The Effects Of Dietary Supplementation With Bacillus Subtilis And Enterococcus Faecalis On Growth Performance,Digestive Metabolism And Immune Function Of Minks

This study investigated the effects of Bacillus subtilis and Enterococcus faecalis on growth performance,digestive metabolism and immune function of minks.Through the effects of growth performance,nutrient utilization,serum biochemical indicators,intestinal morphology and fur quality,the appropriate levels of additives in the minks of the breeding period and winter hairy period were selected to provide theoretical support for actual production.The study consists of three parts:Part 1:Effects of dietary supplementation with Bacillus subtilis and Enterococcus faecalis on growth performance,digestion and metabolism and serum biochemical indexes of mink during growing periodThe experiment was designed using a single factor complete randomized trial.Seventy healthy60-day-age male minks with average weight of（957.37±93.96）g were randomly divided into 7 groups with 10 replicates and 1 mink per replicate.Group I was fed the basal diet as the control group,group II,III,and IV were treated with the B.subtilis,B.subtilis was added to the basal diet at concentrations of10⁹,10¹⁰ and 10¹11 CFU/kg;group V,VI,and VII was treated with E.faecalis.E.faecalis was added to the basal diet at concentrations of 10⁸,10⁹,and 10¹⁰ CFU/kg,respectively.The pre-test for 7 days,the formal trial for 60 days.The results showed as follows:Compared with that of the control group,the final weight of B.subtilis 10¹00 CFU/kg treatment group significantly increased（P<0.05）,the average daily feed intake of B.subtilis 10¹¹ CFU/kg treatment group was significantly reduced（P<0.05）.The dry matter digestibility of B.subtilis 10⁹,10¹⁰ CFU/kg and E.faecalis 10⁸ CFU/kg treatment groups was significantly higher than that of the control group（P<0.05）,and the dry matter digestibility of E.faecalis 10⁸ CFU/kg treatment group significantly higher than the B.subtilis 10¹¹ CFU/kg and other E.faecalis treatment groups（P<0.05）;the protein digestibility of E.faecalis 10⁸ CFU/kg treatment group was significantly higher than that of the control group and the treatment group of E.faecalis 10¹⁰ CFU/kg（P<0.05）.The fecal nitrogen of the B.subtilis 10¹11 CFU/kg and E.faecalis 10⁸,10⁹ CFU/kg treatment groups was significantly lower than that of the control group（P<0.05）;the urinary nitrogen of the E.faecalis 10⁸and 10⁹ CFU/kg treatment group was significantly lower than that of the control group（P<0.05）;the net protein utilization of B.subtilis 10¹⁰ CFU/kg treatment group and E.faecalis 10⁸ CFU/kg treatment group was significantly higher than that of the control group（P<0.05）;the protein biological value of B.subtilis 10¹⁰ CFU/kg treatment group was significantly higher than that of the control group（P<0.05）.The concentration of serum immunoglobulin M of the E.faecalis 10⁹ CFU/kg treatment group was significantly higher than that of the control group（P<0.05）.It was concluded that the addition of 10¹⁰ CFU/kg of Bacillus subtilis or 10⁸ CFU/kg of Enterococcus faecalis to the diets of minks can better improve the minks of growth performance,nutrient digestibility,net protein utilization and protein bioactivity of value.Part 2:Effects of dietary supplementation with Bacillus subtilis and Enterococcus faecalis on growth performance,digestion and metabolism and pelt quality of minks during winter fur-growing season.The experiment was designed using a single factor complete randomized trial.Seventy healthy135-day-age male minks with average weight of（1767.94±174.2）g were randomly divided into 7groups with 10 replicates and 1 mink per replicate.Group I was fed the basal diet as the control group;group II,III,and IV were treated with the B.subtilis,B.subtilis was added to the basal diet at concentrations of 10⁸,10⁹,and 10¹⁰ CFU/kg;group V,VI,and VII was treated with E.faecalis.E.faecalis was added to the basal diet at concentrations of 10⁸,10⁹,and 10¹00 CFU/kg,respectively.The pre-test for 5 days,the formal trial for 70 days.The results showed as follows:Compared with that of the control group,the final body weight of the B.subtilis 10¹⁰ CFU/kg treatment group was significantly increased（P<0.05）;the average daily weight gain of the B.subtilis 10¹⁰ CFU/kg treatment group and the E.faecalis 10⁹,10¹⁰ CFU/kg treatment group was significantly increased（P<0.05）;the feed/weight of B.subtilis 10⁹,10¹⁰ CFU/kg treatment group and all E.faecalis treatment groups was significantly reduced（P<0.05）.The protein digestibility of the E.faecalis 10¹⁰ CFU/kg treatment group was significantly higher than that of the control group,B.subtilis 10⁸ CFU/kg treatment group,and E.faecalis 10⁹ CFU/kg treatment group（P<0.05）;all B.subtilis and E.faecalis treatment group significantly improved the fat digestibility（P<0.05）.The nitrogen deposition of B.subtilis 10¹00 CFU/kg treatment group and E.faecalis 10⁹CFU/kg treatment group was significantly higher than that of the control group（P<0.05）.It was concluded that the addition of 10¹⁰ CFU/kg of B.subtilis or 10⁸ CFU/kg of E.faecalis to the diets of the winter fur-growing season minks,can better improve the growth performance,fat digestibility and nitrogen deposition of minks.Part 3:Effects of dietary supplementation with Bacillus subtilis and Enterococcus faecalis on serum biochemical indices,immune organ index,and intestinal morphology of minks during winter fur-growing season.The experimental design is the same as the part 2.The results showed as follows:The total protein concentration of serum of B.subtilis 10¹⁰ CFU/kg treatment group was significantly higher than that of the control group（P<0.05）,the albumin concentration of B.subtilis 10¹⁰ CFU/kg treatment group was significantly higher than that of other treatment groups（P<0.05）;the concentration of alanine aminotransferase of the B.subtilis 10⁸ CFU/kg treatment group was reduce than that of the control group,but there was no significant difference（P>0.05）,and it was significantly lower than that of the E.faecalis 10⁹ CFU/kg treatment group（P<0.05）;the total cholesterol concentration of control group and the B.subtilis treatment group was significantly lower than that of the E.faecalis 10¹⁰ CFU/kg treatment group（P<0.05）;the concentration of the immunoglobulin A of the B.subtilis 10⁸ CFU/kg treatment group was significantly increase than that of the other groups（P<0.05）.The spleen index of the B.subtilis 10⁸ CFU/kg treatment group was significantly increase than that of the control group（P<0.05）.The crypt depth of the B.subtilis 10¹⁰CFU/kg and E.faecalis 10⁹ CFU/kg treatment groups was significantly reduce than that of the control group（P<0.05）,and the villus height/crypt depth was significantly increased（P<0.05）.In conclusion,when the winter fur-growing season of addition of 10⁹ CFU/kg E.faecalis,the serum total protein and albumin content of minks significantly increased.And addition of 10¹⁰ CFU/kg of B.subtilis,the IgA content significantly increased.When the winter fur-growing season of the addition of 10¹⁰ CFU/kg of B.subtilis or 10⁹ CFU/kg of E.faecalis can promoted intestinal development.