肉仔鸡维持氨基酸模式和需要量的研究

Amino acid profile and requirements for maintenance in broiler chickens

【目的】确立肉仔鸡的维持氨基酸需要模式,并依此估测肉仔鸡用于维持的氨基酸需要量。【方法】以体重基本一致的6周龄AA肉鸡为供试动物,设计无氮和低氮2种饲粮进行氮平衡试验,以无氮饲粮来估测内源氮排泄量,以低氮饲粮来估测肌酐排泄总量和羽毛、皮屑等体表氮损失量(沉积氮量),合计不同途径的氮损失量估算蛋白质维持需要量。通过屠宰试验分析胴体和羽毛的氨基酸组成,并将胴体蛋白质和羽毛蛋白质的氨基酸组成模式,分别作为内源氮中非氨态氮和体表损失氮的氨基酸组成模式,肌酐形式的氨基酸损失以等物质量的甘氨酸、精氨酸和蛋氨酸替代,综合内源氨基酸排泄量和体表氨基酸损失量,确定肉仔鸡的维持氨基酸模式,并根据蛋白质维持需要量和氨基酸组成模式计算维持氨基酸的需要量。【结果】肉仔鸡采食低氮饲粮时的沉积氮量为509.27 mg/d,肌酐排泄量为12.22 mg/d,采食无氮饲粮时内源氮排泄总量为510.71 mg/d。肉仔鸡蛋白质维持需要量(mg/d)为3 414.38×体重0.75。【结论】肉仔鸡维持氨基酸模式(质量分数,%):天冬氨酸7.68,苏氨酸4.52,丝氨酸6.75,谷氨酸10.42,甘氨酸8.20,丙氨酸5.18,胱氨酸4.16,缬氨酸6.30,蛋氨酸1.64,异亮氨酸4.59,亮氨酸7.77,酪氨酸3.17,苯丙氨酸4.16,赖氨酸4.37,组氨酸2.04,精氨酸6.86,脯氨酸7.65,色氨酸0.76。肉仔鸡维持氨基酸需要量(mg/(kg0.75.d))为:天冬氨酸262.22,苏氨酸154.33,丝氨酸230.47,谷氨酸355.78,甘氨酸279.97,丙氨酸176.86,胱氨酸142.04,缬氨酸215.11,蛋氨酸56.00,异亮氨酸156.72,亮氨酸265.30,酪氨酸108.24,苯丙氨酸142.04,赖氨酸149.21,组氨酸69.65,精氨酸234.23,脯氨酸261.20,色氨酸25.95。

【Objective】 The study was to establish maintenance amino acid profile for broiler chickens using the factorial approach and to estimate amino acid requirements for maintenance according to the profile.【Method】 Parameters used to calculate protein requirement for maintenance were obtained from two balance trials with 6-week broilers.The N-low diet was formulated to estimate skin protein loss and creatitine loss and the N-free diet to estimate endogenous protein and amino acid excretion.The protein requirement for maintenance was calculated by summing up the different losses.Protein and amino acid analyses of nude carcass and feather in the comparative slaughter experiment were used to obtain their own amino acid patterns which were regarded as amino acid composition of non-amino nitrogen in endogenous nitrogen and skin integuments nitrogen respectively.Creatinine excretion was replaced by equivalent mol of glycine,arginine and methionine.Amino acid profile and requirements for maintenance were calculated by summing the endogenous amino acid excretion and losses of the skin integuments.【Result】 Nitrogen retention and creatinine excretion were determined at 509.27 and 12.22 mg/d in protein-fed birds.Birds fed on Nfree diet excreted 510.71 mg/d nitrogen as a result of endogenous losses.The protein requirement for maintenance was 3 418.38 BW0.75.【Conclusion】 Amino acid profile（%） and requirements for maintenance were listed as follows：profile,Asp 7.68,Thr 4.52,Ser 6.75,Glu 10.42,Gly 8.20,Ala 5.18,Cys 4.16,Val 6.30,Met 1.64,Ile 4.59,Leu 7.77,Tyr 3.17,Phe 4.16,Lys 4.37,His 2.04,Arg 6.86,Pro 7.65,Trp 0.76;requirement,Asp 262.22,Thr 154.33,Ser 230.47,Glu 355.78,Gly 279.97,Ala 176.86,Cys 142.04,Val 215.11,Met 56.00,Ile 156.72,Leu 265.30,Tyr 108.24,Phe 142.04,Lys 149.21,His 69.65,Arg 234.23,Pro 261.20,Trp 25.95.