采用净能体系设计高含量副产品原料日粮对猪消化和氮平衡的影响

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采用净能体系设计高含量副产品原料日粮对猪消化和氮平衡的影响
J. A. Acosta, R. D. Boyd and J. F. Patience

　　越来越高的饲料成本要求业内寻求降低生产成本的策略。由于并没有证据表明净能预测值是可靠的，因此很多生产商在采用净能体系方面踟蹰不前，尽管如此，采用净能系统仍是一个解决办法。本试验的目的就是去比较梯度添加副产品原料且采用净能体系设计的不同日粮的能量、营养的表观总肠道消化率（ATTD）以及氮沉积（NR）。五种日粮处理组包括了一个玉米-豆粕基础日粮作为对照（CTL）；在玉米豆粕日粮的基础上再分别加入6%的玉米干酒糟可溶物（DDGS）、玉米芽粕和麦麸同时通过添加豆油使得日粮净能值与对照组一致（CONS-18）；把CONS-18日粮中的豆油去除使其净能值比对照组低（DECL-18）；在对照组基础上添加12%的玉米干酒糟可溶物、玉米芽粕和麦麸，且通过添加豆油将净能调整至与对照组相当的水平（CONS-36）；在CONS-36日粮的基础上不加豆油保持其净能低于对照组（DECL-36）。这些配方制成后用于生长阶段（GP；40到70 kg）和育肥阶段（FP；70到110 kg）。将40个小母猪（PIC337 × C22 或C29; 初始重为38.5±0.4 kg ）随机分到各处理组，自由采食和饮水（每个处理8头猪）。试验猪生长期和育肥期的最后13天转移至代谢笼中饲养。将这两个代谢笼饲养阶段的第4-6天与第11-13天期间的尿和粪全收集起来。生长期饲喂的日粮所含的副产物原料与对照组相比其干物质、氮和总能的表观总肠道消化率更低（P < 0.050）。在育肥期随着副产品原料的含量从0增加至18%和36%，氮和总能的表观总肠道消化率逐渐的降低（P < 0.010）。在生长期和育肥期，CONS-18与DECL-18相比或CONS-36与DECL-36相比其干物质、氮或总能的表观总肠道消化率并没有差异（P > 0.050）。在生长期内，含副产品原料的所有日粮的氮沉积显著下降（P = 0.010），且在育肥期内也有下降的趋势（P =0.079）。CONS-18与DECL-18相比或CONS-36与DECL-36相比其氮沉积并无差异（P > 0.050）。总的来说，含高达36%副产品原料且采用净能体系的日粮的消化会导致期望中的消化能和代谢能值；含副产品日粮的氮沉积低于对照组基础日粮，而这些与能量估值的精确性无关，倒是与其它因素，如氨基酸含量的不平衡或吸收后的能量代谢有关，当然还有一些当前能量体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.

来源：猪营养国际论坛CSIS  翻译：李光燃

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