Richards C J, Swanson K C, Paton S J, Harmon D L, Huntington G B
Department of Animal Sciences, University of Kentucky, Lexington 40546-0215, USA.
J Anim Sci. 2003 Apr;81(4):1051-6. doi: 10.2527/2003.8141051x.
Our objective was to evaluate the effect of postruminal protein infusion on pancreatic exocrine secretions. One Holstein, two crossbred, and five Angus steers (305 +/- 5 kg) with pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were used in a replicated 4 x 4 Latin square. All steers were abomasally infused with 1,050 g/d of raw cornstarch with treatments of 0, 60, 120, or 180 g/d of sodium casein suspended in water to yield 6,000 g/d of infusate daily. Steers were limit-fed (1.5 x NEm; 12 equal portions daily) a 90% corn silage, 10% supplement diet formulated to contain 12.5% CP. Periods consisted of 3 d of adaptation to infusion, 7 d of full infusion, 1 d of collection, and 7 d of rest. Pancreatic juice was collected in 30-min fractions continuously for 6 h. Total juice secreted and the pH of individual fractions were recorded, a 10% subsample was retained to form a composite sample, and remaining fluid was returned to the duodenum. Juice composite samples were stored (-30 degrees C) until analyzed for total protein and activities of alpha-amylase, trypsin, and chymotrypsin. Casein infusion linearly increased alpha-amylase concentration (182 to 271 units/mL; P < 0.02; 17.5 to 24.6 units/mg of protein; P < 0.03) and secretion rate (26,847 to 41,894 units/h; P < 0.01). Total juice secretion (155 g/h), pH of pancreatic juice (8.13), secretion rate of protein (1,536 mg/h), and concentration of protein (10.2 mg/mL) in pancreatic secretions were not affected (P > 0.05) by casein infusion. Similarly, casein infusion did not change 0.05) trypsin and chymotrypsin concentrations (1,379 and 349 units/L or 0.134 and 0.033 units/mg of protein, respectively) or secretion rates (206 and 52 units/h, respectively). Abomasal infusion of protein with starch stimulated a greater pancreatic secretion of alpha-amylase activity into the intestine than infusion of starch alone.
我们的目标是评估瘤胃后蛋白质输注对胰腺外分泌的影响。选用1头荷斯坦牛、2头杂交牛和5头安格斯阉牛（体重305±5千克），这些牛安装了胰腺小袋-十二指肠折返插管和皱胃输注导管，采用重复4×4拉丁方设计。所有阉牛皱胃内每天输注1050克生玉米淀粉，处理方式为分别向水中悬浮0、60、120或180克/天的酪蛋白钠，以使每日输注液总量达到6000克。阉牛采用限量饲喂（1.5×维持净能；每天12等份），日粮为90%玉米青贮料和10%补充料，日粮配方中粗蛋白含量为12.5%。试验期包括3天的输注适应期、7天的全量输注期、1天的收集期和7天的休息期。连续6小时每隔30分钟收集一次胰液。记录分泌的胰液总量和各部分的pH值，保留10%的子样本以形成混合样本，其余液体返回十二指肠。胰液混合样本储存于-30℃，直至分析总蛋白以及α-淀粉酶、胰蛋白酶和糜蛋白酶的活性。酪蛋白输注使α-淀粉酶浓度呈线性增加（从182至271单位/毫升；P<0.02；从17.5至24.6单位/毫克蛋白；P<0.03）以及分泌速率增加（从26,847至41,894单位/小时；P<0.01）。酪蛋白输注对胰液总分泌量（155克/小时）、胰液pH值（8.13）、蛋白质分泌速率（1,536毫克/小时）以及胰腺分泌物中蛋白质浓度（10.2毫克/毫升）均无影响（P>0.05）。同样，酪蛋白输注也未改变胰蛋白酶和糜蛋白酶的浓度（分别为1,379和349单位/升或0.134和0.033单位/毫克蛋白）或分泌速率（分别为206和52单位/小时）。与单独输注淀粉相比，皱胃内同时输注蛋白质和淀粉刺激胰腺向肠道分泌更多的α-淀粉酶活性。
