台灣乳牛分娩前飼糧原料陽陰離子差值之探討

本研究的目的係調查台灣乳牛分娩前的日糧原料中，包括精料和粗料的陽陰離子差（cation-anion difference, CAD）值，並印證國外所建議的適當CAD值（-10 meq／100 g），冀期供作酪農、推廣人員和飼料配製廠商參考。本文共採集17個精料和15個粗料樣品，進行水份、粗蛋白質、鈣、磷和鈉、鉀、氯、硫等含量的分析，進而利用後四種電解質離子以〔（Na+K）-（Cl+S）〕方式計算CAD值，並以毫當量／100克表示之。台灣乳牛分娩前所採食的17種精料（除2種為廠商標示乾乳牛專用外，其餘大都為泌乳牛料），其CAD值除啤酒粕（-3.04 meq／100 g）外，其餘皆為正值，範圍是-3.04～+39.97 meq／100 g；而其中6種精料的CAD值高於25 meq／100 g的原因為鈉（平均0.59％）和鉀（平均1.18％）含量皆較高。至於15個粗料的CAD值皆為正值，範圍為+6.48～+46.63 meq／100 g；而其中7種粗料的CAD值高於25 meq／100 g的原因為鉀含量（平均2.07％）較高，且比精料者（平均1.18％）高，然而玉米青貯料則是低硫含量（0.080％）所致。雖然乾乳牛所採食的精料之CAD值皆不符合乾乳牛的理想值，但除完全混合日糧、生長牛料和乾乳牛專用料外，大部分精料的CAD值皆符合泌乳牛的理想值（+17.5～+37.5 meq／100 g）。

關鍵字

乾乳牛；飼糧陽陰離子差；乳熱

並列摘要

The objective of the study was to survey the dietary cation-anion difference (DCAD) in the concentrates and roughages of preparturient dairy ration in Taiwan. Seventeen concentrates and 15 roughages were collected. The analyzed values of electrolytes (including Na, K, Cl and S) were used to calculate the DCAD value [(Na + K) - (Cl + S)] in milliequivalents per 100 gram of dry matter (meq/100 g). Results showed that CAD values were positive in concentrates, except brewer's grains which contained -3.04 meq/100 g and ranged from - 3.04 to 39.97 meq/ 100 g. Six concentrates contained high CAD value (＞ 25 meq/100 g) which was attributed to high Na (0.59%) and high K (1.18%) concentration. All of the roughages contained positive CAD values and ranged from 6.48 to 46.63 meq/100 g. High CAD values (＞ 25 meq/100 g) of 7 roughage samples were due to high K concentration (2.07%) which was higher than that of the average concentrates (1.18%). The high CAD value of corn silage was attributed to the low S concentration (0.080%). Although most of the concentrate samples did not contain optimal DCAD (-10 meq/100 g) for preparturient dry cows, they contained optimal DCAD (17.5-37.5 meq/100g) for lactating cows with exception of samples from the commercial TMR, growing heifer diet and dry cow diet.

並列關鍵字

Dry cow ； Dietary cation-anion difference (DCAD) ； Milk fever

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