Abstract:

This experiment was conducted to determine the effects of different force-feeding amounts on growth performance, carcass quality and body fat deposition in Mule ducks. Fifty-six 91-day-old health male Mule ducks (male Albatre Muscovy duck × female Pekin duck) with similar body weight were randomly assigned into 7 treatments with 8 replicates per treatment and 1 Mule ducks per replicate. The experimental feeding period lasted 12 d from 91 to 102-day-old and the corn diet was provided to the seven groups of ducks. The treatment groups were fed by force-feeding and the feed intake in the first 2 days was the same in 330 g·d^-1 at 91-day-old and 390 g·d^-1 at 92-day-old in all groups, and then the force-feeding levels in each treatment remained unchanging during the next 10 days and were 450,540,630,720, 810,900 and 990 g·d^-1, respectively. The results showed that:（1）The mean final body weight were significant differences (P<0.05) and increased gradually with the increasing feeding levels. Average daily gain (ADG) reached to peak when the feeding level was up to 900 g·d^-1 and then decreased with the increasing feeding level. Feed/Gain (F/G) were no significant differences between each treatment groups (P>0.05). Based on the average daily gain (ADG) data, the broken-line regression model was used, the optimum feeding levels for force-feeding Mule ducks was 884.0 g·d^-1（R²=0.992，P<0.000 1）;（2）No significant differences in dressing percentage (DP), eviscerated percentage (EP), breast muscle weight (BMW), breast muscle percentage (BMP), leg muscle weight (LMW) and leg muscle percentage (LMP) were observed among different treatments(P>0.05);（3）Body fat deposition index of Mule ducks increased gradually with the increasing feeding level and significant differences in liver weight (LW) and liver fat percentage (LFP) were observed (P<0.05) among different treatments. Based on the liver fat percentage (LFP) data, the broken-line regression model was used, the optimum feeding levels for force-feeding Mule ducks was 879.8 g·d^-1（R²=0.916,P=0.007 0）. In conclusion, overfeeding of Mule ducks can increase average daily gain and induce fat deposition in adipose tissues and hepatocyte, but growth performance is never unchanged when the feeding level is up to 900 g·d^-1.