Urea 와 Extruded Urea 가 반추위미생물(反芻胃微生物)의 단백질합성 효율과 질소축적율(窒素蓄積率) 그리고 Starch 와 Cellulose 이용률에 미치는 영향 = Effects of Urea and Extruded Urea on the Rumen Microbial Protein Yield , Nitrogen Retention and Fermentation Rates of Starch and Cellulose

국문 초록 (Abstract)

Urea와 extruded urea가 窒素利用率, 徵生物 純蛋白質 合成率과 炭水化物 代謝에 미치는 影響을 究明하기 위하여 in vitro 實驗과 緬羊代謝實驗을 實施하였다.
Urea와 extruded urea를 窒素源으로 하여 培養시키면 徵生物의 純蛋白質 生成量은 에너지源으로 starch를 添加한 것보다 cellulose에서 더 높았고, extruded urea의 效果는 starch에서는 없었으나 cellulose에서는 뚜렷이 나타났다.
可消化 炭水化物 100㎎ 當 徵生物 純蛋白質生成量도 cellulose에서는 urea와 extruded urea에서 各各 8.59와 12.02㎎이었는데 비해 starch에서는 各各 5.90과 4.81㎎로 比較的 낮았다.
培養時間當 徵生物 總蛋白質의 增加率은 starch가 에너지源이었을 때, urea가 16.59%/h 그리고 extruded urea에서 時間當 15.87%/h이고 mean doubling time은 各各 4.18과 6.38時間으로 urea가 窒素源이었을 때 더 높았다.
그러나 cellulose를 에너지源으로 했을 때 徵生物 純蛋白質 增加率이 urea에서 16.70%/h 그리고 extruded urea에서 16.98%/h 그리고 mean doubling time은 各各 4.15와 4.08時間으로 오히려 extruded urea가 窒素源이었을 때 더 높았다.
培養液중의 암모니아 濃度는 urea가 extruded urea에서 보다 더 높았다. 한편 starch의 fermentation rate는 urea에서 9.61%/h 그리고 extruded urea에서는 8.49%/h로서 urea에서 더 높았으나 cellulose의 fermentation rate는 urea에서 2.51%/h 그리고 extruded urea에서 2.91%/h로서 extruded urea에서 더 높았다.
緬羊 代謝試驗에 의한 各種 營養素의 消化率은 urea와 extruded urea에서 差異가 없었다. urea와 extruded urea가 添加된 飼料를 給與한 緬羊에서 蛋白質의 消化率에는 差異가 없었으나 尿中 窒素 排泄量이 urea에서 extruded urea에서 보다 높았고, 따라서 窒素蓄積率이 extruded urea에서 urea보다 높았다. 可消化 에너지 含量도 urea 飼料에서 보다는 extruded urea 사료에서 多少 높았다.
反芻胃內 암모니아 濃度와 pH는 urea 飼料를 給與했을 때 extruded urea 사료보다 높았고, 總 VFA 生成量은 extruded urea에서 높았으나 VFA 組成은 서로 差異가 없었다.

다국어 초록 (Multilingual Abstract)

Effects of urea and extruded urea on the nitrogen utilization, microbial true protein synthesis, and fermentation rate of starch and cellulose were studied in vitro method and sheep metabolism trials were also conducted to measure the digestibilities of nitrogen, nitrogen retention, and ammonia and volatile fatty acid production patterns in sheep rumen fed purified diet containing urea and extruded urea as sole nitrogen sources. Rumen microbial true protein yields were higher
Rumen microbial true protein yields were higher in cellulose than starch as an energy source when urea and extruded urea were adoas sole sources of nitrogen, and extruded urea were stimulated microbial true protein yield in-cellulose but not in starch. Rumen microbial true protein yield was 5.90㎎ in urea and 4.81㎎ in extruded urea per 100㎎ digested starch, but it was 8.59㎎ and 12.02㎎, respectively per 100㎎ digested cellulose, which were much higher in cellulose as compared with starch. Rates of rumen microbial true protein yield in urea and extruded urea were 16.59%/h and 15.87%/h and mean doubling times were 4.18 and 6.38 hr. with starch as an energy source, and these values were 16.70 and 16.98%/h, and 4.15 and 4.08hr, respectively with cellulose as an energy source.
Ammonia concentration in incubation media were much higher in urea as compared with extruded urea with both starch and cellulose as an energy sources. Fermentation rates of starch in urea and extruded urea were 9.61 and 8.49%/h and fermentation rates of cellulose in urea and extruded urea were 2.51 and 2.91%/h which were lower in extruded urea with starch and higher in extruded urea with cellulose as an energy source. In sheep metabolism trials, digestibilities of all nutrients were not different from feeds containing urea and extruded urea as sole sources of nitrogen. Nitrogen digestibility was not different between urea and extruded urea feeds, but there were much higher urinary nitrogen excretion in urea feed than in extruded urea feed, and thus nitrogen retention was higher in feed containing extruded urea.
Digestible energy content was slightly higher in extruded urea diet. Ruminal ammonia concentration and pH were higher in urea feed and total volatile fatty acid(VFA) concentration was higher in extruded urea diet, but VFA concentrations were not different between urea and extruded urea diets.