不同能氮平衡指数日粮对泌乳奶牛消化代谢及微生物蛋白合成的影响
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摘要
本研究以3头安装永久性瘤胃瘘管的荷斯坦奶牛作为瘤胃液供体,采用体外发酵试验确定不同RDN/FOM比例为20、25、30、35处理的能氮平衡指数;并研究日粮对瘤胃液体外发酵特性及微生物蛋白合成的影响;通过随机区组试验设计,研究了饲喂不同能氮平衡指数日粮对泌乳奶牛生产性能、血液指标、营养物质消化代谢和微生物蛋白合成的影响;研究结果表明:
1.体外培养根据奶牛饲料降解特性所配制的不同RDN/FOM比例日粮底物,根据Peter Lebzien(2007)的计算公式得出不同日粮的能氮平衡指数,RDN/FOM为20、25、30、35时的各自能氮平衡指数分别为0.66、0.72、0.55、0.88,RDN/FOM与SI值之间无明显相关关系。
2.不同SI值底物引起瘤胃微生物的发酵环境变化,pH值处于正常发酵范围,NH3-N浓度随日粮RDP水平的升高而升高。微生物蛋白产量以SI为0.66组最高。0.55组乙酸浓度最高,0.88组最低。0.88组丙酸浓度最低,0.66组最高。乙酸的摩尔百分比随底物中RDN/FOM的升高而升高,0.66组最低,0.88组最高,丙酸的摩尔百分比0.66组最高,0.72组最低。丁酸的摩尔百分比随底物中RDN/FOM水平的升高而降低,0.66组显著高于0.88组。乙丙比接近3:1。
3.不同能氮平衡指数日粮对奶牛产奶量和乳脂率无显著影响,SI值为0.66时显著提高了乳蛋白和非脂乳固体。饲喂各SI值处理日粮后奶牛的血液生化指标基本处于正常范围内,无酮病和瘤胃酸中毒发生的异常情况。SI为0.66时的干物质、有机物和酸性洗涤纤维消化率最高,0.88时蛋白质消化率最高,0.55时中性洗涤纤维消化率最高。SI为0.72的B处理组对蛋白质的利用率最高。从能量利用率的角度来看,以能氮平衡指数分别为0.66和0.72时为最佳。全收尿法估测微生物蛋白产量为SI为0.88组最高,利用点样法估测微生物蛋白产量所得数据与全收尿法有所出入,SI为0.55时微生物蛋白合成量最高,与全收尿法有所差别。结合试验二结论综合考虑,SI值为0.66时可以达到充分利用饲料、发挥动物生产性能的目的。而能氮平衡指数与微生物蛋白合成效率间未发现存在明显的相关关系。
Three Holstein dairy cows fitted with permanent ruminal cannulas were used in this study. Different ratio of ruminal biodegradable nitrogen and ruminal fermentable organisms (20, 25, 30, 35) were used as substrates to determine the corresponding effect on synchronization index. And study the effect of the different synchronization index diet on rumen fermentation pattems and microbial protein synthesis in the rumen with fermentation experiment in vitro. A randomized experiment was carried out to study the effect of energy-nitrogen synchronization index in diet on the productive performance, blood biochemistry indicators ,digestion and metabolism of nutrients and microbial protein synthesis in the rumen of dairy cows. The results of the study showed:
1. At first make different ratio of RDN/FOM formulas diets according to the characteristics of cows feed degradation .Study the degradable quantities of nitrogen and organism in every four hours’time with the experiment in vitro. Calculating the synchronization index with the degradable quantitiy datas of nitrogen and organism.The SI of different ratio of RDN/FOM diets 20,25,30,35 were 0.66、0.72、0.55、0.88 respectively.There was not obvious relationship between RDN/FOM and SI.
2. Effect of different SI substracts on fermentation pattems were investigated.The highest pH was in 0.72 group.But both the fluctuation range of pH and the average level of it were in the normal range of fermentation in vrtro. With the increase of treatment as 0.66,0.72,0.55,0.88, The NH3-N concentration in rumen increased from 17.34mmol/l to 23.81mmol/l. When the SI was 0.66, microbial protein synthesis yield was highest.The acetate concentration increased as the ratio of RDN/FOM increased in the respective treatment group,the highest was in 0.55 group, and lowest in 0.88 group. The propionate concentration was highest in 0.66 group, and lowest in 0.88 group. The percent of acetate increased, butyrate decreased with the increase of RDN/FOM in the substrate. The percent of propionate was highest in 0.66 group,and lowest in 0.72 group. The proportion of acetate and propionate was close to 3:1.
3. After feeding four different synchronization index diets on 16 cows in early lactating period with the same parity and similar body weight from Yang Zhou University Experimental Farm. The average milk yielding per cow had no significant changes(P>0.05). From the milk ingredients, the milk fat percentage had no apparent difference in the four groups fed on different diets, while the milk protein and NFS had increased significantly when fed SI as 0.66,0.55(P<0.05).And the highest is 0.66. The effects of dietary SI ratio on the blood biochemistry indicators such as ALP、CRE、TG、ST/LT、ALB、LDH、A/G、TCO2、ALT、CHO had no significant changes(P>0.05).But the BUN concentration increased with RDN/FOM increasing, difference was significant(P<0.05). The highest TP and GLU concentration was in the group SI=0.88, lowest in the group 0.55,difference was significant(P<0.05). The highest ratio of A/G was in the group 0.66. difference was significant(P<0.05). All of the blood biochemical indexes were in the normal range after feeding four different synchronization index diets. The highest digestibility of DM,OM,ADF were all in 0.66 group,highest digestibility of CP was in 0.88 group, highest digestibility of NDF was in 0.55 group.The highest digestion efficiency of CP was 0.72 group. The best energy efficiency treatment group were 0.66 and 0.72.
In this study the method of Urinary Purine Derivatives estimating rumen microbial protein production was used to caculating microbial protein synthesis .When collectting complete urine,the most microbial protein production was in the 0.88 group.But when collecting sample urine,the most treatment group was 0.55. And there was no obvious relationship between synchronization index and microbial protein synthesis. Considering the second experiment’result,found that when the SI was 0.66,we can get the diets’best utilization efficiency and the best productive performance of animals.
1.体外培养根据奶牛饲料降解特性所配制的不同RDN/FOM比例日粮底物,根据Peter Lebzien(2007)的计算公式得出不同日粮的能氮平衡指数,RDN/FOM为20、25、30、35时的各自能氮平衡指数分别为0.66、0.72、0.55、0.88,RDN/FOM与SI值之间无明显相关关系。
2.不同SI值底物引起瘤胃微生物的发酵环境变化,pH值处于正常发酵范围,NH3-N浓度随日粮RDP水平的升高而升高。微生物蛋白产量以SI为0.66组最高。0.55组乙酸浓度最高,0.88组最低。0.88组丙酸浓度最低,0.66组最高。乙酸的摩尔百分比随底物中RDN/FOM的升高而升高,0.66组最低,0.88组最高,丙酸的摩尔百分比0.66组最高,0.72组最低。丁酸的摩尔百分比随底物中RDN/FOM水平的升高而降低,0.66组显著高于0.88组。乙丙比接近3:1。
3.不同能氮平衡指数日粮对奶牛产奶量和乳脂率无显著影响,SI值为0.66时显著提高了乳蛋白和非脂乳固体。饲喂各SI值处理日粮后奶牛的血液生化指标基本处于正常范围内,无酮病和瘤胃酸中毒发生的异常情况。SI为0.66时的干物质、有机物和酸性洗涤纤维消化率最高,0.88时蛋白质消化率最高,0.55时中性洗涤纤维消化率最高。SI为0.72的B处理组对蛋白质的利用率最高。从能量利用率的角度来看,以能氮平衡指数分别为0.66和0.72时为最佳。全收尿法估测微生物蛋白产量为SI为0.88组最高,利用点样法估测微生物蛋白产量所得数据与全收尿法有所出入,SI为0.55时微生物蛋白合成量最高,与全收尿法有所差别。结合试验二结论综合考虑,SI值为0.66时可以达到充分利用饲料、发挥动物生产性能的目的。而能氮平衡指数与微生物蛋白合成效率间未发现存在明显的相关关系。
Three Holstein dairy cows fitted with permanent ruminal cannulas were used in this study. Different ratio of ruminal biodegradable nitrogen and ruminal fermentable organisms (20, 25, 30, 35) were used as substrates to determine the corresponding effect on synchronization index. And study the effect of the different synchronization index diet on rumen fermentation pattems and microbial protein synthesis in the rumen with fermentation experiment in vitro. A randomized experiment was carried out to study the effect of energy-nitrogen synchronization index in diet on the productive performance, blood biochemistry indicators ,digestion and metabolism of nutrients and microbial protein synthesis in the rumen of dairy cows. The results of the study showed:
1. At first make different ratio of RDN/FOM formulas diets according to the characteristics of cows feed degradation .Study the degradable quantities of nitrogen and organism in every four hours’time with the experiment in vitro. Calculating the synchronization index with the degradable quantitiy datas of nitrogen and organism.The SI of different ratio of RDN/FOM diets 20,25,30,35 were 0.66、0.72、0.55、0.88 respectively.There was not obvious relationship between RDN/FOM and SI.
2. Effect of different SI substracts on fermentation pattems were investigated.The highest pH was in 0.72 group.But both the fluctuation range of pH and the average level of it were in the normal range of fermentation in vrtro. With the increase of treatment as 0.66,0.72,0.55,0.88, The NH3-N concentration in rumen increased from 17.34mmol/l to 23.81mmol/l. When the SI was 0.66, microbial protein synthesis yield was highest.The acetate concentration increased as the ratio of RDN/FOM increased in the respective treatment group,the highest was in 0.55 group, and lowest in 0.88 group. The propionate concentration was highest in 0.66 group, and lowest in 0.88 group. The percent of acetate increased, butyrate decreased with the increase of RDN/FOM in the substrate. The percent of propionate was highest in 0.66 group,and lowest in 0.72 group. The proportion of acetate and propionate was close to 3:1.
3. After feeding four different synchronization index diets on 16 cows in early lactating period with the same parity and similar body weight from Yang Zhou University Experimental Farm. The average milk yielding per cow had no significant changes(P>0.05). From the milk ingredients, the milk fat percentage had no apparent difference in the four groups fed on different diets, while the milk protein and NFS had increased significantly when fed SI as 0.66,0.55(P<0.05).And the highest is 0.66. The effects of dietary SI ratio on the blood biochemistry indicators such as ALP、CRE、TG、ST/LT、ALB、LDH、A/G、TCO2、ALT、CHO had no significant changes(P>0.05).But the BUN concentration increased with RDN/FOM increasing, difference was significant(P<0.05). The highest TP and GLU concentration was in the group SI=0.88, lowest in the group 0.55,difference was significant(P<0.05). The highest ratio of A/G was in the group 0.66. difference was significant(P<0.05). All of the blood biochemical indexes were in the normal range after feeding four different synchronization index diets. The highest digestibility of DM,OM,ADF were all in 0.66 group,highest digestibility of CP was in 0.88 group, highest digestibility of NDF was in 0.55 group.The highest digestion efficiency of CP was 0.72 group. The best energy efficiency treatment group were 0.66 and 0.72.
In this study the method of Urinary Purine Derivatives estimating rumen microbial protein production was used to caculating microbial protein synthesis .When collectting complete urine,the most microbial protein production was in the 0.88 group.But when collecting sample urine,the most treatment group was 0.55. And there was no obvious relationship between synchronization index and microbial protein synthesis. Considering the second experiment’result,found that when the SI was 0.66,we can get the diets’best utilization efficiency and the best productive performance of animals.
引文
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