Effect of dietary protein level during preparative mating period in female minks

Abstract

One hundred and eighty female minks were assigned randomly to six groups with 30 females each. Group1 to Group 4 received diets of fresh material with protein level of 28.59%, 32.31%, 36.21% and 40.35% respectively. Group 5 to Group 6 received diets of dry powder with protein level of 32.66%, 40.47% respectively. The test included a 7-day pre-trial period and a 44-day test period. The results were as follows: There was no significant difference in DM digestibility, CP digestibility, EE digestibility, nitrogen deposition, NPU and BV between groups fed fresh material diet (P>0.05).With the dietary protein level increased, the indicators mentioned above firstly increased and then decreased, reaching the peak when dietary protein level was 36.21%; Contents of TP, GLU and activity of GOT were significantly lower in the 28.59% protein level group (P<0.05), but all the serum biochemical indicators showed no significant difference between groups with dietary protein level higher than 32.31%; nitrogen deposition, NPU, BV, contents of BUN, ALB, GLU in groups fed dry powder diets were not significantly different with those fed fresh material diet of the same dietary protein level (P>0.05), but the DM digestibility, CP digestibility, EE digestibility, activity of GPT and GOT were significantly lower than their dry powder counterparts (P<0.05). The combination of feeding experiment, digestion metabolism experiment, serum biochemical indicators showed that the optimum dietary protein levels in preparative mating period was approximate 32%.