Effects Of Different Levels And Proportions Of Added Fat On Rumen Fermentation,Nutrient Digestion And Urine Derivatives In Cattle

This study was conducted to investigate the effect of different level and proportion of supplementation fat on rumen fermentation and urinary purine derivative,four Hostein bulls(average weight 580±50 kg,4.5year-old)with permanent rumen fistulas were assigned at a 3×4 factorial arrangement of treatment.The diet NEmf concentration was designed in 1.2 times of maintenance nutrient levels supplemented with 4.0%,5.0% and 6.0% different type of fat at each added level,rumen fat and sesame seed fat prepared with sesame seed oil were prepared in four different proportions: 100:0,85:15,70:30 and 55:45.That is,four diets(Fat supplementation levels(%)/different ratio of RPF to seed of flax(100:0,85,15,70:30 and 55: 45)level in the twelve groups were 4/100(group 1)?4/85(group 2)?4/70(group 3)?4/55(group 4)?5/100(group5)?5/85(group 6)?5/70(group 7)?5/55(group 8)?6/100(group 9)?6/85(group 10)?6/70(group 11)?6/55(group 12),respectively.)forming a total of 12 groups.The effects of different levels and proportions of fat addition on rumen fermentation,apparent digestibility of nutrients and allopurine derivatives were studied under the condition of 1.2 times energy maintenance.The results show that:(1)Different fat levels and proportions had no effect on rumen p H and ammonia nitrogen concentration(P>0.05).There was no significant effect on the concentration of total volatile acid,acetic acid and propionic acid(P>0.05).The ratio of acetic acid to propionic acid in the diet groups added with 6% fat was significantly higher than that in the diet groups added with 4% fat(P<0.01).There was no significant difference in the ratio of acetic acid to propionic acid between the groups(P>0.05).(2)For the rumen CP degradation rate,the ratio of rumen fat to sesame oil(added in the way of seed of flax)was significantly higher in the groups of 70:30 than in the groups of 100:0(P<0.05),and that in the group of 7 was significantly higher than that in the group of 9(P<0.05).No significant difference in rumen effective degradation rate between NDF and ADF(P>0.05).(3)Diet with 4% and 5% fatty groups of CP apparent digestibility significantly higher than that of adding6% groups(P<0.01),1 group was significantly higher than 9 and 12 groups(P<0.01),significantly higher than 10 and 11 groups(P<0.05),the groups of 3,4 and 7 were significantly higher than that in group of 12(P<0.01),significantly higher than 9,10 and 11 groups(P<0.05),2 and 8 groups is significantly higher than 10 and 11 groups(P<0.05);There was no significant difference in apparent digestibility of crude fat between each group at different fat addition levels and proportions(P>0.05),but the apparent digestibility decreased with the amount of fat added.The apparent digestibility of neutral washing fiber(NDF)of the groups added with 4% and 5% dietary fat was significantly higher than that of the groups added with 6%dietary fat(P<0.01).The digestibility/total energy(DE/GE)of the groups adding 4% fat was significantly higher than that of the groups adding 6% fat(P<0.01),the digestibility/total energy(DE/GE)of the groups adding 5% fat was significantly higher than that of the groups adding 6% fat(P<0.05),and the digestibility/total energy(DE/GE)of the groups 1 and 3were significantly higher than that of the group 12(P<0.05).(4)The net nitrogen use rate of the groups with dietary fat content of 4% were significantly higher than that of the groups with dietary fat content of 6%(P<0.01),the 5% groups were significantly higher than the 6% groups(P<0.05),and the net nitrogen use rate of the group of 8 was significantly higher than that of the group of 12(P<0.05).(5)The concentrations of allantoin and allantoin derivatives in the diet groups with 6% fat were significantly higher than those in the diet groups with 4% fat(P<0.01),significantly higher than those in the diet groups with 5% fat(P<0.05),and the concentrations of allantoin and allantoin derivatives in the 9 and 10 groups were significantly higher than those in the 7 group(P<0.05).(6)After adding different levels and proportions of fat,the concentration of acetyl-coa carboxylase(ACC)in groups 1,6,8,9 and 12 were significantly higher than that in group 4(P<0.05).Lipotriglyceride esterase(ATGL)with 4% dietary fat was significantly higher than that with 5% and 6%dietary fat(P<0.01),and that with 6,11 and 12 diets were significantly higher than that with 2,3 and 4diets(P<0.05),and the group with 9 was significantly higher than that of the group with 2(P<0.05).Carnitine palmitoyltransferase(cpt-i)concentration in the 5% and 6% adipose groups were significantly higher than that in the 4% groups(P<0.01),that in the 6 and 7 groups were significantly higher than that in the 2 and 4 groups(P<0.05),and that in the 9 group was significantly higher than that in the 4 group(P<0.05).The concentration of stearyl coenzyme A desaturase(SCD)in group 6 was significantly higher than that in group 9(P<0.05).The triglyceride concentration of the groups with 4% fat were significantly higher than that of the groups with 6% fat(P<0.05).In summary,the optimal amount of added fat was 5%,and the ratio between rumen passing fat and flax oil(added by flax seed)was 70:30.