Study On The Optimum Addition Of Dihydrogen Phosphate In Feed Of Xiangyun Crucian Carp By Two Kinds Of Fat

To research the optimum supplementation of calcium dihydrogen phosphate at two different lipid levels and the effects of the interaction between phosphorus and lipid on growth and metabolism of crucian carp.The experiments was divided into three parts: experiment 1.the optimum supplementation of calcium dihydrogen phosphate at low lipid(4.5%) diet of crucian carp; experiment 2.the optimum of calcium dihydrogen phosphate at high lipid(7.0%) diet of crucian carp; experiment 3.the effects of the interaction between phosphorus and lipid on the growth and metabolism of crucian carp.Experiment 1: Six levels(1.0%、1.5%、2.0%、2.5%、3.0% and 3.5%, respectively) of calcium dihydrogen phosphate were added into low lipid(4.5%) pellet for crucian carp. The feeding trial was conducted in an aquarium feeding cylinder(1.2m×0.5m×0.35m),with an average initial weight of 40.42±0.21 g were randomly divided into 6 groups with 3 replicates and 20 fish per replicate, feeding rate of 3%~5% for eight weeks.The result showed that:1) low lipid diet with appropriate MCP can promote growth and feed conversion for crucian carp,got best growth performance at 2.5% levels.Under this levels, whole body, muscle, visceral and liver crude lipid contents reached lowest,while the whole body crude protein reached highest(P<0.05). whole body moisture was not significantly different in each groups(P> 0.05).2)The group under 2.5% MCP levels, intestinal trypsin, amylase,lipase and serum SOD acitivity reached highest,while liver MDA reached lowest(P<0.05).3)Whole body,vertebrae and serum phosphorus was first increased with increasing MCP levels then plateau over, serum calcium levels between the groups was not significant different(P> 0.05), serum AKP first increased and then decreased thereafter.4) With the increase of MCP levels,liver CPT-1 was not significantly different in each groups(P> 0.05), liver ACC activity was decreasing firstly and then increasing.The serum CHO and TG reached lowest at 2.5% levels(P<0.05).In conclusion,appropriate phosphorus could reduced lipid and CHO,increased body protein and enhanced function of digestion and antioxidant.Quadratic curve model or broken-line model analysis on weight gain, feed conversion rate, whole body phosphorus content and vertebrae phosphorus content estimated the optimum levels at low lipid diet calcium dihydrogen phosphate for crucian carp was 2.61~2.72%.Experiment 2: Six levels(1.0%、1.5%、2.0%、2.5%、3.0% and 3.5%, respectively) of calcium dihydrogen phosphate were added into high lipid(4.5%) pellet for crucian carp. The feeding trial was conducted in an aquarium feeding cylinder(1.2m×0.5m×0.35m),with an average initial weight of 40.00±0.34 g were randomly divided into 6 groups with 3 replicates and 20 fish per replicate, feeding rate of 3%~5% for eight weeks.The results showed that: 1) high lipid diet with appropriate MCP can promote growth and feed conversion for crucian carp,got best growth performance at 2.5% levels.Under this levels, whole body, muscle, visceral and liver crude lipid contents reached lowest,while the whole body crude protein reached highest(P<0.05). whole body moisture was not significantly different in each groups(P> 0.05).2)The group under 2.5% MCP levels, intestinal trypsin, amylase,lipase and serum SOD acitivity reached highest,while liver MDA reached lowest(P<0.05).3)Whole body,vertebrae and serum phosphorus was first increased with increasing MCP levels then plateau over, serum calcium levels between the groups was not significant different(P> 0.05), serum AKP first increased and then decreased thereafter.4) With the increase of MCP levels,liver CPT-1 and CHO was not significantly different in each groups(P> 0.05), liver ACC activity was decreasing firstly and then increasing.The serum TG reached lowest at 2.5% levels(P<0.05).In conclusion,appropriate phosphorus could reduced lipid and CHO,increased body protein and enhanced function of digestion and antioxidant.Quadratic curve model or broken-line model analysis on weight gain, feed conversion rate, whole body phosphorus content and vertebrae phosphorus content estimated the optimum levels at high lipid diet calcium dihydrogen phosphate for crucian carp was 2.55%~2.71%.Experiment 3:Comprehensive the results of two experiments,the analysis showed that:the interaction of lipid and phosphorus had no significant effects on food intake,weight gain rate and feed conversion rate(P>0.05).The interaction of lipid and phosphorus had signigicant effects on body composition(P<0.05),whole body crude protein of low lipid group was significantly higher than high lipid group(P<0.05),the whole body crude lipid of low lipid group was significantly higher than high lipid group(P<0.05),howere,the liver crude lipid of low lipid group was significantly lower than high lipid group(P<0.05). The interaction of lipid and phosphorus had signigicant effects on serum CHO、 intestinal lipase activity、trypsin activity、serum SOD contents and liver MDA activity(P<0.05),serum SOD content of low lipid group was significantly lower than high lipid group(P<0.05).