Bowman G R, Beauchemin K A, Shelford J A
Faculty of Agricultural Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
J Dairy Sci. 2003 Feb;86(2):565-75. doi: 10.3168/jds.S0022-0302(03)73635-2.
Four multiparous and four primiparous lactating dairy cows fitted with ruminal cannulas were used in a duplicated 4 x 4 Latin square design to study the effects of parity and inclusion of a fibrolytic enzyme product (Agribrands International, St. Louis, MO) on feeding and chewing behavior, salivation, and ruminal pH. Diets consisting of rolled barley, barley silage, and alfalfa haylage (55% forage, DM basis) differed in enzyme application: 1) control, 2) enzyme applied to concentrate (45% of TMR), 3) enzyme applied to supplement (4% of TMR), and enzyme applied to a premix (0.2% of TMR). Enzyme supplementation did not alter daily time spent eating or ruminating, but when enzymes were added to the ration daily, saliva production increased, with no difference among enzyme application treatments. Multiparous cows consumed a greater amount of feed, but spent a similar amount of time eating, compared to primiparous cows. Primiparous cows had shorter ruminating episodes, resulting in lower daily ruminating time compared with multiparous cows. Primiparous cows had lower daily saliva output compared with multiparous cows. These results indicate that application of this fibrolytic enzyme product did not alter the physical structure of the feed, as measured by feeding and chewing variables. The increase in total saliva production observed in cows fed enzyme-supplemented diets may be attributed to a physiological response to compensate for the increase in fermentation products during digestion. The increased intake for multiparous cows is attributed to increased eating rate and not to increased time spent eating. The higher DMI of multiparous cows resulted in increased rumination time needed to process the additional feed and increased salivation to buffer the greater production of VFA.
选用4头经产泌乳奶牛和4头初产泌乳奶牛，安装瘤胃瘘管，采用4×4重复拉丁方设计，研究胎次和添加纤维分解酶产品（阿格瑞班国际公司，密苏里州圣路易斯）对采食和咀嚼行为、唾液分泌及瘤胃pH值的影响。由压片大麦、大麦青贮和苜蓿青贮组成的日粮（55%粗饲料，干物质基础）在酶添加方式上有所不同：1）对照组，2）酶添加到精料中（占全混合日粮的45%），3）酶添加到补充料中（占全混合日粮的4%），以及酶添加到预混料中（占全混合日粮的0.2%）。添加酶并未改变每日采食或反刍所花费的时间，但当每日在日粮中添加酶时，唾液分泌量增加，各酶添加处理间无差异。与初产奶牛相比，经产奶牛采食的饲料量更多，但采食时间相近。初产奶牛的反刍时间较短，导致其每日反刍时间低于经产奶牛。与经产奶牛相比，初产奶牛的每日唾液分泌量较低。这些结果表明，通过采食和咀嚼变量测定，这种纤维分解酶产品的应用并未改变饲料的物理结构。在采食添加酶日粮的奶牛中观察到的总唾液分泌量增加，可能归因于一种生理反应，以补偿消化过程中发酵产物的增加。经产奶牛采食量增加归因于采食速度提高，而非采食时间增加。经产奶牛较高的干物质采食量导致处理额外饲料所需的反刍时间增加，以及唾液分泌增加以缓冲更多挥发性脂肪酸的产生。
