不同方法测定瘤胃非降解蛋白质小肠消化率及相关性分析

本试验分别采用移动尼龙袋法、改进三步体外法、原始三步体外法和酸性洗涤不溶氮(ADIN)估测法测定13种精料的瘤胃非降解蛋白质(RUP)小肠消化率,并对移动尼龙袋法与其他方法的测定结果进行相关性分析,同时对常规营养成分和RUP小肠消化率作回归分析,旨在寻找替代移动尼龙袋法测定RUP小肠消化率更简单快速的方法.试验采用单因素试验设计,选取3头装有永久瘤胃瘘管和十二指肠T型瘘管的奶牛.结果表明:移动尼龙袋法测得的豆粕、棉籽粕、菜籽粕、葵花粕、芝麻粕、玉米胚芽粕、玉米、米糠、米糠粕、米糠饼、大麦、麦麸和玉米麸质饲料的RUP小肠消化率分别为98.13％、87.37％、88.47％、82.60％、85.73％、75.40％、93.23％、69.27％、77.83％、92.10％、91.27％、72.37％和79.03％.改进三步体外法测定结果与移动尼龙袋法测定结果的相关系数为0.8383;原始三步体外法测定结果与移动尼龙袋法测定结果的相关系数为0.7899;ADIN估测法预测结果与移动尼龙袋法测定结果无显著相关(P＞0.05);饲料RUP小肠消化率与饲料常规营养成分含量显著相关(P＜0.05).改进三步体外法比原始三步体外法替代移动尼龙袋法测定饲料RUP小肠消化率效果更好.应用体外法替代移动尼龙袋法测定蛋白质饲料RUP小肠消化率比测定能量饲料RUP小肠消化率效果更好.用饲料的常规营养成分含量可较好地预测RUP小肠消化率.     

The effect of microbial phytase on ileal phosphorus and amino acid digestibility in the broiler chicken

1. The study aimed to assess the effect of a commercially available microbial phytase on phytate phosphorus and total phosphorus content at the terminal ileum as well as true ileal amino acid digestibility. 2. Five diets, each containing a different plant-based feedstuff, were supplemented with microbial phytase and fed, along with a non-supplemented corresponding diet, to 28-d-old broiler chickens, Chromic oxide was used as an indigestible marker. Ileal contents were collected and analysed, along with the diets, for total phosphorus, phytate phosphorus and amino acids. 3. Endogenous phosphorus determined at the terminal ileum was 272 +/- 108 mg/kg food dry matter (mean +/- SE). Endogenous ileal amino acid flows ranged from 58 +/- 10 mg/kg food dry matter for methionine to 568 +/- 47 mg/kg food dry matter for glutamic acid. 4. Supplementation with microbial phytase resulted in a significantly greater phytate P disappearance from the terminal ileum for rice bran (17% units), but not for soyabean meal, maize, wheat or rapeseed meal. Similarly total phosphorus digestibility was significantly (P < 0.05) higher when microbial phytase was added to the rice-bran-based diet but not for any of the other feedstuffs. 5. Amino acid digestibility was significantly greater in the presence of microbial phytase for all the amino acids examined in wheat, for several of the amino acids each in maize and rapeseed meal and for one amino acid in rice bran and soyabean meal. The average increase in amino acid digestibility for those amino acids affected, was 13, 6, 10, 7 and 12% units for wheat, maize, rapeseed meal, rice bran and soyabean meal, respectively. 6. It appears that microbial phytase improves phosphorus digestibility and amino acid digestibility for certain plant-based feedstuffs.     

In vitro analyses for predicting standardised ileal digestibility of protein and amino acids in actual batches of feedstuffs and diets for pigs

In vitro digestibility analyses of feedstuffs and diets are integrated in the new Danish feed evaluation system for pigs. This system is based on potential physiological energy and standardised digestible amino acids. For characterisation of the energy value of actual batches of feedstuffs and complete diets for pigs, two different in vitro methods have been developed and proved to analyse precisely the digestibility of organic matter at faecal, as well as at ileal, level in the pigs. For characterisation of the protein value in the diet, table values for standardised digestibility of amino acids from the individual feedstuffs are used for calculation of their contribution to the amino acid recommendations for the specific pig category. The results in the present paper indicate that in vitro analyses for digestibility of crude protein in feedstuffs are a reliable tool for calculation of standardised ileal digestibility of the individual amino acids. Thus, the results may question the need for future experiments with surgically modified pigs for analysing ileal digestibility of amino acids in protein sources. Alternatively, in vitro digestibility analyses appear to have a general potential for a precise evaluation of amino acid digestibility in actual batches of feedstuffs and pig diets.     

Amino acid profile of escaped feed protein after rumen incubation and their intestinal digestibility.

The crude protein content and amino acid profile of seven feedstuffs (linseed meal, maize gluten meal, rapeseed meal, rapeseed meal protected, soybean meal, fullfat soybean extruded and sunflower meal) were determined before and after ruminal incubation for 16 h in three bulls with large rumen cannulas. The intestinal disappearance of amino acids was measured using mobile bag technique. Ruminal incubation affected amino acid profile of all experimental feedstuffs. Crude protein degradation varied from 29.3% for maize gluten meal to 86.4% for rapeseed meal. A tendency towards increased disappearance was observed for glutamic acid, histidine, lysine and proline and decreased disappearance for branched-chain amino acids. The intestinal crude protein digestibility was higher than > 80%, except rapeseed meal (66.4%) and sunflower meal (77.8%). The least digestible individual amino acids were methionine and isoleucine in rapeseed meal, histidine and methionine in rapeseed meal protected and arginine in sunflower meal. In general, the lowest amino acid digestibilities were found in feedstuffs with the highest fibre content. The feedstuffs show that they have different potential for supplying of limiting amino acids. Of particular value are the feedstuffs with low crude protein degradability in the rumen and high intestinal digestibility of amino acids.     

Standardized ileal protein and amino acid digestibility by growing pigs and sows

Experiments were conducted to determine the effect of the physiological condition of swine on standardized ileal digestibility coefficients (SID). The apparent ileal digestibility coefficients were determined for crude protein and amino acids in six feed ingredients (corn, barley, wheat, soybean meal, canola meal, and meat and bone meal) in growing pigs and in gestating and lactating sows. Growing pigs and lactating sows were given free access to their diets, whereas gestating sows were allowed to consume only 2 kg of feed daily. The nonspecific (basal) endogenous losses of protein and amino acids were determined under similar feeding regimens after feeding a protein-free diet. The SID for crude protein and amino acids were calculated by correcting the apparent ileal digestibility coefficients for the nonspecific endogenous losses of protein and amino acids. With a few exceptions, there were no differences (P > 0.05) in the SID for crude protein and amino acids between growing pigs and lactating sows. Overall, gestating sows had higher (P < 0.05) SID for crude protein and all amino acids, except for tryptophan and aspartate, compared with growing pigs. Likewise, the SID of most amino acids obtained by gestating sows were higher (P < 0.05) than those obtained by lactating sows. Interactions (P < 0.05) between animals and diets were observed for gestating sows compared with growing pigs as well as gestating sows compared with lactating sows. As a consequence, it is not possible to extrapolate data from one feed ingredient to another. On most occasions, the lowest SID among the indispensable amino acids was calculated for threonine, valine, and lysine. It is concluded that gestating sows fed 2 kg of feed per day have higher standardized digestibility coefficients than do growing pigs and lactating sows given free access to their diets. This difference may be due to differences in daily feed intake rather than to the physiological status of the animals.     

Influence of age on the apparent ileal amino acid digestibility of feed ingredients for broiler chickens

The apparent ileal digestibility of amino acids in 8 feed ingredients was determined using 14-, 28- and 42-d-old male broiler chickens. The ingredients included three cereals (wheat, sorghum and maize), one cereal by-product (mill run), three oilseed meals (canola, cottonseed and soybean meals) and one animal protein meal (meat and bone meal). Dietary crude protein in the assay diets was supplied solely by the test ingredient. All diets contained 20 g/kg acid-insoluble ash as an indigestible marker, and each diet was offered ad libitum in mash form to 5 replicate pens from 11 to 14 d, 25 to 28 d and 39 to 42 d post-hatching. There were 12, 6 and 6 birds per pen for the 14, 28 and 42 d samplings, respectively. The results suggest that the age of broilers significantly influenced the apparent ileal digestibility of amino acids. The effects, however, varied among amino acids and ingredients. In wheat, the digestibility of most amino acids was higher in 14- than in 28- and 42-d-old broilers. In maize, the digestibility coefficients of amino acids were higher at 28 and 42 d than at 14 d. The digestibility coefficients in maize and wheat at 28 and 42 d were similar. The digestibility of amino acids in sorghum at 42 d was higher than those at 28 d, but similar to those at 14 d except for histidine, lysine, serine and glycine, which were significantly higher at 42 d. Digestibility of amino acids in sorghum was similar between 14 and 28 d except for isoleucine, leucine, phenylalanine, glutamic acid and alanine. The digestibility of amino acids in mill run at 42 d was significantly higher than those at 14 and 28 d. There were no differences in digestibility between 14 and 28 d. In general, the digestibility of amino acids in canola meal, soybean meal and, meat and bone meal was higher at 28 and 42 d compared to those at 14 d, and similar between 28 and 42 d of age. In cottonseed meal, age had no effect on the digestibility coefficient of amino acids, except for lysine and arginine, which increased with age. Analysis of the combined results for the 8 feed ingredients showed that, in general, the digestibility coefficients of amino acids increased with advancing age of broiler chickens.     

Replacement of soybean meal with levels of inclusion of soya waste in the diet of growing goats

An experiment was conducted to investigate the effect of replacing soybean meal with soya waste at different levels on intake, digestibility and growth in goats. Eighteen male goat kids with initial body weight (BW) of 13.0 kg were distributed equally to three dietary groups. They were fed Napier grass (Pennisetum purpureum) and concentrate mixture, and each goat was assigned to an individual pen. Soybean meal in the concentrate mixture was replaced with soya waste at 0% (T1), 50% (T2) and 100% (T3) levels in respective dietary groups. These diets were isocaloric and isonitrogenous. Results showed that animals fed T3 diet exhibited higher Napier grass intake than those fed T1 or T2 diet. There was no influence on total intakes of dry matter (DM), organic matter (OM), crude protein (CP), metabolic BW, per cent BW and metabolisable energy by the dietary groups. However, there was an increasing trend on intake and digestibility of neutral detergent fibre (NDF) with increasing levels of soya waste in the diets. Animals fed T3 diet showed higher intake and digestibility of NDF than those fed T1 diet. There was no influence of the dietary groups on digestibilities of DM, OM and CP. Similarly, there was no effect of them on the final BW, total BW gain, daily BW gain, feed conversion ratio and feed cost. Soya waste can replace 100% soybean meal in diets for growing goats, because no change was observed in nutrient intake, digestibility and growth performance; inclusion of soya waste enhanced the intake and digestibility of NDF.

     

Influence of processing cassava peels on the hydrogen cyanide concentration, nutritive value and performance of growing rabbits

Forty-eight rabbits used to investigate the response of growing rabbits to diets containing differently processed cassava peel meals were divided into four groups balanced for sex and weight. These groups were then assigned at random to the experimental treatments. Four diets were formulated such that the diets contained 200 g/kg of the experimental feedstuffs, sun-dried cassava peel meal (S), ensiled cassava peel meal (E) and retted cassava peel meal (R), and the control did not contain any cassava peels. Hydrogen cyanide (HCN) concentration in the processed cassava peel meal was lower relative to the unprocessed meal. It was, however, lowest in R and highest in E. With the exception of S, fibre fractions were lower in the processed meal compared to the unprocessed meal. The E depressed (p < 0.05) feed and digestible nutrient intakes, weight gain, nutrient digestibility, digestible protein (DP), digestible energy (DE) and DP/DE ratio but increased protein intake to gain and feed to gain ratios compared to other diets. Intake of HCN decreased (p < 0.05) successively in this order: R, S and E. The results indicate that retting and sun-drying are more effective in cassava peel detoxification than ensiling, and dietary HCN concentration and intake of 56 and 4 mg/kg BW, respectively, were not toxic under the conditions of the experiment.     

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.     

青鱼对8种饲料原料中营养物质的表观消化率

本试验旨在研究青鱼(Mylopharyngodon piceus)对国产鱼粉、蝇蛆粉、玉米蛋白粉、大豆粕、花生粕、棉籽粕、菜籽粕和米糠8种饲料原料干物质、粗蛋白质、氨基酸、粗脂肪、总磷和总能的表观消化率。试验饲料由70%基础饲料和30%待测饲料原料组成,并以0.1%的三氧化二钇(Y2O3)为外源指示剂。选取平均体重为(60.17±1.28)g的青鱼270尾,随机分成9组,每组3个重复,每个重复10尾鱼。对照组试验鱼饲喂基础饲料,试验组试验鱼分别饲喂1种试验饲料。饲喂1周后采用自排法收集粪便待测。结果表明:8种饲料原料的干物质、粗蛋白质、粗脂肪、总磷、总能以及总氨基酸的表观消化率的范围分别是62.17%～86.47%、83.34%～95.84%、78.93%～100.06%、37.33%～81.99%、66.75%～89.86%、86.33%～96.58%。在8种饲料原料中,玉米蛋白粉的干物质、总磷和总能的表观消化率最高,而大豆粕的粗蛋白质、粗脂肪和总氨基酸的表观消化率最高;棉籽粕的干物质和总能的表观消化率最低,米糠的粗脂肪和总磷的表观消化率最低。各饲料原料中总氨基酸表观消化率与粗蛋白质表观消化率的变化趋势一致,其中以蝇蛆粉最低。由此可见,大豆粕和玉米蛋白粉是青鱼的优质植物蛋白质源,可适量替代鱼粉;蝇蛆粉中粗蛋白质和氨基酸的消化率都较低,在青鱼饲料中的添加量不宜过高;花生粕、棉籽粕和菜籽粕也是较好的植物性蛋白质源,在青鱼饲料中适量添加既有利于饲料的营养平衡,还可降低饲料成本;米糠作为青鱼的能量原料必须保持新鲜,并控制其在饲料中的用量。     

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.     

The evaluation of the mobile nylon bag technique for determining the apparent protein digestibility in a wide variety of feedstuffs for pigs

Studies were conducted with four (50 to 70 kg) barrows to evaluate the mobile nylon bag technique (MNBT) for determining the apparent protein digestibility (AD) in a variety of feedstuffs. One-gram samples of each feedstuff, ground through a 1.0-mm mesh screen, were enclosed in nylon bags (25 X 40 mm; 48 microns mesh). Following predigestion (.01 N HCl; 4,000 Folin Intestinal Pepsin Units/liter), four bags of each sample were inserted into each pig via a duodenal T-cannula. The indigested contents were pooled within pig and feedstuff prior to crude protein analysis. The AD of each feedstuff was determined previously with four barrows according to the conventional method (CM), based on a 5-d total collection of feces following a 14-d adaptation period. The following results, AD (%), were obtained with the MNBT (n = 4) and CM (n = 4), respectively. Barley, 70.1 vs 81.2 (P less than .05); corn, 72.3 vs 82.1 (P less than .05); wheat, 79.6 vs 86.4 (P less than .05); corn gluten feed, 73.9 vs 70.9; rice bran, 57.3 vs 57.4; wheat middlings, 70.8 vs 79.4 (P less than .05); soybean meal, 89.9 vs 93.0; a mixture of soybean meal and hulls, 86.9 vs 88.8; coconut expeller, 65.0 vs 69.8; fababeans, 79.5 vs 78.5; peas, 87.6 vs 88.1; meat meal, 83.2 vs 84.0; complete diet (4.3% crude fiber), 76.3 vs 83.6 (P less than .05); and complete diet (13.6% crude fiber), 56.5 vs 55.0.(ABSTRACT TRUNCATED AT 250 WORDS)     

Digestion of soybean meal and canola meal protein and amino acids in the digestive tract of young ruminants

Eight male Holstein calves (body weight 68 +/- 5 kg; age 75 +/- 6 d), each with a permanent re-entrant pancreatic cannula and T-type ileal and duodenal cannulas, were used in a crossover design with four animals per group to determine amino acid kinetics and digestibilities in the digestive tract of calves fed soybean meal (SBM) and canola meal (CM) protein. The SBM and CM diets were fed twice daily at a level of 900 g at each feeding time (air-dry basis). With the exception of methionine, crude protein and amino acid flows at the proximal duodenum, expressed as a percentage of intake, were not influenced by dietary protein source. Apparent ileal and total tract digestibilities of CP and amino acids were reduced (P less than .05) by feeding CM compared to SBM, but apparent ileal digestibility of methionine was not affected by dietary protein source. Except for methionine, net disappearance of all amino acids in the small intestine, relative to the amount fed, was higher for the SBM diet than for the CM diet. Net disappearance or synthesis of amino acids in the large intestine were not affected by dietary protein source. Similarly, dietary protein source did not affect (P greater than .05) the secretion of pancreatic juice or concentrations of protein, chymotrypsin and trypsin in pancreatic juice. Soybean meal protein has higher ileal and total gastrointestinal tract digestibility than CM protein for young, growing calves.     

Creatine and creatinine contents in different diet types for dogs – effects of source and processing

The concentrations of creatine and its degradation product creatinine were determined in a variety of unprocessed as well as processed feedstuffs suitable for dogs. Unprocessed feedstuffs were categorised as single feedstuffs, bone and raw food diets (BARF), and small vertebrates, for example prey animals. Processed feedstuffs were categorised as meat/meat and bone meals, complete wet diets and complete dry diets. The feedstuffs were chosen to cover a broad range of each of the three defined processed and unprocessed feed categories available on the market without further subclustering. The creatine content of the samples was compared on a dry matter, protein and energy basis. The relation of creatine to crude protein permitted a rating of the meat quality in terms of muscle tissue. Results: We found no difference in creatine concentrations between the three categories of unprocessed feedstuffs (raw single feedstuffs, prey and BARF diets), neither on a dry matter basis nor when expressed relative to crude protein and metabolisable energy respectively. Significantly lower levels were determined in meat/meat and bone meal and commercial dry diets (e.g. 303 mg creatine/MJ ME in unprocessed vs. 6 mg/MJ ME in processed feedstuffs; p < 0.001). We conclude that in relation to ME, the exclusive use of conventionally processed diets for dogs, especially dry diets, leads to considerably lower intake of creatine which is a natural compound of the diet of this carnivorous and omnivorous species.     

饲粮纤维源及粗纤维水平对肉兔营养物质消化率、肠道消化酶活性及盲肠菌群多样性的影响

本试验旨在研究饲粮纤维源及粗纤维(CF)水平对肉兔营养物质消化率、肠道消化酶活性及盲肠菌群多样性的影响。试验采用双因子试验设计,依据等能等氮原则,设2种纤维源(苜蓿草粉、稻壳粉)、3个CF水平(12%、14%、16%),共配制6种试验饲粮。选择144只70~80日龄、平均体重(2 002±77)g的健康伊拉生长肉兔,随机分为6组,每组4个重复,每个重复6只兔,单笼饲养。饲养试验为期4周,饲养试验期末,采用全收粪法进行消化试验,之后进行屠宰,取肠道食糜用于消化酶活性及盲肠菌群多样性的测定。结果表明:1)苜蓿草粉组干物质(DM)、CF、酸性洗涤纤维(ADF)、木质素(ADL)的消化率显著或极显著高于稻壳粉组(P0.05或P0.01),粗蛋白质(CP)消化率则极显著低于稻壳粉组(P0.01);12%CF水平组DM、中性洗涤纤维(NDF)、ADF的消化率显著高于14%CF水平组(P0.05),同时该组能量的消化率及表观消化能(ADE)极显著高于14%、16%CF水平组(P0.01)。2)稻壳粉组十二指肠胰蛋白酶活性极显著高于苜蓿草粉组(P0.01)。与14%、16%CF水平组相比,12%CF水平组的空肠淀粉酶、胰蛋白酶活性及盲肠纤维素酶活性均最低。3)纤维源对盲肠菌群丰富度和香农指数无显著影响(P0.05),但苜蓿草粉组的盲肠菌群均衡指数极显著高于稻壳粉组(P0.01)。CF水平对盲肠菌群丰富度和香农指数有显著影响(P0.05),其中16%CF水平组的数值均为最高。综上所述,在本试验条件下:1)苜蓿草粉组肉兔DM、CF、ADF、ADL的消化率及盲肠菌群均衡指数显著或极显著高于稻壳粉组,但十二指肠胰蛋白酶活性极显著低于稻壳粉组。2)饲粮CF水平为12%时肉兔的ADE和各主要营养物质的消化率最高;CF水平越高,肉兔空肠淀粉酶、胰蛋白酶活性和盲肠纤维素酶活性越高;饲粮CF水平为16%时肉兔盲肠菌群的多样性较高。     

不同粉碎粒度的豆粕对断奶仔猪生长性能和养分消化率的影响

本试验研究不同粉碎粒度的豆粕对断奶仔猪生长性能和养分消化率的影响,选用26～28日龄断奶(7.9±0.7)kg杜×长×大健康仔猪80头,按体重、性别相同原则随机分为4个处理,每处理设5个重复,每个重复4头猪。各个处理组采用相同的日粮组成,对照组饲喂含常规粉碎豆粕(目标粒径为750μm)的日粮,处理1、2、3分别饲喂含目标粒径为150、30、6μm豆粕的日粮。结果表明:使用粉碎粒度低于30μm豆粕的日粮提高了断奶仔猪日增重(P<0.05),明显提高采食量(P>0.05),降低饲料增重比(P<0.05),显著降低断奶仔猪的腹泻频率;使用粉碎粒度低于30μm豆粕的日粮提高断奶仔猪日粮氮、磷表观消化率(P<0.05),改善能量消化率(P=0.063)和有机物表观消化率(P=0.082),显著提高必需氨基酸的表观消化率(P<0.05)。粉碎粒度低于30μm的超微粉碎豆粕可显著提高断奶仔猪日粮蛋白质的消化效率,提高断奶仔猪的生长性能,改善了豆粕作为蛋白质营养源的生物适应性。     

Measurement of the postruminal digestibility of crude protein by the bag technique in cows

A new method has been developed which permits the crude protein digestibility of feedstuffs in the intestine of cattle to be measured with little effort in terms of samples and experimental work. It consists of welding 0.4 ... 0.8 g of the feedstuff (particle size: 125 ... 1000 micron) into polyamide fabric bags (25 X 40 mm) which are inserted via cannulae into the digestive tracts of fistulated cows from the abomasum/duodenum to the ileum or from the abomasum/duodenum to the faeces. The mean retention time of the bags in the animal was 8.5 +/- 2.7 h from the abomasum to the end of the ileum and (13.3 +/- 1.9 h from the abomasum to the faeces. Up to 15 bags per day and cow may be used. The random error of the method is 1.3% (absolute) when the measurements are performed on two animals using two bags each. Intestinal digestibilities of over 90% were measured for concentrate proteins (except linseed meal) and of 72 ... 95% for forage proteins. Post-ruminal digestion was virtually finished at the end of the small intestine.     

Optimum ratio of histidine in the piglet ideal protein model and its effects on body metabolism. I. Basal diet formulation based on digestible amino acids according to the ideal protein model for 10 to 20 kg piglets.

A 4 x 4 Latin square design was used to determine ileal apparent digestibility of amino acids (AAs) in corn, soybean meal, feather meal and dried whey in young pigs. The data were then to be used in formulating a basal diet for studies on AA metabolism in young pigs. Eight castrates T-cannulated at terminal ileum (average initial body weight 12.5 +/- 0.62 kg) were divided into 4 groups on the basis of body weight and transferred to individual metabolism crates. They were then fed four experimental diets containing the four feedstuffs to be tested (corn, soybean meal, feather meal and dried whey). The trial lasted 20 days, which included 4 five-day periods for ileal digesta collection. It was found that the digestibility of the AAs was similar to that reported in literature. Based on the findings a basal diet for this research was formulated according to an ideal protein model for the 10 to 20 kg piglet, on the basis of digestible AAs and containing 14.13 MJ/kg digestible energy, 18.22% crude protein, 1.04% digestible lysine and 0.23% digestible histidine.     

Nutritional value of quality protein maize for starter and finisher swine.

Growth trials with starter (n = 120, 6.8 kg initially, 28 d of age, Exp. 1) and finisher (n = 70, 59 kg initially, Exp. 2) pigs were conducted to compare quality protein maize (QPM, .40% lysine) and normal corn (.31% lysine) in simple corn-based diets containing the same levels of soybean meal. In Exp. 1, pig performance was similar (P greater than .10) on all diets, regardless of the level of soybean meal, suggesting that QPM and normal corn have similar feeding value in lysine-adequate (.99 to 1.11%) diets. In Exp. 2, less soybean meal was needed in QPM than in normal corn diets to maximize performance; increasing soybean meal from 10.8 to 13.8% improved rate (P less than .05) and efficiency (P less than .01) of gain of pigs fed normal corn diets but had no effect on performance of pigs fed QPM diets. A QPM-based diet containing 6% soybean meal and supplemental lysine and tryptophan failed to maximize feed efficiency, but growth rate was equal to that obtained on the normal corn diet with 13.8% soybean meal. The apparent fecal digestibility of GE and ileal digestibility of N were similar for QPM and normal corn, but apparent ileal digestibility of most essential amino acids was slightly higher for QPM (Exp. 3). Experiment 4 compared apparent digestibilities of QPM, conventional opaque-2 corn and two high-protein corns. Digestibilities differed (P less than .05) among the corns, but the absolute differences were small and were likely due to differences in amino acid content of the corns.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prediction of protein and amino acid composition and digestibility in individual feedstuffs and mixed diets for pigs using near-infrared spectroscopy

Knowledge of the amounts and digestibility of amino acids in pig feedstuffs is essential for calculating the appropriate inclusion level in a complete diet. Wet chemical analysis and in vivo digestibility trials are time-consuming and costly and cannot be used for routine assessment. Near-infrared spectroscopy (NIRS) offers a rapid, cost effective and environmentally friendly method for evaluating feedstuffs. Calibrations models were developed using NIRS to predict the content of crude protein and 18 amino acids from a wide range of feedstuffs used in pig production (n = 607). The samples ranged from single feed ingredients (containing amino acids from 0.3 to 129.8 g/kg of dry matter) to feed mixtures (containing amino acids from 1.2 to 53.2 g/kg of dry matter). The predictive ability of the calibrations was tested with an independent dataset (n = 150) and with cross-validation. Furthermore, we compare these calibrations with calibrations developed on more narrowly defined groups of samples and with predictions from regression analysis of crude protein. The models were able to predict the concentrations of crude protein and 18 amino acids with good levels of precision and high coefficients of determination for calibration (RSQ ^CAL) from 0.91 to 0.99 and validation (RSQ^VAL) from 0.87 to 0.97. Calibration models were able to predict all amino acids except tryptophan and valine with greater accuracy than those from protein regression. We also developed calibration models to predict the apparent ileal and total tract digestibility of protein and amino acids. With the exception of tryptophan, RSQ values (>0.7) and standard error of cross validation (SECV) values (<5%) were obtained for the digestibility of most of the amino acids. In conclusion, NIRS can be used to predict crude protein and amino acid concentrations from a wide range of single ingredients and feed mixtures used for pig diets without separate models for each feedstuff. The digestibility of protein and amino acids can be predicted with an acceptable accuracy to be useful in formulating pig diets.