Study On The Net Energy Requirement And Regularity Of Energy Metabolism In Arctic Fox(Alopex Lagopus) During The Growing-furring Period

This paper studied the effects of different feeding level on the production performance,nutrient digestibility,gas metabolism,serum biochemical indexes,organ development change,regularity of energy utilization and deposition of male arctic foxes,by means of feeding experiment,digestion and metabolism trial,respiratory calorimetry measurement,comparative slaughter test and serological test combined with chemical analysis method.We determined the net energy requirements of maintain and production in arctic fox of growing-furring period and based on transcriptome technology,screened out the key genes regulating energy metabolism,which provided a sufficient theoretical basis for the establishment of the nutrition standard and elaborative breeding of arctic fox in China.This paper includes six experiments,the main contents and results are as follows:Experiment 1:It was conducted to study the effects of ad libitum and different feeding restrictions levels on the growth performance,nutrient digestion and serum biochemical indexes of arctic fox during the growth period.Forty male arctic foxes of 85-day-old with similar body weight,randomly were divided into 4 groups with 10 replicates per group and 1 fox per replicate and were fed ad libitum group?AL?,80%of ad libitum group?IR80?,60%of ad libitum group?IR60?and 40%of ad libitum?IR40?,respectively.The results showed:proper restricted feeding?IR60?promotes the digestion of nutrients,reduces the content of serum glycol lipids parameters,ensures the normal growth and health of the body,and is conducive to improve the feed conversion efficiency.Experiment 2:It was conducted to study the effects of ad libitum and different feeding restrictions level on the energy and nitrogen digestion and metabolism as well as gas metabolism of arctic fox during the growth period.Thirty-six 85-day-old male arctic foxes with similar body weight,randomly were divided into 4 groups with 9 replicates per group and 1 fox per replicate and experiment design was the same as above.The results showed that feeding level significantly influence energy metabolism,N metabolism and gas metabolism?P<0.05?,but did not significantly influence fasting metabolism?P>0.05?.The maintenance net nitrogen?NN_m?requirement of arctic fox was179.6mg/kgBW^0.75·d^-1,and the maintenance net protein?NP_m?requirement was 1.123g/kgBW^0.75·d^-1during the growth period of arctic fox.Experiment 3:It was conducted to study the effects of ad libitum and different feeding restrictions levels on production performance,nutrient utilization,serum biochemical indexes and organ development of arctic fox during the winter fur growth period.Forty 161-day-old male arctic foxes with similar body weight were randomly divided into 4 groups and experiment design was the same as the experiment 1.The results showed that proper restricted feeding?IR80?does not affect the normal development of the body organs of arctic fox during the winter fur growth period,which can ensure the weight gain and fur quality,improve the feed conversion efficiency,and reduce the risk of obesity caused by excessive energy deposition.Experiment 4:It was conducted to study the effects of ad libitum and different feeding restrictions level on the energy and nitrogen digestion and metabolism as well as gas metabolism of arctic fox during the winter fur growth period.Thirty-six 161-day-old male arctic foxes with similar body weight and experiment design was the same as experiment 2.The results showed that feeding level significantly influence energy metabolism,N metabolism and gas metabolism?P<0.05?,but did not significantly influence fasting metabolism?P>0.05?.The maintenance net nitrogen requirement was calculated to be 676.3mg/kgBW^0.75·d^-1,and the maintenance net protein requirement was4.227g/kgBW^0.75·d^-1 during the winter fur growth period of arctic fox.Experiment 5:It was conducted to study the parameters of the maintenance energy and gr owth energy of the arctic fox during the growth and winter fur growth periods,so as to provid e basic data for the establishment of the nutrition standard of the arctic fox in China.It includ ed two tests:respiratory calorimetry test?test A?and comparative slaughter test?test B?.Test A design was the same as test 2 and test 4.Test B design was the same as test 1 and test 3.The results showed:1)during the winter fur growth period,the maintenance net energy?NE_m?was 209-217kJ/kgBW^0.75·d^-1,the net growth energy?NE_p?of arctic fox was 1019.06kJ/kgBW^0.75·d^-1,in which NE_p for fur growth was 504.76 kJ/kgBW^0.75·d^-1 and carcass growth NE_p was 514.30kJ/kg BW^0.75·d^-1,and total requirements of NE was 1232.06kJ/kgBW^0.75·d^-1.During the winter fur growth period,the maintenance metabolic energy?ME_m?was 225-230kJ/kgBW^0.75·d^-1,and maintenance efficiency of ME?k_m?was 0.929-0.943;growth metabolic energy?ME_g?was 1077.23kJ/kgBW^0.75·d^-1,growth efficiency of ME?k_g?was 0.946,and total requirements of ME was1304.73kJ/kgBW^0.75·d^-1.2)During the winter fur growth period,NE_m was 89-92kJ/kgBW^0.75·d^-1,NE_p was 966.75kJ/kgBW^0.75·d^-1,in which NE_p for fur growth was 566.84kJ/kgBW^0.75·d^-1and ca rcass growth NE_p was 399.91kJ/kgBW^0.75·d^-1,and total requirements of NEwas1057.25kJ/kgBW^0.75·d^-1.During the winter fur growth period,ME_m was 90.39-94.0kJ/kgBW^0.75·d^-1,and k_m was 0.979-0.985,ME_g was 979.48kJ/kgBW^0.75·d^-1,k_g was 0.987,and total requirements of ME was 1071.68kJ/kgBW^0.75·d^-1.Experiment 6:Based on transcriptome technology,it was conducted to study the effects of feeding level on differential genes expression of arctic fox liver during the winter fur growth period,which provided some reference data for the research of its energy metabolism and deposition.High-throughput sequencing analysis was carried out on 20 liver samples of arctic fox at the end of winter fur growth period.The results showed that:it gathered 7 KEGG pathways including fat digestion and absorption,PPAR signaling pathway,regulation of lipolysis in adipocytes,adipocytokine signaling pathways,insulin resistance,insulin signaling pathway,AMPK signaling pathway between different feeding restrictions and ad libitum.Four target genes screened were Apo A-IV,L-FABP,PCK1,IRS2,respectively.These four genes directly involve in the body fatty acid oxidation and glycolysis as well as sugar dysplasia,and regulate insulin signaling pathway,which plays an important role in maintaining the energy balance of arctic fox.