Abstract:

This experiment was conducted to determine the effects of different forcefeeding levels on carcass quality, body fat deposition and apparent digestibility of nutrients for Pekin ducks. Ninetysix 35dayold health male Pekin ducks with similar pen weight were randomly assigned into 8 treatments with 6 replicates per treatment and 2 Pekin ducks per replicate. Apparent digestibility of nutrients was determined with chromic oxide (Cr2O3) at an inclusion rate of 0.5% in basal diet. The experimental feeding period lasted 7 d from 35 to 42 d of age and the cornsoybean diet was fed to the eight groups of ducks, the control group by ad libitumfeeding and the experimental groups by forcefeeding. The forcefed intake was 260 g·d-1 at 35 d of age and increased to 300 g·d-1 at 36 d of age. The forcefed intake unchanged during the other five days and they were 300,330,360,390,420,450 and 480 g·d-1 each treatments, respectively. The results showed as follows: （1）No significant differences in dressing percentage（DP），eviscerated percentage（EP），breast muscle percentage（BMP)，leg muscle weight（LMW) and leg muscle percentage（LMP）were observed among treatments(P>0.05). Breast muscle weight(BMW) increased with increasing feeding level from the control group to 390 g·d-1 (P<0.05) and then decreased (P>0.05). Based on the brokenline regression model analysis with BMW data, the optimum feeding levels for forcefeeding Pekin ducks was 390.7 g·d-1; These were significant differences among treatments in body fat deposition index(P<0.05). But body fat deposition were unchange when forcefeeding levels reached a certain value (P>0.05).（2）For the final overfeeding period, there were significant differences in apparent digestibility of dry matter and crude protein (P<0.05), whereas apparent digestibility of energy had no significant differences (P>0.05) between different treatments. In conclusion, overfeeding of Pekin ducks can induces a strong fattening of subcutaneous adipose tissues and muscles and forcefeeding has a significant effect on breast muscle growth. However, nutrients digestibility decrease and body fat deposition keep unchange with increasing forcefeeding levels.