Determination of amino acid digestibility using caecectomised and intact adult cockerels

Four subsamples of meat and bone meal (MBM) were heated (150 degrees C) for 0, 1.5, 3 and 5 h and then incorporated into four individual diets (100 g MBM/kg diet). The diets were precision-fed to 10 caecectomised and 10 intact adult cockerels. The apparent amino acid digestibility (ApAAD) and true amino acid digestibility (TAAD) of the diets were determined by analysis of the excreta. The digestibility coefficients measured using caecectomised birds were lower than those determined with intact birds. Coefficients of digestibility were statistically examined by analysis of variance for the effects of bird type (caecectomised or intact), type of calculation (apparent or true) and diet (heat-treatment) with and without accommodation for individual bird variability. If individual bird variability was not considered in the analysis the bird type X diet interactions (P less than 0.01) included glutamic acid, tyrosine and serine. When individual bird variability was included in the analysis, significant (P less than 0.01) bird type X diet interactions occurred for aspartic acid, serine, glutamic acid, leucine, tyrosine and lysine and the precision of the data was markedly improved. Amino acid digestibility using the precision-feeding procedure is affected by the selection of either intact or caecectomised birds.     

True ileal amino acid digestibility and endogenous ileal amino acid losses in growing pigs fed wheat shorts- or casein-based diets

Use of dietary AA in growing pigs reflects digestion and use of digested AA for various body functions. Before evaluating dietary effects on use of digestible AA intake for body protein deposition, a digestibility study was conducted to investigate true ileal AA digestibility and endogenous ileal AA losses in growing pigs fed graded levels of wheat shorts (WS) or casein (CS; control). A casein-based basal diet (basal) was formulated to contain 0.27 g of standardized ileal digestible (SID) Lys per MJ of DE, to which extra Lys was added from WS (WS2, +0.10 g of SID Lys per MJ of DE; WS3, +0.20 g of SID Lys per MJ of DE) or casein (CS3, +0.20 g of SID Lys per MJ of DE). A fifth diet was formulated to be similar in CP level and source as CS3 but in which 6% pectin, a source of soluble non-starch polysaccharides (NSP), was included at the expense of cornstarch (CS3 + pectin). Five Yorkshire barrows (17.5 +/- 1.5 kg of BW) were fitted with a T-cannula at the distal ileum and randomly assigned to 1 of the 5 experimental diets in a 5 x 5 Latin Square design. Apparent ileal digestibility (AID), true ileal digestibility (TID), and endogenous ileal protein losses (EPL) were determined using the homoarginine method. Diet CS level did not influence (P > or = 0.10) TID of most essential AA or EPL (10.4 g/kg of DM intake). Including pectin in the diet did not influence TID of AA (P > or = 0.10) but increased EPL (15.6 g/kg of DM intake; P > or = 0.01). Inclusion of WS in the diet reduced TID of most essential AA (P < 0.01). The TID values for most essential AA, however, were the same (P > or = 0.10) for both dietary WS levels, except for Lys and Met, which were further reduced at the greatest dietary WS level. Increased EPL (P < 0.01) was only observed for WS3 (16 g/kg of DMI). We concluded that (1) the effects of dietary protein source on AID of AA can be attributed both to reduced TID of AA and increased EPL, (2) the impact of dietary WS level on TID of AA and EPL does not seem to be linear, (3) soluble NSP from pectin or WS exerts a greater effect on EPL than insoluble NSP, and (4) because of the metabolic cost associated with EPL and the impacts of feed composition on microbial fermentation in the gut lumen, the effects of feed ingredients on the use of ileal digestible AA for protein deposition should be investigated further.     

Influence of caecectomy and dietary protein concentration on apparent excreta amino acid digestibility in adult cockerels

1. The influence of caecectomy and dietary crude protein content (50, 100, 150, 200 and 250 g/kg diet) on the apparent excreta amino acid digestibilities in adult cockerels fed on semi‐purified diets containing soyabean meal (SBM) or cottonseed meal (CSM) as the sole source of protein was investigated.

2. Caecectomy had no influence on the apparent digestibilities of most amino acids in SBM, the exceptions being histidine, arginine and lysine, but lowered the apparent digestibility of amino acids in CSM.

3. The protein content in assay diets has a strong influence on the apparent amino acid digestibility values for poultry. Apparent values are lower when the dietary protein content is low.

4. The use of a single endogenous amino acid output value, generated by regression analysis or protein‐free diets, for true digestibility adjustments across a wide range of protein intakes is questioned. In particular, such an application will penalise estimates of apparent digestibility when the dietary protein content is high.     

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.     

饲料回肠末端氨基酸消化率测定方法的研究

畜禽饲料回肠消化率是一项评评价饲料营养价值更有效的指标,和以配制日粮,更符合畜禽对营养物质的需要,饲料因种类,来源及加工处理不同,回肠消化率也表现出差异;同时饲料回肠消化率又受动物年龄,性别、生长阶段及生产目的影响。     

Nitrogen balance and ileal amino acid digestibility in growing pigs fed diets reduced in protein concentration

Two studies were conducted to assess the effect of dietary protein reduction on N utilization, N excretion, and AA digestibility in growing pigs. The objective was to determine whether pigs fed diets with a reduced CP concentration could maintain the same N retention as pigs fed an adequate diet. The second objective was to test whether reducing dietary CP concentration decreases AA digestibility. In each study, six barrows were allotted to one of six dietary treatments in a Latin square design. Treatments consisted of four corn-soybean meal-based diets containing 15, 12, 9, and 6% CP, a casein-based diet containing 15% CP, and a protein-free diet. Crystalline AA were included in the 12, 9, and 6% CP diets. The indispensable:dispensable AA ratio was maintained at 45:55 with the addition of L-glutamic acid to the 9 and 6% CP diets. The casein-based and protein-free diets were used to determine endogenous total tract N and ileal AA losses. In the first study, total N losses and N absorbed decreased linearly (P < 0.001) as dietary CP concentration decreased from 15 to 6%. Both a linear (P < 0.001) and a quadratic (P < 0.05) decrease in N retention were found with decreasing dietary CP concentration. Nitrogen retained as a percentage of intake and absorbed increased (P < 0.001) as dietary CP concentration was reduced from 15 to 6%. In the second study, six barrows were surgically fitted with a T-cannula at the terminal ileum to determine ileal AA digestibility. For all dispensable and most indispensable AA, apparent and standardized ileal digestibility increased linearly (P 0.01, and for arginine, P < 0.05) as dietary CP concentration decreased. These results indicate that dietary CP concentration can be decreased from 15 to 12% with crystalline AA supplementation to meet an ideal AA profile without adversely affecting N retention, and that decreasing dietary CP concentration from 15 to 6% increases both dispensable and indispensable AA ileal digestibility.     

Determination of basal ileal endogenous losses and standardized ileal digestibility of amino acids in barley fed to growing pigs

Background: Basal ileal endogenous amino acid(AA) losses(IAA_(end)) and standardized ileal digestibility(SID) values of cereal grains, such as barley, are apparently underestimated when determined according to the nitrogen(N)-free method. Regression analysis between the dietary apparent ileal digestible content(c AID) and total crude protein(CP) and AA can be considered as alternative approach to obtain more accurate values for IAA_(end)and SID of AA in cereal grains.Methods: Eight hulled barley genotypes were used, with barley being the only source of CP and AA in the assay diets. The diets contained 95 % as-fed of these eight barley genotypes each, ranging in CP content between 109.1 and 123.8 g/kg dry matter(DM). Nine ileally T-cannulated barrows, average body weight(BW) 30 ± 2 kg, were allotted to a row-column design comprising eight periods with 6 d each and nine pigs. On d 5 and the night of d 6 of every period, ileal digesta were collected for a total of 12 h. The IAA_(end) and the SID were determined by linear regression analysis between c AID and total dietary CP and AA.Results: There exist linear relationships between cA ID and total CP and AA(P 0.001). The IAA_(end) of CP, Lys, Met, Thr and Trp amounted to 35.34, 1.08, 0.25, 1.02 and 0.38 g/kg DM intake(DMI), respectively, which are greater compared to average IAA_(end) determined previously under N-free feeding conditions. The SID of CP, Lys, Met, Thr and Trp was 90,79, 85, 79 and 86 %, respectively, and was greater when compared to tabulated values. Moreover, these SID values were greater than those reported in literature, based on correction of apparent ileal digestibility(AID) of CP and AA for their IAA_(end)values. Summarized, the results of the present regression analysis indicate greater IAA_(end)in barley-based diets compared to those obtained by N-free feeding.Conclusions: For low-protein feed ingredients like barley the regression method may be preferred over correction of AID values for their IAA_(end)determined under N-free feeding conditions, as intercepts and slopes of the linear regression equations between cA ID and total dietary CP and AA provide direct estimates of IAA_(end)and SID of CP and AA in the presence of the assay feed ingredient.     

Standardised amino acid digestibility of wheat distillers' dried grains with solubles in force-fed cockerels

1. In recent years, policies encouraging the production of ethanol from maize or wheat have stimulated an increased production of distillers' dried grains with solubles (DDGS) for which the nutritional value for poultry is poorly described, especially in the case of wheat DDGS. 2. DDGS samples (19) were obtained from 7 plants in Europe from June to September 2007. Each sample was analysed for chemical composition and 10 representative samples were measured for amino acid (AA) content and their standardised digestibility (SDD) in caecectomised cockerels. Lightness score (L) of each DDGS was also measured. 3. Results indicated a rather stable crude protein content (327 to 392 g/kg DM) but the AA profile was variable between samples. Lysine (LYS) was the most affected AA with contents ranging between 0·83 and 3·01 g/100 g CP. In addition, only 0·76 of total LYS were free if estimated by the fluoro-dinitro-benzene procedure and 0·85 of total LYS were free if estimated by the furosine procedure. 4. The SDD of LYS was also highly variable (-0·04 to 0·71) with the lowest values observed for DDGS samples with a low LYS content in CP; these latter samples had also a high occurrence of Maillard reactions and low L values (<50). Consequently, both LYS content in CP (r = 0·63) and SDD of LYS (r = 0·64) values were positively related with L. 5. Our data indicate that LYS SDD can be accurately predicted from LYS content in CP according to a quadratic (R(2 )= 0·94) or a linear-plateau model (R(2 )= 0·90; breakpoint for 1·9 g/100 g lysine in CP and a 0.63 plateau SDD value).     

The rat as a model animal for the growing pig in determining ileal amino acid digestibility in soya and milk proteins

The growing pig is an established model animal for humans to determine protein digestibility to the end of the small intestine. An ileal amino acid digestibility assay based on the laboratory rat offers an alternative. True ileal amino acid digestibility in high quality refined protein sources was determined and compared between the laboratory rat and the growing pig. Both species of animals were fed their daily ration in nine separate meals. Ileal digesta were collected at slaughter and chromic oxide was used as an indigestible marker. For several of the amino acids examined, there were no significant (p < 0.05) differences between the two species for true ileal amino acid digestibility, but for aspartic acid, serine, cysteine, methionine, tyrosine, phenylalanine and histidine, significant (p < 0.05) interspecies differences were found. The overall average amino acid digestibility, for all amino acids and all diets, was 95.8% for the pig and 96.1% for the rat. Cysteine digestibility was highly variable between individual animals fed the same diet. The extent of amino acid digestion and absorption appears to be broadly similar across the two species, but some important differences in digestibility were recorded.     

Linear regression approach to study amino acid digestibility in broiler chickens

1. An experiment was conducted to investigate whether a linear regression approach is a suitable tool for determining the amino acid (AA) digestibility up to the terminal ileum of broiler chickens. Solvent-extracted rapeseed meal (RSM) was used as the model ingredient. 2. Ten diets with 5 different inclusion rates of RSM (60, 120, 180, 240 and 300 g/kg, corresponding to crude protein concentrations from 170 to 250 g/kg in the diet), each without or with a supplementation of phytase (500 U/kg), were fed ad libitum to broiler chickens between 14 and 21 d of age. Seven pens of 12 chickens were allocated to each treatment. Digesta were sampled on a pen basis from the section of the gastrointestinal tract between Meckel's diverticulum and 2 cm anterior to the ileo-caeco-colonic junction. Titanium dioxide was included as an indigestible marker. 3. The amounts of crude protein and AAs digested up to the terminal ileum constantly increased with increasing AA intake over the entire range of intakes. When the amount of an AA digested at the terminal ileum is linearly regressed against its intake, the deviation of the slope from 1 is caused by both the unabsorbed AA from RSM and from specific endogenous losses related to RSM. These slopes varied between 0.68 and 0.88 for individual AAs, and the slopes were unaffected by phytase supplementation. 4. It is suggested that a linear regression approach be adopted to study the AA digestibility of raw materials in chickens. Digestibility determined this way does not need any correction for basal endogenous loss.     

生长猪常用饲料中氨基酸消化率评定的研究

运用平衡试验法,以在回肠末端装有简单T型瘘管的去势生长公猪为试材,以玉米淀粉-葡萄糖-玉米芯粉为基础饲粮,用待测饲料原料替代玉米淀粉的方法,配制成试验饲粮,采用4×4拉丁方设计,先后评定了生长猪用18种常规饲料回肠末端氨基酸的表观消化率。试验结果表明,采用平衡试验法,评定饲料中氨基酸猪回肠末端表观消化率的方法是可行的。试验的结果为猪全价无公害饲粮的合理配置提供了科学依据,同时也丰富了我国饲料数据库。     

精油对生长猪蛋白质和氨基酸等回肠末端表观消化率的影响

试验旨在通过采用T型瘘管法,研究精油对生长猪蛋白质和氨基酸等回肠末端表观消化率的影响。试验选用6头(杜×长×大)去势公猪([28.6±1.3)kg],采用3×3双拉丁方试验设计,分别饲喂正对照日粮:玉米-豆粕型基础日粮+抗生素;负对照日粮:无抗基础日粮;精油组日粮:负对照+0.01%精油。每个试验期为7 d,前5 d为适应期,后2 d为食糜收集期。结果表明,在日粮中添加精油可提高(P<0.05)蛋白质、能量、精氨酸、赖氨酸、亮氨酸、色氨酸、蛋氨酸、丙氨酸、总必需氨基酸、总氨基酸的回肠末端表观消化率,并有提高干物质、苏氨酸、天冬氨酸、丝氨酸和酪氨酸表观消化率的趋势(P<0.10)。在日粮中添加0.01%的精油可提高生长猪蛋白质、能量、总必需氨基酸和总氨基酸的回肠末端表观消化率,并有提高干物质表观消化率的趋势。     

Evaluation of a high-protein DDGS product in broiler chickens: performance,nitrogen-corrected apparent metabolisable energy,and standardised ileal amino acid digestibility

ABSTRACT

1. New production processes and additional uses for corn co-products have increased the availability of distiller’s dried grains with solubles (DDGS) with varying energy and amino acid digestibility, for use in poultry feed. The objective of this study was to determine the performance, N-corrected metabolisable energy (AME_n), and amino acid (AA) digestibility of a 34% CP (as fed) high-protein DDGS (HP-DDGS) included in poultry diets for Cobb 500 broiler chickens.

2. A total of 832 Cobb 500 broilers were randomly assigned to four dietary treatments containing 5% conventional DDGS (CV-DDGS) as a control or 10%, 15% and 20% HP-DDGS and fed for 42 d. After the performance trial, 240 birds from the original 832 were selected for a concurrent AME_n and AA digestibility experiment consisting of two AME_n diets and two AA diets.

3. Birds fed diets containing 15% and 20% HP DDGS gained less weight than birds fed the CV-DDGS (P < 0.05) but did not differ in feed intake (FI), and therefore had a less efficient FCR than the control (P < 0.05). The AME_n of HP-DDGS was determined to be 11.4 MJ/kg. The standardised ileal amino acid digestibility (SIAAD) of the essential amino acids Lys and Met were determined to be 80.9% and 88.6%, respectively.

4. HP-DDGS can be included in broiler diets up to 10% without any negative impact on performance or requiring supplemental Lys and Arg. The results from the AA digestibility study indicated that HP-DDGS could be a good source of digestible Lys.     

鲁梅克斯K-1草粉猪氨基酸回肠真消化率的测定

选用8头平均体重为(35.5±1.5)kg去势公猪(约克夏×长白×北京黑),分别在回肠末端安装简单T型瘘管,待恢复10d后,挑选其中恢复良好的5头猪,根据5×5拉丁方设计,分别饲喂5种以玉米淀粉为基础配制成的半纯合日粮。其中4种玉米淀粉—豆粕型日粮分别包括39.0%,37.1%,35.1%和31.2%的豆粕及0,5%,10%和20%的鲁梅克斯K-1草粉。第5种日粮为酪蛋白日粮,用于测定内源氨基酸的排出量。分别采用差减法和回归法比较测定了鲁梅克斯K-1草粉氨基酸回肠真消化率。结果表明,随着日粮中鲁梅克斯K-1草粉含量的增加,除组氨酸、缬氨酸和丙氨酸外,其它氨基酸及粗蛋白质的回肠真消化率均显著降低(P<0.05)。当利用差减法测定鲁梅克斯K-1草粉的氨基酸消化率时,其可靠性随着鲁梅克斯K-1草粉在日粮中比例的提高而提高,当鲁梅克斯K-1草粉在日粮中的含量较高时(20%的鲁梅克斯K-1草粉),利用差减法和回归法测得鲁梅克斯K-1草粉粗蛋白质或氨基酸的回肠真消化率没有显著差异。     

生长猪回肠氨基酸消化率的标准化测定方法

根据荷兰CVB(1996)和德国GfE(2002、2005)的最新规定,提出了生长猪回肠氨基酸消化率测定的一个标准化方法。本文从①试验动物、猪舍环境和饲喂条件,②消化糜的收集及处理,③回肠氨基酸消化率测定方法三个方面比较了这些规定之间的差异和相似性。     

Standardization of methods for the determination of ileal amino acid digestibilities in growing pigs

Based on current recommendations of the CVB (1996) in the Netherlands and the GfE (2002, 2005) in Germany, a standardization of methods for the determination of ileal amino acid digestibilities in growing pigs is proposed. Differences and similarities between these protocols in terms of (i) animals, housing and feeding conditions (ii), methods for digesta collection and handling, and (iii) approaches to determine ileal amino acid digestibilities are described.     

Apparent and true amino acid digestibility of a crystalline amino acid mixture and of casein: comparison of values obtained with ileal-cannulated pigs and cecectomized cockerels.

Six ileal-cannulated pigs that averaged 100 kg BW and 16 adult cecectomized cockerels that averaged 2.35 kg BW were used to determine apparent and true digestibilities of amino acids (AA) in a complete crystalline AA mixture and in casein. A protein-free (PF) diet was included as a treatment to estimate endogenous AA losses. Fasted cockerels were compared to cockerels fed PF diets for calculation of true digestibility of AA in cockerels. For the AA diet, true digestibility of indispensable AA in the pig ranged from a low of 97.2% for leucine to a high of 100.5% for arginine (Arg). True digestibility of indispensable AA in casein ranged from a low of 93.5% for isoleucine (Ile) to a high of 99.9% for Arg. Correcting for endogenous losses increased digestibilities of lysine (Lys) and threonine (Thr) in pigs fed the AA diet by 2.4 and 7.1%, respectively, and increased Lys and Thr digestibility in pigs fed the casein diet by 1.8 and 6.1%, respectively. Feeding a PF diet to chickens to correct for endogenous losses resulted in higher true digestibility values for all AA with the exception of tryptophan, methionine, and Arg than those obtained using fasted animals. True digestibilities of Thr were 88.3 and 86.6% for AA and casein diets, respectively, using fasted controls but were 97.5 and 94.5% when the PF control was used. Proline digestibility was increased (P < .05) substantially in both pigs and cockerels when the PF control was used to correct for endogenous AA losses. Regardless of species, Ile in casein had a lower true digestibility value than any other indispensable AA. The results of this study indicated that true digestibilities of AA in a mixture of crystalline AA and in casein are essentially 100% in both pigs and cockerels.     

Effect of dietary fibre and caecectomy on the excretion of endogenous amino acids from adult cockerels

1. Eight diets based on maize starch and sucrose were prepared, containing ground maize husks or semi-purified wood cellulose, with 30, 60, 90 or 120 g fibre source/kg diet dry matter (DM). 2. The diets were precision-fed to 12 caecectomised and 12 intact adult male domestic fowls. The quantities of amino acids and faecal N excreted over the 48 h following each feeding were measured. 3. Diet had no influence on the quantities of endogenous amino acids or endogenous faecal N excreted. 4. A proportion of the amino acids and N of the maize husks and of endogenous origin appeared to be degraded or retained in the caeca of intact birds.     

Ileal amino acid digestibility and performance of growing pigs fed wheat-based diets supplemented with xylanase

Two experiments were conducted to determine the effect of supplementation of xylanase to a wheat-based diet on the apparent ileal digestibility (AID) of AA and the performance of growing pigs fed diets limiting in AA. In Exp. 1, eight pigs (average initial BW = 20.5+/-1.2 kg) fitted with a simple T-cannula at the distal ileum, were fed four diets according to a repeated 4 x 4 Latin square design. Diet 1 was a basal diet that contained 97.6% wheat. Diets 2, 3, and 4 were the basal diet supplemented with xylanase at rates of 5,500, 11,000, and 16,500 units of xylanase activity (XU), respectively (as-fed basis). There were linear and quadratic effects (0.062 < P < 0.001) of xylanase supplementation on the AID of CP and most of the AA. The largest increases in AID of CP and AA were obtained when xylanase was supplemented at a rate of 11,000 XU; no further increases were observed with xylanase supplementation at a rate of 16,500 XU. In Exp. 2, 30 pigs (average initial BW 21.4+/-1.8 kg) were randomly allotted to six dietary treatments. Diets 1 to 4 were similar to those used in Exp. 1. Diet 5 was the same as Diet 1, but supplemented with 0.53% lysine, 0.12% threonine, and 0.05% methionine. Diet 6 (positive control diet) was a wheat-soybean meal diet that contained 18.2% CP (as-fed basis). The total contents of lysine, threonine, and methionine were similar for Diets 5 and 6. There was a linear effect of xylanase supplementation on ADG (P = 0.093) and feed:gain ratio (P = 0.089), and a quadratic effect on ADG (P = 0.067) and feed:gain ratio (P = 0.074). But, the greatest response was obtained with the supplementation of 11,000 XU. The supplementation of lysine, threonine, and methionine to Diet 1 increased (P = 0.001) ADG and ADFI and improved (P = 0.01) feed:gain ratio. There was no difference (P = 0.508) in the performance of pigs fed the AA-supplemented or control diet. In conclusion, the supplementation of xylanase to a diet in which wheat provided the sole source of protein and energy improved the AID of AA, ADG, and feed:gain ratio; however, this improvement was very small compared with that obtained with the supplementation of synthetic amino acids.     

味精菌体蛋白粉在肉仔鸡中的能量和回肠氨基酸表观消化率的研究

通过两个试验测定了味精菌体蛋白粉在肉仔鸡中的能量和回肠氨基酸的表现消化率.试验1选用体重相近的22日龄健康肉仔鸡64只,随机分成2个组,每组8个重复,其中一组饲喂基础日粮,另一组饲喂供试日粮.选用二氧化钛(TiO2)为外源指示剂进行代谢试验.以评定肉仔鸡对味精蛋白粉的能量利用率.结果表明:味精菌体蛋白粉对内仔鸡的氮校正能量的表观利用率为(36.07±2.76)%.试验2选用体重相近的26日龄健康肉仔鸡32只,随机分为8组,选用TiO2为外源指示剂,采用回肠末端法进行代谢试验,对味精菌体蛋白粉的回肠末端氨基酸的表现消化率进行评定.结果表明:肉仔鸡时味精菌体蛋白粉中4种限制性氨基酸的回肠末端表现消化率分别为:赖氨酸(44.45±0.04)%、蛋氨酸(64.66±0.11)%、苏氨酸(45.16±0.04)%、胱氨酸(90.12±0.03)%;肉仔鸡对味精菌体蛋白粉中17种氨基酸的回肠末端表观消化率平均值为(48.23±0.62)%.表明内仔鸡对味精菌体蛋白粉中能量和氨基酸的利用率均较低.