Relationship between the quality of dietary proteins and the functional status of the adrenal cortex. Variations in the content of transcortion, free corticosterone and total corticosterone in the blood plasma of rats fed with proteins of various quality]

Growing male Wistar rats were used to test in which way variations in the quality of dietary proteins (10% absorbable crude protein; casein supplemented with 4% methionine (K); casein/gelatine (1 : 3); maize gluten supplemented with 4 amino acids; and maize gluten) influenced the binding capacity of blood plasma for corticosterone, and the concentration of corticosteroid-binding globulin ("CBG"), total corticosterone, free corticosterone and albumin-bound corticosterone in blood plasma. The binding capacity of the blood plasma for corticosterone and the total concentration of corticosterone, CBG, free corticosterone and albumin-bound corticosterone were found to rise with the improving quality of the dietary proteins (r = 0.830). A close correlation was found to exist between the concentration of total corticosterone in the blood plasma and CBG. Increases in the total concentration of corticosterone in blood plasma are, in 84% of all cases, brought about by increases in CBG concentrations. In conclusion, reference is made to the significance which such results may have for the control of regulatory processes.     

The effect of proteinase inhibitors in rats. 1. Report. Effect of a short-term application on the N balance, the free amino acids in liver and muscles and the biological half-life of the intestinal tissue proteins]

Short-term trials with a triazin derivative and a peptide aldehyde were carried out to investigate the in-vivo administration of proteinase inhibitors in rats for improving the N balance of the animals. The results of N balances suggest that the peptide aldehyde may be regarded as a promising substance that may be used to increase the rate of utilization of the absorbed N in the intermediary metabolism. The short-term use of both active compounds did not affect the true N digestibility. The two compounds did not influence the concentration of free amino acids in the liver and muscle tissue under the experimental feeding conditions used. Similarly, tests of the biological half-life of proteins taken from the small and large intestine did not reveal any changes due to the presence of the inhibitors. Animals receiving a protein-free diet exhibited longer half-life periods for proteins from the small and large intestine compared with animals of the other groups. A protein-free nutrition of the animals caused a general increase in the levels of free non-essential amino acids in the liver. This was accompanied by a simultaneous decrease in essential amino acids. The same type of nutrition led to a general decline in the concentration of free amino acids in muscular tissue, particularly of the essential amino acids. High-protein nutrition led especially to an increase in the concentration of branched-chain amino acids in both types of tissues investigated.     

Protein digestability and amino acid absorption in various segments of the digestive tract of pigs. 1. Methods of animal experimentation, protein content and amino acid patterns of the digesta in the small intestine and in feces after feeding different feeds]

Re-entrance cannulae were applied by way of operations at the end of the small intestine of a larger number of growing pigs. After a post-operative phase these animals were fed with various rations (N-free diet, fattening feed for pigs, rations with dried skim milk resp. wheat gluten + lysine and wheat + wheat gluten + lysine). During the main experiment periods the ileum digesta (24 hour-periods of collecting) and the feces were quantitatively registered. The protein and amino acid content ascertained in the feed rations, the digesta and feces samples are reported, comparatively evaluated and discussed. The amount of amino acids (in mg per kg intake of dry matter) contained in the ileum digesta after N-free feeding were statistically calculated with regard to differences occuring between the animals and days. For most amino acids a significant decrease in the ileum digesta could be detected during the course of the N-free feeding period. Moreover, the amount of amino acids in the ileum digesta was compared with the metabolic fecal amino acids, from which conclusions could be drawn concerning the disappearance rate of the individual amino acids in large intestine.     

Bacterial responses to different dietary cereal types and xylanase supplementation in the intestine of broiler chicken.

Several studies were carried out to investigate the influence of dietary cereals differing in soluble non starch polysaccharides (NSP) content and a xylanase preparation on selected bacterial parameters in the small intestine of broiler chicken. Compared to a maize diet colony forming units (CFU) of mucosa associated bacteria were higher in a wheat/rye diet, most notably for enterobacteria and enterococci. Xylanase supplementation to the wheat/rye diet generally led to lower CFU, especially in the first week of life. However, xylanase supplementation also displayed higher in vitro growth potentials for enterobacteria and enterococci. Bacterial growth of luminal samples in minimal media supplemented with selected NSP showed that the wheat/rye diet enhanced bacterial capacities to utilize NSP only in ileal samples. The xylanase application generally shifted respective maximum growth to the proximal part of the small intestine. The presence of soluble NSP from wheat or rye in the diet per se did not enhance bacterial NSP hydrolyzing enzyme activities in the small intestine, but xylanase supplementation resulted in higher 1,3-1,4-beta-glucanase activity. Compared to a maize diet the activity of bacterial bile salt hydrolases in samples of the small intestine was not increased due to inclusion of wheat/rye or triticale to the diet. However, xylanase supplementation led to a reduction with a corresponding increase of lipase activity. It was concluded that dietary cereals producing high intestinal viscosities lead to increased overall bacterial activity in the small intestine. The supplementation of a xylanase to cereal based diets producing high intestinal viscosity, changes composition and metabolic potential of bacterial populations and may specifically influence fat absorption in young animals.     

Influence of diet on assimilation and turnover of 13C in the tissues of broiler chickens

The 13C turnover rates of the liver and thoracic pectoral muscle of growing broilers were determined by feeding diets with varying 13C content. Male chicks (1-d-old) were subjected to treatments based on free choice of 5 different mixes of energy and protein sources from plants with C3 and C4 photosynthetic pathways that had differing 13C content. Rice bran (R) and soybean meal (S) were the C3 sources, while maize (C) and maize gluten meal (G) were the C4 sources. Choices were R + S, C + G, R + G, C + S or R + C + G + S. The 6th treatment was a complete feed (CF) that was similar to a commercial broiler feed. The isotopic composition of the birds' tissues was representative of the isotopic composition of the diets. The assimilation was faster for C3, in both liver and muscle, than for C4 diets, and give the delta per mil difference between the diet and tissues. The liver is the most active metabolic tissue and gave more rapid isotope turnover than in muscle.     

Protein utilization of mixed feed rations in lactating pigs with reference to the essential amino acid content of the feed proteins. 2. Report. Utilization of the feed proteins in the use of soy bean extraction residue, waste liquor yeast, horse bean meal fish meal and maize gluten for a basic ration]

Nitrogen trials were performed on lactating pigs to investigate the utilization of protein from some feeding rations. The basal ration fed to the sows consisted of ground barley+oats+flaked potatoes or ground barley+sugar beet chips. The basal ration was supplemented with a protein source. The protein feeds used were extracted soya bean meal, horse bean meal, fish meal, maize gluten and waste liquor yeast. Data for the average biological value of the dietary proteins were as follows (in the given order of protein feeds): 61%, 59%, 54%, 58% and 37%. PPV data were: 44%, 43%, 39%, 44% and 28%. The proteins of nearly all rations were deficient in lysine when compared with the range of amino acids present in the proteins of sow milk.     

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

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

Action of proteinase inhibitors in rats. 3. Influence of leupeptin on the rate of protein synthesis and the intracellular protein degradation by use of a test system including constant infusion of labelled amino acids, estimation of 3-methyl-histidine excretion and a triple-labelling technique

Male Wistar rats (initial body weight 90 g) were fed ad libitum a whole-egg diet containing 10,5% crude protein. The animals of the experimental group received in each case of 1 mg leupeptin per 100 g of body weight in 12 hrs-intervals by i. p.-injection (3 days of treatment). Control animals got a leupeptin free solution. In addition, lysine dihydrochloride-alpha-15N was applied during the first three days of experiment to all animals and the nitrogen balance was determined. Urine from the N-Balance collection was analysed for 3-methyl-histidine excretion in order to calculate the degradation rate of myofibrillar proteins. On the fourth day the fractional rate of protein synthesis in several organs was estimated using the continuous infusion technique with 14C-leucine and 14C-lysine. The apparent biological half-lives of tissue protein were determined by a triple labelling technique, with (14C)-guanidino-L-arginine, L-5-3H-arginine and 15N-Lysine. The short-term treatment 3 days) with leupeptin did not affect the weight gain, the apparent digestibility of nitrogen and the N-balance. The fractional rate of protein synthesis was highest in the small intestine followed by the large intestine, liver and skeletal muscle and no influence of leupeptin treatment was observed. Furthermore no differences in the degradation rates of myofibrillar proteins between treated and untreated animals were found. The 3-methyl-histidine excretion via urine was 1.44 mg . kg-1 day-1 in both groups corresponding to a fractional rate of degradation of myofibrillar proteins of 2,5% per day. Apparent half-lives of tissue proteins in the small intestine, large intestine and liver, respectively, were shortest when estimated from the decay curves for the 14C-label and longest from the curves for the 15N-label. Leupeptin treatment resulted in prolonged apparent half-lives of the proteins in the large intestine and of the slowly turning over proteins in the liver. However, this effect seems to be caused rather by an increased reutilization of labelled amino acids than by a decreased protein degradation. Before continuing this kind of work the rate of uptake of injected leupeptine into tissues has to be investigated. Studies dealing with the in vivo action of proteinase inhibitors on protein metabolism have to include estimations of N-balance, protein synthesis rate, intracellular degradation rate of proteins as well as amino acid reutilization.     

Effect of acute deficiency of dietary proline on proline balance in the rat small intestine and liver

Introduction Proline is widely found in all types of mammalian tissue, and accounts for about 20% of the amino acids that constitute collagen (A dams 1970). Proline is nutritionally nonessential but biologically it is an important amino acid and consequently mammalian organisms synthesize the required amounts of proline even in the absence of sufficient proline consumption via food. The metabolism of higher animals is unique, and amino acid metabolism differs from one tissue to the next. Some organs are capable of synthesizing nonessential amino acids for use throughout the body. For example, arginine is primarily synthesized in the kidney and then released and distributed throughout the body. Pyrroline-5-carboxylate reductase is the enzyme responsible for the final stage of proline synthesis, and its activity has been confirmed in many important organs and tissue such as the cartilage, liver, small intestine, kidney and thymus gland (H erzfeld et al. 1977; S mith and P hang 1978). However, the different levels of pyrroline-5-carboxylate reductase activity among these organs has led to the belief that different amounts of proline are synthesized in these organs. In order to ascertain biological responses to dietary proline deficiency, it is important to identify the organs that release and distribute proline throughout the body when insufficient proline is consumed through the diet, thus reducing the blood proline concentration. Few studies have investigated this issue, but when ascertaining biological responses to dietary proline deficiency, it is more important to elucidate the effect of dietary proline deficiency on the metabolism of proline and other amino acids that are closely related metabolically to proline, in proline synthesizing organs. One of the most effective ways to assess amino acid metabolism in a target tissue of higher animals is to measure the difference between the arterial and venous concentrations of amino acids. I shikawa (1974) measured arteriovenous differences in order to examine the release of proline from the kidney and small intestine of fasted rats and the uptake of proline by the liver. In a previous study, it was found that when the plasma proline concentration was reduced to the fasting level by the consumption of a proline-deficient diet, proline was released from the kidney (W atanabe et al. 1995, 1997). In the present study, to ensure the induction of dietary proline deficiency, a completely purified diet containing all amino acids except for proline was prepared and fed to rats under experimental conditions. To investigate the role of the small intestine and liver in supplying and ingesting proline when the uptake of proline through food is restricted, the release and uptake of amino acids in the small intestine and liver were assessed by measuring carotid artery–portal vein and portal–hepatic vein differences in proline in rats.     

Histological studies on cow intestinal mucosa and electron microscopic studies of the ruminal epithelium of cows fed a deficient diet for a prolonged time]

Histological and histochemical studies were carried out on the gastro-intestinal mucosa of three experimental cows (roughages/maize silage) and three control animals. The animals were slaughtered on termination of the long-term trial. Mucosa samples were taken, for further study, from the rumen, the duodenum, the jejunum, the large intestine and the appendix. Histochemical analysis did not reveal any essential differences in the activities of non-specific esterase, alkaline and acid phosphatase and lactic acid dehydrogenase in the mucosa of the rumen, the large and the small intestine and the appendix of both the experimental animals and the controls. The experimental animals were found to exhibit a higher rate of glutamate-dehydrogenase activity in the ruminal mucosa and in the mucosa of the large and small intestine. A higher succinate dehydrogenase activity was observed in the ruminal mucosa of the experimental animals, relative to that of the controls, while the activity in the intestinal mucosa was decreased. Only slight changes were noted in the activity of the enzymatic systems tested. Electron microscopic studies did not reveal any differences in the ultrastructure of the epithelial cells of the ruminal mucosa in both the experimental animal and the controls.     

Quantification of melamine absorption, distribution to tissues, and excretion by sheep

Eight D?hne Merino rams were used to quantify apparent absorption, distribution to tissues, and excretion of dietary melamine in sheep. Two batches of concentrate pellets were made; one (CON) contained corn gluten meal with no detectable melamine and the other (MEL) contained corn gluten meal that was previously found to be highly contaminated with melamine at 15,117 mg/kg. The MEL pellets contained 1,149 mg/kg of melamine. During a 10-d adaptation period, all the animals received a forage-based diet supplemented with 600 g/d of the CON pellets. This was followed by an 8-d collection period during which 6 of the animals received MEL pellets and 2 received CON pellets. Melamine intake of sheep that received MEL pellets was 0.69 g/d. Blood samples were taken before first ingestion of MEL pellets on d 1 and again on d 3, 6, and 8 of the collection period for melamine and serum creatinine analyses. Feces and urine were collected quantitatively over the 8 d for proximate and melamine analyses. All the animals were slaughtered at the end of the trial, and samples of the LM, liver, kidneys, and abdominal fat were taken for melamine analysis. Data of the 2 sheep that received CON pellets for the duration of the trial confirmed that no melamine was detected in any of the samples, and no statistical analyses were performed on these data. The apparent digestibility or efficiency of absorption of ingested melamine was 76.7%. Melamine was detected in the urine, blood, muscle (LM), and fat tissue of all the sheep that received MEL pellets. Serum melamine concentrations reached 5.4 mg/kg on d 8 of the collection period, and the meat (LM) contained 9.6 mg/kg of melamine. Calculations on the partitioning of ingested melamine suggested that urine is the major excretion route accounting for 53.2%, whereas feces accounted for 23.3% of ingested melamine. Approximately 3.5% of the ingested melamine was detected in muscle. It was concluded that ingested melamine is highly absorbable from the small intestine and that a pathway exists for the distribution of dietary melamine to meat.     

Nitrogen and amino acid resorption in the small intestine of growing swine. 1. Animal study method, nitrogen content and amino acid composition of the small intestine chyme by administration of various proteins

The amount of endogenous N in the chyme at the end of the small intestine and the amino acid composition of the ileum chyme were ascertained with growing pigs with ileorectostomy after feeding qualitatively differentiated protein sources. In dependence on the protein used, distinct differences turned out for some amino acids with regard to their content in the ileum chyme. Bacteriologic and histologic investigations subsequent to the dissection of the test animals showed that - in comparison to the control animals-the functions of the small intestine remained the same during the time of the experiment. The experiment method described appears to be suitable for absorption investigations up to the end of the small intestine of growing pigs.     

Effects of soybean agglutinin on nitrogen metabolism and on characteristics of intestinal tissues and pancreas in rats.

Two experiments were conducted to investigate the effects of increasing concentrations of supplemental purified soybean agglutinin on performance, apparent nitrogen digestibility, plasma insulin and cholecystokinine (CCK) levels in rats as well as on the growth of the small intestine and pancreas. In Experiment 1, a 10-day nitrogen balance trial was conducted with 24 male Sprague-Dawley rats (mean BW 85 g) that were randomly allotted to one of four dietary treatments. Rats in each group were provided daily with 7 g of a casein-cornstarch based diet (control) or a diet supplemented with purified soybean agglutinin at 0.4, 0.6 or 0.8 mg/g. Urine and faeces were collected daily and stored at -20 degrees C until analysis. In Experiment 2, 30 male Sprague-Dawley rats (mean BW 75 g) were divided into five groups for a 20-day growth experiment. Each rat was fed daily 7 g of a casein-cornstarch based diet (control) or a diet supplemented with purified soybean agglutinin at 0.4, 0.8, 1.2 or 2.0 mg/g. All experimental diets were adjusted to contain a similar level of nutrients. Results from the two experiments showed that supplementation of soybean agglutinin below 2.0 mg/g diet had no significant effect on rat performance. However, rats receiving 2.0 mg soybean agglutinin per gram of diet showed a significant reduction in weight gain compared to the control group. Incorporation of soybean agglutinin in the diet reduced apparent nitrogen digestibility and the retention of dietary nitrogen by increasing nitrogen loss from the faeces and urine. In addition, plasma CCK level increased with increasing inclusion of soybean agglutinin in the diet. On the contrary, the plasma insulin level declined as soybean agglutinin level increased. Soybean agglutinin induced a polyamine-dependent hyperplastic and hypertrophic growth of the small intestine and pancreas by increasing the contents of protein, RNA and DNA, though the increase in weight of small intestine was not significant. Furthermore, 1.2 and 2.0 mg soybean agglutinin per gram of diet promoted proliferation of the jejunum mucosa, while the structure of the brush border epithelium of small intestinal had no damaging change and no diarrhoea was observed in any treatment group. Based on these results, supplementation of low doses of soybean agglutinin or soy protein to parenterally-fed animals affected by atrophic small intestine may promote small intestinal growth.     

Nitrogen balance and amino acid disappearance from the small intestine in calves fed soybean meal-, toasted soybean meal- or corn gluten meal-supplemented diets

Nine crossbred (Hereford X Angus X Charolais) heifer calves (139 kg; 6 mo of age) with abomasal and ileal cannulas were used in a repeated design to evaluate N balance and amino acid disappearance in the small intestine. Calves were fed either soybean meal (SBM), toasted SBM (TSBM, 93 C for 90 min) or corn gluten meal (CGM) as supplemental protein sources. Each calf received approximately 83 g N/d from a cottonseed hull-corn based diet with 43% of the total dietary N supplied by the test proteins. Each experimental period consisted of a 10-d adaptation, 6-d digesta collection and 5-d excreta collection. Following the first 21-d period, calves were randomly re-allotted to treatment and the sampling process was repeated. Dry matter (64%) and N digestibilities (61%) and N retention (36.8 g/d) were similar (P greater than .10) among treatments. Nitrogen flow to the small intestine was similar for TSBM- and CGM-fed calves (119.1 g/d), but greater (P less than .01) than for those offered SBM (96.3 g/d). Offering TSBM and CGM resulted in greater quantities of essential, nonessential and total amino acids reaching the abomasum compared with SBM. Total amino acid flow to the small intestine was 100, 120 and 128% of intake for SBM, TSBM and CGM, respectively. Numerically, amino acid digestibility was lower in CGM-fed calves. Methionine digestibility was highest (64.6%), while histidine was lowest (43.7%). Feeding CGM may result in greater quantities of amino acids reaching the small intestine; however, several of these amino acids may be less digestible than for TSBM.     

Influence of dietary zinc and copper on digestive enzyme activity and intestinal morphology in weaned pigs

The current study was conducted to investigate the effects of high dietary concentrations of Zn as zinc oxide and Cu as copper sulfate on the activity of digestive enzymes in the pancreas and the intestinal mucosa, intestinal morphology, and mucin histochemistry in pigs after weaning. Thirty-two pigs were weaned at 4 wk of age. The pigs were fed standard weaning diets supplemented with Zn (100 or 2,500 ppm) and Cu (0 or 175 ppm) in a 2 x 2 factorial arrangement of treatments for a 14-d period. In pancreatic tissue, the activity of amylase, carboxypeptidase A, chymotrypsin, trypsin, and lipase increased (P < 0.01) in pigs fed 2,500 ppm of Zn, whereas the activity of carboxypeptidase B and carboxylester hydrolase was unaffected. Copper had no effect on the activity of pancreatic enzymes. In small intestinal contents, the total activity of amylase and carboxypeptidase A was greater in pigs fed 100 ppm of Zn (P < 0.05), whereas feeding 2,500 ppm of Zn increased the chymotrypsin activity (P < 0.001). The remaining enzymes were unaffected by dietary Zn concentration. The villi were longer in the cranial small intestine (P < 0.001) in pigs fed 100 ppm of Zn than in pigs fed 2,500 ppm of Zn, but otherwise there were no clear effects of Zn and Cu supplementation on intestinal morphology. In the cranial small intestine, the activity of maltase (P < 0.001), sucrase (P < 0.001), and lactase was greater in pigs fed 100 ppm of Zn, even though there was a Zn x Cu interaction (P < 0.05) in lactase activity. In the middle and caudal small intestine, no clear differences between dietary treatments were observed. The activity of gamma-glutamyl transpeptidase in the intestinal mucosa was not affected by dietary Zn or Cu. In pigs fed 100 ppm of Zn, the activity of aminopeptidase N was greater in the caudal small intestine, but dietary Zn or Cu had no effect on aminopeptidase N in the cranial and middle small intestine. No effect of dietary Zn or Cu supplementation was found on carbohydrate histochemistry in the caudal small intestine, whereas high dietary Zn increased the area of neutral, acidic, and sulfomucins in the cecum (P < 0.01) and in the colon (P < 0.001). In summary, high dietary Zn increased the activity of several enzymes in the pancreatic tissue and increased the mucin staining area in the large intestine, whereas Cu had no clear effect on these variables. However, no definite answers were found as to how the growth promoting and diarrhea reducing effects of excess dietary Zn are exerted.     

Dietary protein level affects in vitro peristaltic reflex in the small intestine of young pigs

The aim of the study was to investigate the effect of dietary protein level on contractility of the small intestine in young pigs. Animals (about 15 kg BW initially) were fed during 40 days with isoenergetic diets containing 16, 18, or 20% of crude protein. Higher protein levels in the diets as well as similar concentration of essential amino acids were attained by substitution of corn starch with wheat gluten and crystalline amino acids. At about 40 kg BW, the animals were sacrificed and the longitudinal strips of duodenum and mid-jejunum were taken for analysis of smooth muscle mechanical activity in vitro. Spontaneous activity, responses to electrical field stimulation (EFS), and responses to acetylcholine (ACh) were recorded. Frequency and amplitude of spontaneous contractions were similar in all groups, both in the duodenum and the mid-jejunum. In the duodenum, responses to EFS and ACh were the same irrespective of the dietary protein level. Responses to EFS in the mid-jejunum were significantly enhanced in the animals receiving the diet with 20% protein; however, the response to ACh was not changed. The mechanism of neuronal response may involve primary afferent pathways “sensing” contents in the lumen of the intestine through enterochromaffin cells. The enteric neuronal pathways may also be activated by a higher level of free amino acid(s) or by dietary peptides and proteins.     

Studies on the endocrine and spermiogenic functions of testes. I. Relationship between the quality of dietary protein and testosterone content in testicular tissue of pubertal rats]

Growing, male Wistar rats were fed for 21 days one of four qualitatively different proteins, as follows: 1. casein and 4% methionine (group K) 2. maize meal and amino acid supplement (group M + As) 3. maize meal alone (group M) 4. casein plus 4% of a 1:3 mixture of methionine and gelatin (group K/G) (These rations constitute a decreasing range of biological activity of the diet.) After 21 days of feeding these rations, the testosterone content per 100 g body weight averaged 80 ng in groups K and M + As, compared with 8 ng in groups M and K/G. Body weight increment averaged 48 g in group K, 40 g in group M + As, 19 g in group M and -9g in group K/G. Total testicular mass averaged 1658, 1730, 1485 and 641 mg in the four groups, respectively.     

Effects of dietary energy level and protein source on nutrient digestion and ruminal nitrogen metabolism in steers.

Four Simmental steers with ruminal, duodenal, and ileal cannulas were used to examine effects of dietary forage: concentrate ratio and supply of ruminally degradable true protein on site of nutrient digestion and net ruminal microbial protein synthesis. Steers (345 kg) were fed ammoniated corn cob (high forage; HF)- or corn cob/ground corn/cornstarch (low forage; LF)-based diets supplemented with soybean meal (SBM) or a combination of corn gluten meal and blood meal (CB). Diets were fed at 2-h intervals with average DM intake equal to 2.2% of BW. Feeding LF vs HF increased (P less than .05) OM digestion (percentage of intake) in the stomach, small intestine, and total tract. Efficiency of microbial CP synthesis (EMCP; g of N/kg of OM truly fermented) decreased (P less than .05) for LF vs HF (24.1 vs 26.8), but microbial N and total N flows to the small intestine were similar (P greater than .05) between energy levels (average 112 and 209 g/d, respectively). Total N flows to the small intestine were 13.1% greater (P less than .05) for CB than for SBM because of increased (P less than .05) passage of nonmicrobial N. Feeding SBM vs CB increased (P less than .05) EMCP (27.3 vs 23.3) and microbial N flow to the small intestine (127.5 vs 112.5 g/d), but these increases were not likely due to increased ruminal concentrations of ammonia N (NH3 N). Decreased (P less than .05) incorporation of NH3 N into bacterial N and slower turnover rates of ruminal NH3 N for SBM vs CB suggest that direct incorporation of preformed diet components into cell mass increased when SBM was fed. Results of this study suggest that the inclusion of ruminally degradable protein in the diet may increase the supply of products from proteolysis and that this can increase EMCP and microbial protein flow to the small intestine.     

Intestinal supply of amino acids in sheep fed alkaline hydrogen peroxide-treated wheat straw-based diets supplemented with soybean meal or combinations of corn gluten meal and blood meal

The intestinal supply of amino acids (AA) in sheep fed alkaline hydrogen peroxide-treated wheat straw (AHPWS)-based diets supplemented with soybean meal (SBM) or corn grain plus combinations of corn gluten meal (CGM) and blood meal (BM) was measured in a 5 X 5 latin square. Sheep (avg wt 45 kg) with ruminal, duodenal and ileal cannulas were fed diets containing 65% AHPWS supplemented with the following protein sources: soybean meal (SBM), corn gluten meal (CGM), blood meal (BM), 2/3 CGM:1/3 BM and 1/3 CGM:2/3 BM. Total nitrogen (N) flow at the duodenum was not affected (P greater than .05) by protein source. Flows of bacterial N and AA increased (P less than .05) and flows of nonbacterial N and AA decreased (P less than .05) when wethers were fed SBM vs corn plus other protein sources. When diets contained SBM, quantities of total AA at the duodenum were lower (P less than .05) and the profile of AA supplied to the intestine was altered substantially. Total flows of AA at the duodenum and total quantities of AA disappearing from the small intestine were similar (P greater than .05) for all diets containing BM and CGM, but flows and disappearance of valine, histidine, lysine and arginine increased linearly (P less than .05), whereas flows and disappearance of leucine, isoleucine and methionine decreased linearly (P less than .05) as BM replaced CGM in the diets. Results suggest that quantities of individual AA flowing to the duodenum and disappearing from the intestine of wethers fed AHPWS-based diets can be altered by source of dietary protein. Furthermore, feeding protein sources resistant to ruminal degradation in combination may improve the profile of AA supplied to the intestine.