| Trace minerals play an important role in improving animals’ growth performance,reproductive performance and the quality of animal products.However,there is a problem of excessive addition of inorganic trace minerals in livestock and poultry production,causing serious environmental pollution and even food safety problems.The bioavailability of organic trace minerals is higher,and many studies have shown that the reduction and replacement of organic trace minerals can maintain the normal physiological function of the body and reduce the excretion of trace elements in feces.However,the current research on reduction and total replacement of organic trace minerals mainly focuses on chickens and pigs,and there are few reports on the research of meat ducks.In order to achieve energy saving and emission reduction,and improve the effective utilization of resources,this experiment explored the effect of compound organic trace minerals to replace inorganic minerals on the growth performance,meat quality,antioxidant capacity,immunity and trace mineral metabolism of meat ducks,to provide a theoretical basis for the promotion and application of low-level organic trace minerals in meat duck production.A total of 450 1-day-old Cherry Valley Ducks were randomly divided into 5 groups with 6 replicates in each group and 15 in each replicate.The inorganic control group(ITM group)was supplemented with inorganic trace minerals recommended by NRC(1994)in the basal diet(iron,copper,manganese,zinc and selenium was added 40,10,50,60,0.2 mg/kg);the blank control group(NC group)was fed basal diet without additional iron,copper,manganese,zinc and selenium;the 1/2NRC inorganic group(1/2ITM group)and the 1/2NRC organic group(1/2OTM group)were added 50%of the NRC recommended amount of inorganic or organic trace elements(iron,copper,manganese,zinc and Selenium was added 20,5,25,30,0.1 mg/kg);and the 1/2ITM+1/2OTM group was added 50%of the NRC recommended amount of inorganic trace elements and organic trace elements in the basal diet.The trial period is 42 days.The major results were as follows:1.Effect of low-level organic trace elements replacing inorganic trace elements on the production performance and meat quality of meat ducks1)Compared with the ITM group,the body weight(BW)and average daily gain(ADG)of 1～21 and 1～42-day-old meat ducks in the NC and 1/2ITM groups were significantly lower(P<0.05),while there was no significant difference in BW,ADG and feed conversion rate(FCR)of meat ducks in thel/2OTM group and 1/2ITM+1/2OTM group at each stage(P>0.05).The BW and ADG of meat duck in the 1/2OTM group were significantly higher than 1/2ITM group at each stage(P<0.05).2)Except the breast muscle drip loss of meat ducks in NC group was significantly increased compared with the ITM group(P<0.05),there were no significant differences in pH,meat color,drip loss and cooking loss of the breast muscle among groups(P>0.05).2.Effects of low-level organic trace elements to replace inorganic trace elements on the metabolism of trace elements in meat ducks1)Compared with the ITM group,the NC group significantly reduced the contents of iron and zinc in serum,the contents of iron,copper,manganese,zinc and selenium in tibia,the depositions of selenium in breast muscle,the depositions of iron,manganese,zinc and selenium in liver,as well as the depositions of iron,manganese and selenium in kidney were significantly decreased(P<0.05);contents of zinc in serum,copper,manganese,zinc and selenium in tibia,iron,manganese,selenium in liver,and the depositions of selenium in the kidney of 1/2ITM ducks were significantly decreased(P<0.05);the contents of copper and selenium in the tibia of meat ducks in the 1/2OTM group were significantly decreased(P<0.05),and the content of selenium of breast muscle in the 1/2ITM+1/2OTM group is highest among all of the groups.Compared with the 1/2ITM group,the content of manganese,zinc and selenium in the tibia of the meat duck in the 1/2OTM group were significantly increased(P<0.05),however,the content of zinc in the serum,the depositions of zinc and selenium in the liver,selenium in the kidney were slightly improved,but the difference were not significant(P>0.05).2)Compared with the ITM group,the fecal iron,copper,manganese,and zinc excretion of meat ducks in the NC,1/2ITM,1/2OTM and 1/2ITM+1/2OTM groups were significantly reduced(P<0.05),especially,fecal iron,copper,manganese,and zinc in the 1/2OITM group were significantly reduced by 19.68%,38.40%,17.58%,41.30%and 37.83%(P<0.05)than those in the positive control group.The fecal trace elements of the 1/2OTM group decreased to varying degrees in comparison with the 1/2ITM group,and the excretion of heavy metals followed the order overall:NC<1/2OTM<1/2ITM<1/2ITM+1/2OTM<ITM.3.Effects of low-level organic trace elements to replace inorganic trace elements on serum biochemistry,antioxidant and immune functions in meat ducks1)Compared with the ITM group,there were no significant differences in the serum glucose(GLU),total cholesterol(T-CHO),triglyceride(TG),lactate dehydrogenase(LDH),uric acid(UA)of 21-day-old and glucose(GLU),total cholesterol(T-CHO)and triglyceride(TG)of 42-day-old meat duck(P>0.05).At the same time,the activity of alkaline phosphatase(ALP)was significantly decreased(P<0.05),and Alanine aminotransferase(ALT),aspartate aminotransferase(AST),lactate dehydrogenase(LDH)and uric acid(UA)content of 42-dayold meat duck were significantly increased(P<0.05).Compared with the 1/2ITM group,the serum ALP of the 21-day-old meat ducks in the NC group was significantly decreased(P<0.05),and the serum ALP activity of the 1/2OTM group meat ducks was increased at the 21day and 42-day age,and the UA content decreased at 42 days of age,but all of the differences were not significant(P>0.05).2)At the age of 21 and 42 days,there were no significant differences in the blood routine indexes of meat ducks among each group(P>0.05).3)Compared with the ITM group,the antioxidant capacity of meat ducks in the NC group and the 1/2ITM group were significantly decreased,which was manifested as a significant increase in the content of malondialdehyde(MDA)in serum and liver(P<0.05).At the same time,the total antioxidant capacity(T-AOC)in serum and liver significantly decreased(P<0.05),and the activities of various antioxidant enzymes decreased to varying degrees;There were no significant changes in serum antioxidant indexes(except glutathione peroxidase GSHPx activity)of 1/2 OTM group meat duck(P>0.05),although the activity of some antioxidant enzymes in the liver decreased,but the contents of T-AOC and MDA were not change significantly(P>0.05);The antioxidant capacity of meat ducks in the 1/2ITM+1/2OTM group was slightly improved,among which the GSH-Px activity in serum was significantly increased(P<0.05),and the MDA content and GSH-Px activity in the liver of meat ducks at 42 days of age were improved,but the differences were not significant(P>0.05).Compared with the 1/2ITM group,the antioxidant capacity of the 1/2OTM group was improved,the MDA content in the meat duck serum and liver was significantly decreased(P<0.05),meanwhile,the TAOC was significantly increased(P<0.05),and the other antioxidase activity also increased to varying degrees.4)Compared with the ITM group,the GLOB,TP,IgA and IgM contents in serum of 21day-old and 42-day-old meat ducks and the IgG content of 42-day-old meat ducks in the NC group were significantly decreased(P>0.05),The levels of GLOB,TP and IgG in serum of 21-day-old meat ducks in the 1/2ITM group and the levels of GLOB,TP,IgA,and IgM in the 42-day-old meat ducks were significantly decreased(P<0.05).The level of IgG was also significantly decreased(P<0.05).The level of IgG in the serum of 21-day-old meat ducks in the 1/2ITM+1/2OTM group was significantly increased(P<0.05).Compared with the 1/2ITM group,the GLOB level in serum of the 42-day-old meat ducks in the 1/2OTM group was significantly increased(P<0.05),and the levels of GLOB,TP and IgG at the 21-day-old and TP,IgA,IgM levels at the 42-day-old duck increased,but the differences were not significant(P>0.05).5)Compared with the ITM group,the pancreas index,spleen index,bursal index at the age of 21 and the bursal index at the age of 42 were significantly decreased in the NC group(P<0.05).The bursal index of ducks at 42 days of age decreased significantly(P<0.05),and there was no significant difference in other organ indices among the groups(P>0.05).Compared with the 1/2ITM group,the bursal index of 42-day-old meat ducks in the 1/2OTM group was significantly increased(P<0.05),and the bursal index of 21-day-old ducks was increased,but the difference was not significant(P>0.05).Overall,under the conditions of this experiment,it is recommended to add 50%of the NRC-recommended dose of complex organic trace elements to the meat duck corn-soybean meal diet to reduce the amount of inorganic trace elements,which can maintain the normal growth performance,meat quality and body antioxidant of the meat duck,but also and can significantly reduce the excretion of iron,copper,manganese,zinc and selenium in the feces. |
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