采用凈能體系設計高含量副產品原料日糧對豬消化和氮平衡的影響

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采用凈能體系設計高含量副產品原料日糧對豬消化和氮平衡的影響
J. A. Acosta, R. D. Boyd and J. F. Patience

　　越來越高的飼料成本要求業內尋求降低生產成本的策略。由于并沒有證據表明凈能預測值是可靠的，因此很多生產商在采用凈能體系方面踟躕不前，盡管如此，采用凈能系統仍是一個解決辦法。本試驗的目的就是去比較梯度添加副產品原料且采用凈能體系設計的不同日糧的能量、營養的表觀總腸道消化率（ATTD）以及氮沉積（NR）。五種日糧處理組包括了一個玉米-豆粕基礎日糧作為對照（CTL）；在玉米豆粕日糧的基礎上再分別加入6%的玉米干酒糟可溶物（DDGS）、玉米芽粕和麥麩同時通過添加豆油使得日糧凈能值與對照組一致（CONS-18）；把CONS-18日糧中的豆油去除使其凈能值比對照組低（DECL-18）；在對照組基礎上添加12%的玉米干酒糟可溶物、玉米芽粕和麥麩，且通過添加豆油將凈能調整至與對照組相當的水平（CONS-36）；在CONS-36日糧的基礎上不加豆油保持其凈能低于對照組（DECL-36）。這些配方制成后用于生長階段（GP；40到70 kg）和育肥階段（FP；70到110 kg）。將40個小母豬（PIC337 × C22 或C29; 初始重為38.5±0.4 kg ）隨機分到各處理組，自由采食和飲水（每個處理8頭豬）。試驗豬生長期和育肥期的最后13天轉移至代謝籠中飼養。將這兩個代謝籠飼養階段的第4-6天與第11-13天期間的尿和糞全收集起來。生長期飼喂的日糧所含的副產物原料與對照組相比其干物質、氮和總能的表觀總腸道消化率更低（P < 0.050）。在育肥期隨著副產品原料的含量從0增加至18%和36%，氮和總能的表觀總腸道消化率逐漸的降低（P < 0.010）。在生長期和育肥期，CONS-18與DECL-18相比或CONS-36與DECL-36相比其干物質、氮或總能的表觀總腸道消化率并沒有差異（P > 0.050）。在生長期內，含副產品原料的所有日糧的氮沉積顯著下降（P = 0.010），且在育肥期內也有下降的趨勢（P =0.079）。CONS-18與DECL-18相比或CONS-36與DECL-36相比其氮沉積并無差異（P > 0.050）。總的來說，含高達36%副產品原料且采用凈能體系的日糧的消化會導致期望中的消化能和代謝能值；含副產品日糧的氮沉積低于對照組基礎日糧，而這些與能量估值的精確性無關，倒是與其它因素，如氨基酸含量的不平衡或吸收后的能量代謝有關，當然還有一些當前能量體系方法中忽略的因素。


Digestion and nitrogen balance using swine diets containing increasing proportions of coproduct ingredients and formulated using the net energy system
J. A. Acosta, R. D. Boyd and J. F. Patience

　　Rising feed expenditures demand that our industry pursues strategies to lower the cost of production. One option is the adoption of the NE system, although many producers are hesitant to proceed without proof that NE estimates are reliable. The objective of this experiment was to compare the apparent total tract digestibility (ATTD) of energy and nutrients and the N retention (NR) of diets formulated using the NE system with increasing quantities of coproduct ingredients. The 5 dietary treatments included a control corn–soybean meal diet (CTL); the CTL plus 6% each of corn distiller’s dried grains with solubles (DDGS), corn germ meal, and wheat middlings and NE equal to the CTL by adding soybean oil (CONS-18); the CONS-18 diet, without oil added, with NE content lower than the CTL (DECL-18); the CTL plus 12% each of corn DDGS, corn germ meal, and wheat middlings and NE equal to the CTL by adding soybean oil (CONS-36); and the CONS-36 diet, without oil added, with NE content lower than the CTL (DECL-36). Diets were formulated for both the growing period (GP; 40 to 70 kg) and the finishing period (FP; 70 to110 kg). Forty gilts (PIC 337 × C22 or C29; 38.5 ± 0.4 kg initial BW) were randomly assigned to treatment and received feed and water ad libitum (8 pigs per treatment). For the last 13 d of the GP and FP, pigs were transferred to metabolism crates, where 2 total urine and fecal collections (d 4 to 6 and d 11to 13) were performed. The GP fed diets with coproduct ingredients had lower ATTD of DM, N, and GE than those fed the CTL (P < 0.050). The ATTD of N and GE progressively decreased as coproduct inclusion increased from 0 to 18 to 36% in the FP (P < 0.010). In the GP and FP, there were no differences in ATTD of DM, N, or GE between CONS-18 and DECL-18 or between CONS-36 and DECL-36 (P> 0.050). The NR declined on all coproduct diets in the GP (P = 0.010) and tended to decline in the FP (P = 0.079). There were no differences in NR between CONS-18 and DECL-18 or between CONS-36 and DECL-36 (P > 0.050). In conclusion, digestion of diets containing up to 36% coproducts and formulated using NE resulted in expected DE and ME values; NR of diets with coproducts was lower than that of the simple CTL, which is not related to the accuracy of the energy estimations but rather to other factors such as imbalances in the AA concentrations or to postabsorptive energy metabolism, factors not accounted for by the current energy systems approach.

來源：豬營養國際論壇CSIS  翻譯：李光燃

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