A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry.

1. The apparent ileal and excreta digestibilities of amino acids in 15 samples representing 12 food ingredients were determined using 5-week-old male broiler chickens. The ingredients included 3 samples of cereals (wheat, maize and sorghum), 6 samples of plant protein meals (soyabean meal, cottonseed meal, canola meal and sunflower meal) and 6 samples of animal protein meals (meat meal, meat-and-bone meal, feather meal and fish meal). 2. The test ingredients were incorporated as the sole source of dietary protein in assay diets. Each diet was offered ad libitum to 3 pens (4 birds/pen) from d 35 to d 42 post-hatching. Total collection of excreta was carried out during the last 4 d. All birds were killed on d 42 and the contents of the lower half of the ileum were collected. Apparent ileal and excreta amino acid digestibilities were calculated using acid-insoluble ash as the indigestible marker. 3. The influence of site of measurement was found to vary among food ingredients, among samples within an ingredient and among different amino acids within an ingredient. Ileal amino acid digestibility values were similar in some ingredients, but significantly lower or higher in others than the corresponding excreta values. 4. Average ileal and excreta amino acid digestibilities in sorghum and maize were similar, but significant differences were observed for individual amino acids. In contrast, ileal amino acid digestibility values were higher than the corresponding excreta digestibility values in wheat. 5. The average ileal and excreta digestibilites of amino acids in the 3 soyabean meal samples were similar although small, but significant differences were noted for individual amino acids. Site of measurement had no effect on the digestibility of amino acids in canola meal. Digestibilities of valine, isoleucine, phenylalanine, histidine, glutamic acid, alanine and tyrosine in sunflower meal and those of valine, methionine, isoleucine, leucine, lysine, glutamic acid and alanine in cottonseed meal were lower by excreta analysis. 6. Digestibilities in animal protein meals, with the exception of blood meal and fish meal, were consistently higher by excreta analysis. Ileal-excreta differences in individual amino acid digestibilities were more evident in feather meal, meat meal and meat-and-bone meal. 7. Threonine and valine were the indispensable amino acids that were more frequently influenced by the site of measurement. Of the dispensable amino acids, aspartic acid, serine, glutamic acid and alanine were the most affected. 8. Differences determined between ileal and excreta digestibilities in the present study clearly demonstrate that amino acid metabolism by hindgut microflora in chickens may be substantial and that digestibilities measured in the terminal ileum are more accurate measures of amino acid availability than those measured in the excreta.     

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.     

Effects of preservation method and beta-glucanase supplementation on ileal amino acid digestibility and feeding value of barley for poultry.

1. Effects of preservation method (drying or air-tight storage of whole grain and ensiling of rolled high-moisture grain) and beta-glucanase supplementation (Econase) on apparent ileal amino acid digestibilities and metabolisable energy content of barley were evaluated with Ross broiler chickens. In addition, the effect of barley preservation method was assessed using Leghorn cockerels. 2. Birds were given either a semi-purified soyabean meal basal diet or a mixture of the basal diet and barley (50:50 on dry matter basis). Apparent ileal digestibilities (AID) of nutrients were assessed using the slaughter technique. AID of nutrients and nutrient digestibility measured using excreta (AED) were determined using chromium mordanted straw as an indigestible marker. 3. In broilers, AID of amino acids, dry matter and organic matter were lower for dried than air-tight stored barley, particularly for diets based on ensiled barley. In cockerels, barley preservation method had no effect on amino acid AID. The AED of nutrients and nitrogen corrected apparent metabolisable energy content (AMEn) was highest for ensiled barley across both experiments. 4. beta-glucanase supplementation increased nutrient digestibility, phosphorus retention and AMEn content of air-tight stored and dried barley diets in particular but had only negligible effects on ensiled barley. Beta-glucanase improved the AID of amino acids in dried barley but not in air-tight stored or ensiled barley. 5. Amino acid digestibilities were lower in broilers than cockerels and the effect of barley preservation on feeding value of barley was different for broilers and cockerels.     

A comparison of amino acid digestibility bioassays for broilers

1. Apparent amino acid digestibilities determined in the lower ileum of broilers given free access to a diet containing normal or heat‐damaged soya protein were similar to “true” digestibilities determined with excreta using the Sibbald rapid bioassay.

2. Higher ileal digestibilities were obtained with the Farrell rapid bioassay than with birds given free access to food. This pattern was reversed when measurements were made on excreta.

3. Maximum absorption of amino acids had occurred by the time the di‐gesta had reached the upper ileum in birds fed on normal but not heat‐damaged soyabean protein.

4. Heat damage to the soyabean protein was detected with all the bioassay procedures.

     

Comparison of amino acid digestibility using the ileal digesta from growing chickens and cannulated adult cockerels

Meat-and-bone meal (MBM), which had been heated (150 degrees C) for 0, 1.5, 3 or 5 h, was used along with an indigestible marker in four diets which were fed to young growing chickens and adult cockerels fitted with ileal cannulae. The ileal digesta from each group of birds were sampled and the apparent amino acid digestibilities of the four diets containing MBM were determined. The apparent digestibility values from growing chickens were higher (P less than 0.05) than those from cannulated cockerels. Differences in apparent digestibility of amino acids between diets as a result of heat treatment were consistent for all amino acids when comparing both techniques, with the exception of glutamic acid and arginine.     

Ileal digestibility of amino acids in pigs fed barleys differing in protein content

The apparent digestibility of nitrogen and amino acids was measured by the ileal and faecal methods in pigs fed nine barleys differing in nitrogen content (from 1.73 to 2.16 per cent/DM). A positive (r = 0.87) and significant relationship was found between the apparent nitrogen digestibility at the end of the ileum and the crude protein content of barley. Generally, the higher the protein of the grain, the higher the ileal digestibilities of the amino acids. For most amino acids the faecal values were greater than the ileal ones. This being specially so for threonine, tryptophan, histidine and cystine belonging to the nutritionally important amino acid group. When the relationship between the amino acid and nitrogen digestibilities at the level of ileum is considered, the values were found to be similar to that of nitrogen in the case of tryptophan, higher for isoleucine, valine (both 2-3 units), cystine, histidine, leucine, methionine (all 5-6 units) and phenylalanine (10 units) and lower only for lysine and threonine (7-8 dig. units).     

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.     

Apparent digestibility of nitrogen and amino acids in protein feedstuffs by growing pigs

Eight digestion trials were conducted with pigs fitted with ileal T-cannulas to determine the apparent digestibilities of N and amino acids in common protein feedstuffs. Trial-to-trial variation was minimal as determined by the variation in digestibilities for soybean meal, which was evaluated in each trial. Apparent digestibilities varied widely; ileal N digestibility ranged from 88 to 63%, and ileal lysine digestibility ranged from 93 to 40%. In general, ring-dried blood meal, corn gluten meal, Menhaden fish meal, poultry-by-product meal and extruded whole soybeans were the most digestible, followed by canola meal, sunflower meal, peanut meal and meat and bone meal. Cottonseed meal and feather meal were the least digestible. Mean values for each feedstuff agree well with published data. Variation in digestibilities among samples of the same feedstuff was greater for the meat and bone meals. Regression of ileal essential amino acid digestibilities on ileal and fecal N digestibility indicated that amino acid digestibilities can be predicted more precisely from ileal N digestibility than from fecal N digestibility. However, neither ileal nor fecal N digestibility could be used with a high degree of certainty to predict ileal amino acid digestibilities.     

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.     

Comparative protein and amino acid digestibilities in growing pigs and sows.

An experiment was conducted to compare apparent total tract protein digestibilities and apparent ileal digestibilities of protein and amino acids in growing pigs and adult pregnant and lactating sows. Twelve growing pigs and 12 sows were used and surgically fitted with simple T-cannulas at the distal ileum. Six experimental diets based on corn, barley, wheat, soybean meal, canola meal, or meat and bone meal were formulated, and each diet was fed to growing pigs, gestating sows, and lactating sows for 7 d. Chromium oxide was included in all diets as an indigestible marker (.25%) for calculating nutrient digestibilities. Fecal material was collected on d 5 of each feeding period by grab sampling, and ileal samples were collected for 12 h/d during the last 2 d of each feeding period. Apparent fecal protein digestibilities for all feed ingredients were higher (P < .05) in gestating and lactating sows compared to growing pigs, but no differences between the two groups of sows were observed (P > .05). At the distal ileum, no differences (P > .05) in protein digestibilities were detected between sows and growing pigs regardless of feed ingredient. For all feed ingredients tested, lactating sows had apparent ileal digestibilities of most amino acids that were two to six percentage units higher than those obtained in growing pigs, but not all of the differences were significant. Gestating sows had digestibilities of most amino acids that were intermediate between those of growing pigs and lactating sows. The combined results from the six feed ingredients showed that lactating sows had higher (P < .05) digestibilities of all indispensable amino acids except arginine, and gestating sows had higher (P < .05) digestibilities of five of the indispensable amino acids than did growing pigs. The results of this experiment indicate that apparent fecal protein and apparent ileal amino acid digestibilities obtained in growing pigs are not always representative of digestibilities in either gestating or lactating sows.     

Evaluation of homoarginine as a marker for the determination of endogenous amino acid concentrations in poultry excreta

1. Endogenous amino acid losses in ileal digesta and excreta of adult cockerels fed on diets containing guanidinated forms of casein, soyabean meal and cottonseed meal were determined using homoarginine as a marker.

2. The ileal endogenous amino acid losses were markedly higher (P< 0–001) in birds given the cottonseed meal diet compared to those given the other two diets. The ileal endogenous protein was rich in aspartic acid, serine and glutamic acid.

3. Negative values were obtained for endogenous amino acid output in excreta. These aberrant values were caused by high concentrations of homoarginine in the excreta. A subsequent study with broiler chickens showed that the homoarginine in excreta was of urinary origin.

4. These results indicate that the homoarginine technique is not suitable for determining endogenous amino acid losses in excreta, but applicable when determinations are made in the terminal ileum.     

Ileal amino-acid digestibility of wheat, autoclaved wheat and spaghetti by-products for broiler chicks

An experiment was conducted to determine true and apparent ileal amino‐acid digestibility of a native cultivar of wheat (Mahdavi), autoclaved wheat (120°C for 30 min) and spaghetti by‐products available in Iran. One hundred 21‐day‐old broiler chickens were fed a standard corn–soybean meal starter diet from day 0 to 28 post hatch. At 28 days 80 chicks were distributed according to possessing very nearly the same average bodyweight to 20 wire cages. The experimental units were allocated at random to five dietary treatments with four replicates per treatment. The basal diet contained corn and soybean meal as the major ingredients. Three test diets were formulated containing wheat, autoclaved wheat and spaghetti by‐products as the sole source of dietary protein and each test diet was combined with a basal diet 50:50 on a weight basis to form three assay diets. The apparent and true digestibility of amino acid in the test ingredients were estimated from those in the assay diets basal/test diet mixtures, using the difference method. The apparent and true amino‐acid digestibility of the test ingredients were significantly different (P < 0.01). Autoclaving of wheat increase its amino‐acid digestibility (P < 0.01). Among the test ingredients, the average ileal amino‐acid digestibility of spaghetti by‐products was higher than wheat and autoclaved wheat but it was lower than values for the basal diet (P < 0.01).     

The effects of dietary concentrations of minerals, source of protein, amino acids and antibiotics on the growth of and digestibility of amino acids by broiler chickens

1. The effects of dietary calcium, available phosphorus, amino acid and antibiotic supplements on the digestibilities of amino acids and growth of broiler chickens were investigated in two experiments. 2. The performance of chickens fed on diets containing high concentrations of calcium and available phosphorus was poorer with meat meal-based diets than with soyabean-based diets. Methionine supplementation improved the performance of chickens fed meat meal-based diets. 3. A high dietary content of calcium (25.9 vs 11.8 g/kg) reduced chick performance and the digestibility of glutamic acid, leucine and phenylalanine but increased the digestibility of lysine and histidine. 4. High dietary contents of calcium and available phosphorus (24.3 and 13.0 vs 11.8 and 4.0 g/kg) reduced chick performance and the digestibilities of most amino acids. 5. Antibiotic supplementation did not improve the performance of chickens, but increased the digestibilities of most amino acids in chickens fed on diets with a high calcium or high calcium and available phosphorus contents. 6. It was concluded that excess dietary calcium alone, or calcium and phosphorus together, reduced chick performance and the digestibilities of most amino acids. Growing chickens tolerated excess dietary calcium and available phosphorus better in well-balanced amino acid diets, such as soyabean meal or methionine-supplemented meat meal diets, than in poorly balanced amino acid diets, such as unsupplemented meat meal diets.     

Evaluation of apparent ileal digestibility of amino acids in Chinese corn by-products for growing-finishing pigs.

Twelve crossbred barrows (BW 47 +/- 2.81 kg) were fitted with a T-cannula in the terminal ileum and fed one of ten diets containing corn gluten meal, dried distillers grain or dried distillers grain with solubles as the sole protein source, according to a 6 x 6 Latin Square design. Lysine, tryptophan and methionine were, the first, second and third limiting amino acids in these by-products. The ileal apparent digestibility of methionine, tyrosine, leucine and phenylalanine in corn gluten meal was high. The ileal apparent digestibility of tryptophan, tyrosine and leucine differed significantly in corn gluten meal. The ileal apparent digestibility of amino acids was higher in dried distillers grain with solubles than in dried distillers grain. To predict the ileal apparent digestibility of tryptophan, methionine and threonine linear regression equations were derived. The results suggested that processing technique can influence the ileal apparent digestibility ofamino acids in corn by-products. It was concluded that the direct technique cannot accurately determine the ileal apparent digestibility of tryptophan in dried distillers grain with solubles and dried distillers grain, due to its low content. The content of an amino acid in a feedstuff used as the sole source of protein must meet the minimum requirement of pigs when the ileal apparent digestibility of constituent amino acids is determined using the direct technique.     

True ileal digestibility of amino acids in sow's milk for 17-day-old pigs

The digestibility of amino acids in sow's milk consumed by young pigs is currently unknown because of difficulties associated with collecting an adequate quantity of milk, and also problems in cannulating suckling pigs. A total of 14 kg of sow's milk was collected, two soluble indigestible markers (Co-EDTA and YbC13) were added, and the milk was fed to four pigs at 17 d of age that were fitted with a simple T-cannula at the terminal ileum. Another four cannulated pigs were offered a similar amount of a 20% DM liquid diet based on enzymatically hydrolyzed casein and lactose to assess endogenous amino acid losses. All pigs were fed about 875 g of each diet per day in 10 hourly meals from 0700 to 1700. Following 2 d of adaptation, ileal digesta were collected from 0800 to 1800 for 2 d. Diets and digesta were analyzed for amino acids using appropriate hydrolysis and preoxidation procedures. Average nitrogen true digestibility was 88%, whereas amino acid true digestibilities ranged from 84% (cystine and threonine) to 100% (methionine, histidine, and glutamic acid); the average for all amino acids was 92 +/- 4%. Based on average values, true digestibility of essential amino acids was not different from that of nonessential amino acids (P > 0.10). In whole milk, amino acids found in abundance in whey proteins (i.e., cystine, glycine, and threonine) were less (P < 0.05) digestible than amino acids predominating in casein proteins (i.e., glutamic acid, proline, and methionine). When true ileal digestible amino acid concentrations in sow's milk were expressed as ratios to digestible lysine, it appeared that threonine, tryptophan, and arginine were lower than what might be considered optimal. In conclusion, amino acids in sow's milk were highly digestible, but most of the amino acids had true ileal digestibility values significantly less than 100%.     

Strategies to improve the nutritive value of rice bran in poultry diets. IV. Effects of addition of fish meal and a microbial phytase to duckling diets on bird performance and amino acid digestibility

1. Ducklings were given diets with vegetable protein (VP) and 0 or 600 g rice bran/kg; fish meal (60 g/kg) and a phytase (+,-) were added to the diets (VP + AP). An additional 40 g soyabean meal/kg was added to the diet with rice bran (VP ++). Amino acid digestibility and mineral retention were measured in the lower ileum of ducklings killed at 23 d of age. Acid insoluble ash was used as an inert marker. Trypsin and amylase activities were also measured and weights of the pancreas and small intestine recorded at slaughter. 2. Addition of soyabean meal (VP ++) to the diet with rice bran improved growth rate and food intake compared to the diet without (VP) and gave the same food intake and growth rate as the comparable basal diet (VP) without rice bran. Fish meal improved growth rate on the diets without rice bran and improved food intake on this diet (VP + AP). Rice bran depressed growth rate and food conversion ratio (FCR); protein source affected growth rate, food intake and FCR; phytase increased food intake only. There were several interactions. 3. Determined total amino acid composition of the diets appeared to meet the essential amino acid requirements of ducklings. Rice bran depressed the ileal digestibility of virtually all amino acids and phytase had no direct effect, although there were interactions. Fish meal addition to diets with rice bran improved the apparent digestibility of several essential amino acids as well as that of dry matter and crude protein. 4. Ileal retention of some minerals and tibia ash content were reduced by rice bran. Fish meal and phytase inclusion increased P retention and ash in tibia. 5. Higher intestinal trypsin activity and increased pancreas size were seen in ducklings on diets with rice bran compared to those without. Intestinal amylase activity was reduced in ducklings given rice bran, probably because of its low starch content. 6. The stimulating effect of fish meal on duckling performance was probably caused in part by the improvement in the digestibility of some amino acids. The addition of small amounts of minerals in fish meal may have increased mineral retention. Phytase gave benefits anticipated from our previous work, but also improved lysine and threonine digestibility in diets containing vegetable protein only.     

Digestibilities of amino acids in soyabean, sunflower and groundnut meals, determined with intact and caecectomised cockerels

1. Three isonitrogenous diets were formulated in which soyabean (dehulled), sunflower (hulled) and groundnut (dehulled) meals were the sole protein sources. 2. 50 g of each diet was tube-fed to each of 24 intact and 24 caecectomised cockerels, which had been previously starved for 48 h. Excreta were collected, individually, for 48 h. The concentrations of amino acids in the diets and excreta were determined, and digestibility coefficients calculated. 3. Differences between intact and caecectomised birds for true digestibility evaluations reached significance for threonine, glycine and lysine only. Deamination of threonine and glycine, and synthesis of lysine, in the caeca was implied. 4. Neither the true digestibility of nitrogen, nor that of the sum of the amino acids differed between protein sources. 5. True digestibilities of most essential amino acids, considered individually, in sunflower and groundnut meals were similar to or greater than, those of soyabean meal. Exceptionally, lysine was more digestible in soyabean (0.879) than in sunflower (0.722) or groundnut (0.788) meals.     

The effect of source of fiber on ileal and fecal amino acid digestibility and bacterial nitrogen excretion in growing pigs.

Studies were carried out with six barrows (initial BW 50 kg) to determine the effect of two fiber sources on the apparent ileal and fecal N and amino acid digestibilities and bacterial N excretion in feces. The pigs, fitted with a simple T-cannula at the distal ileum, were fed three cornstarch-based diets formulated to contain 16% CP from soybean meal according to a repeated 3 x 3 Latin square design. Diet 1 did not contain additional fiber. Diets 2 and 3 contained 10% powdered cellulose and 10% barley straw (ground through a 2-mm mesh screen), included at the expense of cornstarch, respectively. The pigs were fed 900 g at each meal twice daily, 0800 and 2000. Feces were collected for 48 h after a 10-d adaptation period. Thereafter, ileal digesta were collected for 24 h. Chromic oxide was used as a digestibility marker. With the exception of leucine, the inclusion of fiber did not affect (P greater than .05) the ileal digestibilities of the indispensable amino acids. The values for the average of the ileal digestibilities of the indispensable amino acids were 85.3, 82.9, and 83.2% for diets 1, 2, and 3, respectively. On the other hand, the inclusion of fiber decreased (P less than .05) the fecal digestibilities of all the indispensable amino acids. The values for the average of the fecal digestibilities of the indispensable amino acids were 91.7, 87.4, and 89.1% for diets 1, 2, and 3, respectively. These decreases resulted from an increase (P less than .05) in the excretion of bacterial N, which was measured using 2,6-diaminopimelic acid as a marker. In conclusion, as measured with the ileal analysis method, the inclusion of fiber had little effect on the digestible amino acid supply.     

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.     

The effect of chaya (Cnidoscolus aconitifolius) leaf meal and of exogenous enzymes on amino acid digestibility in broilers

1. The apparent ileal nitrogen (N) and amino acid digestibilities in chaya leaf meal (CLM) (Cnidoscolus aconitifolius) with added enzymes, and the same variables in diets containing different amounts of CLM were studied in chickens. 2. In the first experiment pectinase, beta-glucanase, and pectinase + beta-glucanase were added to CLM. In the second experiment, there were three diets based on maize and soybean: 0, 150 and 250 g/kg CLM. 3. Pectinase significantly increased both lysine and overall amino acid digestibilities in CLM. 4. In experiment 2, the amino acid digestibility in birds fed on CLM250 was lower than that from birds fed on either control or CLM150. Only the digestibilities of alanine, arginine and proline were lower in birds fed on CLM150 than in those fed on the control diet. Nitrogen digestibility was lower in birds fed on the CLM250 diet than on either control or CLM150 diets. These findings were attributed to the increasing concentration of fibre with increasing dietary CLM.