Oba M, Mewis J L, Zhining Z
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
J Dairy Sci. 2015 Jan;98(1):586-94. doi: 10.3168/jds.2014-8697. Epub 2014 Oct 30.
The objective was to evaluate effects of a ruminal dose of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells. Six ruminally cannulated nonlactating nonpregnant Holstein cows (body weight=725±69.6kg) were assigned to treatments in a 3×3 Latin square design with 7-d periods; 1d for data and sample collection followed by a 6-d washout period. Cows were fed a diet containing whole-crop barley silage and dry ground corn, and dietary neutral detergent fiber and crude protein contents were 41.8 and 13.2% [dry matter (DM) basis], respectively. Treatment was a pulse-dose of sucrose, lactose, and corn starch (3.0, 3.0, and 2.85kg of DM, respectively; providing similar amounts of hexose across the treatments) through the ruminal cannulas. All treatments were given with alfalfa silage (1.75kg DM) to prevent acute rumen acidosis. Rumen pH was continuously monitored, and rumen fluid was sampled at 0, 30, 60, 90, 120, 150, and 180min after the dose. In addition, ruminal papillae were sampled from the ventral sac at 180min after the dose. Ruminal dosing with sucrose and lactose, compared with corn starch, increased ruminal total volatile fatty acid concentration and molar proportion of butyrate from 60 to 180min after the dose, and expression of genes for sodium hydrogen exchanger isoforms 1 and 2, and ATPase isoform 1 in ruminal epithelial cells. Ruminal dosing with sucrose, compared with lactose and corn starch, decreased rumen pH from 120 to 180min after the dose and molar proportion of acetate in ruminal fluid from 60 to 150min after the dose, and increased molar proportion of propionate in ruminal fluid from 60 to 150min, and expression of genes involved in butyrate metabolism (3-hydroxy-3-methylglutaryl-coenzyme A synthase isoform 1) and anion exchange across ruminal apical cell membrane (putative anion transporter isoform 1). These results suggest that replacing dietary starch with sugars may affect ruminal fermentation and metabolism regulating intracellular pH and fermentation acid absorption in ruminal epithelial cells, and that these effects can be greater for sucrose than lactose.
目的是评估瘤胃内注射蔗糖、乳糖和玉米淀粉对瘤胃发酵及瘤胃上皮细胞基因表达的影响。选用6头装有瘤胃瘘管的非泌乳、非妊娠荷斯坦奶牛（体重=725±69.6kg），采用3×3拉丁方设计，试验期7天；第1天用于数据和样本采集，随后为6天的洗脱期。给奶牛饲喂含全株大麦青贮和干磨玉米的日粮，日粮中性洗涤纤维和粗蛋白含量分别为41.8%和13.2%[以干物质（DM）计]。处理方式为通过瘤胃瘘管脉冲注射蔗糖、乳糖和玉米淀粉（分别为3.0、3.0和2.85kg DM；各处理提供相似量的己糖）。所有处理均搭配苜蓿青贮（1.75kg DM）以预防急性瘤胃酸中毒。连续监测瘤胃pH值，并在注射后0、30、60、90、120、150和180分钟采集瘤胃液。此外，在注射后180分钟从腹囊采集瘤胃乳头。与玉米淀粉相比，瘤胃注射蔗糖和乳糖可使注射后60至180分钟瘤胃总挥发性脂肪酸浓度及丁酸摩尔比例升高，并使瘤胃上皮细胞中钠氢交换体亚型1和2以及ATP酶亚型1的基因表达增加。与乳糖和玉米淀粉相比，瘤胃注射蔗糖可使注射后120至180分钟瘤胃pH值降低，使注射后60至150分钟瘤胃液中乙酸摩尔比例降低，并使注射后60至150分钟瘤胃液中丙酸摩尔比例升高，以及使参与丁酸代谢（3-羟基-3-甲基戊二酰辅酶A合酶亚型1）和瘤胃顶端细胞膜阴离子交换（假定阴离子转运体亚型1）的基因表达增加。这些结果表明，用糖替代日粮淀粉可能会影响瘤胃发酵和代谢，调节瘤胃上皮细胞内的pH值和发酵酸吸收，且蔗糖的这些影响可能比乳糖更大。
