| This experiment was conducted to investigate the effect of different dietary protein levels on the secretion performance,protein metabolism,digestive performance and fur quality of muskrat,and to explore the mechanism of the effect of dietary protein levels on the secretion of muskrats,so as to accumulate more data for efficient feeding of muskrat.A total of 60 1-year-old and weighing 0.938±0.086 kg muskrats were randomly divided into 5 groups,each group has 6 replicates,each replicate with 2 muskrats(1male and 1 female),5 treatment groups were fed 5 protein level diet(16%,18%,20%,22% and 24%)respectively,and five treatments were numbered as group Ⅰ to Ⅴ.10 days pre-feeding period was designed before 73 days experimental period.Each muskrat was weighed before and after the experiment.During the trial period,the muskrats were collected secretion three times in vivo to calculate the amount of fragrance,and detected the content of the active ingredient muscone and cyclopentadecanone.After the experiment,samples of blood and intestinal contents were collected,and indicators such as digestive enzyme activity and blood sex hormone content were measured.Finally,the fur was processed to test the quality index.The results showed that:(1)After the experiment,there was no significant difference in weight gain among all groups,but there was a trend of difference(0.01 > P > 0.05),but the body weight of test group Ⅱ,Ⅲ and Ⅴ showed a decreasing trend after the experiment,and the body weight of test group Ⅰ and Ⅳ were increased,indicating that the 22%protein level diet can alleviate the adverse effects of the weight loss of the muskrat due to the aroma production.(2)At the first time of fragrant collection,there was no significant difference in the secretion of muskrat fragrance among group I,II,III and IV(P > 0.05).The yield of muskrat fragrance in group V was significantly lower than that in group II,III,and IV(P < 0.05),and it also lower than that in group I but the difference was not significant(P > 0.05).During the second fragrant collection,the muskrat fragrance secretion in experiment group IV was significantly higher than that in other experiment groups(P < 0.05),and the secretion of fragrance liquid in other experiment groups had a gradual increase but the difference was not significant(P >0.05).The muskrats in group V had the lowest aroma production.At the third time of fragrant collecting,the secretion of muskrat fragrance in experiment group IV was the highest and was significantly higher than that among other groups(P < 0.05).The yield of scented liquid in other experiment groups had a gradual increase but the difference was not significant(P > 0.05),muskrat in experiment group V had the lowest secretion production.(3)There was no significant difference in the moisture content of the fragrance liquid in each experiment group(P > 0.05),the content of cyclopentadecanone in the experiment group IV was significantly higher than that among other groups(P < 0.05),and the difference in other groups was not significant(P > 0.05).But the content of cyclopentadecanone in experiment group V was the lowest.(4)There were no significant differences in the surface area and weight of the scent glands and testis of the muskrat among all experiment groups(P > 0.05).(5)The level of androgen and estrogen in experiment group I were significantly lower than those in other experiment groups(P < 0.05),and the androgen content in experiment group II was significantly lower than those in experiment group III and group IV(P < 0.05),lower than that in experiment group V,but the difference was not significant(P > 0.05),and the experiment group III was slightly lower than the experiment group V but the difference was not significant(P > 0.05).The content of estrogen in experiment group II was significantly lower than that in experiment group V(P < 0.05),slightly lower than that in experiment group III and experiment group IV,but the difference was not significant(P > 0.05),experiment group III was slightly lower than experiment group V but the difference was not significant(P > 0.05).(6)The content of BUN in experiment group I was significantly lower than that in other experiment groups(P < 0.05),experiment group III was lower than experiment group II and experiment group V,experiment group III was significantly lower than that in experiment group IV(P < 0.05),and the difference in other groups was not significant(P > 0.05).The TP content of muskrat in experiment group V was significantly lower than that in other groups(P < 0.05),but the difference among these experiment groups was not significant(P > 0.05).The content of ALB in experiment group I was significantly lower than that in other experiment groups(P <0.05),the content in group V was significantly lower than that in experiment group III(P < 0.05),and the difference among other groups was not significant(P > 0.05).(7)Among all groups,there were no significant differences in trypsin and lipase activities in intestinal tract of muskrat(P > 0.05).The amylase activity of experiment group V was significantly lower than that of other experiment groups(P < 0.05),the amylase activity of experiment group IV was significantly higher than that of experiment group I(P < 0.05),and the amylase activity of experiment group III was higher than that of experiment I,was lower than experiment group IV,but the difference was not significant(P > 0.05).The cellulase activity of experiment group I,III,and IV was significantly lower than experiment group II and experiment group V(P < 0.05),experiment group Ⅱ was slightly lower than experiment group Ⅴ but the difference was not significant(P > 0.05),there was no significant difference in cellulase activity among experiment group I,Ⅲ and Ⅳ(P > 0.05).(8)There were no significant differences in the weight of muskrat fur,the thickness of the skin,and the length of the needle hair in each experiment group.There was no significant difference in fur area among experiment group Ⅰ,Ⅱ,Ⅲ and Ⅴ(P > 0.05),and with the increase of protein level,the area of muskrat fur also increased,and the area of fur in group Ⅰ,Ⅱ,and Ⅲ was significantly lower than that in group IV(P < 0.05),group V was lower than group IV but the difference was not significant(P > 0.05).In conclusion,with the increase of dietary protein level,the content of sex hormones which regulate the secretion performance of muskrat also increased,and the amount of secretion of muskrat also increased,as well as the quality of aroma liquor,the content of cyclopentanone,which determines the quality of the aroma,also increased.The skin size of muskrat increased with the increase of dietary protein level.When dietary protein level was 22%,muskrat had the highest amount of fragrance secretion,the best quality of fragrance production and the largest skin area,so the economic performance of muskrat was the best at this protein level. |
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