Evaluation Of Metabolizable Energy Value And Effects Of Different Rapeseed Oil On Growth Performance And Health In Meat Duck

It is important to evaluate the metabolisable energy?ME?of rapeseed oils from different varieties in duck.It is necessary to determine the proportion of oil substituting to basal diet and the suitable duck age when evaluationg the oil ME by TME method.In this paper the objective was to evulate the ME of four kinds of rapeseed oil with different euric acid content in duck with different age.Three trials were conducted.Firstly,the effect of rapeseed oil substitution ratio on metabolisable energy?ME?and duck age was explored to determine the appropriate oil substitution ratio.Then effects of different weeks of ducks on ME evaluation of 4 kinds of rapeseed oil was further studied.At last a duck growth performance was used to compare the two kinds of rapeseed oils?high and low erucic acid content?with three ME value evaluated at 7,13,and 19 weeks of agein duck on the growth performance,and health in meat ducks.Exp 1:The study of the oil appropriate substitution ratio on metabolisable energy of rapeseed oil in duckThe purpose of this experiment was to explore the effect of oil substitution ratio to corn on ME of rapeseed oil in meat ducks at different ages.Two metabolisable tests were conducted on male Cherry Valley Ducks at age 7 weeks?BW 2.7±0.3 kg?and 19 weeks?BW 3.1±0.3 kg?respectively.Each experiment was designed according to completely randomized block design with six treatment groups:corn group,starvation endogenous group,and four different proportion groups of rapeseed oil substitution?rapeseed oil substitution for corn at 5%,10%,15%and 20%,respectively?.Each treatment had 12replicates and one duck per replicate.Metabolisable test was carried out by“TME”method.The results showed that:1)With the increase of substitution ratio,the utilization of dietary dry matter?DM?increased firstly and then decreased gradually,while the utilization of crude protein?CP?and crude fat?EE?decreased gradually with the increase of substitution ratio,and the CP and EE of 20%group were significantly lower than those of 5%group,but the apparent metabolizable energy?AME?,true metabolizable energy?TME?,nitrogen corrected apparent metabolizable energy?AMEn?and nitrogen corrected true metabolizable energy were significantly lower than those of 5%group.The value of TMEn increased gradually?P<0.05?.2)Weekly age significantly affected the utilization of dietary DM and CP in ducks,and the utilization of dietary DM in 19-week-old ducks was significantly higher than that in 7-week-old ducks,while the utilization of CP was significantly lower than that in 7-week-old ducks?P<0.05?.3)The ME of rapeseed oil decreased with the increase of substitution ratio,and ME of 15%and 20%substitution groups was significantly lower than that of 5%and 10%substitution groups?P<0.05?.4)Substitution ratio and weekly age had significant interaction effect on rapeseed oil ME?P<0.05?,which showed that rapeseed oil ME of 19-week-old ducks was relatively stable.The results showed that the suitable ratio of rapeseed oil to substitute the corn was 10%,and the 19-week-old duck was more stable in evaluating rapeseed oil ME.Exp 2:Effect of duck ages and different varieties rapeseed oil on the ME of oil in meat ducksThe aim of this experiment was to study the effects of age and rapeseed oil varieties on metabolic energy?ME?values of rapeseed oil in ducks.Metabolisable tests were carried out in meat ducks at 7?BW,2.7+0.3 kg?,13?BW,3.2+0.3 kg?and 19?BW,3.1+0.3 kg?.At each week,a corn group,a starving endogenous group and four rapeseed oil groups?Deyou 6:2.1%erucic acid;Mianbang oil 1:7.3%erucic acid;Deyou 5:36%erucic acid;Silicone oil 3:54%erucic acid?were set up,with 12 replicate per treatment with one duck for each replicate.The metabolisable test was carried out by“TME”method,and the substitution ratio of rapeseed oil was 10%.The results showed that:1)The dietary dry matter?DM?utilization rate of 13 and 19 week-old ducks was significantly higher than that of 7 week-old ducks,while the dietary protein utilization rate was significantly lower than that of 7 week-old ducks?P<0.05?;the crude fat and DM utilization rate of low erucic acid rapeseed oil group was significantly higher than that of high erucic acid rapeseed oil group?P<0.05?.2)The age of ducks had no effect on ME of rapeseed oil?P>0.05?;the AME,TME,AMEn and TMEn of 54%erucic acid rapeseed oil were significantly lower than those of the other three rapeseed oil groups?P<0.05?.3)In terms of interaction effect,the erucic acid content of rapeseed oil in 7-week-old duck and 13-week-old duck had significant effects on AME,TME,AMEn and TMEn of rapeseed oil?P<0.05?,which showed that under 7-week-old and 13-week-old conditions,high erucic acid content decreased the ME value of rapeseed oil.The results showed that erucic acid content in rapeseed oil could affect the utilization efficiency and ME of rapeseed oil in meat ducks,and the difference of ME for rapeseed oil with high erucic acid compared to low erucid acid content could be shown at 7 weeks or 13 weeks age but not at 19 weeks age in duck.The AME evaluated at 7,13,and 19-week-old ducks are respectively:8.71Mcal/kg forMG,9.63Mcal/kg for DG,9.90Mcal/kg for MD,9.91Mcal/kg for DD.Exp 3:Effects of high and low erucic acid rapeseed oil with different ME on growth performance and health of meat ducksThe purpose of this experiment was to verify the accuracy of metabolic energy values of low erucic acid rapeseed oil?DD;erucic acid:2.1%?and high erucic acid rapeseed oil?MG;erucic acid:54%?at three ages in experiment 2,and to study their effects on growth performance and health of meat ducks.According to the ME of low and high erucic acid rapeseed oil in three ages assessed in experiment 2,the formula of isoenergetic isonitrogen diet was designed,and soybean oil control group was set up.There were 7 treatments,8replicates in each treatment,12 meat ducks in each replicate,672 Cherry Valley meat ducks in total.The amount of oil added was 6%.The experiment started at 15d and ended at 30d.The results showed that:1)Compared with soybean oil group,high and low erucic acid rapeseed oil and its energy had no significant effect on body weight?BW?,body weight gain?BWG?,feed intake?FI?,feed-weight ratio?FCR?and mortality of meat ducks?P>0.05?.BW,BWG and FI of meat ducks in high erucic acid group were significantly lower than those in low erucic acid group?P<0.05?.Compared with AME₇,there was no significant difference in FI in AME₁₃ group,but FI in AME₁₉ group decreased significantly?P<0.05?;there was no significant difference in BWG between AME₇ and AME₁₉9 ducks,but BWG of AME₁₃ group was significantly higher than that of AME₁₉ ducks.Compared with soybean oil group,high and low erucic acid and its energy had no significant effect on the utilization of crude protein,crude fat,energy and dietary AME of meat ducks?P>0.05?.2)The relative weight of liver in high erucic acid group was significantly higher than that in low erucic acid rapeseed oil group?P<0.05?.3)Compared with soybean oil group,the levels of glutamic-pyruvic transaminase,glutamic oxaloacetic aminotransferase,total cholesterol,triglyceride,high density lipoprotein cholesterol,low density lipoprotein cholesterol and very low density lipoprotein cholesterol in serum of 30-day meat ducks were not significantly affected by high and low erucic acid group?P>0.05?;the total cholesterol content in serum of high erucic acid group was significantly lower than that of low erucic acid group?P<0.05?.4)High or low erucic acid and its energy had no significant effect on the pathological score of liver sections?P>0.05?.The results showed that the metabolisable energy of meat ducks with high and low erucic acid rapeseed oil was accurately assessed,especially at the age of 7 weeks.High erucic acid rapeseed oil significantly reduced production performance?BW,BWG and BWG?,increased liver relative weight and serum total cholesterol content.In conclusion,to evaluation the ME value by TME method of rapeseed oil,the suitable oil substitution ratio to corn was 10%with the young age of duck may be more sensitive to the content of euric acids.The ME of rapeseed oil for the four kinds rapeseed oil at 7,13,19 weeks were 8.71Mcal/kg forMG,9.63Mcal/kg for DG,9.90Mcal/kg for MD,9.91Mcal/kg for DD;The high level of eruic acids in rapeseed oil would resulted the reduced growth performance,increased liver relative weight and serum total cholesterol content.