The Effect Of Overfeeding On Fat Deposition And Apparent Digestibility Of Nutrients For White Pekin Ducks

This thesis studyed the effect of force-feeding on production performance, serum biochemicalparameters, carcass quality, body fat deposition and apparent digestibility of nutrients for Pekin ducksthrough feeding experiment, slaughter experiment, and blood biochemical analysis so on. The resultprovided a way for actual production.Experiment1was conducted to determine the effects of different force-feeding levels onproduction performance, serum biochemical parameters and liver histology for Pekin Ducks. Ninety-six35-day-old health male Pekin ducks with similar body weight were randomly assigned into8treatmentswith6replicates per treatment and2Pekin ducks per replicate. The experimental feeding period lasted7d from35to42d of age and the corn-soybean diet was provided to the eight groups of ducks. Thecontrol group was fed ad libitum and the treatment groups were fed by force-feeding. The feed intake ofseven treatment groups in the first2days was the same in260g/bird at35d and300g/bird at36d of age,and then the amount of feed provided to the ducks in each treatment remained unchanging during theother5days and was300,330,360,390,420,450and480g/d、bird for each treatment group respectively.The results showed that（:1）The final mean body weight and ADG were significantly were higher in theforce-feeding groups than those in the control group（P<0.05）. Final mean body weight and ADGincreased with increasing feeding level from the control group to the group with420g/d （P<0.05） andthen were changeless over that level （P>0.05）. F/G were no significant differences between eachforce-feeding group and the control group（P>0.05）. Based on the broken-line regression model analysiswith average daily gain（ADG） data, the optimum feeding level for force-feeding Pekin ducks is414.2g/d;（2）No significant differences in serum Glu、GOT and GGT levels were observed amongtreatments（P>0.05）. Serum TG、CHO and GPT levels increased with increasing feeding level and thedifferences between the control group and each force-feeding group were significant（P<0.05）.Histology observation showed that swelling of hepatocyte was observed and the cytoplasm was full offat in force-fed group compared to the control group. In conclusion, overfeeding of Pekin ducks caninduce a strong fat deposition in subcutaneous adipose tissues, muscles and hepatocyte, but growthperformance was changeless over the feeding level of420g/d.Experiment2was conducted to determine the effects of different force-feeding levels on carcassquality, body fat deposition and apparent digestibility of nutrients for Pekin Ducks. Ninety-six35-day-old health male Pekin ducks with similar pen weight were randomly assigned into8treatmentswith6replicates per treatment and2Pekin ducks per replicate. Apparent digestibility of nutrients wasdetermined with chromic oxide （Cr₂O₃） at an inclusion rate of0.5%in basal diet. The experimentalfeeding period lasted7d from35to42d of age and the corn-soybean diet was fed to the eight groups ofducks, the control group by ad libitum-feeding and the experimental groups by force-feeding. Theforce-fed intake was260g/bird at35d of age and increased to300g/bird at36d of age. The force-fedintake remains unchanged during the other five days and they are300,330,360,390,420,450and 480g/bird each treatments, respectively. The results showed as follows:（1）No significant differencesin dressing percentage（DP），eviscerated percentage（EP），breast muscle percentage（BMP），legmuscle 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 to390g/d（P<0.05） and then decreased over that level （P>0.05）. Based on the broken-line regression modelanalysis with BMW data, the optimum feeding levels for force-feeding Pekin ducks is390.7g/d; Thesewere significant differences among treatments in body fat deposition index（P<0.05）. But body fatdeposition were changeless when force-feeding levels reached a certain value （P>0.05）（.2）For the finaloverfeeding period, there were significant differences in apparent digestibility of dry matter and crudeprotein （P<0.05） whereas apparent digestibility of energy had no significant differences （P>0.05）. Inconclusion, overfeeding of Pekin ducks can induces a strong fattening of subcutaneous adipose tissuesand muscles and force-feeding has a significant effect on breast muscle growth. However, nutrientsdigestibility decrease and body fat deposition keep changeless with increasing force-feeding levels.Experiment3was conducted to determine the effects of different levels of a commercial enzymecomplex on production performance, serum biochemical parameters and liver histology for Pekin Ducksby overfeeding. Ninety-six35-day-old health male Pekin ducks with similar body weight wererandomly assigned into4treatments with6replicates per treatment and4Pekin ducks per replicate. Thecorn-soybean diet was provided to the four groups of ducks: the control diet and the other three enzymecomplex supplemented diets which were100mg/kg,200mg/kg and300mg/kg enzyme complexsupplemented to the control diet, respectively. The feed intake of four treatment groups in the first2days was the same in260g/bird at35d and300g/bird at36d of age, and then the amount of feedprovided to the ducks in each treatment remained unchanging during the other5days and was400g/d、bird for each treatment group respectively. The experimental feeding period lasted7d from35to42dof age. The results showed that:（1）Compared with the control group and the group of100mg/kgenzyme complex, the Pekin ducks overfed the diets supplemented with200mg/kg and300mg/kgenzyme complex had better ADG and F/G（P<0.05）. However, growth performance was no significantdifferences between the group of100mg/kg enzyme complex and the control group （P>0.05）, the200mg/kg enzyme complex group and the300mg/kg enzyme complex group （P>0.05）.（2）Nosignificant differences in serum Glu、TG and HDL levels were observed among treatments （P>0.05）while serum CHO and LDL levels had significant differences （P<0.05）.（3）Histology observationshowed that swelling of hepatocyte were observed and the cytoplasm was full of fat in each group. Nowhole cell shape was observed and the cell nuclei are squeezed to one side. Enzyme can increase fatdeposition of hepatocyte in force-feeding ducks. In conclusion, supplementation of enzyme complexwas beneficial for overfed Pekin ducks, while excess enzyme complex can not induce a betterperformance.This thesis discussed the optimum force-feeding level and the effect of enzyme on productionperformance for Pekin ducks.This study was barely reported before.It provided ways for reducingforce-feeding levels, improving the efficiency of feed utilization and shortening the breeding cycle in production,which would be of important practical significances.