Study On Effect And Mechanism Of Dietary Calcium,Phosphorus And Manganese On Blue Fox Performance

The blue fox is a precious special economic animal.Its fur has excellent performance and can be used to make various high-end fur products.Mineral nutrition is an indispensable type of nutrients for the animal body.Calcium,phosphorus and manganese are essential mineral nutrients for the animal body.It has a wide range of biological functions and participates in bone development and is involved in the metabolism of protein,fat and carbohydrates.There are few reports on calcium,phosphorus and manganese nutrition of fur animal blue foxes.There is no standard for the suitable calcium,phosphorus and manganese requirements of blue foxes in different physiological periods suitable for China.In addition,the impact of calcium,phosphorus and manganese on the production performance of blue foxes is still unclear.The sensitive indicators for evaluating the biological utilization of calcium,phosphorus and manganese in blue foxes need to be explored.The purpose of this study was to evaluate the effects of dietary calcium,phosphorus and vitamin D₃levels on the growth performance,nutrient digestibility,biochemical indicators and fur quality of blue foxes during the growing period and winter fur period through feeding experiments,slaughter experiments and transcriptomics.As well as the influence mechanism,on this basis,further analyze the influence of the source and level of dietary manganese on the production performance of the blue fox during the growing period,and provide scientific support for scientifically and rationally matching blue fox diets and determining the appropriate calcium,phosphorus and manganese addition levels.Experiment 1 The effect of dietary calcium,phosphorus and vitamin D₃on the production performance of blue fox during the growing periodThe experiment adopted a 3×3 two-factor experiment design,and selected 135 60-day-old male blue foxes(average weight±standard deviation,1.93±0.27 kg)randomly divided into 9 groups,15replicates in each group,1 replicate in each group.The calcium to phosphorus ratio was constant at1.5/1,and the 9 groups of diets contained 3 calcium levels of 0%,0.4%and 0.8%,and 3 vitamin D₃levels of 1,000,2,000,and 4,000 IU·kg^-1.The calcium and vitamin D₃levels in the basal diet were 0.8%and 327 IU·kg^-1,respectively.Therefore,the calcium and vitamin D₃levels of the 9diets were 0.8%and 1 327 IU·kg^-1,0.8%and 2 327 IU·kg^-1,0.8%and 4 327 IU·kg^-1,1.2%and1327 IU·kg^-1,1.2%and 2 327 IU·kg^-1,1.2%and 4 327 IU·kg^-1,1.6%and 1 327 IU·kg^-1,1.6%and 2327 IU·kg^-1,1.6%and 4 327 IU·kg^-1.The pre-feeding period was 10 days and the trial period was60 days.This part of the experiment aims to study the effects of dietary calcium,phosphorus and VD₃levels on the growth performance,apparent digestibility of nutrients and nitrogen metabolism of blue foxes during the growing period.The results showed that:(1)Vitamin D₃level had a significant effect on the growth performance of blue foxes during the breeding period(P<0.05);(2)Calcium level had a linear effect on protein and carbohydrate digestibility(P<0.05);(3)Fat digestibility first increased and then decreased with the increase of calcium supplementation level(P<0.05);(4)Calcium level linearly increased net protein utilization but decreased calcium and phosphorus digestibility(P<0.05);(5)The dietary calcium and vitamin D₃levels have a significant interaction effect on the blue fox's intake of nitrogen,nitrogen deposition,net protein utilization and protein biological value during the growing period(P<0.05).High-dose calcium has a mutual promotion effect on the nitrogen deposition and protein biological value of vitamin D₃(P<0.05);(6)In terms of fecal phosphorus,high-dose calcium has an antagonistic effect on vitamin D₃(P<0.05).Under the condition of a fixed calcium to phosphorus ratio of 1.5/1 during the growing period,when adding 0.4-0.8%calcium and vitamin D₃2000 IU·kg^-1to the blue fox diet during the growing period,the total calcium is 1.2-1.6%and vitamin D₃2327 IU·kg^-1is more appropriate.Experiment 2 The effect of dietary calcium,phosphorus and vitamin D₃on the production performance of blue fox in winter furThe experiment selected a 3×3 two-factor experiment design.135 120-day-old male blue foxes(average weight±standard deviation,4.03±0.25 kg)were randomly divided into 9 groups,each with 15 replicates,each replicate 1.The ratio of calcium to phosphorus was constant,1.4/1.The calcium and phosphorus levels of the 9 groups were the same as Experiment 1.The pre-feeding period was 10 days and the test period was 87 days.This part of the experiment aims to study the effects of dietary calcium,phosphorus and VD₃levels on the growth performance,apparent digestibility of nutrients and nitrogen metabolism of blue foxes during winter fur.The results showed that:(1)the growth performance of blue foxes in winter fur was decreased linearly with the increase of calcium level(P<0.05);(2)calcium level reduced nutrient digestibility(P<0.05);(3)calcium level Increased fecal calcium and fecal phosphorus content reduced phosphorus digestibility(P<0.05);(4)The interaction of dietary calcium,phosphorus and vitamin D₃had a significant impact on calcium and phosphorus digestibility(P<0.05);(5)The body length of blue foxes was significantly reduced with the increase of dietary calcium level(P<0.05).When the dietary calcium level was 0%,the body length of blue foxes was the largest;(6)Vitamin D₃level had an effect on the body length and skin of blue foxes.(P>0.05);(7)With the increase of dietary calcium level,the calcium content of blue fox tibia increased significantly(P<0.05).When the dietary calcium level was 0.8%,blue fox tibia Calcium content is the highest;(8)Vitamin D₃level has a significant effect on blue fox tibia ash content(P<0.05);(9)The addition of dietary calcium significantly reduces the heart and liver index(P<0.05).Under the condition of a fixed calcium to phosphorus ratio of 1.4/1 in the winter fur period,add 0-0.4%calcium and vitamin D₃1000 IU·kg-1 to the blue fox diet during the winter fur period,which means total calcium0.8-1.2%and vitamin D₃1327 IU·kg^-1is more suitable.Experiment 3 Transcriptomics analysis of the effects of dietary calcium and phosphorus on blue fox bone marrowBased on the results of this experiment that the optimum addition amount of vitamin D₃for blue foxes during the winter fur period is 1000 IU·kg-1,the 3 calcium levels in 2.2.1 when the addition amount of vitamin D₃is 1000 IU·kg-1 are selected to be 0%,0.4%and 0.8%of 3 blue foxes in each group were the research objects.After the feeding experiment,they were slaughtered,and the bone marrow of the tibia was taken for transcriptome sequencing and analysis.This part of the experiment aims to reveal part of the molecular mechanism of the effect of dietary calcium and phosphorus on blue fox production performance.Perform functional annotations on Unigene,including comparisons with NR,Swiss-Prot,KEGG,COG,KOG,GO,and Pfam databases.A total of 32,499 Unigene annotation results were obtained.Based on the amount of gene expression in different samples,differentially expressed genes are identified.Using the edge R program analysis,the two parameters are FDR=0.05 and FC=2,and the results found that there are 1085 differential genes in the transcriptome,of which 650 genes are up-regulated and 435 genes are down-regulated.Perform pattern clustering,function annotation and enrichment analysis of differentially expressed genes.The analysis results show that the enrichment analysis of the differentially expressed genes between the sample groups of the GO database revealed the RNA-guided DNA biosynthesis process,fructose 1,6-ketose metabolism process,glycerol decomposition process,and vacuolar proton transport V-ATPase complex Functions such as assembly are the most significant functions in enrichment analysis.Different genes in the COG classification chart are mostly related to functions such as post-translational modification,protein turnover and molecular chaperones.Enrichment analysis of KEGG pathway found that differential genes are most enriched in peroxisome proliferator-activated receptor(PPAR)signaling pathway.The q PCR method was used to verify the expression levels of 10 genes.The results show that the results of q PCR method and transcriptome analysis are basically the same.Experiment 4 The effects of different sources and levels of manganese in diets on the production performance of blue foxes during the growing periodOn the basis of determining the amount of calcium and phosphorus added,the experiment adopted a 2×3+1 two-factor experimental design,with 2 manganese sources(manganese sulfate and amino acid chelated manganese)and 3 manganese levels(20,40,60 mg/kg),1 control group,selected 70 male blue foxes with a healthy age of 56 days and similar weights,randomly divided into 7 groups,each group had 10 replicates,each replicated 1 blue fox,and explored the influence of manganese level and manganese source on blue fox growth Performance and immune indicators are affected.The results showed that:(1)The average daily feed intake of blue foxes increased with the increase of manganese addition level,and the daily weight gain,feed-to-weight ratio,dry matter intake and dry matter digestibility were not significantly different between the two groups(P>0.05);(2).The digestibility of crude protein and crude fat showed an upward trend with the increase of manganese addition level,and the organic chelated manganese added group was higher than the inorganic manganese added group.In summary,this study draws the following conclusions:(1)This study found that under the condition of a fixed calcium-phosphorus ratio of 1.5/1 during the growing period,0.4-0.8%calcium and vitamin D₃2000 IU·kg^-1.It is more suitable when kg-1 is total calcium 1.2-1.6%and vitamin D₃2327 IU·kg-1.(2)Under the condition of a fixed calcium-phosphorus ratio of 1.4/1 in winter fur period,add 0-0.4%calcium and vitamin D₃1000 IU·kg-1 to the blue fox diet in winter fur period,that is,total calcium 0.8-1.2%,vitamin D₃1327 IU·kg-1 is more suitable,which can improve the utilization of protein and phosphorus and reduce the excretion of fecal calcium and phosphorus,thereby improving the environment.(3)In the molecular mechanism of dietary calcium and phosphorus levels affecting blue fox production performance,functional genes involve RNA-guided DNA biosynthesis process,fructose 1,6-ketose metabolism process,glycerol decomposition process,vacuolar proton transport V-ATPase complex.(4)Under the condition of1.5/1 calcium-phosphorus ratio in the blue fox growing period,when the total calcium is 1.40%,the appropriate amount of organic manganese is 40mg/kg.