日糧凈能預(yù)測(cè)育肥豬生長(zhǎng)性能模型的建立和驗(yàn)證

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　　2015. J. Anim. Sci. 93(6): 2826-2839

　　日糧凈能預(yù)測(cè)育肥豬生長(zhǎng)性能模型的建立和驗(yàn)證

　　S. Nitikanchana, S. S. Dritz, M. D. Tokach, J. M. DeRouchey, R. D. Goodband和B. J. White

　　本論文收集41個(gè)試驗(yàn)報(bào)告（共285個(gè)能量水平處理），通過(guò)薈萃分析（Meta分析）建立運(yùn)用日糧凈能預(yù)測(cè)生長(zhǎng)性能的模型。日糧能量和營(yíng)養(yǎng)水平由NRC原料數(shù)據(jù)庫(kù)計(jì)算得到。本論文研究了生長(zhǎng)性能和影響因子（如凈能、體重、粗蛋白、SID賴(lài)氨酸、粗纖維、中性洗滌纖維NDF、酸性洗滌纖維ADF、脂肪、灰分）的相關(guān)關(guān)系（線性相關(guān)和二次線性相關(guān)關(guān)系），以及影響因子之間的互作關(guān)系，并且以AIC（Akaike information criteria）為準(zhǔn)則，確定合適的預(yù)測(cè)模型。最初的預(yù)測(cè)模型中包括了凈能和粗蛋白的互作或凈能和SID賴(lài)氨酸的互作。但是當(dāng)SID賴(lài)氨酸低于需要量的試驗(yàn)數(shù)據(jù)移除后，這些互作對(duì)生長(zhǎng)性能的影響就不再顯著。在含凈能和體重的模型中增加日糧脂肪這一影響因素后可以顯著改善模型G:F（增重耗料比）的預(yù)測(cè)效果，表明日糧凈能可能低估了脂肪對(duì)G:F的影響。Meta分析表明，只有在日糧中其它營(yíng)養(yǎng)素（如賴(lài)氨酸）都能滿(mǎn)足動(dòng)物需要后，日糧凈能才能準(zhǔn)確預(yù)測(cè)不同日糧原料和環(huán)境條件下豬只的日增重。統(tǒng)計(jì)結(jié)果表明隨著日糧凈能和體重的增加，日增重隨之提高，但是在體重高于87kg時(shí)日增重隨之降低。G:F值隨日糧凈能和脂肪含量的提高而提高，但是隨體重的增加而降低。本論文還通過(guò)2個(gè)試驗(yàn)、5個(gè)日糧處理、543頭育肥豬評(píng)估模型預(yù)測(cè)的生長(zhǎng)性能與實(shí)際生長(zhǎng)性能的差異。5個(gè)日糧處理包括3個(gè)不同水平的凈能（通過(guò)在玉米-豆粕型基礎(chǔ)日糧中添加次粉、大豆皮、含油8-9%的DDGS和精煉動(dòng)物油，調(diào)節(jié)凈能水平）。具體處理信息如下：1）30%DDGS、20%次粉、4-5%大豆皮（低能處理組）；2）20%次粉、4-5%大豆皮（低能處理組二）；3）玉米豆粕型日糧（對(duì)照組，中等能量水平）；4）處理二日糧添加3.7%精煉動(dòng)物油使其凈能水平與處理三相同；5）玉米豆粕型日糧添加3.7%精煉動(dòng)物油（高能組）。試驗(yàn)結(jié)果（日增重和G:F）與模型預(yù)測(cè)結(jié)果十分接近，但是纖維含量最高的低能量組（30%DDGS日糧）偏差較大，模型預(yù)測(cè)的日增重和G:F高估了3%和6%。因此，本模型可以準(zhǔn)確預(yù)測(cè)不同凈能水平下生長(zhǎng)育肥豬的生長(zhǎng)速度和飼料效率，在超高纖維低能量日糧的極端情況下效果相對(duì)不理想。

　　譯者注：

　　薈萃分析為一種對(duì)不同研究結(jié)果進(jìn)行收集、合并及統(tǒng)計(jì)分析的方法。薈萃分析的主要目的是將以往的研究結(jié)果更為客觀的綜合反映出來(lái)。研究者并不進(jìn)行原始的研究，而是將研究已獲得的結(jié)果進(jìn)行綜合分析。

　　AIC信息準(zhǔn)則是衡量統(tǒng)計(jì)模型擬合優(yōu)良性的一種標(biāo)準(zhǔn)，為日本統(tǒng)計(jì)學(xué)家赤池弘次創(chuàng)立和發(fā)展的，可以權(quán)衡所估計(jì)模型的復(fù)雜度和此模型擬合數(shù)據(jù)的優(yōu)良性。

　　Regression analysis to predict growth performance from dietary net energy in growing-finishing pigs

　　S. Nitikanchana, S. S. Dritz, M. D. Tokach, J. M. DeRouchey, R. D. Goodband and B. J. White

　　Data from 41 trials with multiple energy levels (285 observations) were used in a meta-analysis to predict growth performance based on dietary NE concentration. Nutrient and energy concentrations in all diets were estimated using the NRC ingredient library. Predictor variables examined for best fit models using Akaike information criteria included linear and quadratic terms of NE, BW, CP, standardized ileal digestible (SID) Lys, crude fiber, NDF, ADF, fat, ash, and their interactions. The initial best fit models included interactions between NE and CP or SID Lys. After removal of the observations that fed SID Lys below the suggested requirement, these terms were no longer significant. Including dietary fat in the model with NE and BW significantly improved the G:F prediction model, indicating that NE may underestimate the influence of fat on G:F. The meta-analysis indicated that, as long as diets are adequate for other nutrients (i.e., Lys), dietary NE is adequate to predict changes in ADG across different dietary ingredients and conditions. The analysis indicates that ADG increases with increasing dietary NE and BW but decreases when BW is above 87 kg. The G:F ratio improves with increasing dietary NE and fat but decreases with increasing BW. The regression equations were then evaluated by comparing the actual and predicted performance of 543 finishing pigs in 2 trials fed 5 dietary treatments, included 3 different levels of NE by adding wheat middlings, soybean hulls, dried distillers grains with solubles (DDGS; 8 to 9% oil), or choice white grease (CWG) to a corn-soybean meal-based diet. Diets were 1) 30% DDGS, 20% wheat middlings, and 4 to 5% soybean hulls (low energy); 2) 20% wheat middlings and 4 to 5% soybean hulls (low energy); 3) a corn-soybean meal diet (medium energy); 4) diet 2 supplemented with 3.7% CWG to equalize the NE level to diet 3 (medium energy); and 5) a corn-soybean meal diet with 3.7% CWG (high energy). Only small differences were observed between predicted and observed values of ADG and G:F except for the low-energy diet containing the greatest fiber content (30% DDGS diet), where ADG and G:F were overpredicted by 3 to 6%. Therefore, the prediction equations provided a good estimation of the growth rate and feed efficiency of growing-finishing pigs fed different levels of dietary NE except for the pigs fed the low-energy diet containing the greatest fiber content。

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