| China is the world's largest producer and consumer of ducks.With the improvement of living standards,the consumption has changed from the weight of the duck carcasses to the duck quality with smaller bodies,delicious meat,and high nutritional value.The purpose of this study was to determine the optimum stocking density under the net flat-raising pattern based on growth performance,dermatitis incidence,survival rate and feed conversion ratio indicators.The Shuzhou duck body measurement index,slaughter performance,and conventional meat quality were measured.At the same time,the amino acid,fatty acid,mineral elements and cholesterol content were measured of Shuzhou duck and Cherry Valley duck.Finally,the spatio-temporal expression levels of muscle-related MyoD,Myf5 and IGF genes were analyzed in order to elucidate the muscle growth,meat quality,and molecular regulation mechanisms of Shuzhou duck.The main findings of this study were as follows.1.In the net flat-raising mode,the growth performance of the Shuzhou duck was compared between different stocking densities.The feed conversion ratio was 2.81:1 and the incidence of dermatitis was 1.26%and the survival rate was as high as 99.8%at 3 animals per square meter.The 49-day-old slaughter weight reached 1957.50 g,which was the optimum breeding density.2.The body measurement index and slaughter performance of Shuzhou duck were measured under the above feeding conditions.At the same time,amino acids,fatty acids,mineral elements and cholesterol were detected in muscles of two kinds of ducks.The results were found that the Cherry Valley duck weight was significantly heavier than the Shuzhou duck(P<0.05).The breast muscles ratio were more than 11%and the leg muscles ratio were more than 10%and the abdominal fats rate were less than 2%and the carcass rate were more than 80%and percentage of eviscerated yield were above 70%of two kind of ducks.The intramuscular fat and collagen in Shuzhou duck from were significantly higher than those from 42-day-old Cherry Valley duck(P<0.05).The 49-day-old Shuzhou duck was higher than the 42-day-old Cherry Valley duck in the deposition of mineral elements Fe,Cu,Zn,and Ca in the breast muscle.The content of mineral elements Fe and Cu was higher than that of Cherry Valley duck,but the difference was not significant(P>0.05).The total amount of amino acids in breast muscles and leg muscles of Shuzhou duck at 49 days was 19.01%and 18.70%,respectively,higher than 42-day-old Cherry Valley duck.The total unsaturated fatty acids in breast muscle of 49-day-old Shuzhou duck and 42-day-old Cherry Valley duck were 52.67%and 50.50%,respectively(P<0.05).dThe content of unsaturated fatty acids of leg muscles were significantly higher than that of breast muscles(P<0.05).The cholesterol of 42-day-old Cherry Valley duck was significantly higher than that of Shuzhou duck(P<0.05).And the cholesterol content of 49 days old Shuzhou duck breast muscle was significantly higher than the leg muscle(P<0.05).3.Comparing the developmental rules of muscle fiber,we found that there was no significant difference in fiber diameter between the two ducks in the first 5 weeks.The diameter was smaller of the Shuzhou duck which meant more delicious at the 7 week.In the regulation of muscles development,the MyoD and Myf5 genes expression decreased first,then increased,decreased finally as the age increased.The MyoD and Myf5 genes expression were higher at the 1 and 5 weeks and lower at the 3 and 7 weeks.The IGF gene expression decreased with the increase of age and was highest at the 1 week and lowest at the 7 week.Three genes expression indicated that MyoD,Myf5 and IGF had important influence on the early muscles development.To sum up,the best breeding density was 3 animals per square meter of Shuzhou duck in the net flat-breeding mode.The Shuzhou duck(49-day-old)slaughter weight reached 1957.50g.Comparing with Cherry Valley duck,its slaughter performance,carcass quality was better and muscles were fresh.The total amino acids,essential amino acids,unsaturated fatty acids,mineral elements,low cholesterol content and small muscle fiber diameter were better than Cherry Valley duck.It was suitable for further promotion as a high-quality small body duck. |
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