Prediction of digestible energy value of extruded dog food: comparison of methods

The proposal of National Research Council (NRC), based on the use of modified Atwater factors, is nowadays the widely used method to estimate digestible energy (DE) content of pet foods. Recently, alternative methods have been suggested for predicting energy content of commercial canine dry food. Factorial equations including food fibre content as estimator, in vitro digestions methods or near-infrared spectroscopy (NIRS) techniques have been considered as good approaches to predict the energy content of dog foods. The aim of this study was to compare the accuracy of some of those estimation methods. Seventeen samples of commercial extruded dog food were used to validate and compare some estimation methods of energy digestibility (Ed, %) and DE value [MJ/kg dry matter (DM)]. The apparent Ed and DE of each food were previously determined by in vivo trials. In vivo Ed and DE of foods ranged from 79.30% to 91.05% and from 16.25 to 21.82 MJ/kg DM, respectively, and their crude fibre (CF) content ranged from 0.72% to 3.28% (in DM base). The % Ed of each sample was estimated by the factorial equation (% Ed = 91.2 - 1.43 x CF %) and by the in vitro digestion method [% Ed(in vitro) = -2.45 + 0.98 organic matter (OM) disappearance(in vitro)%]. The set of samples also was analysed by NIRS, using a calibration equation developed from a set of 69 samples of commercial extruded dog food (0.76 and 0.89 cross-validation r(2) and 2.33 and 0.61 cross-validation SE for Ed and DE respectively). The in vitro method gave better estimations of Ed in vivo than NIRS and factorial methods, although all the methods assessed showed a very good and similar accuracy in the prediction of DE value. These three methods showed a slight better accuracy than that previously proposed by the NRC. To consider constant digestibility values of nutrient content of food can result in bias and error in the estimated energy values. The alternative prediction methods used in this study take into account differences of ingredient composition and availability of nutrients of different extruded dog foods thus could be better systems of valuating energy content in a wider range of different kind of foods than in use method.     

Prediction of digestible protein content of dry extruded dog foods: comparison of methods

The aim of this study was to check the accuracy of laboratory methods to predict the apparent protein digestibility (CPd, %) and digestible protein content (DP, g/kgDM) of dog foods, avoiding the use of experimental animals in digestion trials. Twenty‐eight commercial dry extruded dog foods were tested by three different methodologies: an adaptation of the in vitro incubation method described by Hervera et al. (J Anim Physiol Anim Nutr 2007, 91 : 205) for estimation of digestible energy of commercial dog foods, a modification of the pH drop methodology proposed by Hsu et al. (J Food Sci 1977, 42 : 1269) for protein evaluation of human foods and the Near Infra Red Spectroscopy (NIRS) technology. All the methods assessed revealed very good, similar accuracy in the prediction of DP content either using the in vitro method (r = 0.99; RSD = 6.76; CV = 2.31%), the pH drop method (r = 0.99; RSD = 6.94; CV = 3.02%) or the NIRS (R2 = 0.96; SECV = 10.50) method, although the in vitro digestion method showed the highest accuracy approach of in vivo crude protein apparent digestibility: CPd in vitro (r = 0.81; RSD = 2.01; CV = 2.41%); CPd pH‐drop (r = 0.78; RSD = 2.48; CV = 2.98%) and NIRS (r²cv = 0.53; SECV = 2.37).     

单胃动物饲料消化能评定方法剖析

从单胃动物消化能评定方法的研究进展入手,详细综述了评定饲料消化能的各种非生物学方法,并对这些方法的实际应用效果和应用价值进行了评价。同时,对各种方法所存在的问题进行了剖析,从生物学和营养学的角度探讨了非生物学法评定饲料消化能值的可行性。     

The effect of crude fibre on apparent digestibility and digestible energy content of extruded dog foods

The apparent digestibility of nutrients and energy of 38 commercial dry extruded dog foods was measured using six adult (2 to 3 year-old) female Beagles. Diets contained [in g/kg dry matter (DM)]: 164–360 crude protein (CP); 79–261 ether extracts (EE); 8–33 crude fibre (CF) and 318–585 nitrogen free extracts (NFE). Apparent energy digestibility ranged from 77.3 to 91.6%, and was closely related to CF content ( r =–0.85), yielding the resultant equation: GED (%)=94.00 – 4.04 × CF (% DM). The estimation of digestible energy content of foods from digestibility coefficients predicted from the above equation and gross energy measured or estimated from the Weende fractions, provides a more accurate prediction of experimental values than the Atwater approach followed by the National Research Council and the Association of American Feed Control Officials.     

猪脱酚棉籽蛋白能量及粗蛋白质消化率的比较评定

研究旨在评定猪对脱酚棉籽消化能和粗蛋白表观消化率,并比较脱酚棉籽蛋白(DCP)与豆粕(SBM)之间差异。选用体重(36.2±1.6)kg的杜×长×大三元杂交猪6头,采用套算法、双3×3拉丁方试验设计,试验日粮分别为脱酚棉籽蛋白日粮、豆粕日粮和基础日粮,每个拉丁方阶段包括5 d预饲期、5 d正式期,整个试验共30 d。结果表明,脱酚棉籽蛋白、豆粕消化能含量分别为12.41 MJ/kg、13.62 MJ/kg。脱酚棉籽蛋白、豆粕中粗蛋白表观消率化分别为73.35%、82.05%,表观可消化粗蛋白含量分别为37.92%、35.45%。脱酚棉籽蛋白是新型蛋白质原料,其消化能含量为豆粕的91.11%,粗蛋白表观消率化为豆粕的89.39%,可消化粗蛋白含量为豆粕的106.99%。脱酚棉籽蛋白在猪饲料中的应用具有广阔的前景。     

Comparison of digestible and metabolizable energy and digestible phosphorus and amino acid content of corn ethanol coproducts from Brazil and the United States produced using fiber separation technology for swine

Three experiments (exp.) were conducted to determine and compare the digestibility of nutrients and energy of corn distillers dried grains with solubles (DDGS) from the United States (USDDGS), a dried mixture of corn bran with solubles (CBS) from Brazil (BRCBS), and high protein corn distillers dried grains (HP-DDG) from the United States (USHPDG) and Brazil (BRHPDG) in growing pigs. The feed ingredients were evaluated for apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), crude protein (CP), ether extract, neutral and acid detergent fiber (NDF and ADF, respectively), and digestible and metabolizable energy (DE and ME, respectively) using the total collection and index methods in exp. 1; ATTD and standardized total tract digestibility (STTD) of phosphorus (P) in exp. 2; and apparent (AID) and standardized (SID) ileal digestibilities of CP and amino acids (AA) in exp. 3. Fifty crossbred barrows (32.4 ± 6.9, 38.3 ± 5.2, and 46.2 ± 5.3 kg body weight [BW], in exp. 1, 2, and 3, respectively) were fed a corn basal diet in exp. 1, a P-free diet in exp. 2, and an N-free diet in exp. 3 or diets with 40% inclusion of test ingredients to provide 10 replications per treatment. Pigs were housed individually in metabolism cages (exp. 1) or in pens (exp. 2 and 3) and fed at 2.8 times the maintenance DE requirement (110 kcal/kg BW^0.75) based on their BW at the beginning of each experiment. Except for ATTD of NDF, which tended (P = 0.058) to be greater by the index method compared with the total collection method, no difference between the total collection and index methods was observed for ATTD of remaining nutrients and DE. The ATTD of DM, GE, NDF, and DE content of BRHPDG were greater (P < 0.001) than USHPDG, BRCBS, and USDDGS. The AID of CP, Arg, His, Ile, Leu, Lys, Thr, and Val and the SID of His, Leu, Lys, and Val of BRHPDG were 8% to 36% greater (P < 0.05) than those from USHPDG. Except for Trp, all AID and SID AA values were greater (P < 0.05) in BRHPDG than in USHPDG. The ATTD of DM, GE, NDF, and ADF; DE and ME content; AID of CP, Arg, Ile, Leu, Phe, Thr, and Trp; and SID of CP, Arg, Phe, and Thr of USDDGS were 9% to 45% greater (P < 0.05) than those in BRCBS. The ATTD and the STTD of P in USHPDG and USDDGS were 26% to 42% greater (P < 0.05) compared with BRHPDG and BRCBS. In conclusion, BRHPDG had a greater digestibility of energy and most of the AA than USHPDG, while the BRCBS evaluated had lower nutritional value than the USDDGS source.     

Development of a model to predict dietary metabolizable energy from digestible energy in beef cattle

Understanding the utilization of feed energy is essential for precision feeding in beef cattle production. We aimed to assess whether predicting the metabolizable energy (ME) to digestible energy (DE) ratio (MDR), rather than a prediction of ME with DE, is feasible and to develop a model equation to predict MDR in beef cattle. We constructed a literature database based on published data. A meta-analysis was conducted with 306 means from 69 studies containing both dietary DE and ME concentrations measured by calorimetry to test whether exclusion of the y-intercept is adequate in the linear relationship between DE and ME. A random coefficient model with study as the random variable was used to develop equations to predict MDR in growing and finishing beef cattle. Routinely measured or calculated variables in the field (body weight, age, daily gain, intake, and dietary nutrient components) were chosen as explanatory variables. The developed equations were evaluated with other published equations. The no-intercept linear equation was found to represent the relationship between DE and ME more appropriately than the equation with a y-intercept. The y-intercept (−0.025 ± 0.0525) was not different from 0 (P = 0.638), and Akaike and Bayesian information criteria of the no-intercept model were smaller than those with the y-intercept. Within our growing and finishing cattle data, the animal’s physiological stage was not a significant variable affecting MDR after accounting for the study effect (P = 0.213). The mean (±SE) of MDR was 0.849 (±0.0063). The best equation for predicting MDR (n = 106 from 28 studies) was 0.9410 ( ± 0.02160) +0.0042 ( ± 0.00186) × DMI (kg) – 0.0017 ( ± 0.00024) × NDF(% DM) – 0.0022 ( ± 0.00084) × CP(% DM). We also presented a model with a positive coefficient for the ether extract (n = 80 from 22 studies). When using these equations, the observed ME was predicted with high precision (R² = 0.92). The model accuracy was also high, as shown by the high concordance correlation coefficient (>0.95) and small root mean square error of prediction (RMSEP), <5% of the observed mean. Moreover, a significant portion of the RMSEP was due to random bias (> 93%), without mean or slope bias (P > 0.05). We concluded that dietary ME in beef cattle could be accurately estimated from dietary DE and its conversion factor, MDR, predicted by the dry matter intake and concentration of several dietary nutrients, using the 2 equations developed in this study.     

Predicting metabolizable energy from digestible energy for growing and finishing beef cattle and relationships to the prediction of methane

Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. A previously developed database that included 87 treatment means from 23 respiration calorimetry studies has been updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926; r² = 0.99, root mean square prediction error [RMSPE] = 0.04, and P < 0.01 for the intercept and slope. The slope did not differ from unity (95% CI = 0.936 to 1.065); therefore, the intercept (95% CI = −0.567 to −0.218) defines the value of ME predicted from DE. For practical use, we recommend ME = DE – 0.39. Based on the relationship between DE and ME, we calculated the citation-adjusted loss of methane, which yielded a value of 0.2433 Mcal/kg of dry matter intake (DMI; SE = 0.0134). This value was also adjusted for the effects of DMI above maintenance, yielding a citation-adjusted relationship: CH₄, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance; r² = 0.536, RMSPE = 0.0245, and P < 0.01 for the intercept and slope. Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. These two approaches were evaluated using a second, independent database comprising 129 data points from 29 published studies. Four equations in the literature that used DMI or intake energy to predict methane production also were evaluated with the second database. The mean bias was substantially greater for the two new equations, but slope bias was substantially less than noted for the other DMI-based equations. Our results suggest that ME for growing and finishing cattle can be predicted from DE across a wide range of diets, cattle types, and intake levels by simply subtracting a constant from DE. Mean bias associated with our two new methane emission equations suggests that further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane.     

Evaluation of a thermotolerant xylanase on broiler growth performance and dietary ileal digestible energy value

Two experiments were conducted to evaluate the impact of a thermotolerant xylanase on male broiler performance and dietary ileal digestible energy (IDE). The first experiment consisted of 3 treatment groups with 12 replications per treatment each containing 35 Cobb 500 males for a total of 1,260 broilers placed in floor pens for a 42 d grow-out. The experiment treatments included a corn/soy diet with DDGS control formulated at a low energy level, and the control supplemented with one of 2 concentrations of xylanase (20,000 XU/kg [XYL20] and 40,000 XU/kg [XYL40]). No significant differences in body weight were observed with the inclusion of xylanase when compared to the control diet throughout the experiment. At d 28, the inclusion of XYL20 improved (P < 0.05) mortality corrected feed conversion ratio (FCR) compared to the control diet. Feed conversion ratio was also improved (P < 0.01) at d 42 for birds fed XYL20 when compared to the control. At d 42, inclusion of XYL20 and XYL40 significantly (P < 0.05) increased IDE compared to the control. Experiment 2 consisted of 4 treatment groups with 10 replications per treatment each containing 44 Cobb 500 males for a total of 1,760 broilers placed in floor pens for a 41 d grow-out. The dietary treatments included a positive control (PC) based on a corn/soy diet containing DDGS and phytase, a negative control (NC) diet (PC -150 kcal/kg in AME), NC + xylanase at 10,000 XU/kg (XYL10), and NC + xylanase at 20,000 XU/kg (XYL20). A significant increase (P < 0.05) in BW was observed in broilers fed the inclusion of XYL20 in the NC diet increased (P < 0.05) on d 14. A significant increase in cumulative body weight gain was observed on d 27 and d 41 with xylanase (XYL20) inclusion compared to the NC. These data demonstrate that xylanase inclusion increased energy utilization through improvements in IDE, which improved broiler performance.     

用化学分析法预测大豆蛋白类饲料猪消化能值的模型建立

试验探讨用化学分析法预测大豆蛋白类饲料猪消化能值。选取体重(35±2)kg、遗传基础相似的健康杜×长×大三元杂交阉公猪8头,采用2个4×4拉丁方设计,运用套算法测定豆饼、豆粕、干法膨化全脂大豆等8种大豆蛋白类饲料的表观消化能(DE),分析并计算出各种饲料的常规成分。结果表明:(1)在大豆蛋白类饲料猪消化能值回归预测中,ADF是最佳预测因子。(2)最佳预测方程为①DE(MJ/kg,DM基础)=16.407-85.982ADF+0.328GE(R2=0.88,RSD=0.264%,P<0.01);②DE(MJ/kg,DM基础)=30.319-89.999ADF+9.659SCHO-184.115Ash(R2=0.95,RSD=0.189%,P<0.01);③DE(MJ/kg,DM基础)=23.882-84.418ADF-7.877NFE+19.71CF(R2=0.95,RSD=0.281%,P<0.01),上述最佳方程经检验适用于与本试验类似的饲料。     

热应激条件下日粮消化能水平对肉兔生产性能和养分消化率的影响

试验旨在研究热应激条件下日粮消化能水平对肉兔生产性能和饲粮养分消化率的影响。选择30日龄断奶新西兰兔150只,随机分成5个处理组,每个处理5个重复,每个重复6只兔,分别饲喂8.79、9.62、10.46、11.30MJ/kg和12.13 MJ/kg消化能的饲粮。结果显示,热应激条件下,随着日粮消化能的增加,肉兔采食量和料重比均一定程度下降(P>0.05或P<0.05),日增重呈先升高后降低的趋势;干物质、粗蛋白质和粗灰分消化率随着消化能水平的提高,呈现先上升后下降的趋势,粗脂肪和粗纤维的消化率随着消化能水平的提高,呈现逐渐升高的趋势。综合来看,在热应激条件下肉兔饲粮的消化能水平以10.46～11.30 MJ/kg为宜。     

Commercial dry dog food in the north central United States is not contaminated by Dermatophagoides house dust mites

Contamination of home-stored cereal grain food products with Dermatophagoides spp. house dust mites (HDM) was reported recently, along with anaphylaxis after consumption of these foods by dust mite-allergic people. We hypothesized that commercial dry dog food could become similarly contaminated, particularly if stored improperly, and could eventually contribute to allergic signs in dogs. Newly purchased bags of dry dog food (n = 30), from a variety of sources and manufacturers, and client samples of dry dog food (n = 50), stored under a variety of conditions, were obtained. Food samples were extracted in aqueous buffer, and extracts were assayed using ELISA for Dermatophagoides group II (Der II) allergen, as a marker for the presence of HDM. Der II allergen was not detected in any of the 30 newly purchased or 50 stored samples tested. Positive control samples consisting of house dust or dog food mixed with house dust, similarly extracted, and Dermatophagoides commercial allergen extract were positive for Der II in the same assay. We could find no evidence of HDM contamination in newly purchased or stored commercial dry dog food in the north central United States.     

Evaluation of serum allergen-specific IgE for the diagnosis of food adverse reactions in the dog

A new monoclonal enzyme-linked immunoassay (ELISA; CMG IMMUNODOT, Fribourg, Switzerland) measuring food antigen-specific serum IgE was used in an attempt to investigate food allergen-specific IgE in dogs. The serum of eight dogs with clinically proven adverse reactions to specific proteins was tested for beef, cow's milk, pork, lamb, hen's egg, soybean, fish mix (cod/sole), peanut, maize and wheat flour. The control group consisted of three healthy dogs, three dogs with nonallergic skin disease, two dogs with atopy, a cat and a horse. Only three mild positive reactions to beef, lamb and peanut, respectively, were found in this study; the sera were from two control dogs with the clinical diagnosis of dermatophytosis and atopy. None of the animals with confirmed food adverse reactions showed positive reactions. This study indicates that the diagnosis of food adverse reactions in the dog by measuring allergen-specific IgE with the used mononuclear ELISA is unreliable.     

可消化纤维替代蛋白质对肉兔生长性能、能量和氮平衡及盲肠内容物组分的影响

文章旨在研究日粮不同可消化纤维与蛋白质比例对肉兔生长性能、能量和氮平衡及盲肠内容物组分的影响。试验选择32 d断奶的肉兔120只,随机分为4组,每组6个重复,每个重复5只。试验日粮分为4种,日粮可消化纤维与蛋白质比例分别为1.0(处理1组)、1.15(处理2组)、1.35(处理3组)和1.55(处理4组),试验共进行6周。结果 :处理3、4组较处理1、2组显著提高中性洗涤的表观消化系数(P <0.05),较处理1组显著提高了酸性洗涤纤维和粗纤维表观消化系数(P <0.05)。处理1组半纤维素表观消化系数最低(P <0.05),但可消化蛋白质和蛋能比最高(P <0.05)。处理1组较其他三组显著提高了氮的摄入量(P <0.05),处理3、4组较处理1组显著提高了能量沉积系数(P <0.05),日龄和日粮对尿氮排泄量和氮沉积量的影响具有显著交互效应(P <0.05)。处理1组较处理4组显著提高了盲肠内容物干物质含量(P <0.05)。结论 :日粮采用高比例可消化纤维替代蛋白质可以降低肉兔生长后期粪氨气和尿氮排泄量,提高氮沉积量。     

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs

Background

The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy (DE) and metabolisable energy (ME) content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China (Jilin, Hebei, Shandong, Liaoning, and Henan) to obtain a range of quality.

Results

The DE and ME contents of the 100 corn samples were measured in 35.3 ± 1.92 kg growing pigs (six pigs per corn sample). Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg (dry matter basis), respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows: DE, kcal/kg of DM = 1062.68 + (49.72 × EE) + (0.54 × GE) + (9.11 × starch), with R² = 0.62, residual standard deviation (RSD) = 48 kcal/kg, and P < 0.01; ME, kcal/kg of dry matter basis (DM) = 671.54 + (0.89 × DE) – (5.57 × NDF) – (191.39 × ash), with R² = 0.87, RSD = 18 kcal/kg, and P < 0.01.

Conclusion

This experiment confirms the large variation in the energy content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be used to predict the DE and ME content of individual corn samples.     

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs

Background： The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy （DE） and metabolisable energy （ME） content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China （Jilin, Hebei, Shandong, Liaoning, and Henan） to obtain a range of quality. Results： The DE and ME contents of the 100 corn samples were measured in 3.5.3 ±1.92 kg growing pigs （six pigs per corn sample）. Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg （dry matter basis）, respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows： DE, kcal/kg of DM = 1062.68 ＋ （49.72 ×EE） ＋ （0.54 × GE） ＋ （9.1 ] x starch）, with R^2 = 0.62, residual standard deviation （RSD） = 48 kcal/kg, and P 〈 0.01; ME, kcal/kg of dry matter basis （DM） = 671.54 ＋ （0.89 ×DE） - （5.57 × NDF） - （191.39 ×ash）, with R^2 = 0.87, RSD = 18 kcal/kg, and P〈 0.01. Conclusion： This experiment confirms the large variation in the energy content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be     

Digestible energy content of pasture species in growing European wild boar (Sus scrofa L.)

The objectives were to determine the apparent energy digestibility of six pasture species frequently grazed by European wild boar (Sus scrofa L.) and to estimate the digestible energy (DE) consumption from pasture by grazing wild boar. Seven diets were prepared; a base diet (BD) which did not contain any pasture species, diets D1 to D5 which included 75% of the BD and 25% of the dried pasture species Lolium perenne (D1), Festuca arundinacea (D2), Agrostis capillaris (D3), Bromus staminius (D4) or Trifolium repens (D5) and D6 which contained 85% BD and 15% dried Plantago lanceolata. Seven purebred European wild boar (initial liveweight 24.4 ± 0.8 kg, average ± SEM) were given access to the diets following a Latin Square design. The animals received each diet for eight days, with faecal sampling on days 6, 7 and 8. The total apparent DE consumption from pasture by grazing wild boar was estimated using previously collected pasture consumption data from wild boar. The digestibility coefficients and DE contents of the pasture species ranged from 0.29 to 0.65, and 5.8 to 12.6 MJ/kg DM respectively, with L. perenne and P. lanceolata having the greatest digestibility coefficients and DE contents. The wild boar were estimated to satisfy between 52% and 142% of their maintenance energy requirements through pasture consumption. Grazing wild boar are able to utilise an important proportion of the energy present in pasture species.     

Effects of the standardized ileal digestible lysine to metabolizable energy ratio on performance and carcass characteristics of growing-finishing pigs

A total of 2,121 growing-finishing pigs (Duroc × Landrace × Large White) were utilized in six experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine (SID-Lys) to metabolizable energy (ME) on the performance and carcass characteristics of growing-finishing pigs. Exps. 1 (30 to 50 kg), 2 (52 to 70 kg) and 3 (81 to 104 kg) were conducted to find an optimum ME level and then this level was used in Exps. 4 (29 to 47 kg), 5 (54 to 76 kg) and 6 (84 to 109 kg) to test the response of pigs to different ratios of SID-Lys:ME. In Exps.1 to 3, four treatments were used consisting of diets with a formulated ME content of 3.1, 3.2, 3.3 or 3.4 in Exps. 1 and 2 while Exp. 3 used 3.05, 3.15, 3.25 or 3.35 Mcal/kg. A constant SID-Lys:ME ratio of 2.6, 2.3 or 2.0 g/Mcal was used in Exps. 1, 2 and 3, respectively. Weight gain was significantly increased with increasing energy level in Exp.1 while weight gain was unaltered in Exps. 2 and 3. For all three experiments, feed intake was decreased (P < 0.05) and feed efficiency was improved (P < 0.05) with increasing energy level. Tenth rib back fat thickness linearly increased (P < 0.05) with increasing energy level. In Exps. 4 to 6, five treatments were used consisting of diets with a SID-Lys:ME ratio of 2.4, 2.6, 2.8, 3.0 or 3.2 in Exp. 1, 2.1, 2.3, 2.5, 2.7, 2.9 or 3.2 in Exp. 2 and 1.8, 2.0, 2.2, 2.4, or 2.6 in Exp. 3. A constant ME level 3.2, 3.2 and 3.05 Mcal/kg was used in Exps. 1, 2 and 3, respectively (selected based on the results of weight gain). For all three experiments, weight gain increased (P < 0.05) and feed efficiency improved linearly (P < 0.05) as the SID-Lys:ME ratio increased. Tenth rib back fat thickness linearly decreased (P < 0.05) as the SID-Lys:ME ratio increased. Based on a straight broken-line model, the estimated SID-Lys:ME ratio to maximize weight gain was 3.0, 2.43 and 2.2 for 29 to 47, 54 to76 and 84 to 109 kg of pigs, respectively.     

代谢能和可消化赖氨酸水平及互作效应对樱桃谷肉鸭生产性能和胴体指标的影响

选用1日龄公母混合樱桃谷肉仔鸭2400只,随机分为4个组,每组设6个重复,每个重复100只鸭。试验采用2×2试验设计,研究了不同代谢能(ME)和可消化赖氨酸(DLys)水平及互作效应对樱桃谷肉鸭生产性能和胴体指标的影响。结果表明,1～19日龄,代谢能水平对料肉比影响显著(P<0.05),可消化赖氨酸水平对料肉比、日增重和19日龄体重影响显著(P<0.05);20～32日龄,可消化赖氨酸水平对32日龄体重影响显著(P<0.05);33～45日龄,代谢能和可消化赖氨酸水平对生产性能影响不显著(P>0.05);交互作用对生产性能影响不显著(P>0.05);代谢能和可消化赖氨酸水平以及交互作用对肉鸭胴体指标影响不显著(P>0.05)。     

应用套算法估测肉羊精饲料代谢能

本试验旨在应用套算法建立肉羊精饲料代谢能估测模型。选取66只18月龄体重为(49.6±1.3)kg的杜泊×小尾寒羊F1代去势肉羊,采用完全随机区组设计分为11组,包括1个基础饲粮组和10个试验饲粮组,每组6只羊。通过消化代谢试验(为期8 d)和气体代谢试验(为期3 d)并结合套算法计算10种精饲料的消化能和代谢能,建立精饲料代谢能和其概略养分或可消化养分之间的模型。结果表明,1)10种精饲料总能、酸性洗涤纤维含量与消化能呈显著相关(P0.05),有机物含量与消化能达到极显著相关(P0.01);精饲料概略养分与代谢能之间则无显著相关性(P0.05)。2)10种精饲料的可消化养分与代谢能存在极显著相关(P0.01),所建立的预测方程为:ME=-1.907+1.344DE+1.321DDM-5.347DOM-2.093DADF(R2=0.845,n=60,P0.01);ME=-2.105+1.349DE-6.577DOM(R2=0.842,n=60,P0.01)。[ME为代谢能(MJ/kg),DE为消化能(MJ/kg),DDM为可消化干物质(%),DOM为可消化有机物(%),DA DF为可消化酸性洗涤纤维(%)。]综上所述,本试验条件下无法利用精饲料概略养分预测其代谢能,通过精饲料的可消化养分可准确预测其代谢能。