使用氨氮替換生長豬日糧中的非必需氨基酸不會影響胴體沉積蛋白的氨基酸組成

IMCTT

　　2017. J. Anim. Sci. 95(10): 4481-4489
　　使用氨氮替換生長豬日糧中的非必需氨基酸不會影響胴體沉積蛋白的氨基酸組成
　　W. D. Mansilla, J. K. Htoo and C. F. M. de Lange

　　氨基酸用于機體蛋白質的沉積，因此沉積蛋白的氨基酸組成是決定動物生長階段氨基酸需要量的重要指標。本試驗的主要目的在于研究缺乏非必需氨基酸的日糧中添加氨氮對生長豬氮沉積和機體氨基酸組成的影響。試驗選用48頭去勢公豬，初始重13.6±0.7kg。試驗開始時屠宰8頭檢測初始蛋白質量。剩下40頭隨機飼喂以下5中日糧中的一種：1、負對照，95%基礎日糧+5%玉米淀粉（基礎日糧為滿足所有必須氨基酸需要量，但是缺乏非必需氨基酸態氮，8.01%粗蛋白含量）；2、低氨氮組，95%基礎日糧+5%氨氮，氨氮提供額外1.35%粗蛋白；3、高氨氮組，95%基礎日糧+5%氨氮，氨氮提供額外2.7%粗蛋白；4、低非必需氨基酸組，95%基礎日糧+5%非必需氨基酸，非必需氨基酸提供額外1.35%粗蛋白；5、高非必需氨基酸組，95%基礎日糧+5%非必需氨基酸，非必需氨基酸提供額外2.7%粗蛋白。高非必需氨基酸組日糧的標準回腸可消化非必需氨基酸含量與20kg豬的非必需氨基酸組成類似，并且推測可以降低非必需氨基酸的內源合成。豬每天飼喂3次，飼喂量為3倍代謝能維持需要量。3周試驗期過后，屠宰豬只，收集胴體、內臟器官并稱重、冷凍、粉碎，檢測其中蛋白質質量。分析初始豬只、負對照組、高氨氮組、高非必需氨基酸組胴體和內臟中氨基酸組成，計算總氨基酸、沉積的氨基酸、日糧氨基酸效率和最小非必需氨基酸合成量。隨著氮提供量的增加，胴體重和機體氮沉積線性提高（P＜0.05）。不同氮源組豬只胴體重氨基酸組成和蛋白質沉積量沒有顯著差異（P＞0.10），但是非必需氨基酸組中內臟器官中和沉積的蛋白中胱氨酸的含量顯著增加（P＜0.05）。隨著氮提供量的增加，可消化必需氨基酸的沉積效率明顯提高（P＜0.05），但是不同氮源之間沒有顯著差異（P＞0.10）。氨氮組非必需氨基酸的合成量顯著高于添加非必需氨基酸組。總之，缺乏非必需氨基酸的日糧中添加氨氮可以提高氮沉積，而不影響胴體氨基酸組成。

　　Replacing dietary non essential amino acids with ammonia nitrogen does not alter amino acid profile of deposited protein in the carcass of growing pigs fed a diet deficient in non essential amino acid nitrogen

　　W. D. Mansilla, J. K. Htoo and C. F. M. de Lange

　　Amino acid usage for protein retention, and, consequently, the AA profile of retained protein, is the main factor for determining AA requirements in growing animals. The objective of the present study was to determine the effect of supplementing ammonia N on whole-body N retention and the AA profile of retained protein in growing pigs fed a diet deficient in nonessential AA (NEAA) N. In total, 48 barrows with a mean initial BW of 13.6 kg (SD 0.7) were used. At the beginning of the study, 8 pigs were euthanized for determination of initial protein mass. The remaining animals were individually housed and fed 1 of 5 dietary treatments. A common basal diet (95% of experimental diets) was formulated to meet the requirements for all essential AA (EAA) but to be deficient in NEAA N (CP = 8.01%). The basal diet was supplemented (5%) with corn starch (negative control) or 2 N sources (ammonia or NEAA) at 2 levels each to supply 1.35 or 2.70% extra CP. The final standardized ileal digestible (SID) NEAA content in the high-NEAA-supplemented diet (positive control) was based on the NEAA profile of whole-body protein of 20-kg pigs, and it was expected to reduce the endogenous synthesis of NEAA. Pigs were fed at 3.0 times maintenance energy requirements for ME in 3 equal meals daily. At the end of a 3-wk period, pigs were euthanized and the carcass and visceral organs were weighed, frozen, and ground for determination of protein mass. From pigs in the initial, negative control, high-ammonia, and high-NEAA groups, AA contents in the carcass and pooled visceral organs were analyzed to determine the total and deposited protein AA profile, dietary EAA efficiencies, and minimal de novo synthesis of NEAA. Carcass weight and whole-body N retention linearly increased (P < 0.05) with N supplementation. The AA profile of protein and deposited protein in the carcass was not different (P > 0.10) between N sources, but Cys content increased (P <0.05) with NEAA compared with ammonia in visceral organ protein and deposited protein. The dietary SID EAA efficiency for increasing EAA deposition in whole-body protein increased (P < 0.05) with N supplementation, but it was not different (P > 0.10) between N sources. The de novo synthesis of NEAA increased (P < 0.05) for ammonia compared with NEAA supplementation. In conclusion, adding ammonia as a N source to diets deficient in NEAA N increases whole-body N retention without affecting the carcass AA profile.

　　翻譯：朱滔 豬營養國際論壇CSIS