Determination of feeding value based on simple food characteristics. 1. Determination of the digestibility of green foods and their preservation products]

Regression techniques may be used to establish close relations between the crude fibre content and digestibility data of organic materials (total digestibility). It was shown from regression equations calculated for a number of feedingstuffs that the total digestibility of a feedstuff may be calculated, with a sufficient degree of accuracy, from the crude fibre content of the material. The range of variations from most of the digestibility data obtained for various feedstuffs, was clearly below the limit given (2.5%). When regression equations are used the variation limits should always be indicated for which they had been established. Differences within the different groups of feedstuffs are so small that in many instances, the same equation may generally be used for feedstuffs of the same group. Similarly, equations for calculating digestibility values may be derived on the basis of the lignin content of a material, although the range of variations will, in this case, be wider when compared with the crude fibre content. The reason for this must be seen in the greater uncertainty of the lignin method. Analogous regression equations may be found for the different conserving products of green feeds, in which certain alterations have to be made corresponding to the different methods of conserving used. On the one hand, these are accounted for by changes in the crude fibre content brought about by biochemical reactions during the conserving process on the other hand a special influence of conserving form can be observed. The content of digestible crude protein in green feeds can be established, with a high degree of accuracy, from the crude protein content of the material. The content of digestible organic matter can be calculated from the digestibility of organic matter and from the ash content of the material. The content of digestible organic matter is, in turn, closely related to the content of energetic feed units in a particular material.     

Studies in male sheep on the feeding value of excreta from young hens and broilers]

5 digestibility trials were carried out, each with 4 male sheep, to investigate the excreta of young hens and broilers produced as litter in hen batteries for rearing and fattening stock. Data on the digestibility of organic matter and energy of broiler excreta were 76.0% and 76.4%; i.e. these values were only slightly lower than those for the basal ration (barley + dried green lucerne: 76.6% and 76.8%). Digestibility coefficients for organic matter and energy content in the excreta of young hens were 69.4% and 70.4%, respectively. The protein digestibility of excreta of broilers and young hens was 82.3% and 84.3%; that is to say, the investigated dropping contained 330 g and 260 g of digestible crude protein per kg of dry matter. Due to the high ash content of the samples the energy content of the analyzed excreta was only 474 EFr and 421 EFr per kg of dry matter.     

云南省反刍家畜主要饲料营养价值评价

通过对云南省 9个牛羊饲养基地县饲料样品的常规营养成份、范氏纤维及干物质体外消化率 ( IVDMD)的测定发现 :1 )用营养成份和 IVDMD等指标进行评定 ,所有牧草以白三叶、红三叶和青苕子的营养价值最高 ;秸秆类粗饲料营养价值由高到低依次为 :蚕豆秆、黄豆秆、玉米秆、稻草和小麦秆 ;2 )饲料中 ADF、NDF含量与 CP、EE含量呈极显著负相关 ( P<0 .0 1 ) ;各结构碳水化合物成份含量与 CF含量都呈正相关 ,其中 ADF、 NDF含量和 C (纤维素 )含量相关极显著 ( P<0 .0 1 )。粗饲料中 ADF、NDF、HC(半纤维素 )、C及 AIA含量与常规成份都有显著的回归关系 ;3)饲料 IVDMD与 CP含量呈极显著正相关 ,与 NDF含量呈极显著负相关 ( | r| >0 .8) ( P<0 .0 1 )。各饲料的 IVDMD与 CP、 EE、 ASH、 NFE、 NDF和 ADL含量之间存在着显著的回归关系 ( P<0 .0 5 ) ,利用回归方程可以用饲料营养成份含量来预测饲料的IVDMD。     

Possibilities of prediction the digestibility of crude nutrients by fullgrown and growing sheep from the crude nutrient content of the rations. 2. Rations with a higher content of crude fibers (mixtures of straw and concentrated feed as sole feed]

Eight variants of recipes for mixtures of straw and concentrated feed with 10 to 60 per cent straw more or less finely ground (86 to 314 g crude fibre per kg dry matter) and fattening feed for lambs (50 g crude fibre per kg dry matter) were checked concerning the digestibility of crude nutrients for fullgrown wethers and 60 to 80-, 80 to 100-and 100 to 120-day-old lambs which had been ablactated at an age of 60 days. The digestibility for wethers was significantly higher than for lambs, between the age groups of which there were no significant differences concerning the digestibility. In accordance with the results with rations on the basis of concentrated feed as checked and described in the first piece of information, the content of crude fibres in the rations had a negative influence on the digestibility of organic matter, NFE and energy whereas there was a positive relation with the digestibility of crude fibres. The regression functions established for mixtures of straw and concentrated feed concerning the dependence of the digestibility on the content of crude fibres showed a relatively good coincidence in the range of a low content of crude fibres with the corresponding regression functions which were described in the first piece of information for rations of concentrated feed. The equations for the digestibility of crude fibres were an exception. In contrast to this, the quantitative relations between crude fibres and the digestibility as established in the first piece of information for rations with a low content of crude fibres cannot be transferred to rations with a higher content of crude fibres.     

Alternative prediction methods of protein and energy evaluation of pig feeds

Precise knowledge of the actual nutritional value of individual feedstuffs and complete diets for pigs is important for efficient livestock production. Methods of assessment of protein and energy values in pig feeds have been briefly described. In vivo determination of protein and energy values of feeds in pigs are time-consuming,expensive and very often require the use of surgically-modified animals. There is a need for more simple, rapid,inexpensive and reproducible methods for routine feed evaluation. Protein and energy values of pig feeds can be estimated using the following alternative methods: 1) prediction equations based on chemical composition; 2)animal models as rats, cockerels and growing pigs for adult animals; 3) rapid methods, such as the mobile nylon bag technique and in vitro methods. Alternative methods developed for predicting the total tract and ileal digestibility of nutrients including amino acids in feedstuffs and diets for pigs have been reviewed. This article focuses on two in vitro methods that can be used for the routine evaluation of amino acid ileal digestibility and energy value of pig feeds and on factors affecting digestibility determined in vivo in pigs and by alternative methods. Validation of alternative methods has been carried out by comparing the results obtained using these methods with those acquired in vivo in pigs. In conclusion, energy and protein values of pig feeds may be estimated with satisfactory precision in rats and by the two-or three-step in vitro methods providing equations for the calculation of standardized ileal digestibility of amino acids and metabolizable energy content. The use of alternative methods of feed evaluation is an important way for reduction of stressful animal experiments.     

The feed value of pasto estrella (Cynodon nlemfuensis) of Panamanian origin in Cuba. 2. Relation of easily determined parameters of feed value and the digestibility of organic substances

The relations between nutrient content and the digestibility of the organic matter (DOM) was to be studied in the tropical grass pasto estrella p. (Cynodon nlemfuensis) in order to draw conclusions as to the causes of changes of the feed value and to estimate DOM with the help of easily determinable parameters. Comparative studies of cellulase solubility from the organic matter also served this purpose. Grass samples from three continuous digestibility studies were used as test material. There is a strong negative dependence of DOM on the content of cell wall substances (crude fibre, lignin) which is characterized by regression coefficients (-1.68, -4.00). Due to a low average protein content changes in the crude protein content had a particularly positive influence on DOM. Regression equations are recommended for the estimation of DOM, the content of metabolizable energy and NEFUcattle from the content of crude fibre, lignin, crude protein and cellulase solubility of the organic matter (biostatistical residual dispersion = 2.1-2.3% DOM; 0.35-0.36 MJ metabolizable energy or 0.2-0.21 MJ NEFUcattle).     

The energy requirement of heifers. 4. Comparison of the digestibility and rumen physiologic parameters in heifers and full-grown sheep

In 159 comparative studies with fully grown sheep and heifers of the digestibility and of rumen physiologic values at a variation of the feed ration in the crude fibre content between 112 and 318 g, in the crude protein content between 94 and 194 g and in the content of nitrogen free extractive between 484 and 641 g/kg DM is provided that the digestibility of energy in heifers was, on average, 4 digestibility units lower than in sheep. The corresponding values for the digestibility of crude protein and crude fibre are 12 and 3.5 digestibility units. Due to the lower methane energy excretion of the heifers the difference at the level of metabolizable energy is reduced to 1.5% of the gross energy. The level of the differences in digestibility is influenced by the development of the young cattle and the composition of the rations. In young cattle of the live weight range between 100 and 150 kg the digestibility of the energy is 6-8 units lower than in sheep. A higher crude fibre content in the ration diminishes the difference in the digestibility of energy and the nutrients between the two animal species.     

The digestibility of crude nutrients in horses. 2. Comparative studies on the digestive capacity of a thoroughbred horse, pony and wether

The digestibility of the crude nutrients of 6 rations on the basis of oat, hay and wheat straw (in one case a straw-concentrate mixture as sole feed) was compared at a nutrition level of 1.0 and 1.3 resp. with adult geldings of the species "Noble Crossbreed", adult pony geldings and wethers The energy concentration of the rations varied between 424 and 585 EFUcattle/kg DM, the crude fibre content between 17 and 25% of the DM. In the studied field, a good agreement between horse and pony could be ascertained as to the digestibility of the organic matter and NFE. There are partly considerable differences between the apparent digestibility of crude protein and crude fibre. The differences in the digestibility of crude fibre between horse and sheep increase with a growing crude fibre content. The differences of the apparent digestibility between horse and pony on the one hand and sheep on the other were highly significant in all cases.     

Evaluation of the energy concentration of feed mixtures for poultry based on the chemical analytical data

Based on data material available for 33 feed mixtures, several regression equations were developed which make the estimation of energy concentration (EC) on the basis of the content of crude nutrients possible. The values received from the various equations were compared with those resulting from digestibility experiments with colostomized male and female chickens. An estimation equation is recommended resulting from the regressions for the digestibility of the individual crude nutrients: EC = 0.604 X crude protein content + 2.045 X crude fat content + 0.901 X crude carbohydrate content-158.3.     

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.     

The apparent prececal and fecal crude protein digestibility and amino acid absorption of coarse animal feed in fattening pigs

Digestibility experiments were made with nearly full-grown female fattening pigs supplied with large-scale T-cannulae implanted in the distal ileum to collect the digesta in order to test 11, mainly dried and pelleted, kinds of forage plants (9 samples of lucerne cut at different times as well as green rye and whole plants of maize) as supplements to a basic diet. All samples were analysed to their content of HCl-insoluble ash as marker and their content of amino acids (AA). The calculation of the apparent precaecal and faecal crude protein (CP) digestibility and of the absorption values of the essential AA lysine, methionine, cystine, isoleucine, threonine and tryptophan as well as of glutamic acid was carried out according to the difference method. CP digestibility of the experimental diets was precaecally reduced by 5 to 20 and faecally by 3 to 13 units by supplements of at least 25% of the dry matter; for some of the AA the reduction was even bigger and dispersion between the values of the individual animals was essentially increased in comparison with the basic ration. Faecally, the precaecal differences of CP digestibility and AA absorption caused by the various alfalfa samples, are largely blurred. The CP and AA digestibility of the forage plants partly showed very big individual differences between the animals. Precaecally, a CP digestibility of more than 48% could not be ascertained. Similarly to the lysine content, precaecal lysine absorption from the kinds of roughage showed big differences. Whereas the absorption values for methionine of between 60 and 87% were relatively high, those for cystine were mostly very low, often in the negative range. This underlines that normal digestion processes are strongly influenced by high supplements of forage plants so that the constancy of the digestibility of the basic ration must be doubted under these conditions. The bacterial processes in the large intestine greatly level out the differences found precaecally between the various kinds of feedstuffs. The faecal digestibility and absorption values were considerably above those measured precaecally; methionine digestibility only was mostly considerably diminished in comparison with precaecal values due to synthesis in the large intestine. A significant positive correlation could be calculated between the lysine content of the 9 alfalfa samples (4.0 to 6.6 g/16 g N) and the apparent precaecal values of lysine absorption (2.2 to 67.6%).(ABSTRACT TRUNCATED AT 400 WORDS)     

Energy utilization by swine of nutritive fiber-rich by-products from the milling and food industry

Growing pigs (from 20 to 80 kg body weight) were fed diets containing equal amounts of soybean, pea (pisum sativum), millet and barley hulls as well as a mixture of these fibre sources. The effects of these fibrous components on the digestibility of energy and nutrients were investigated. Although some rations had a similar nutrient composition, important differences in the digestibility of energy could be observed: e.g. soybean hulls and pea hulls had a similar content in crude fibre but differed in the digestibility of energy by a factor 1:2. The difference in the digestibility of energy was even more pronounced between the rations with soybean hulls and millet hulls (factor 1:11, respectively) although the crude fibre and ADF fibre content were similar. Therefore the magnitude of the difference in digestibility of energy shows a considerable variation between the fibre sources. This seems to be caused partially by differences in the chemical nature of the fibrous by-products. Soybean hulls and barley hulls proved to be very well suited for growing pigs (11.4 MJ DE/kg DM and 10.0 MJ DE/kg DM, respectively). The pea hulls showed a mean content of digestible energy (5.6 MJ DE/kg DM) whereas the millet hulls (1.1 MJ DE/kg DM) didn't contribute significantly to the energy supply of the pigs.     

The use of the mobile bag technique in swine. 2. Determination of the apparent and true crude protein digestibility of 15N-labeled feed]

In a series of experiments in two ileo-rectostomized pigs the precaecal apparent and true digestibilities for crude protein of seven 15N-labelled feedstuffs were studied using the mobile bag technique. True digestibility values of crude protein calculated with the help of isotope dilution were 4-14 units higher than the corresponding apparent digestibility values. This is caused by the infiltration of the bag residues with endogenous unlabelled nitrogen. In dependence on the kind of feedstuff the endogenous N portion in the bags amounted to 25-70% of the total N. In addition, the contamination is influenced by differences between the animals (mean 4-7%) and by different treatments of bags after gut passage (3-10%).     

Digestibility and absorption of nutrients as affected by fibre content in the diet of the pig. Quantitative aspects

An attempt has been made to assess some quantitative aspects of the influence of fibre content in feedstuffs and diets on the digestibility and absorption of nutrients in pigs. The study is based on selected published literature and data from Danish experiments.The digestibility of nutrients consistently decreases with increasing fibre content in the diet, regardless of the analytical method used. However, the magnitude of this negative influence depends on the type and origin of the fibre source, technical treatment, feeding level, age and live weight of the pigs, etc.Increasing the content of crude fibre in diets is related to increasing the content of less digestible carbohydrate (hemicellulose) and a concurrent decrease in the content of easily digestible substances. It is shown that for each 1% increase in the crude fibre content, the content of starch + sugars in the NFE-fraction is decreased by 2.1–2.7%. This results in a reduced ileal digestibility, enhanced fermentation in the hindgut and an overall reduction of the digestibility of gross energy.Experimental data from this institute comprising 246 diets and 257 single feedstuffs were used to generate equations for prediction of the digestibility of gross energy. A single carbohydrate fraction (NDF or crude fibre) alone accounted for about 70% of the variation in digestibility in diets and 85% of the variation in digestibility of single feedstuffs.Fibre determination values based on either detergent methods (NDF) or crude fibre analysis supplemented with enzymic determination of starch + sugars were equally good as predictors of the digestibility of gross energy.     

Nitrogen and amino acid absorption in the small intestine of growing pigs. 2. Apparent and true crude protein digestibility and amino acid absorption to the end of the small intestine

Studies of the apparent and true ileal digestibility of crude protein and the apparent and true amino acid (AA) absorption were carried out with 7 female pigs in the live weight range between 22 and 34 kg after ileorectostomy. Protein sources of varied quality with regard to the method of treatment (toasted) and untoasted soybean oilmeal) and to the AA composition (vital gluten or vital gluten + L-lysine X HCl) were used. Distinct differences regarding the apparent ileal digestibility of crude protein and the apparent absorption of amino acids were discovered between the protein sources, the cause of which is to be seen in the different amounts of endogenous N. The true ileal digestibility of crude protein and amino acid absorption were partly distinctly higher than the values of the apparent ileal digestibility of crude protein and AA absorption. On the whole one can say that the results of the investigation gained by means of ileorectostomy can be compared to the values gained from cannulated animals. Thus the experimental method used is suitable for studying the absorption process to the end of the small intestine of pigs.     

Nutrient composition of some newly bred high protein and/or high lysine grains and their digestibility determined on growing pigs

With the view to complementing the feedstuff data store and, consequently, to further improving the GDR Feed Evaluation System, some newly bred high-protein and/or high-lysine cereal varieties and strains (spring barley, winter wheat, maize) were studied for their nutrient composition and digestibility. Apart from from WEENDER's feed analysis technique, more recent methods were applied to determine total fat (after HCl treatment), carbohydrates (enzymatic method), lignin and amino acids. The digestibility of the nutrients was determined using growing pigs of different live weight, the test rations being made up of the cereals under and supplementations of limiting amino acids as well as vitamins and minerals. In comparison with the values from currently applied tables, the newly bred strains and varieties proved to have markedly higher contents of crude protein, digestible crude protein, lysine and energetic feed equivalents. Compared to crude fat, the total fat values proved markedly higher in the barley and wheat samples. The readily soluble and easily hydrolizable carbohydrates found with the new analysis procedure suggested, were 100% digestible in all cereal samples used. Lignin proved the constituent most difficult to digest and must be regarded as virtually undigestible in the case of pigs.     

Ruminal protein degradation and protein value of feeds

The relationship between dry matter (DM) degradation and crude protein (CP) degradation in the dairy cow's rumen was determined with a view to defining the protein value of feeds for ruminants. The nylon bag technique was applied for these studies. For all the feeds investigate (green fodder and preserves from cocks-foot, ryegrass, alfalfa/grass and meadow grass, as well as alfalfa, extracted soybean meal) a significantly positive relationship was found to exist between the levels of DM and CP degradation (r = 0.73 to 1.0). The regression coefficient b1 (CP degradation as regressor) was found to average 0.87. The positive relationship between DM degradation and CP degradation implies that microbial protein amount and unfermented feed protein at the duodenum are negatively correlated. Model calculations show that, on account of the compensation between microbial protein and feed protein at the duodenum, in feeds with a CP concentration below 200 g/kg DM, the extent of ruminal protein degradation does not exert a marked influence on duodenal protein passage. The partial calculation of the duodenal protein supply on the basis of undegraded feed protein and microbial protein, as practiced in the new models of protein evaluation, leads to systematic errors unless the relationship between DM degradation and CP degradation is considered.     

The use of the mobile bag technique in swine. Determination of the apparent crude protein digestibility and amino acid absorption of feed and rations]

The mobile bag technique (MBT) was used in two ileorectostomized and two intact pigs with duodenal cannulae, in order to estimate the precaecal and total crude protein digestibility and amino acid (lysine, methionine, cystine, threonine, tryptophan) absorption of ten single feedstuffs (field bean, lupin, rapeseed meal, fish meal, barley, wheat) and three diets. For each feed 36 bags were applied per animal. After a peptic predigestion in vitro, application of the bags through the duodenal cannula into the intestine and their passage through the gut, the residues remaining in the bags were pooled to collective samples and just as the original feed material analysed on dry matter, nitrogen and amino acids. The directly determined MBT-digestibilities (BV) and the values obtained by regressive calculations (BVb) have been compared with apparent digestibilities (sV) conducted from conventional digestion experiments. 74 per cent of all BV data was higher than the corresponding sV values. Similarities of BV with sV showed in 58 per cent, those of BVb with sV only in 17 per cent. In all cases differences of > +/- 4 digestibility units showed. Checking additivity of diet-BV by means of calculations from the BV of their single ingredients did not generally lead to the same results as the directly estimated diet-BV; in some cases the results were contrary. Therefore the use of MBT for mixed feed diets has to be further investigated. For single feedstuffs the MBT can be used successfully as a rapid and simple technique when regressive calculations are employed.     

不同类型黑麦草营养价值评估

文章旨在通过体内外试验评估不同类型黑麦草的营养价值。试验选择平均体重为（66.87±2.34）kg的绵羊12头,随机分成3组,每组4个重复,每个重复1头。3组绵羊分别饲喂新鲜、青贮和晒干黑麦草。经过14?d的饲养试验后收集粪便和牧草样品进行后续分析。结果：晒干黑麦草的干物质、有机物和无氮浸出物含量均表现最高（P＜0.05）。新鲜黑麦草粗蛋白质和半纤维素含量较青贮黑麦草分别显著提高42.10%和10.82%（P＜0.05）。青贮黑麦草粗脂肪、粗纤维、中性洗涤纤维和酸性洗涤纤维含量显著高于其他两种类型的黑麦草（P＜0.05）。新鲜、青贮和晒干黑麦草的粗蛋白质、粗脂肪和粗纤维表观消化率无显著差异（P＞0.05）。晒干黑麦草干物质表观消化率较新鲜和青贮黑麦草显著提高6.34%和6.21%（P＜0.05）,同时晒干黑麦草有机物表观消化率较新鲜黑麦草显著提高6.65%（P＜0.05）,无氮浸出物表观消化率较青贮黑麦草显著提高15.44%（P＜0.05）。当体外代谢能值以MJ/kg有机物表示时,新鲜和青贮黑麦草代谢能值较晒干黑麦草分别显著提高21.34%和22.41%（P＜0.05）,而当体外代谢能值以MJ/kg干物质表示时,新鲜黑麦草能值最高,青贮黑麦草能值次之,晒干黑麦草能值最低（P＜0.05）。结论：新鲜、晒干和青贮黑麦草在不同营养成分上各有优势,但3种牧草主要营养物质的表观消化率和代谢能值无显著差异。因此,无论是新鲜、晒干还是青贮黑麦草都可以作为反刍动物粗饲料的良好来源。 [关键词]黑麦草;青贮;营养价值;消化     

家兔对玉米秸能量及主要营养成分消化率的测定

为了探讨玉米秸对家兔的饲用价值，进行了玉米秸能量及主要营养成分在家兔的消化率测定。结果，总能（ＧＥ）消化率为５９．６４％，消化能（ＤＥ）含量９．１７ＭＪ／ｋｇ，粗蛋白（ＣＰ）、粗脂肪（ＥＥ）、无氮浸出物（ＮＦＥ）、灰分（ａｓｈ）、干物质（ＤＭ）和有机物（ＯＭ）消化率分别为４０．３９％、２３．４９％、８３．３％、７６．５４％、３８．３４％、５３．０９％和５３．５２％。玉米秸对家兔有较高的ＤＥ含量及ＮＦＥ和ＣＦ消化率，但ＣＰ消化率较低，家兔日粮中使用玉米秸时要注意补加蛋白质饲料