Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A8.
J Dairy Sci. 2012 Oct;95(10):5961-77. doi: 10.3168/jds.2012-5491. Epub 2012 Aug 3.
The objective of this study was to determine the interactive effects of barley grain processing and source of supplemental fat on ruminal nutrient digestion, duodenal nutrient flow, microbial protein synthesis, and milk fatty acid (FA) profiles in dairy cows. Four Holstein cows (656 ± 28 kg of BW; 80 ± 12 d in milk) fitted with permanent ruminal and duodenal cannulas were used in a 4×4 Latin square design with a 2×2 factorial arrangement of experimental treatments, in which barley was either dry-rolled (DRB) or pelleted (PB) and supplemented with full-fat canola seed (canola) or full-fat flaxseed (flaxseed). Cows fed DRB consumed 1.8 to 3.5 kg/d more dry matter compared with those fed PB. Mean ruminal pH was lower and the duration (min/d) and area (pH × min) of total ruminal acidosis (RA; ruminal pH <5.8), mild RA (5.8 >ruminal pH >5.5), and severe RA (5.5 >ruminal pH >5.2), and the duration of acute RA (ruminal pH <5.2) were greater in cows fed PB compared with those fed DRB. Milk yield was unaffected by diet. Milk fat content and yield were greater in cows fed DRB than in cows fed PB. Cows fed PB had greater duodenal flows of C18:1 trans, C18:1 cis, C18:2 trans-9,trans-12, C18:2 trans-9,cis-12, C18:2 trans-11,cis-15, and C18:2 trans-10,cis-12 compared with those fed DRB. Duodenal flows of C18:1 cis, C18:1 trans, total C18:1, C18:2n6, C18:2 cis-9,trans-11, C18:2 trans-10,cis-12, C18:2 trans-11,trans-13, total conjugated linoleic acid (CLA), and C18:3n3 were greater in cows fed flaxseed compared with those fed canola. Milk concentrations of C18:3n3 and total CLA tended to be greater in cows fed PB compared with those fed DRB. When compared with cows fed canola, milk concentrations of C18:2 trans-11,cis-15, C18:2 cis-9,trans-11, C18:2 trans-11,trans-13, total CLA, and C18:3n3 were greater in cows fed flaxseed. Ruminal digestion of neutral detergent fiber and acid detergent fiber was greater in cows fed DRB compared with those fed PB. Duodenal flow of ammonia-N tended to be greater in cows fed PB compared with those fed DRB. Duodenal flow of nonammonia nonmicrobial N was greater in cows fed flaxseed compared with those fed canola; however, barley grain processing did not affect duodenal nonammonia nonmicrobial N flow. Duodenal flow of microbial nonammonia N and microbial efficiency were not affected by diet. In summary, barley grain processing and source of fat altered ruminal FA biohydrogenation, and this was reflected in changes in duodenal FA flow and milk FA profiles; however, ruminal microbial protein synthesis was unaltered.
本研究旨在确定大麦谷物加工和补充脂肪源对奶牛瘤胃养分消化、十二指肠养分流量、微生物蛋白合成以及乳脂肪酸（FA）谱的交互影响。使用 4 头荷斯坦奶牛（656 ± 28 kg BW；泌乳 80 ± 12 d），采用 4×4 拉丁方设计，进行 2×2 因子处理的实验安排，其中大麦经过干压（DRB）或制粒（PB）处理，并补充全脂油菜籽（菜籽油）或全脂亚麻籽（亚麻籽油）。与 PB 相比，饲喂 DRB 的奶牛干物质采食量增加了 1.8 至 3.5 kg/d。与 DRB 相比，PB 组奶牛的平均瘤胃 pH 值更低，总瘤胃酸中毒（RA；瘤胃 pH <5.8）、轻度 RA（5.8 > 瘤胃 pH >5.5）、严重 RA（5.5 > 瘤胃 pH >5.2）以及急性 RA（瘤胃 pH <5.2）的持续时间（min/d）和面积（pH × min）更大。与 PB 相比，饲喂 DRB 的奶牛的产奶量不受影响。与 PB 相比，饲喂 DRB 的奶牛的乳脂含量和产量更高。与 PB 相比，饲喂 PB 的奶牛的 C18:1 trans、C18:1 cis、C18:2 trans-9,trans-12、C18:2 trans-9,cis-12、C18:2 trans-11,cis-15 和 C18:2 trans-10,cis-12 的十二指肠流量更大。与 PB 相比，饲喂 PB 的奶牛的 C18:1 cis、C18:1 trans、总 C18:1、C18:2n6、C18:2 cis-9,trans-11、C18:2 trans-10,cis-12、C18:2 trans-11,trans-13、总共轭亚油酸（CLA）和 C18:3n3 的十二指肠流量更大。与 PB 相比，饲喂 PB 的奶牛的乳中 C18:3n3 和总 CLA 浓度趋于更高。与饲喂 PB 的奶牛相比，饲喂 flaxseed 的奶牛的乳中 C18:2 trans-11,cis-15、C18:2 cis-9,trans-11、C18:2 trans-11,trans-13、总 CLA 和 C18:3n3 的浓度更高。与饲喂 canola 的奶牛相比，饲喂 flaxseed 的奶牛的瘤胃中性洗涤纤维和酸性洗涤纤维的消化率更高。与饲喂 DRB 的奶牛相比，饲喂 PB 的奶牛的十二指肠氨氮流量趋于更高。与饲喂 canola 的奶牛相比，饲喂 flaxseed 的奶牛的非氨非微生物氮的十二指肠流量更高；然而，大麦谷物加工对非氨非微生物氮的十二指肠流量没有影响。与饲喂 canola 的奶牛相比，饲喂 flaxseed 的奶牛的微生物非氨氮和微生物效率不受饮食的影响。总之，大麦谷物加工和脂肪源改变了瘤胃 FA 的生物氢化作用，这反映在十二指肠 FA 流量和乳 FA 谱的变化中；然而，瘤胃微生物蛋白合成不受影响。
