饲喂水平对冬毛生长期北极狐能量、氮及气体代谢的影响

本试验旨在研究饲喂水平对冬毛生长期北极狐能量、氮及气体代谢的影响.选取36只161日龄、平均体重为(7285±6)g的健康雄性北极狐,随机分成4组,每组9个重复,每个重复1只.各组北极狐饲喂相同的饲粮,但饲喂水平分别为自由采食(Ⅰ组)、自由采食量的80％(Ⅱ组)、自由采食量的60％(Ⅲ组)和自由采食量的40％(Ⅳ组)....

Effects of Feeding Level on Energy,Nitrogen and Gas Metabolism of Arctic Foxes during Winter Fur Growth Period

This experiment was conducted to study the effects of feeding levels on the metabolism of energy,nitrogen and gas of Arctic foxes during winter fur growth period.Thirty-six 161-day-old male Arctic foxes with average body weight of(7285±6)g were randomly divided into 4 groups with 9 replicates per group and 1 fox per replicate.All foxes fed the same diet,but the feeding level was ad libitum feeding(Ⅰgroup),80%ad libitum intake(Ⅱgroup),60%ad libitum intake(Ⅲgroup)and 40%ad libitum intake(Ⅳgroup),respectively.The experiment was completed in 6 phases with 3 phases for each feeding level.Six Arctic foxes were selected for each phase and randomly placed into 6 respiratory metabolism chambers,and 1 Arctic fox was put into each respiratory metabolism chamber.The digestion and metabolism trial,respiratory calorimetry measurement test and fasting metabolism test were carried out by the respiration calorimetry measurement device for fox.The trial began on October 2,2017 and ended on December 14,2017.The results showed as follows:1)as the feeding level decreasing,the gross energy intake(GEI),feces energy(FE),urine energy(UE),digestible energy(DE),metabolizable energy(ME),net energy(NE)were extremely significantly reduced(P<0.01),the ME/DE and NE/ME were significantly or extremely significantly decreased(P<0.05 or P<0.01),however,the DE/GE and ME/GE were not significantly influenced(P>0.05);in addition,dietary net energy intake(NEI)was significantly decreased(P<0.05),but the digestible energy intake(DEI)and metabolizable energy intake(MEI)were not significantly affected(P>0.05).2)As the feeding level decreasing,the nitrogen intake(NI),fecal nitrogen(FN),urinary nitrogen(UN),nitrogen retention(RN),RN/NI and RN/digestible nitrogen(DN)were significantly or extremely significantly reduced(P<0.05 or P<0.01),however,the nitrogen apparent digestibility was not significantly influenced by feeding level(P>0.05).3)In the respiration heat test,the respiratory quotient(RQ)in groupⅢwas extremely significantly higher than that in the other three groups(P<0.01),and the O 2 consumption and CO 2 emission in groupⅡwere significantly higher than those in the other three groups(P<0.05).In the fasting metabolism test,feeding level had no significant effects on RQ,O 2 consumption and CO 2 emission(P>0.05).In conclusion,under the conditions of this experiment,restricted feeding significantly reduces the intake and utilization of all kinds of effective energy,the conversion efficiency of DE and ME,and the intake and retention of nitrogen during the winter fur growth period of Arctic fox.Meanwhile,appropriate restriction of feeding does not significantly reduce the utilization of nitrogen,and improves the degree of oxidative metabolism of nutrients,increases O 2 consumption and CO 2 emission.The regression equations of NI and RN are established,and the maintenance net nitrogen and protein requirements for Arctic foxes during the winter fur growth period are 676.3 mg/(kg BW 0.75·d)and 4.227 g/(kg BW 0.75·d),respectively.