| The experiment was conducted to investigate the effects of dietary Ca levels ongrowth performance, incidence of leg abnormality, carcass traits, body measurements traits,Viscera Growth, tibia and toe quality, Serum Biochemical Indices and nutrient availabilityto find the sensitive indices estimating Ca requirement of the dietary, then obtained theoptimal dietary Ca level in princess chickens from0~7weeks by fiting out themathematical model. A total of2401-day-old princess chickens were randomly assigned tofive treatments, which consisted of6replicates with8birds in each. Five levels each of Ca(0.65,0.80,0.95,1.10and1.30%) were fed in a completely randomized design with acorn-soybean basal diet (containing Ca0.65%). water and Feed were provided ad libitiumduring the experimental period of49days. The metabolism trial was conducted for4daysafter feeding trial. The results suggest as follows：(1) Supplemental Ca had significant differences (P<0.05) in growth performance from5~7and0~7weeks but0~4weeks, also the incidence of leg abnormality,mortality(P>0.05), the percentages of leg muscle and abdominal fat had been affectedsignificantly (P<0.05) except for other carcass indices and meat quality. According to trendanalysis and mathematic model, showed the linear broken-line (P<0.05), ADFI showed thequadratic curve (P<0.05), the percentage of leg muscle tended to be a quadratic effect(P=0.072), while ADG, F/G and the percentages of abdominal fat changed linearly (P<0.05)with the increasing of dietary Ca level.(2) The dietary Ca concentrations had significant (P<0.05) influence on Body length,keel length, Shinbone girth, Index of the duodenum, Length of the ileum and cecum butother body size traits and visceral organs (P>0.05). the length of body and keel showed thequadratic broken linear ((P<0.05)), Shinbone girth and Length of the ileum showed thequadratic curve (P<0.05), while the Index of the duodenum changed linearly (P<0.05).(3) The broking strength, weight of tibia Ash and defatted tibia, content of Ash, Caand P, and the ratio of Ca and P in tibia ash had been effected significantly (P<0.05)excepted for the weight of fresh and dry tibia, and content of P in defatted tibia (P>0.05),also effected significantly (P<0.05) in the weight of toe ash, content of toe and Ca in toeash but other indices (P>0.05). According to trend analysis and fiting model, The broking strength, content of Ca in defatted tibia and Ca/P in tibia ash showed the linear broken-line(P<0.05), the weight of tibia Ash and dry defatted tibia, content of Ca in tibia ash, thecontent of toe and Ca in toe ash showed quadratic curve (P<0.05), however, the content ofAsh and P in tibia ash changed linearly (P<0.05).(4) There were significant differences (P>0.05) in serum Ca, P, Ca/P and availabilityof CP and EE, but not in AKP and other nutrient availability (P>0.05). The serum Ca, Pand EE availability showed quadratic curve (P<0.05), while the ratio of Ca to P and CPavailability showed linear effects (P<0.05).In consequence, The keel length, Shinbone girth, Length of the ileu, broking strength,weight of tibia Ash and defatted tibia, Ca, P and the ratio of Ca and P in tibia ash, toe ash,the serum P and EE availability could be more credible used to assess the Ca requirements,the optimal dietary Ca levels of pricess chicken fed a corn-soybean meal diet from0~7weeks were calculated to be0.88～1.02%based on the best fitting mathematic modelamong the broken-line and quadratic curve of the above indices. The final Ca requirementwas suggested to be1.02%. |
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