【豬】第九十四期：在日糧中缺乏非必需氨基酸態(tài)氮時，氨氮、游離氨基酸、蛋白都可...

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

　　在日糧中缺乏非必需氨基酸態(tài)氮時，氨氮、游離氨基酸、蛋白都可以有效改善豬的生長性能

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

　　在低蛋白日糧中缺乏非必需氨基酸時可能可以通過添加非蛋白氮來彌補蛋白的不足。我們通過兩個試驗驗證在缺乏非必需氨基酸的低蛋白日糧中添加非蛋白氮或特定非必需氨基酸對豬生長性能的影響。試驗1選用48頭小母豬（初始重15.2±1.3kg），每圈2頭，每個處理6圈，隨機分為4個處理：1、正對照，蛋白和必需氨基酸能滿足需要，并且所有氮均為蛋白（豆粕和酪蛋白）或晶體氨基酸提供；2、負對照，與正對照組必需氨基酸含量一致，但是非必需氨基酸不足；3、低非蛋白氮組，負對照組添加氨氮，提高1.45%粗蛋白；4、高非蛋白氮組，負對照組添加氨氮，提高2.90%粗蛋白，與正對照組可消化氮含量相同。豬只自由采食，每周記錄采食量和日增重，試驗期共3周。肉料比隨著氨氮的添加呈線性提高（P＜0.05）。高非蛋白氮組肉料比與正對照組非常相似（分別為0.51和0.52，P=0.496）。試驗2選用72頭單欄飼喂的去勢公豬（初始重13.5±0.6kg，每個處理8頭），隨機分為9個日糧處理。基礎日糧非必需氨基酸缺乏，其必需氨基酸態(tài)氮與總氮比值為0.74。試驗日糧在基礎日糧的基礎上通過添加4種氮源（尿素、氨、谷氨酸、非必需氨基酸混合物），通過添加量的多少，調(diào)節(jié)必需氨基酸態(tài)氮與總氮的比值至0.63或0.55。每頭豬在9天預飼期和3周試驗期飼喂量為維持需要的3倍。每周記錄體重，試驗結(jié)束時，收集腹主動脈和門靜脈血液樣品，檢測氨氮和尿氮含量。末重、日增重、肉料比隨氨氮、谷氨酸和非必需氨基酸混合物的添加而顯著改善（P＜0.05），而尿素對此無影響。氨氮組、谷氨酸組和非必需氨基酸混合物組末重、日增重和肉料比沒有顯著差異（P＞0.10）。腹主動脈和門靜脈血樣中尿素氮含量隨尿素攝入量的增加而顯著提高（P＜0.05）。總之，在日糧中缺乏非必需氨基酸態(tài)氮時，生長豬可以利用氨態(tài)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.


　　來源： 豬營養(yǎng)國際論壇CSIS 翻譯：朱滔