Optimal Level Of Energy, Protein, Calcium And Phosphorus For Mule Duck Diets

The trials were adopted 4×3 orthogonal design to study on the optimal level of energy, protein, calcium and phosphorus for mule duck by feeding, metabolism and comparative slaughtering trials. Two phases(1-3 weeks and 4-8 weeks) were conducted in this studies.468 1-d-old mule ducks were randomly divided to 9 dietary treatments, each containing 4 replicate pens with 13 mule ducks per pen in the first phase, and in the second phase,324 22-d-old mule ducks were randomly divided to 9 dietary treatments, each containing 4 replicate pens with 9 mule ducks per pen. Nine experimental diets were formulated to have 3 levels of ME, CP, Ca and P, respectively, in each phase:11.30,11.80, 12.30 MJ/kg ME; 16.50.18.50,20.50% CP; 0.70,0.90,1.10% Ca with 0.45,0.50,0.55% P in the earlier stage(1-3 weeks); and 11.80,12.30,12.80 MJ/kg ME; 14.50,16.50, 18.50% CP; 0.70,0.80%,0.90% Ca with 0.45,0.50,0.55% P in the later stage(4-8 weeks). The growth performance, carcass characteristics, body composition and blood biochemistry indexes were evaluated during the two phases. The growth performance was major indexes to decide the requirements. The calculation formula of requirements were too predicted by linear regression analysis. The results were as follows.Growth performance and carcass characteristic:In 1-3 weeks, the average daily gain, feed intake and feed conversion were significantly affected by the levels of dietary energy, crude protein, calcium and phosphorus of mule duck(P<0.01). The average daily gain and feed conversion are best when the level of energy, crude protein, calcium and phosphorus was respectively 11.90 MJ/Kg,18.94%,0.89% and 0.50%. and the higher concentration of dietary energy, crude protein, calcium and phosphorus decreased daily gain and feed conversion. In 4～8 weeks, the average daily gain was significantly affected(P<0.05) by dietary energy instead of crude protein, calcium and phosphorus of mule duck. Dietary energy and crude protein rather than calcium and phosphorus affected significantly on feed conversion, and feed conversion increased with raising dietary crude protein. The average daily gain and feed conversion were better when the level of energy, crude protein, calcium and phosphorus was respectively 12.36MJ/Kg,16.33%,0.80%and 0.44%. Feed intake all decreased as dietary energy increased in the two phases.There was no regular change for body composition along with dietary energy, crude protein, calcium and phosphorus changes. Carcass ratio, semi-eviscerated carcass ratio, eviscerated carcass ratio and leg muscle rate weren't influenced by concentrations of dietary energy, crude protein, calcium and phosphorus. But dietary crude protein levels only significantly affected on breast muscle rate, and the breast muscle rate raised with the crude protein level increased; Dietary energy levels only significantly affected on abdominal fat rate, and abdominal fat rate raised with increasing the energy level.Deposition regularity:The deposition of dietary energy, crude protein, calcium and phosphorus was respectively 524.10kj/W075,11.61g/W0.75,0.45g/W0.75 and 0.45g/W0.75in 1-3-wk-old mule duck body, and 242.40kj/W0.75,7.10g/W0.75,0.34g/W0.75 and 0.24g/W0.75. The deposition of prophase was higher than that of anaphase. There was adverse effect on its own retention in mule duck body when dietary energy and crude protein level were too high or low.Blood biochemistry indexes:For 1-3-wk-old mule duck, blood urea nitrogen concentration and serum total cholesterol were significantly affected by dietary crude protein level (P<0.05), and decreased with increasing the level of dietary crude protein, and the two was lowest as crude protein level was 20.50%. For 4-8-wk-old mule duck, blood urea nitrogen concentration was significantly affected by dietary crude protein level (P<0.05), and decreased with increasing the level of dietary crude protein, and BUN was lowest when crude protein level was 18.50%. The energy level hadn't effect on TC and TG in 1～3 week(P>0.05), but had in 4-8 week(P<0.05). TC was lowest at the 12.80MJ/kg level of energy, and TG was lowest at the 11.80MJ/kg level of energy. Serum calcium and phosphorus weren't significantly affected by dietary calcium and phosphorus concentration in the trial(P>0.05).Calculation formula of requirements:The results of linear regression analysis showed, to 1-3-wk-old mule duck, that the calculation formula of energy requirement is Y(kJ)=961.8W0.75(kg)+12.72△W(g), that of crude protein requirement is Y(g)=5.19W0.75(kg)+0.35△W(g), calcium requirement is Y(g)=0.1528+0.0154△W(g), and phosphorus requirement is Y(g)=0.0699+0.009△W(g); To 4～8-wk-old mule duck, the calculation formula of energy requirement is Y(kJ)=1113.6W0.75(kg)+9.87｀W(g), that of crude protein requirement is Y(g)=4.70W0.75(kg)+0.44△W(g), calcium requirement is Y(g)=0.1403+0.0253△W(g), and phosphorus requirement is Y(g)=0.0343+0.0151△W(g).Conclusion:The optimal level of energy, crude protein, calcium and phosphorus for 1～3-wk-old mule duck is respectively 11.89 MJ/Kg,18.54%,0.74% and 0.50%; The optimal level of energy, crude protein, calcium and phosphorus for 4-8-wk-old mule duck is respectively 12.39MJ/Kg,16.49%,0.72% and 0.40%.