蛋白质和过瘤胃脂肪对晋南牛瘤胃发酵和尿嘌呤衍生物的影响

为探究蛋白质和富含不饱和脂肪酸的过瘤胃脂肪对瘤胃发酵和尿嘌呤衍生物的影响,选用4头装有永久性瘤胃瘘管的晋南阉牛,按照蛋白质需要量的85%、100%和115%设计3个水平,并在此基础上添加0、2.5%、5.0%和7.5%的亚麻油制作的钙皂作为过瘤胃脂肪,采用3×4两因素设计,共形成12组饲粮组合,测定瘤胃pH、氨态氮浓度(NH_3-N)浓度、挥发性脂肪酸(VFA)含量以及尿嘌呤衍生物(PD)的排出量。结果表明,蛋白质和过瘤胃脂肪水平对瘤胃pH均无显著影响。蛋白质水平对NH_3-N浓度影响显著,9组NH_3-N显著高于1、2、3、4和8组,10组显著高于3和8组;对丙酸和乙酸、丁酸、乙酸/丙酸及总酸分别具有极显著和显著影响,5组的乙酸浓度较1、2、3和4组显著提高,9、10和11组瘤胃液中的丙酸浓度较1和2组显著提高,12组较2组显著提高,10组的丁酸浓度显著高于7和8组,1和2组的乙酸/丙酸比值显著高于9、10和11组;对精补料养分有效降解率影响极显著,对秸秆有机物(OM)和酸性洗涤纤维(ADF)分别具有极显著和显著影响,10组精补料粗蛋白质(CP)瘤胃有效降解率显著高于2、3、4、5、6、7和8组,1、9、11和12组显著高于4、5、6、7和8组;对玉米秸秆中ADF瘤胃有效降解率6、7和8组显著高于除5和12组之外的其余各组,5和12组显著高于除9和11组之外的其余各组;对尿囊素和尿嘌呤衍生物有显著影响,12组的尿囊素和尿嘌呤衍生物显著高于1和4组,11组尿酸显著高于其余组。综上,饲粮蛋白质水平对瘤胃发酵和尿嘌呤衍生物具有显著影响,饲粮蛋白质水平为饲养标准需要量前提下,过瘤胃脂肪适宜添加量为饲粮的5%。本研究结果为肉牛养殖中日粮过瘤胃脂肪添加量及蛋白质水平提供了一定的依据。

Effect of Crude Protein and Rumen Protected Fat on Rumen Fermentation and Urinary Purine Derivative Contents in Steers

This study was conducted to investigate effect of diet crude protein and rumen protected fat on rumen fermentation and urinary purine derivatives.Four Jinnan steers with permanent rumen fistulas were assigned at a 3 × 4 factorial arrangement of treatment,the diet protein concentration was designed in 3 levels which were at 85％,100％ and 115％ of 1.15 times maintenance nutrient levels supplemented with 0,2.5％,5.0％ and 7.5％ rumen protected fat.There were 12 diets in all,determine rumen pH,NH3-N,VFA concentrationand the excretion of urine purine derivatives.The results showed as follows:diet protein and rumen protected fat had no significant effect on rumen pH,however,diet protein levels had significant effect on concentration of ammoniacal nitrogen.The concentration of ammoniacal nitrogen in group 9 was significantly higher than that in groups of 1,2,3,4 and 8,and the group 10 was significantly higher than that in groups of 3 and 8.The diet protein levels had very significant effect on concentration of propionic acid and significant effect on concentration of acetic,butyric acid and ratio of acetic/propionic,respectively.The concentration of acetic acid in group 5 was significantly higher than that in groups of 1,2,3 and 4,The concentration of propionic acid in groups 9,10 and 11 was significantly higher than that in groups of 1 and 2,and the group 12 was significantly higher than the group 2.The concentration of butyrate was significantly higher than the group 7,8 The ratio of acetic acid/propionic acid was significantly higher than the group the group of 9,10 and 11 The diet protein levels had very significant effect on nutrients degradability of concentrate supplement,and very significant effect on OM degradability of maize straw and ADF respectively.The crude protein degradability in group 10 was significantly higher than that in groups 2,3,4,5,6,7 and 8,furthermore,it in groups 1,9,11 and 12 was significantly higher than that in groups 4,5,6,7 and 8;the ADF degradability in groups 6,7 and 8 were significantly higher than the other groups except for groups 5 and 12,the degradability in groups 5 and 12 were significantly higher than the other groups except for groups 9 and 11.The diet protein levels had significant effect on allantoin and urinary purine derivatives.The allantoin and urinary purine derivatives content in group 12 rose significantly than in groups 1 and 4,and the uric acid content in group 11 rose significantly than in the other group.These results indicated that the diet protein levels has significant effect on rumen fermentation and urinary purine derivative contents.The optimum rumen protected fat supplemental levels under the standard protein condition of 5.0％.The results provided the certain basis in supplementation rumen protected fat for beef cattle production.