation coefficient betweenthe rate of caJcium absorption per either 1 cmintestinal lenjth orper1 1m intestinal dry weight andtotal lengths or total dry wellhts of differentintestinal relion. differed in their magnitudeaccord1n, to either inte.tinal part or the proteinlevel. However. they were allot hilh and positivevalue.a.oood .xp.rt ••nt I1. Para •• tars of growth pertor.ance1. Body wei,ht.a - Highest body weilht average (1262.12 g_> wasfound in chicks fed fish meal as a source of animalprotein.b - Dietary protein levels and source had significanteffect on the average of body weight from the 4th wk or from the 3rd wk up to the end of theexperimental period.2. Weight gain:Dietary protein source showed significant effecton average body weight gain at 4th and 5th wks ofchicks age, while the effect of protein level wassignificant from the 3rd wk up to the end ofexperimental period.3. Rate of growth.Significant variation in average growth rate wasfound, during 2 - 3, 3 - 4 and 4 - 5 wks of age due todietary protein source. However, dietary protein levelwas found to have insignificant effect on the rate ofgrowth along the experimental period except during 2-3wk of chick’s age.4. Keel and shank lengthsa - Dietary protein source affected keel length ata 11 agesvariationexcept at 1~ and 6th weeks. However,in shank length due to this treatment wasobserved allover the experimental period except at1~, 3rd and 4th weeks of chicks age.b - Dietary protein level significantly affectedaverage of keel length during the period from the 1~wk to the 5th wk of chicks age.II Feed consumption and efficiency:Feed consumption varied significantly at 6ih wkaccording to dietary protein source, while significanteffect was found at 2nd and 5th wks for dietary proteinlevel. No significant variation in feed efficiencycould be detected due to either dietary protein sourcesor levels.III - Parameters of carcass quality:a - No significant effect was found due to dietaryprotein levels or source and the interaction betwe.nthem on various traits of killina, dressing andeVisceratin, losses except the absolute weight of bloodwhich showed sianificant response to dietary proteinsubstitution.b - Sianificant variations due to dietary proteinsource were found in absolute weights of edible meat.Variations In all traits
