| The giant salamander(Andrias davidianus),commonly known as the baby fish,is a national second-class protected animal and is known as "water ginseng",which has high edible and medicinal value.With the development of artificial breeding,the demand for compound feed is increasingly urgent.After five years of technical research,the research team has carried out research and development work on the nutritional physiology of giant salamanders,assessment of nutritional requirements,and the application of green feed additives,and created a special compound feed for giant salamanders,and completed the domestication of feed and demonstration of breeding technology.In order to further optimize the feed formula,improve the antioxidant and immune capabilities of the salamander body,and promote its healthy growth,this experiment added different gradients of vitamin C to its basic feed.The following two researches were carried out to determine the compound feed of the giant salamander.Suitable dosage:1.The effect of vitamin C on the growth,muscle composition,plasma biochemical indexes,antioxidant and immune abilities of giant salamanderUsing fish meal,chicken meal as protein source,fish oil as fat source to prepare basic feed for giant salamander.Add 0 mg/kg(D1),150 mg/kg(D2),300 mg/kg(D3),450 mg/kg(D4),600mg/kg(D5)and 750mg/kg(D6)of vitamin C(vitamin C phosphate,35% content)to the basic feed,formulated into 6 kinds of test feeds with isonitrogen and other lipids,and the initial body weight of test salamander is(34.14±0.15)g.The results showed that when the vitamin C addition amount was 0-300 mg/kg,the giant salamander’s terminal body weight(FBW),weight gain rate(WGR)and protein efficiency(PER)showed an upward trend and reached the maximum in the 300 mg/kg group.The difference between 300-750mg/kg was not significant(P>0.05),and the feed coefficient(FCR)showed the opposite trend;the vitamin C of 300mg/kg group significantly increased the crude protein content of giant salamander muscle(P<0.05),There was no significant change in moisture,crude fat and crude ash content(P>0.05);both hemoglobin and thrombus cells showed a tendency to increase first and then decrease,respectively reaching the maximum in D4 and D3 groups.There was no significant change in the number of white blood cells(P>0.05);plasma glucose content and triglyceride Ester,total cholesterol,high-density lipoprotein cholesterol and low-density lipoprotein cholesterol have no significant changes(P>0.05).The total superoxide dismutase(T-SOD)in plasma first rises and then tends to stabilize,reaching the highest at the D4 group,malondialdehyde(MDA)showed the opposite trend and reached the lowest in the D3 group,plasma acid phosphatase(ACP)and alkaline phosphatase(AKP)both increased first and then decreased,reaching the highest in the D5 and D4 groups respectively;The amount of vitamin C deposition,T-AOC and lysozyme activity in the stomach,intestine,liver,pancreas,spleen,skin,muscle and plasma of the giant salamander all increased first(D1-D3)and then stabilized(D3-D6).The order of vitamin C deposition in various organs is as follows:liver>muscle>intestinal tract>plasma>pancreas,stomach,spleen,skin.In summary,with WGR and FCR as the effect indicators,the appropriate amount of vitamin C in the artificial compound feed for giant salamanders is 311.73-320.53 mg/kg.The added amount can improve the growth performance and feed efficiency of the giant salamander,and improve the anti-oxidation and non-specific immunity of various tissues.2.The effect of vitamin C on the structure and digestive function of the gastrointestinal hepatopancreas of giant salamanderFeeding giant salamanders with the above 6 groups of feeds,the results of the study on the structure and function of the giant salamander’s digestive organs showed that with the increase of vitamin C addition,the activities of gastric pepsin and H+-K+-ATPase reached the highest in the D3 group.Statistics of the thickness of the muscle layer and the height of the villi of the stomach slices,the addition of 300mg/kg vitamin C is more beneficial to the development of the giant salamander’s stomach than the addition of 0,600mg/kg(P < 0.05);intestinal chymotrypsin,lipase and Na+-K+-ATP Enzyme activities increased first and then tended to stabilize,reaching the highest in group D4(P<0.05),and had no significant effect on intestinal amylase(P>0.05).Through statistics of intestinal slice muscular layer thickness and villus height,The addition of 300mg/kg vitamin C is more beneficial to the development of the giant salamander’s intestines than the addition of 0,600mg/kg;the activities of pancreatic chymotrypsin and lipase both increased first and then stabilized,reaching the maximum in the D3 and D4 groups respectively(P< 0.05),no significant effect on pancreatic amylase(P>0.05);liver MDA,AST and ALT activities all decreased first and then increased,and reached the lowest in D3 group,while CAT,T-SOD,ACP and AKP However,there was a trend of rising first and then falling.CAT,T-SOD,and ACP reached the highest peak in the D4 group,and AKP reached the highest in the D3 group.It was found through liver slices that the addition of 300mg/kg vitamin C was compared with the addition of 0,600mg/ The infiltration of inflammatory cells in kg was significantly reduced,and the number of liver macrophages was significantly increased.In summary,vitamin C can significantly improve the digestion and absorption-related enzyme activities of the giant salamander’s stomach,intestines,liver,and pancreas,enhance the liver’s antioxidant and immune capabilities,reduce liver damage,and promote the development of the stomach,intestine and liver morphology and structure. |
