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|標題:||利用in situ及in vitro法評估飼料原料蛋白質及碳水化合物份化物瘤胃降解之動態變化
Study on the ruminal degradation dynamic of protein and carbohydrate fractions of ingredient through in situ and in vitro methods
|關鍵字:||protein and carbohydrate fractions;蛋白質及碳水化合物份化物;degradation rate;degradability;regression equation;降解速率;降解率;迴歸方程式||出版社:||畜產學系||摘要:||
本試驗為有效應用NRC淨能與代謝蛋白質系統於台灣地區之乳牛，故必須先建立主要飼料原料(分芻料、精料及加工副產物等18種)蛋白質與碳水化合物相關之消化動力學資料，並採用3頭瘤胃開窗牛隻，利用in situ尼龍袋法進行9個時間點的瘤胃培養，以非線性模式系統計算出瘤胃降解速率及其有效降解率，同時並進行in vitro體外培養求得24及48小時之降解率，藉統計分析以求得此三種方法間之相關迴歸。試驗結果顯示蛋白質份化方面，非蛋白態氮(fraction A)以芻料及加工副產物較精料為高。快速降解蛋白質(fraction B1)以玉米明顯較高。而大部份的飼料原料皆以緩速降解蛋白質(fraction B2)佔CP的比例為最多。慢速降解蛋白質(fraction B3)以百慕達及啤酒粕較高。至於不降解不可利用蛋白質(fraction C)以高梁酒粕及米酒粕明顯較高。在碳水化合物方面，最快速降解碳水化合物(CHO A)以百慕達、盤固草、啤酒粕及米酒粕含量較低，而大豆粕較高。快速降解碳水化合物(CHO B1)以玉米及高梁酒粕顯著較高。緩速降解碳水化合物(CHO B2)以禾本科牧草及啤酒粕較豆科牧草、精料及其他加工副產物為高。至於不降解不可利用碳水化合物(CHO C)以棉籽及米酒粕含量較高。營養分之瘤胃降解速率，乾物質以精料最快，加工副產物次之，芻料最慢。蛋白質則以豆科牧草之苜蓿最快。中洗纖維與酸洗纖維皆以加工副產物明顯較芻料為快。降解率(8%通過速率)方面，乾物質以精料最多，芻料之豆科牧草次之。蛋白質則以豆科牧草有較大值。中洗纖維以高梁酒粕及米酒粕有較高之情形，而酸洗纖維則以狼尾草及高梁酒粕較多。在迴歸方程式方面，豆科牧草與禾本科牧草蛋白質及碳水化合物份化值皆可較準確預估in situ降解速率，其R2分別為0.9917與0.6455 (P<0.05)，而加工副產物雖然P值不顯著，但有其趨勢的存在(R2=0.9576, P>0.05)。然豆科牧草及禾本科牧草也可較準確預估in vitro降解率(R2=0.9992 vs R2=0.6595, P<0.05)。
Before the NRC net energy and metabolizable protein system can be effectively applied to local dairy farming in Taiwan, digestive kinetic information regarding the protein and carbohydrate fractions of the major feedstuff used in dairy diets should be established. Three fistulated cows were used in an in situ nylon bag study with nine consecutive ruminal incubation times for each duplicate sample to derive the degradation rate and availability (or degradability) of feedstuff calculated through a nonlinear regression model system. The degradability of feedstuff at 24 and 48hr incubations was derived via in vitro method using a DAISY incubator. Data from the different methods were analyzed through step-wide regression analysis. Results showed that the roughage and by-products contained higher fraction A (soluble non-protein nitrogen) than most of the concentrates. Corn in concentrates contained the highest fraction B1 (soluble protein). Fraction B2 (intermediately degraded protein) contained the greatest percentage of crude protein of the tested feedstuff. Bermuda hay and brewer's grains contained higher fraction B3 (slowly degraded available protein) as compared to the other ingredients. Sorghum distillers' grains and rice grain contained more fraction C (undegraded unavailable protein) than the other feedstuffs. From carbohydrate fractionalization, Bermuda hay and Pangola grass contained the lowest fraction A (fast degradable) among the forages, with brewers' grain and rice distillers' grains having the lowest by-products. Soybean meal contained the largest amount of fraction A among the concentrates. Corn among concentrates and sorghum distillers' grains among by-products contained higher B1 (intermediate degradable) fractions compared to the other ingredients. Where graminaceous herbage in forages and brewers' grain in by-products contained higher fraction B2 (slow degradable) than legumes, concentrates and other by-products. Cottonseed in concentrates and rice distillers' grains in by-products contained higher fraction C (non-degradable non-usable) than the forages. Our data also showed that the dry matter in the concentrates degraded fastest, by-products next, and forage degraded the slowest. Alfalfa showed the fastest protein degradation rate among the forages. The degradation rate of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in by-products was faster than in the forages. The degradability of dry matter (8%/h passage rate) in the rumen in the concentrates was fastest, legume forages was the next. Among the forages, legume protein degraded the greatest. The ruminal NDF availability of sorghum distillers' grains and rice distillers' grains was the greatest. The ruminal ADF availability in Napiergrass and sorghum distillers' grains was the greatest. The in situ degradation rate of legumes and graminaceous herbage could be predicted using protein and carbohydrate fractions with R-squares 0.9917 and 0.6455, respectively although the P value was not significantly different in the by-products (R2=0.9576, P>0.05). The in vitro degradability of legumes and graminaceous herbage could also be predicted from the fractions (R2=0.9992 vs. R2=0.6595, P<0.05).
|Appears in Collections:||動物科學系|
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