| Blue foxes were studied in this experiment, which were fed with diets contained different concentration of melamine, cyanuric acid or the mixture of the two. The effects of physical health and growth performance of blue foxes were investigated from three aspects(animal nutrition, serum biochemical parameters and pathology) in order to provide a theoretical basis for establishment of melamine limit standard in the fox feed.With the single-factor randomized experimental design, forty-eight healthy male blue foxes of 10-week-old were randomly divided into 6 groups, each group had 8 blue foxes. Groupâ… is the control group, orther groups(â…¡,â…¢,â…£,â…¤andâ…¥) were the trail groups. From 0 day to 66th day of the formal experiment, foxes in the control group was fed with the basal diet of growing period, and foxes in groupâ…¡,â…¢,â…£,â…¤,â…¥was fed with the basal diets added with melamine/cyanuric acid 20/0mg/kg, 50/0mg/kg, 100/0mg/kg, 0/20mg/kg and 15/5mg/kg respectively. From 67th day to 126th day of the formal experiment, foxes in the control group was fed with the basal diet of winter hair growth period, and foxes in groupâ…¡,â…¢,â…£,â…¤,â…¥was fed with the basal diets added with melamine/cyanuric acid 50/0mg/kg, 200/0mg/kg, 1000/0mg/kg, 0/50mg/kg, and 37.5/12.5mg/kg for 60 days respectively. The whole time of this experiment is 126 days.The results indicated that:(1) The body weight and daily weight gains of blue foxes were no significant differences among each groups(P>0.05).(2) In various stages of determination serum parameters, compared with groupâ… , the contents of albumin(ALB) and total protein(TP) in serum of blue foxes of groups added with toxic decreased with varying degrees. The activity of Glutamic-pyruvic transaminase(GPT), Glutamic-oxaloacetic transaminase (GOT), Alkaline phosphatase(AKP) and the contents of Creatinine(CRE) and Blood urea nitrogen(BUN) increased with varying degrees.(3) Compared with the control group, the daily feed intake, digestibility of dry matter and feed conversion rate of blue foxes were no significant differences in every trial groups in the growth period and the winter hair growth period(P>0.05). Compared with the control group, the nitrogen intake, fecal nitrogen, urinary nitrogen, nitrogen apparent digestiblity and digestibility of ether extract(EE) were no significant differences in the growth period of blue fox(P>0.05); Nitrogen retention and nitrogen retention ratio of groupâ…¥were significantly lower than the control group(P<0.05), but no significant differences were observed among other groups(P>0.05). In the winter hair growth period, compared with the control group, there were no significant differences observed in the nitrogen intake, fecal nitrogen, urinary nitrogen and nitrogen retention ratio(P>0.05); Digestibility of EE of blue foxes in the control group was significantly higher than that of each goup added with toxic(P<0.01).(4) In aspect of organ weitht: compared with groupâ… , the weight of left kidney of blue foxes in groupâ…£increased significantly(P<0.05), that in other groups also tended to increase(P>0.05); The weight of liver in groups added with toxic was higher than the control group, but significant difference only observed in groupâ…¥(P<0.05); Compared with the control group, the weight of right kidney, heart, lung and spleen of blue foxes in groups added with toxic tended to be increased(P>0.05). In aspect of organ index: compared with the control group, the right kidney index of groupâ…¤was increased significantly(P<0.05); The index of left kidney, heart, lung and spleen of other trial groups tended to increase(P>0.05).(5) By the naked eyes, we found that: the renal surface of blue foxes was uneven and the serious kidneys were swelling and buff in groups added with toxic. The juncture between renal cortex and medulla are not very clear. Some kidneys had punctiform hemorrhagic focus. The results of histopathological observation showed that the organization structure of livers and kidneys were different degrees of tissue damages in the groups added with toxic. Some fat droplets were observed in many liver cells. Some inflammatory cells also could be found in liver. The lesions of kidney tissues were mainly as following: Some inflammatory cells were observed in the renal interstitiumand. A lot of vacuoluses were observed in the lumina of renal tubules, where also were found a few hyaline or cellular casts. Granular degeneration was observed in some epithelial cells.(6) No significant difference was observed on fur quality of blue foxes among each groups.(7) Blue foxes were fed with the diets contained melamine/cyanuric acid 20/0mg/kg, 50/0mg/kg, 100/0mg/kg, 0/20mg/kg and 15/5mg/kg for 66 days respectively. And then they were fed with the diets contained melamine/cyanuric acid 50/0mg/kg, 200/0mg/kg, 1000/0mg/kg, 0/50mg/kg, and 37.5/12.5mg/kg for 60 days respectively. The fur perfomance of blue foxes were not affected significantly, but there were different degrees of tissue damages in liver and kidneys of blue foxes in the toxic groups. Considered with the health of blue foxes, we suggest that the concentration of melamine/cyanuric acid of fox feed in growth period and winter hair growth period should lower than 23.52/2.89mg/kg and 53.65/3.51mg/kg respectively.
|
PDF Full Text Request