| In this study, male and female Gaoyou duck and Jinding duck were selected as the experimental materials. Through breeding and observational experiment, nutrient apparent metabolic utilization experiment, slaughter experiment, real-time quantity PCR experiment and so on during0to8weeks of age, the differences of the growth, meat traits, nutrient apparent metabolic utilization, two blood biochemical parameters, gene expression and the relationships among these traits of Gaoyou duck and Jinding duck were compared and analyzed, which provided some evidences about the nutrition and genetic for researching the differences of the production performance of the two breeds. The results of this research as followed:The body weight cumulative growth curves of Gaoyou duck and Jinding duck during0to8weeks presented S-shape curve. The body weight and the growth rate of Gaoyou duck were very significantly higher and faster than that of Jinding duck (P<0.01). The growth rate of Gaoyou duck was fastest at3weeks of age while that of Jinding duck at4weeks of age. There were significant or very significant differences of body measurements between both of two breeds and two genders (P<0.05or P<0.01). Except for body slope length, the other body measurements of two breeds had very significant positive relations (P<0.01). The shank length, shank circumference, fossil bone length and breast width of two breeds had significant positive relations with slaughter performance (P<0.05). The meat performance of Gaoyou duck was better than that of Jinding duck. Excluding dressed percentage and percentage of half-eviscerated yield, there were very significant differences of the other slaughter performance indicators between two breeds (P<0.01). There were very significant differences of fatness traits between two breeds (P<0.01). Abdominal fat deposition capacity of female ducks was better than male. There were very significant positive relations among most slaughter performance indicators (P<0.01). There was few difference of meat quality between two breeds (P>0.05). The meat quality had no significant relation with slaughter performance (P>0.05). There was significant difference of content of fat in leg muscle between two breeds (P<0.05).The concentration of VLDL and TG in peripheral blood plasma was impacted slightly by the breed and gender (P>0.05). The concentration of TG had significant positive relation with breast muscle weight, percentage of breast muscle (P<0.05). The concentration of VLDL had significant positive relation with abdominal fat weight, percentage of abdominal fat and sebum thickness (P<0.05).The apparent utilization of crude protein, crude fiber and nitrogen free extract in Gaoyou duck with fast growth rate was36.97%,71.96%and44.24%higher than that in Jinding duck with slow growth rate respectively (P<0.05and P<0.01). Though the differences of the apparent utilization of ether extract and energy between two breeds did not research the significant level, there was a trend that the apparent utilization of ether extract in Gaoyou duck was higher than that in Jinding duck and the apparent utilization of energy in Jinding duck was higher than that in Gaoyou duck. There were no significant differences of dry matter, crude ash, calcium and phosphorus between two breeds (P>0.05).Hepatic GH and GHR mRNA expression in ducks had developmental changes. GH and GHR mRNA expressed in liver and leg muscle tissues with varietal difference and tissue specificity. Hepatic GHR mRNA expression in two breeds had significant positive correlation with body weight gain (P<0.05). GH mRNA expression in leg muscle in Gaoyou duck had significant negative correlation with body weight (P<0.05). GHR mRNA expression in leg muscle in Jinding duck had significant negative correlation with body weight (P<0.05). Hepatic GH mRNA expression in two breeds had significant positive correlation with liver weight (P<0.05). GH mRNA expression in leg muscle in Gaoyou duck had significant positive correlation with slaughter weight, eviscerated weight and leg muscle weight (P<0.05). Hepatic GHR mRNA expression in Gaoyou duck had significant or very significant negative correlation with liver weight, percentage of lean meat, slaughter weight, dressed weight, half-eviscerated weight and eviscerated weight (P<0.05or P<0.01). Hepatic GHR mRNA expression in Jinding duck had significant negative correlation with eviscerated weight (P<0.05). GHR mRNA expression in leg muscle in Gaoyou duck had significant negative correlation with eviscerated weight, percentage of eviscerated yield, leg muscle weight, percentage of leg muscle, percentage of lean meat (P<0.05). GHR mRNA expression in leg muscle in Jinding duck had significant negative correlation with eviscerated weight (P<0.05). Hepatic GH and GHR mRNA expression in Gaoyou duck had significant negative correlation with abdominal fat weight and percentage of abdominal fat (P<0.05). Hepatic GHR mRNA expression had significant negative correlation with abdominal fat weight and thickness of skin fat (P<0.05). Hepatic GHR mRNA expression in two breeds had significant negative correlation with concentration of VLDL (P<0.05). |
