Effect Of Interaction Between Energy And Protein Levels On Growth Performance In Early Pekin Ducks

A 5×2 factorial experiment containing five ME levels (12.75, 12.12, 11.45, 10.87, 10.24 MJ/kg) and two CP levels (20.5%,17.5%) was conducted to investigate effects of energy and protein levels on growth performance in 0~3 weeks old Pekin ducks.Five hundred and sixty 1～day～old male Pekin ducks of Z line were randomly assigned into ten groups which contained eight replicates and seven ducks per replicate.The results showed that:(1) the significant positive correlations were observed between energy levels and body weight, daily weight gain (P<0.05), but the significant negative correlations were observed between daily feed intake and feed / gain (P<0.01). It had not significant difference between different protein levels and 3 weeks body weight of pekin ducks, but high protein level had the tendency to improving the body weight.(2)0~3 weeks Pekin ducks energy intake per day kept consistent, and had no effect with energy and protein level. The energy level highly significant decreased protein intake and protein consumption for every gram gain(P<0.01). There were no significant correlations between protein levels and daily feed intake, daily feed protein, different energy.(3)The enery levels highly significant improved abdominal fat weight and the rate of abdominal fat 3 weeks Pekin ducks (P<0.05).High protein level presented significant effect to decrease the rate of abdominal fat(P<0.05). There were no significant correlations between breast meat weight, leg meat weight and different energy and protein levels.The interactive effect of energy and protein levels significantly affected the body weight, daily weight gain and feed/intake of 21～day age pekin ducks. The requirement of energy at high protein levels were estimated by broken～line regression analysis for feed/gain and weight gain as measuring index.(4)There were no significant effect between different protein levels and blood biochemical index, including triglyceride, uric acid and cholesterol (P>0.05).High enery level significantly improved cholesterol, but had no significant effect in triglyceride and uric acid (P>0.05).(5)High energy level highly significant improved liver weight and the rate of liver weight /vivo (P<0.01). The interactive effect of erengy and protein levels highly significant affected liver weight and the rate of liver weight /body weight (P<0.01). (6)The level of energy highly significant improved the apparent metabolic rate of energy(P<0.05),but the level of protein had no significant effect in the apparent metabolic rate of energy(P>0.05);the level of energy and protein had no significant effect in the apparent metabolic rate of protein(P>0.05).The results showed that at 20.5% CP level, to gain the lowest feed/intake and the feed intake, the energy levels should be 12.60 MJ/kg and 12.56 MJ/kg.