Digestibility In Pigs Research Articles

Effect of weaning and dietary galactose supplementation on digesta glycoproteins in pigs

Changes in pig digesta mucin and glycoprotein content at weaning and with the inclusion of galactose in the postweaning diet were studied. Mucus was collected from ileal contents of cannulated pigs pre- and postweaning, and glycoproteins were analysed based on staining patterns and size exclusion chromatography. An increased concentration of intestinal mucin in lumen contents was observed in newly weaned pigs compared to the same pigs prior to weaning. Analysis of O-linked oligosaccharides indicated changes in mucin structure from pre- to postweaning. Supplementing the diet with galactose resulted in modification of mucin in postweaned pigs compared to a control diet and may limit microbial degradation of mucin. These data indicate that weaning and the subsequent transition to a grain-based diet result in changes to digesta mucin and endogenous glycoproteins; and dietary galactose may play a role in the final composition and quantity of these compounds. © 2000 Society of Chemical Industry

Supplementation of pig diet with algal fibre changes the chemical and physicochemical characteristics of digesta

Seaweed extracts, because of their physicochemical characteristics and potential nutritional value, could provide a new source of dietary fibre. This study investigated changes in seaweed fibres (physicochemical and fermentative properties) in different digestive sites and their effects on digesta (viscosity and hydration properties). Sixteen pigs were adapted to a test diet supplemented with 5% algal fibre (either Palmaria palmata (PP), a poorly viscous soluble xylan; or Eucheuma cottonii (EC), a partly insoluble carrageenan; or Laminaria digitata (LD), a highly viscous soluble alginate) or 5% cellulose (reference fibre). PP did not modify the characteristics of digesta and was fermented in the caecum (pH 6.1 ± 0.4; short-chain fatty acids measured in digesta, 1409 ± 691 µmol g−1 dry matter). EC and LD were mainly insoluble in the stomach, becoming soluble in the intestine; EC was slightly fermented in the colon, giving a low concentration of short-chain fatty acids (303 ± 122 µmol g−1 dry matter). Supplementation of the diet with alginate (LD) increased 3.5-fold the ileal viscosity of digesta and their hydration capacity in the ileum and colon. Thus the physicochemical properties of pig digesta largely depend on the physicochemical properties of the ingested seaweed fibre, the pH and ionic conditions prevailing in the gut, and their fermentability. © 2000 Society of Chemical Industry

Nutrient utilization in rats and pigs fed enzyme resistant starch

The influence of 6% dietary raw or retrograded high-amylose corn starch on protein, fat, carbohydrate, energy and mineral utilization was studied in rats and ileum-cannulated pigs fed the same conventional diets. Ileal nitrogen digestibility tended to decrease and faecal nitrogen excretion to increase in pigs fed one of the tested enzyme resistant starch (RS) sources. In rats, the effect from RS intake on faecal nitrogen excretion was more pronounced (P<0.05). These effects were paralleled by a shift of the nitrogen excretion from the renal to the faecal output. As a result, no significant effects from RS on nitrogen retention could be established in pigs and rats. RS consumption tended to lower apparent faecal fat digestibility in rats as well as apparent ileal and faecal fat digestibility in pigs. This effect on faecal fat digestibility was significant in pigs fed retrograded high-amylose corn starch. Faecal starch digestibility was significantly decreased in rats fed RS. Similar effects were found at the terminal ileum in pigs, but not at the anal level possibly due to more intensive fermentation in the large intestine of these animals. Apparent faecal digestible and metabolizable energy values were significantly lower in rats receiving RS. These effects were less pronounced in pigs, although RS intake significantly lowered apparent ileal energy digestibility when retrograded high-amylose corn starch was fed. In vivo determination of the RS concentrations in both test diets using ileum-cannulated pigs revealed values of 2.9% raw and 5.7% retrograded high-amylose corn starch instead of the 6% RS as measured in vitro, indicating that the tested retrograded starch behaved more like RS in the small intestine as compared with the raw starch. RS did not significantly affect apparent faecal absorption or retention of Ca, P, Mg and Zn in rats and pigs. In pigs, RS intake tended to decrease ileal absorption of the minerals, but these effects appeared to be neutralized in the large intestine. Despite the moderate dietary RS content, increases in faecal water content and bulking were found in rats and pigs. In conclusion, the investigated effects from RS ingestion were in general qualitatively similar in both species. Retrograded high-amylose corn starch, as compared with raw high-amylose corn starch, often exerted more pronounced effects, but the differences were not always significant.

Effects of L-Carnitine with Different Lysine Levels on Growth and Nutrient Digestibility in Pigs Weaned at 21 Days of Age

Effects of L-Carnitine with Different Lysine Levels on Growth and Nutrient Digestibility in Pigs Weaned at 21 Days of Age

Determination of endogenous nitrogen associated with bacteria in ileal digesta of pigs receiving cereal-based diets with or without fish meal and various fibre supplements by using a simple &lt;sup&gt;15&lt;/sup&gt;N-dilution technique

Determination of endogenous nitrogen associated with bacteria in ileal digesta of pigs receiving cereal-based diets with or without fish meal and various fibre supplements by using a simple &lt;sup&gt;15&lt;/sup&gt;N-dilution technique

Digestibility of bacterial protein grown on natural gas in mink, pigs, chicken and Atlantic salmon

The composition and amino acid digestibility of bacterial protein meal (BPM) produced by Methylococcus capsulatus (Bath), Alcaligenes acidovorans, Bacillus brevis, and Bacillus firmus grown on natural gas were studied. The BPM contained 959 g kg −1 dry matter, 702 g kg −1 crude protein, 103 g kg −1 fat, and 95 g kg −1 nucleic acids. The amino acid composition of BPM was similar to that of fish meal, except for less lysine (6.1 vs. 8.6 g/16 g N) and more tryptophan (2.1 vs. 0.9 g/16 g N). Total tract apparent digestibility (TTAD) in mink, chickens and pigs, and apparent ileal digestibility (AID) in pigs, were obtained by feeding BPM as the sole source of protein. In salmon, TTAD was measured by regression, using diets where BPM substituted fish meal. The average TTAD of total N from BPM was 79.0%, 85.4%, 80.5%, and 81.9% in mink, pigs, chickens and salmon, respectively. Ileal N digestibility in pigs was 78.1%. There were substantial differences among digestibilities of individual amino acids. Arginine and lysine revealed the highest digstibilities and cystine the lowest. The average TTAD coefficients for lysine were 88.7%, 89.2%, 82.6% and 91.7% in mink, pigs, chickens and salmon, respectively, whereas lysine AID in pigs was 84.5%. Average TTAD for cystine was 47.2% in mink, 77.0% in pigs, 44.7% in chickens and 51.9% in salmon. Cystine AID in pigs was 54.9%. Methionine showed TTAD values ranging from 80.9% in chickens to 84.5% in mink, and a pig AID of 83.8%. There were highly significant correlations among the TTAD coefficients of BPM in mink, chicken and salmon, and among the latter figures and AID in pigs ( p<0.001). Although highly significant, the TTAD coefficients in pigs were less correlated to TTAD in mink, chickens and salmon than pig AID ( p<0.001). It appears that small intestine digestion and overall uptake of amino acids from BPM were similar among the investigated species.

The 15N Amino Acid Dilution Method Allows the Determination of the Real Digestibility and of the Ileal Endogenous Losses of the Respective Amino Acid in Pigs

We assessed the influence of sampling site when using the isotope dilution method to determine ileal endogenous N losses. Three growing pigs were prepared with ileorectal anastomoses and fitted with three catheters (portal, jugular and carotid). A 15N-leucine solution was infused for 24 d, alternating between the carotid artery and the jugular vein. Blood was sampled from the portal catheter and from the systemic catheter not used for the infusion. The pigs were fed successively a protein-free diet, an isolated pea protein diet and a hydrolyzed pea protein diet according to a Latin-square design. The 15N was transferred from leucine to isoleucine, valine, alanine, glycine and proline. Free 15N alanine, glycine and valine enrichments were closer to the respective amino acid enrichments in secretory tissues in the portal vein than in the systemic blood. The enrichment of total nitrogen was higher in the trichloroacetic acid–soluble fraction of the plasma than in the ileal digesta of pigs fed the protein-free diet. Lysine enrichment was significantly different from zero in all tissues except muscle, suggesting that essential amino acids can be synthesized by microflora and used for protein synthesis in the host. We conclude that the total nitrogen isotope dilution method is inappropriate to determine the endogenous loss of amino acids. Moreover, the amino acid dilution method should be performed with portal blood sampling. The main limititation of this method is that a number of essential amino acid losses cannot be determined.

Digestion of Carbohydrate from White Beans (Phaseolus vulgaris L.) in Healthy Humans

Resistant starch (RS) is thought to be present in large amounts in legume seeds; however, it has never been quantified in healthy humans. RS from cooked (atmospheric pressure) white beans was quantified in humans and pigs, and characterized to explain its low digestibility. Six human volunteers were intubated to collect ileal digesta after an experimental meal composed of orange juice, butter and 167 g beans (dry matter basis). The reliability of the intubation method was examined in a pig study in which it was compared with another collection method, ileal cannulation. Chemical analyses, microscopy and size exclusion chromatography were performed on human and pig digesta. The pig study showed that the intubation method may underestimate the quantity of RS. However, no chemical/physical difference was observed between the RS collected by the two techniques. In the human study, 16.5 ± 1.3% (11.3 g) of the ingested starch was recovered as RS. The microscopy of the digesta showed that part of the RS was enclosed in the cell walls. Although the RS was composed mainly of α-glucan molecules with a degree of polymerization (DP) 40 to 60, oligosaccharides and large molecules of DP > 400 were also present. Retrogradation was not found to be the main factor responsible for starch malabsorption. We conclude that white beans may contain a large amount of RS formed mainly by partially degraded molecules protected by the cell walls during their transit through the gut.

Flow of endogenous and exogenous nitrogen in different segments of the small intestine in pigs fed diets with soyabean concentrate, soyabean meal or rapeseed cake

Six barrows of an average initial BW 27.5±1.2 kg were used. Each pig was fitted with two cannulas in different segments of the small intestine: pig 1 in the duodenum (C1) and upper jejunum (C2), pig 2 in C2 and the lower jejunum (C3), pig 3 in C2 and C3, pig 4 in C1 and the terminal ileum (C4), pig 5 in C3 and C4, pig 6 in C1 and C4. Pigs were also fitted with one catheter in the vena jugularis for blood sampling and with a second one in the arteria carotis for continuous infusion of 15N-leucine (4.2 mg/kg0.75 BW/d). Pigs were used in a crossover design experiment with three treatments and three periods of digesta collection (36 h) and blood sampling (36 h). Maize starch-based diets that contained: soyabean concentrate (SC), a mixture of toasted and untoasted soyabean meal (mSBM) of a high trypsin inhibitor activity, or rapeseed cake (RC) of a high NDF content were used in the experiment. The flow of endogenous and exogenous N along the small intestine and the net reabsorption rate of endogenous N were estimated. In the C1 digesta of pigs fed on the SC, mSBM and RC diets, total N was 138, 127 and 126% of the ingested N, respectively. Sixteen, 15 and 10% of the ingested N was absorbed up to C1, and 11.1, 11.6 and 9.4 g of endogenous N (Ed-N) per kg DM intake was secreted, respectively. For corresponding diets in the C2 digesta, total N was 126, 117 and 111% of the ingested N. Thirty four, 11 and 31% of the exogenous N (Ex-N) inflow and -32, 1 and -39% of the Ed-N inflow was absorbed. In the C3 digesta, total N was 44, 47 and 43% of the ingested N, while 81, 71 and 71% of the Ex-N inflow and 54, 38 and 49% of the Ed-N inflow was absorbed, respectively. Accordingly, in the C4 digesta total N was 24, 33 and 33% of the ingested N, and 45, 43 and 4% of the Ex-N inflow was absorbed. True N digestibility at the terminal ileum was 94, 88 and 82% for the SC, mSBM and RC diets. The reabsorption rate of endogenous N before the terminal ileum was estimated as 75, 51 and 69%, respectively. It was concluded that regardless of the dietary protein source, the middle segment of the small intestine is the site of the most intense absorption of endogenous and exogenous N. Reabsorption rather than secretion of endogenous nitrogen along the pig's small intestine seems to be influenced by dietary factors.

Effects of sorghum endosperm hardness and processing on growth performance and nutrient digestibility in pigs and broiler chicks (1998)

Effects of sorghum endosperm hardness and processing on growth performance and nutrient digestibility in pigs and broiler chicks (1998)

Use of the mobile nylon bag technique (MNBT) in combination with the ileo-rectal anastomosis technique (IRA) to determine amino acid digestibility in pigs

Four Large White boars were surgically modified by means of the ileo-rectal anastomosis technique (IRA) and also fitted with a simple duodenal cannula. A conventional ileal digestibility trial (randomised block design with four treatments and six periods used as replicates) collecting total ileum digesta (TIC) was performed ( n = 6). Treatments applied were: maize meal 75%; maize meal + 25% fish meal or sunflower meal (SM); and a standard diet (containing maize meal, fish meal and SM). The MNBT was applied after the digestibility trial, during which the pigs received the standard diet. Polyester bags containing the feed samples (standard diet, fish meal, SM or maize meal) were pre-digested with pepsin. No differences ( P > 0.05) were found in apparent essential amino acid (AA) digestibilities between the two methods for maize meal, SM or the standard diet. MNBT determined apparent AA digestibility values for fish meal were lower ( P ≤ 0.05) for leucine (5.5%), phenylalanine (6.4%), histidine (5.0%), arginine (5.3%) and cystine (5.5%) than that obtained with the TIC-method. Mixed (standard) diet digestibility values calculated for the different AA were consistently lower than actual values directly determined by the MNBT. These results show that the MNBT combined with the IRA-technique can be successfully used to determine the apparent AA digestibility of feedstuffs. Apparent AA digestibility values individually determined with the MNBT can be used with some measure of accuracy to formulate practical pig diets.

Diurnal Variation in the Composition of Ileal Digesta and the Ileal Digestibilities of Nutrients in Growing Pigs

Diurnal variation in the chemical composition of digesta and its effect on nutrient digestibilities of diets varying in dietary fibre content was examined in pigs fitted with a PVTC-cannula at the terminal ileum. The pigs were fed three times a day (08:00, 16:00 and 24:00 h). A barley control diet and four barley-based diets containing two levels (100 or 200 g kg-1 diet) of alfalfa meal or white clover meal and Cr2O3 as an indigestible marker were fed according to a 5×5 Latin square design. In each experimental period, digesta were collected for 1 h every third hour on each of two separate sampling days, covering in total a 24 h period. The concentration of dry matter (DM), crude protein (CP), ash and chromium (Cr) in the ileal digesta varied in relation to time of feeding. However, the patterns were similar after all three meals (08:00, 16:00 and 24:00 h) and independent of diet. The maximum DM, CP and ash contents were reached 4–5 h post-feeding. The highest (P < 0·05) DM concentration was found in the ileal digesta of pigs fed the barley control diet. The DM concentration decreased (P < 0·05) as the inclusion level of alfalfa meal and white clover meal was increased. The lowest DM concentration was found for the highest inclusion level of alfalfa meal. The ileal digestibilities of both organic matter and CP were lower 1–2 h post-feeding compared with those recorded 3–5 h later, indicating that the less digestible components of a diet have shorter transit times. The pooled ileal digestibilities of organic matter and CP from the three 8 h periods (08:00–16:00 h, 16:00–24:00 h, 24:00–08:00 h) did not differ (P < 0·05) from each other. Therefore, the estimate of digestibility can be based on digesta samples collected from any interval between two consecutive meals. However, care must be taken to obtain representative samples of digesta between meals. © 1997 SCI.

Chemical composition of plantain foliage (&lt;i&gt;Musa paradisiaca&lt;/i&gt;) and the effect of its inclusion in the diet on nutrient digestibility in pig

Chemical composition of plantain foliage (&lt;i&gt;Musa paradisiaca&lt;/i&gt;) and the effect of its inclusion in the diet on nutrient digestibility in pig

Ileal and total tract digestibility in pigs of naked and hulled barley with different starch composition

Ileal and total tract digestibility of dietary components and energy in naked and hulled barley containing starch varying in amylose: amylopectin ratio was studied in a 5 × 5 Latin square design with ileal cannulated growing pigs. There were significant differences in ileal and total tract dietary components digestibilities between naked and hulled cultivars as a result of differences in the content of fibrous components between barley types. Apart from the ileal digestibility of starch, total, insoluble and soluble β-glucans of diets with naked and hulled regular barley, the diet based on naked amylopectin-rich barley showed a significantly ( P < 0.05) higher ileal and total tract digestibility of dietary components and energy than diets of the other barley types. Except for crude fat the diet with naked regular barley showed significantly ( P < 0.05) higher total tract digestibilities than diets with hulled regular and hulled amylopectin-rich barley. At the ileal level, the diet with hulled amylose-rich barley showed significantly ( P < 0.05) lower digestibilities of organic matter, nitrogen free extracts and energy than diets with hulled regular and hulled amylopectin-rich barley. Despite a similar fibre content in diets with naked amylopectin-rich and naked regular barley, ileal nutrient digestibilities were significantly ( P < 0.05) lower in the latter. Apart from organic matter, nitrogen free extracts and energy the diet with naked regular barley showed similar ileal digestibilities as the diet with hulled regular barley. Naked barleys showed a marked advantage compared to hulled barleys with respect to the hindgut digestion expressed as a proportion of the ileal flow of dietary components and energy. The present results indicate that other factors in addition to hull, fibre and β-glucan content are of importance for ileal and hindgut dietary components digestion in barley.

Evaluation of the 15N-isotope dilution technique for determining the recovery of endogenous protein in ileal digesta of pigs: effect of the pattern of blood sampling, precursor pools, and isotope dilution technique.

The 15N-enrichments (atom percentage excess) were determined in the plasma free amino acids of blood samples taken at the time of feeding and in samples taken hourly and pooled over 12 h, as well as in ileal digesta, crude mucin, and bacteria collected at the distal ileum of pigs fed barley while continuously administered [15N]leucine intravenously. The branched-chain amino acids were the only indispensable amino acids to exhibit incorporation of 15N (P < .05). All dispensable amino acids exhibited some incorporation. Enrichments in free leucine and alanine were higher (P < .02) in blood samples taken at the time of feeding, compared to those in pooled blood samples, resulting in an underestimation of the endogenous ileal recoveries of these amino acids. Enrichments in amino acids in crude mucin were usually similar to those in pooled plasma samples, providing some support for the use of plasma free amino acids to estimate enrichments in endogenous amino acids in ileal digesta. Enrichments in bacteria were not different (P > .05) from those in ileal digesta. The recoveries of endogenous amino acids in ileal digesta determined with the [15N]leucine and 15N-amino acid dilution techniques demonstrate the overestimation of these criteria with the 15N-isotope dilution technique, applied in its current form, and suggest that modifications in the composition of endogenous protein can occur when pigs are fed protein-containing diets. These study supports the use of 15N-isotope dilution techniques, with modifications, for determining the recovery of endogenous protein in ileal digesta of pigs fed protein-containing diets.

Evaluation of the 15N-isotope dilution technique for determining the recovery of endogenous protein in ileal digestion of pigs: effect of dilution in the precursor pool for endogenous nitrogen secretion.

Three barrows, average initial BW of 35 kg, were fitted with a re-entrant cannula at the distal ileum and catheters in each of the external jugular veins. The barrows were fed twice daily a diet containing barley as the sole source of protein. A 1-d intravenous infusion of saline was followed by an 8-d continuous infusion of [15N]leucine at a rate of 30 mg/(kg BW x d). Blood samples, taken hourly for 9 d, were pooled over the 12-h period between feeding. Ileal digesta were collected hourly on d 3 and 8 of the [15N]leucine infusion and pooled over 12 and 24 h. Enrichments (atom percentage excess 15N) in nitrogen (N), leucine, isoleucine, valine and alanine were measured in the trichloroacetic acid (TCA)-soluble and -insoluble fractions of plasma and in ileal digesta. Although the enrichments in N were similar in all pools, enrichments in amino acids in the TCA-soluble fraction of plasma were at least twice that in the TCA-insoluble fraction and in ileal digesta. The estimated contributions of endogenous N and amino acids to total N and amino acids in ileal digesta were 82.3 +/- 9.38, 39.0 +/- 3.83, 43.8 +/- 6.50, 51.9 +/- 3.24, and 51.9 +/- 9.80 for N, leucine, isoleucine, valine and alanine, respectively. The results from this study indicate that enrichments in total N in the TCA-soluble fraction of plasma may not accurately reflect enrichments in endogenous N secreted into the intestinal lumen. This factor should be considered when using the 15N-isotope dilution technique to estimate the recovery of endogenous protein in ileal digesta of pigs fed protein-containing diets.

Effect of seaweed fibre added in a diet on the physico-chemical characteristics of pig digesta

Effect of seaweed fibre added in a diet on the physico-chemical characteristics of pig digesta

A comparison of methods for measuring the nutritive value for pigs of a range of hulled and hulless barley cultivars

Six hulled and three hulless barley cultivars were each divided into a high and a low density fraction by the use of a gravity table. These fractions were analyzed for density (wt vol −1), 1000 kernel weight, soluble non-starch polysaccharides (S-NSP), insoluble NSP (I-NSP), lignin, total dietary fibre (TDF, S-NSP plus I-NSP plus lignin), β-glucans, gross energy and crude protein content. Measurements were made on pigs and rats for apparent energy digestibility (AED) and true protein digestibility (TPD, apparent digestibility minus metabolic faecal N), apparent dry matter digestibility in pigs by the mobile nylon bag (MNB) technique, and in vitro digestibility of dry matter and N by simulation of enzymatic activity anterior to the terminal ileum and for the whole gastrointestinal tract. The results obtained were examined for the reliability of various measurements for predicting AED and TPD in pigs. Coefficients of determination were assessed for all sets of measurements for both the total 18 samples and for the 12 hulled samples only. For most measurements, the predictive values were greater when 18 samples were used than when 12 samples were used. Best predictions for AED in pigs were AED in rats ( r 2, 0.97, n = 18; 0.88, n = 12), I-NSP ( r 2, 0.97, n = 18; 0.88, n = 12), in vitro organic matter digestibility ( r 2, 0.97, n = 18; 0.82, n = 12) and MNB dry matter digestibility ( r 2, 0.86, n = 18; 0.85, n = 12). Coefficients of determination were not so high for the estimation of TPD in pigs. The only values showing a strong relationship were obtained for the TPD measurements in rats ( r 2, 0.94, n = 18; 0.88, n = 12).

Methodologica aspects of the in vivo measurement of ileal amino acid digestibility in pigs - A Review -

Methodologica aspects of the in vivo measurement of ileal amino acid digestibility in pigs - A Review -

The effect of condensed tannins from heated and unheated cottonseed on the ileal digestibility of amino acids for the growing rat and pig

The effect of condensed tannins (CT) from heated and unheated cottonseed on the apparent ileal digestibility of amino acids for the growing rat and pig was determined. In Expt 1, twenty-four rats were allocated to four semi-purified diets which contained cottonseed kernel and hulls as the only protein source. Two of the diets contained unheated solvent-extracted cottonseed kernel and hulls, while the remaining two diets contained similar material but which had been heat-treated by autoclaving at 110 degrees for 120 min. In Expt 2, twelve rats and twelve pigs were fed on four semi-purified diets containing commercial cottonseed meal (CSM) as the only protein source. Cr2O3 was added to all diets as an indigestible marker. For each pair of diets in both experiments, PEG was either included or excluded. The effect of CT was assessed by comparing control animals (-PEG; CT acting) with PEG-supplemented animals (+PEG; CT inactivated). Ileal contents from the terminal 150 and 450 mm of ileum were collected at slaughter, 7 h from the start of feeding, for the rats and pigs respectively. Apparent ileal amino acid digestibility for rats fed on the diet containing cottonseed kernel and hulls was significantly depressed by the heat treatment, particularly for lysine and threonine. On average, apparent ileal amino acid digestibility in the diets without PEG was decreased from 0.80 to 0.70 by heat treatment. Dietary cottonseed CT depressed apparent ileal protein digestibility in the pig and in the rat. The addition of PEG to the diets significantly increased the apparent ileal digestibility of N and some amino acids for the pigs and the rats. The mean increase in apparent ileal digestibility due to PEG addition for the fourteen amino acids was 2 percentage units in both species fed on the commercial CSM diets, and 2 or 4 percentage units in rats fed on the unheated or the heated cottonseed kernel and hull diets respectively. The effect of PEG was similar in the heated and unheated cottonseed kernel and hulls for most amino acids, but apparent ileal digestibilities of threonine, tyrosine and lysine were increased more by PEG in heated than in unheated CSM. Apparent ileal N digestibility was lower in the pig than in the rat. For several of the amino acids there were significant animal species differences in apparent ileal digestibility. Studies into the effects of cottonseed CT should be carried out in the target animal species. The commercial CSM had a low apparent ileal amino acid digestibility overall, particularly for the essential amino acids lysine and threonine. It was concluded that effects of heating did not eliminate the reversible reactivity of cottonseed CT on amino acid digestion in rats and pigs but rather appeared to increase it for threonine, tyrosine and lysine in Expt 1, causing large reductions in apparent ileal digestibility of these amino acids.