白肉雞飼糧中理想胺基酸組成之建立

Abstract

本研究之目的乃在探討現今商用白肉雞對各必需胺基酸之可消化需要量，以及整體必需胺基酸與整體非必需胺基酸間之比例，藉以建立飼糧中理想胺基酸組成。 本研究分為四個試驗，皆以3日齡之雄性白肉雞（Arbor Acres Plus）為試驗動物，試驗為期7日，至10日齡結束。試驗一以滿足愛拔益加飼養管理手冊0至10日齡各營養分推薦量之玉米–大豆粕實用飼糧餵飼雞隻，並根據每日體重、採食量與飼糧中可代謝能濃度，計算出3至10日齡白肉雞平均每日每公斤代謝體重所對應之可代謝能需要量（k值）為381.10±23.83 kcal。試驗二則參考愛拔益加飼養管理手冊與NRC (1994) 之各必需胺基酸推薦量，配製各必需胺基酸總推薦量之50、75、100、125或150% 半純化飼糧，並且依據雞隻個別代謝體重、k值與處理飼糧之可代謝能濃度，計算每日應有之採食量，進行管飼。試驗結束後，以比較性屠宰法分析其體氮蓄積率，將結果以二次曲線模型進行分析，結果得知在總推薦量百分比為109.75%時，能致使體氮蓄積率表現最佳。試驗三以試驗二之結果為對照組飼糧，其餘組別則分別是以每一個必需胺基酸當成唯一限制胺基酸之缺乏組，且同一缺乏組有兩種不同缺乏程度，分別為對照組的50%與60%。試驗期間之餵食方式亦以管飼進行，試驗結果顯示，將對照組之體氮蓄積率畫成一條水平線，再將各胺基酸缺乏組別所對應的體氮蓄積率進行直線迴歸，各組迴歸直線與對照組的水平線之交點的x軸對應值，即為白肉雞每日每公斤代謝體重對此必需胺基酸用於生長加維持之需要量。而各迴歸直線的斜率之倒數和迴歸直線與x軸的截距，則分別代表雞隻每日每公斤代謝體重對此必需胺基酸用於生長與維持之需要量。另將所求得之生長、維持、生長加維持之各必需胺基酸需要量除以離胺酸組之數值，則得到3至10日齡肉雞生長加維持所需之理想必需胺基酸組成為Lys：Arg：SAA：His：Trp：Leu：AAA：Ile：Thr：Val =100：108：74：32：13：123：123：63：70：81；生長所需之組成為100：113：77：33：13：125：123：66：74：83；維持所需之組成為100：21：5：13：15：58：125：3：11：41。將個別生長與維持所需之需要量，和不同生長階段之體蛋白質蓄積率，與代謝體重進行各生長階段之動態性估測，可求得0至10日齡之理想必需胺基酸組成為100：111：75：32：13：123：123：64：72：81；10至21日齡為100：111：75：32：13：123：123：64：72：81；21日齡至35日齡為100：109：74：32：13：122：123：63：71：81。試驗四以添加不同濃度之非必需胺基酸與試驗三求得之3至10日齡各必需胺基酸生長加維持之需要量，分別配製出五種飼糧中整體必需胺基酸（E）佔總胺基酸（T）比例（E：T）為0.62、0.48、0.39、0.32或0.28之組別，並以管飼進行試驗，試驗結果顯示隨著飼糧中E：T增加，體氮蓄積率呈線性提升（P < 0.01），而氮利用效率則呈線性下降（P < 0.01），兩指標之高原期轉折點分別為0.37與0.44。 綜合上述所建立之理想胺基酸組成，可當成評判商用飼料中必需胺基酸組成良窳之參考，以期能對白肉雞生長性能與飼糧中胺基酸的平衡能有效地提升及改善。

The objective of this study was to establish ideal amino acid pattern (IAAP) of dietary protein for current commercial broiler by using a unique methodology for investigating digestible requirements for individual essential amino acids and to determine a proper proportion between essential and non-essential amino acids. In this study, three-day-old male broilers were used as an experimental animal model. The test lasted for 7 days and ended at 10 days of age. The study was divided into four trials. First trial was to feed the chickens with a practical diet, based on corn and soybean meal, meeting the recommended nutritional requirements in the Arbor Acres broiler feeding management manual. According to the daily body weight, feed intake and the metabolizable energy concentration in the diet, the mean of metabolizable energy requirement (k value) for daily maintenance plus growth based on metabolic body weight was calculated as 381.10±23.83 kcal for 3 to 10 day old broiler. In the second trial, the percentages of all essential amino acids in five diets were designed as 50, 75, 100, 125 or 150% referring to the broiler requirements suggested by the Arbor Acres Broiler Nutrition Supplement (2014) and NRC (1994). According to the individual metabolic body weight of individual broilers, the k value obtaining in trial 1 and the metabolizable energy concentration of the corresponding diet, daily feed intake was computed for intubation. In the end of the experiment, the nitrogen retention rate was calculated by comparative slaughtering. To result in the best nitrogen retention rate for broiler from Day 3-10, the results were computed by a quadratic regression model to acquire an optimum percentage of requirements, 109.75%, recommended by the afore-mentioned literature for all essential amino acids. In the third trial, the results of the trial 2 was served as the diet for the control group. Individual essential amino acids were assigned to be the only limiting amino acid in corresponding deficiency groups, and the deficiency level was 50 or 60% of the control group, respectively. The intubation was also conducted in this trial as well. The x coordinate of an intersection for each straight line, resulting from every two deficient groups with the same limiting amino acid but at different levels, with a horizontal line from the response of the control group represented the daily requirement for the corresponding essential amino acid based on metabolic body weight for growth plus maintenance. The x-intercept and the reciprocal of slope for each straight line stood for the respective requirement for maintenance and growth, respectively, corresponding to the examined amino acid. The each amino acid requirements obtained for growth, maintenance, and growth plus maintenance were divided by the value of lysine to obtain the ideal essential amino acid pattern (IEAAP) for growth plus maintenance from 3 to 10 days of age was Lys: Arg: SAA: His: Trp: Leu: AAA: Ile: Thr: Val =100: 108: 74: 32: 13: 123:123: 63: 70: 81, respectively, for growth was 100: 113: 77: 33: 13 : 125: 123: 66: 74: 83, respectively, and for maintenance was 100: 21: 5: 13: 15: 58: 125: 3: 11: 41, respectively. The requirements for respective growth and maintenance, the body protein accumulation rate and metabolic body weight of different growth stages were used to estimate dynamically the IEAAP at each growth stage. The IEAAP was computed as 100: 111: 75: 32: 13: 123: 123: 64: 72: 81 for 0 to 10 days of age, as 100: 111: 75: 32: 13: 123: 123: 64: 72: 81 for 10 to 21 days of age, and as 100: 109: 74: 32: 13: 122: 123: 63: 71: 81 for 21 to 35 days of age. In the fourth trial, the ratio of overall essential amino acids relative to total amino acids (E: T) was designed as 0.62, 0.48, 0.39, 0.32 or 0.28 by changing dietary non-essential amino acid levels and fixing individual essential amino acid requirement levels for growth plus maintenance from the trial 3. The feeding way was also conducted by intubation. The results showed that the nitrogen retention rate increased linearly (P < 0.01) while the nitrogen utilization decreased linearly (P < 0.01) with the increase of E: T in the diets. The plateau turning points of these criteria were 0.37 and 0.44, respectively. The IAAP established in this study will be utilized as a criterion for checking the amino acid composition of practical diets and improving the balance of amino acids in the diet resulting in better growth performance for broiler.