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.

A study on florfenicol （FF） and florfenicol amine （FFA） residue depletion was conducted in chicken muscle. FF and FFA were extracted from chicken muscle with acetone and dichloromethane. The extract solution was degreased in nhexane saturated with acetonitrile, dried in nitrogen evaporator and residues were dissolved in mobile phase. FF and FFA were determinated by high performance liquid chromatography （HPLC） with fluorescence detector. The mobile phase was acetonitrilemonosodium phosphate solution（0.01 mol·L-1, containing 0.005 mol·L-1 SDS and 0.1% triethylamine）（35:65 by volume）, the flow rate was 1.0 mL ·min-1. The fluorescence detection was with an excitation wavelength of 225 nm and an emission wavelength of 285 nm. Result were as follows: The limits of detection（LODs）of FF and FFA were 1.5 μg·kg-1（S/N=3） and 0.5 μg·kg-1（S/N=3）, respectively. The limits of quantitation （LOQs）were 5 μg·kg-1（S/N=10）and 2 μg·kg-1（S/N=10）, respectively. After the chickens orally administered successively FF capsules of 25.0 mg·kg-1, 50.0 mg·kg-1 and 100.0 mg·kg-1 of body weight one time every day for 5 days, respectively, at the first withdrawal day, the maximum residues of FF and FFA were detected. The residues were rising with the dosage and reducing with the withdrawal time. At the 7th withdrawal day, the total residues of FF and FFA were all lower than the MRLs （100 μg·kg-1）; and all lower than the lowest LOD at 11th withdrawal day. The residues and total residues of FF and FFA in chicken muscle were all positively correlated with FF orally administered doses.