Effects Of Dietary Vitamin B₂ Levels On Production Performance Of Mink

During the trial,vitamin B₂ was used as experimental material,and male short-haired mink was used as the research object.Through feeding test,digestion and metabolism test,serum test and molecular biology test,the appropriate amount of vitamin B₂ added in dietary during mink growth period was determined,which provided a theoretical basis for guiding actual production.Part 1:Effects of different dietary Vitamin B₂ levels on growth performance,nutrient digestibility and nitrogen metabolism of male minks during growing periodNinety-six healthy short black male minks at the age of（65±5）days with the similar body weight were randomly divided into 6 groups with 16 replicates per group and 1 mink per replicate.Six experimental diets were formulated by using single factorial experiment design and the additional level of vitamin B₂ were 0 mg/kg（Ⅰ）、2.5 mg/kg（Ⅱ）、5 mg/kg（Ⅲ）、10 mg/kg（Ⅳ）、20 mg/kg（Ⅴ）、40 mg/kg（Ⅵ）.The adaptation period lasted for 7days and the formal period lasted for 58 days.Weighing once every 15 days,digestion and metabolism tests were carried out in the middle stage of growing period.The results were as follows:1)Dietary vitamin B₂ levels had significant effects on the final weight and feed/gain（F/G）（P<0.05）,had extremely significant effect on average daily gain（ADG）（P<0.01）,among which the average daily gain and the final weight of group V were the maximum while the feed/gain was the minimum.2)Dietary vitamin B₂ levels had extremely significant differences in the fat and protein digestibility（P<0.01）.The fat digestibility of groupⅥwas the maximum.and group ofⅠwas the lowest..The protein digestibility of groupⅤwas the maximum and groupⅤwere extremely higher than groupⅠ（P<0.01）.3)Dietary vitamin B₂ levels had significant effects on the nitrogen deposition、net protein utilization and the biological value of protein（P<0.05）.The net protein utilization rate and the biological value of protein were the highest in group V,which were significantly higher than that in control group（P<0.05）.Nitrogen deposition in group VI was the highest,group I was the lowest,group I was significantly lower than group V and group VI（P<0.05）.Part 2:Effects of different dietary Vitamin B₂ levels on performance,nutrient digestibility and nitrogen metabolism of male minks during winter fur-growing periodNinety healthy short black male minks at the age of（135±5）days with the similar body weight were randomly divided into 6 groups with 15 replicates per group and 1 mink per replicate.Six experimental diets were formulated by using single factorial experiment design and the addtional level of vitamin B₂ were 0 mg/kg（Ⅰ）、2.5 mg/kg（Ⅱ）、5 mg/kg（Ⅲ）、10 mg/kg（Ⅳ）、20 mg/kg（Ⅴ）、40 mg/kg（Ⅵ）.The adaptation period lasted for 5days and the formal period lasted for 63 days.Weighing once every 15 days,digestion and metabolism tests were carried out in the middle stage of growing period.The results were as follows:1)Dietary vitamin B₂ levels had extremely significant effects on feed/gain（P﹤0.01）.The feed/gain ofⅥandⅤwas significantly lower than that of control group（P﹤0.01）.Dietary vitamin B₂ levels had extremely significant effects on guard fur length and underwear fur length（P﹤0.01）.The underwear fur length of groupⅤwas extremely higher than that of groupⅠ（P﹤0.01）,the guard fur length of groupⅣandⅤwas significantly higher than that ofⅠ,Ⅱ,ⅢandⅥgroups（P﹤0.01）.2)Dietary vitamin B₂ levels had no significant effects on DM digestibility,protein digestibility and fat digestibility（P﹥0.05）.3)Dietary vitamin B₂ levels had no significant effects on nitrogen intake,urine nitrogen,fecal nitrogen and nitrogen deposition（P﹥0.05）.It had significant effects on net protein utilization and biological value of protein（P﹤0.05）,and groupⅤhad the highest net protein utilization.Part 3:Effects of dietary Vitamin B₂ level on lipids metabolism,immune indicators and antioxidant capacity of minks during growing periodMink blood samples were taken on the 40th and 85th days of the whole experiment.Eight healthy minks were selected from each group.Lipid metabolic index,antioxidant index and immune index were determined by kit.1)Dietary vitamin B₂ supplementation significantly affected triglyceride,cholesterol and low density lipoprotein cholesterol（P<0.05）,with the lowest triglyceride and cholesterol content in group V.There was no significant effect on triglyceride、cholesterol and low density lipoprotein cholesterol level in mink during winter fur-growing period（P>0.05）.2)Vitamin B₂ supplementation had significant effect on the activity of T-AOC（P<0.05）,and the activity of T-AOC was the highest in group IV.The levels of vitamin B₂ in winter hair period significantly affected the activities of GSH-PX,T-SOD and T-AOC in mink serum（P<0.01）.The activity of GSH-PX in control group was significantly lower than that in group III,IV,V and VI（P<0.01）.T-AOC activity in group III was significantly higher than that in control group（I）and other groups（P<0.01）.The activity of T-SOD in control group（I）was significantly lower than that in group II,III and IV（P<0.01）,and significantly lower than that in group V and VI（P<0.05）.3)Vitamin B₂ had a significant effect on serum immunoreactive factor Ig A of mink（P<0.05）,but had no significant effect on serum immunoreactive factor Ig G and Ig M（P>0.05）.The maximum content of Ig A was group IV.Part 4:Effects of Vitamin B₂ on GR,CPT I and ACADS gene expression in minks during winter fur-growing periodAt the end of winter wool period,8 minks were slaughtered in each group,and liver tissues were selected to determine the expression of related genes.Vitamin B₂ significantly affect the expression of CPT1 and ACADS genes in mink liver during winter fur-growing period（P<0.05）,and GR gene expression was significantly affected（P<0.01）.When the supplement of vitamin B₂ was 5 mg/kg,the expression of CPT I gene was the highest in mink liver.While the ADACS and GR genes expression were the highest in mink liver with the supplement of vitamin B₂ was 5 mg/kg.Considering with four experiments,it can be concluded that the supplementation level of vitamin B₂ in the growing period is 13.35²3.35mg/kg,and 7.99²2.99 mg/kg in the winter fur-growing period.