【猪】第九十四期：在日粮中缺乏非必需氨基酸态氮时，氨氮、游离氨基酸、蛋白都可...

IMCTT

　　2017. J. Anim. Sci. 95(7): 3093-3102

　　在日粮中缺乏非必需氨基酸态氮时，氨氮、游离氨基酸、蛋白都可以有效改善猪的生长性能

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

　　在低蛋白日粮中缺乏非必需氨基酸时可能可以通过添加非蛋白氮来弥补蛋白的不足。我们通过两个试验验证在缺乏非必需氨基酸的低蛋白日粮中添加非蛋白氮或特定非必需氨基酸对猪生长性能的影响。试验1选用48头小母猪（初始重15.2±1.3kg），每圈2头，每个处理6圈，随机分为4个处理：1、正对照，蛋白和必需氨基酸能满足需要，并且所有氮均为蛋白（豆粕和酪蛋白）或晶体氨基酸提供；2、负对照，与正对照组必需氨基酸含量一致，但是非必需氨基酸不足；3、低非蛋白氮组，负对照组添加氨氮，提高1.45%粗蛋白；4、高非蛋白氮组，负对照组添加氨氮，提高2.90%粗蛋白，与正对照组可消化氮含量相同。猪只自由采食，每周记录采食量和日增重，试验期共3周。肉料比随着氨氮的添加呈线性提高（P＜0.05）。高非蛋白氮组肉料比与正对照组非常相似（分别为0.51和0.52，P=0.496）。试验2选用72头单栏饲喂的去势公猪（初始重13.5±0.6kg，每个处理8头），随机分为9个日粮处理。基础日粮非必需氨基酸缺乏，其必需氨基酸态氮与总氮比值为0.74。试验日粮在基础日粮的基础上通过添加4种氮源（尿素、氨、谷氨酸、非必需氨基酸混合物），通过添加量的多少，调节必需氨基酸态氮与总氮的比值至0.63或0.55。每头猪在9天预饲期和3周试验期饲喂量为维持需要的3倍。每周记录体重，试验结束时，收集腹主动脉和门静脉血液样品，检测氨氮和尿氮含量。末重、日增重、肉料比随氨氮、谷氨酸和非必需氨基酸混合物的添加而显著改善（P＜0.05），而尿素对此无影响。氨氮组、谷氨酸组和非必需氨基酸混合物组末重、日增重和肉料比没有显著差异（P＞0.10）。腹主动脉和门静脉血样中尿素氮含量随尿素摄入量的增加而显著提高（P＜0.05）。总之，在日粮中缺乏非必需氨基酸态氮时，生长猪可以利用氨态氮，并且利用效率同完整蛋白和非必需氨基酸。

　　Nitrogen from ammonia is as efficient as that from free amino acids or protein for improving growth performance of pigs fed diets deficient in nonessential amino acid nitrogen

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

　　Inclusion of NPN in diets may compensate the deficient supply of nonessential AA (NEAA) in very low CP levels. To assess this, 2 studies were conducted to determine the effect of supplementing NPN and specific NEAA to diets severely deficient in NEAA nitrogen (NEAA-N) on growth performance of pigs. In Exp. 1, 48 gilts (initial BW 15.2 ± 1.3 kg; 2 pigs perpen; 6 pens per treatment) were randomly assigned to 1 of the 4 dietary treatments: 1) positive control (Pos Ctrl), not deficient in essential AA (EAA) and total N, with all N supplied from intact protein (casein and soybean meal) or crystalline EAA, (2) negative control (Neg Ctrl), supplying the same amount of potentially limiting EAA as Pos Ctrl but deficient in NEAA-N, 3) Neg Ctrl plus 1.45% CP from ammonia-N (low NPN), and 4) Neg Ctrl plus 2.90% CP from ammonia-N (high NPN), supplying the same amount of digestible N as the Pos Ctrl diet. Pigs were fed ad libitum, and ADG and ADFI were monitored weekly during a 3-wk period. Gain:feed improved linearly (P < 0.05) with supplementation of ammonia-N in diets. Gain:feed for high NPN was similar (P = 0.496) to that for Pos Crtl (0.51 and 0.52, respectively). In the Exp. 2, 72 individually housed barrows (initial BW 13.5 ± 0.6 kg; 8 pigs per treatment) were assigned to 9 dietary treatments. A basal diet was formulated to be deficient in NEAA-N with a ratio of EAA-N to total N (EAA-N:TN) of 0.74. The basal diet was supplemented with 1 of 4 different N sources (urea, ammonia, glutamic acid, and a mixture of NEAA) at 2 levels each, decreasing the final EAA-N:TN to 0.63 and 0.55, respectively. Pigs were fed at 3.0 times maintenance energy requirements during 9 d of adaptation and 3 wk of observations. Body weight was monitored weekly. At the end of the experiment, blood samples from the portal vein and abdominal aorta were collected to determine ammonia- and urea-N concentrations. Final BW, ADG, and G:F increased (P < 0.05) with supplemented ammonia, glutamate, and the NEAA mix but not (P> 0.10) with urea. Final BW, ADG, and G:F were not different (P > 0.05) between pigs fed the ammonia, glutamate, and NEAA mix supplemented diets. Urea concentration in portal and arterial blood plasma increased linearly (P < 0.05) with urea intake. In conclusion, growing pigs can utilize N from ammonia as efficiently as intact protein or NEAA as a source of extra N when diets are severely deficient in NEAA-N.


　　来源： 猪营养国际论坛CSIS 翻译：朱滔