Making oats safer for patients with coeliac disease.

(Table is included in full-text article). Studies suggest that oats can be tolerated in the gluten-free diet by a majority of patients with coeliac disease. Concerns remain, however, about the possibility of contamination of commercially available oat products by wheat, barley and rye. The R5 ELISA allows the identification and quantification of wheat, barley and rye prolamins, and has demonstrated significant contamination in a range of products. If patients with coeliac disease are to take oats, it is important that those consumed are free of contamination. This assay should allow the identification of safe oat products.

Herbicidal effects on nontarget vegetation: investigating the limitations of current pesticide registration guidelines.

The impact of herbicide exposure on nontarget vegetation within agroecosystems has sparked extensive research that revealed that current pesticide registration guidelines may be inadequate at predicting the effects of herbicides on wild plants and habitats. This study extends the current interest by presenting three experiments highlighting some of the limitations to current phytotoxicity testing guidelines. Several crops and wild plant species were grown under greenhouse conditions following standard protocol for phytotoxicity testing. Plants were sprayed with five different herbicides at the four- to six-leaf stage, and biomass was recorded at 28 d after spray. Results showed that current regulatory protocol will likely underestimate herbicide phytotoxicity if testing does not include data for the complete tank-mix formulation. The present study also showed that the range in herbicide sensitivity among cultivars of the same crop can be quite extensive and that, depending on the cultivar included in a risk assessment, conclusions regarding the phytotoxicity of any given herbicide may differ. Although no significant differences in sensitivity were found between crops and related wild species, results revealed that current guidelines are too rigid in terms of species selection. Considering the variability among crop cultivars, coupled with the ecological importance and the ease of germination of many noncrop plant species, pesticide regulatory guidelines would be improved if wild species were included in testing. Findings of the present study indicate that current pesticide regulatory guidelines require modifications to ensure a more accurate assessment of herbicide effects on nontarget plant species.

Wheat bran diet reduces tumor incidence in a rat model of colon cancer independent of effects on distal luminal butyrate concentrations.

To investigate the effects of dietary fibers in colonic luminal physiology and their role in the prevention of colon cancer, a study was conducted using two diet groups and two treatment groups in a 2 x 2 factorial design. The two diets differed only in the type of dietary fiber, wheat bran and oat bran, and the two treatments were injection with the colon-specific carcinogen azoxymethane, or saline, as a control. There were 34 rats in the carcinogen-injected groups and 11 saline-injected rats per diet group. The goal of the study was to determine if a moderate consumption (6 g/100 g diet) of wheat bran or oat bran would alter the development of colonic tumors in this rat model of colon cancer, and if the differences in tumor incidence were correlated to luminal butyrate concentrations, luminal pH or fecal bulk. Short-chain fatty acid concentrations (SCFA) were measured in feces during the first half of the study (the promotion phase of tumor development) and again at the end of the study. Rats consuming oat bran had greater body weights (P < 0. 002), produced much larger concentrations of all SCFA, including butyrate, in both the proximal and distal colon (P < 0.0001), had more acidic luminal pH values (P < 0.0001), but also had significantly more development of colon tumors (P < 0.03). Alternatively, rats consuming wheat bran produced more typical molar ratios of the SCFA (65:10:20), had a relatively greater concentration of butyrate than propionate, and produced a larger volume (P < 0.05) and more bulky stool than the rats fed oat bran. The results of this study support other evidence that an acidic luminal pH is not protective in and of itself, and that diets containing wheat bran are protective against colon cancer development. In addition, these data show that large luminal butyrate concentrations in the distal colon alone, as were present in the rats consuming oat bran diets, are not protective of tumor development.

Escape protein supplementation of steers fed grass silage-based diets.

Beef steers (Trials 1 and 2, 280 +/- 2 kg; Trial 3, 330 +/- 2 kg) were fed diets of 67.5% wheat (Trial 1) or oat silage (Trials 2 and 3), 20.5% barley, and 12% supplement in randomized complete block design growth trials. Dietary treatments were graded levels of supplemental escape protein (EP) from corn gluten meal (Trial 1, 0 to 213 g/d escape protein) or animal by-products (1:1:1 DM mixture of blood, feather, and meat and bone meals, 0 to 223 or 0 to 317 g/d of escape protein in Trials 2 and 3, respectively) to titrate amounts needed to maximize steer live weight gain. As supplemental EP from corn gluten meal increased, steer live weight gain increased linearly (P < .001) and feed-to-gain decreased linearly (P < .001). Supplementation with 135 g/d of corn gluten meal EP (335 g/d of corn gluten meal) increased average daily gain from .76 to .91 kg/d. As supplemental EP from animal by-products increased, steer live weight gain increased quadratically (P < .05) and feed-to-gain decreased linearly (P < .01). Supplementation with 223 or 317 g/d of animal by-product EP increased live weight gain by .27 kg/d. Supplemental escape protein was needed to increase live weight gain of steers consuming ensiled forage diets due to low EP contents of silages (7, 3, and 23% of CP in Trials 1, 2, and 3, respectively) and barley (15, 27, and 22% of CP in Trials 1, 2, and 3, respectively) and limited microbial protein synthesis.

Apparent and true metabolizable energy values of feedstuffs for ducks.

Two experiments were conducted, each with 24 White Pekin ducks, to determine the AME and TME content of five feedstuffs for ducks. In each experiment, fasting losses were obtained from six ducks and six ducks were used for each feedstuff. Each experiment lasted 102 h with an initial 48-h period and a 54-h excreta collection period. During the first 48-h period, all birds were tube-fed dextrose (30 g/100 mL of water) at 8 and 32 h after feed was withdrawn. Thirty grams of each feedstuff were tube-fed (30 g/100 mL of water) at 48 and 54 h after feed was withdrawn. The birds from which fasting losses were obtained were intubated with 30 g dextrose (30 g/100 mL of water) at 48 and 54 h after feed was withdrawn. Excreta were collected during the last 54 h into bags screwed onto lids sutured around the vent of each bird. In the first experiment, the feedstuffs evaluated were corn, dehulled oats, and wheat. The fasting energy and nitrogen losses per bird in the 54-h collection period were 12.1 kcal and 0.29 g, respectively. The AMEn values for the birds fed corn, dehulled oats, and wheat were 3.10, 3.48, and 3.14 kcal/g, respectively. The TMEn values for the respective feedstuffs were 3.27, 3.64, and 3.30 kcal/g. In the second experiment, the feedstuffs evaluated were corn, parboiled rice, and rye. The fasting energy and nitrogen losses per bird in the 54-h collection period were 18.9 kcal and 1.09 g, respectively. The AMEn values for the birds fed corn, parboiled rice, and rye were 3.24, 3.45, and 2.69 kcal/g, respectively. The TMEn values for the respective feedstuffs were 3.40, 3.61, and 2.85 kcal/g. The data provide new information on AMEn and TMEn values of corn, wheat, parboiled rice, dehulled oats, and rye for ducks.

Feeding and excreta collection techniques in metabolizable energy assays for ducks.

Feeding and excreta collection techniques, lasting 102 h, for the determination of ME in feed ingredients for ducks are described. Eight and 32 h after feed withdrawal, all ducks received 30 g of dextrose in 100 g of water by orogastric administration. By orogastric administration, ducks received 30 g of test ingredients or dextrose (for ducks used in estimation of endogenous losses of energy and nitrogen) in 100 g of water at 48 and 54 h after feed withdrawal. The collection of excreta involved suturing a threaded plastic retainer ring to the vent and screwing a Whirl-Pak plastic bag, mounted on the top portion of a Playtex baby nurser set plastic bottle cut off 3 cm below the threads, to the retainer ring. Excreta were collected by replacing the Whirl-Pak bags at 54, 60, 72, 84, 96, and 102 h after feed withdrawal. In each of two experiments, ducks with an average weight of 3.7 kg were assigned to treatments. In Experiment 1, four ducks were assigned to each of three test ingredients (corn, dehulled oats, and wheat) and four ducks were assigned to be deprived of feed for estimation of endogenous losses of nitrogen and energy. In Experiment 2, six ducks were assigned to each of two test ingredients (corn and sorghum) and six ducks were assigned to be deprived of feed. Ducks lost an average of 537 g (Experiment 1) and 462 g (Experiment 2) during the 102-h experimental period and all the lost weight was regained within 7 d of return to full feed. Losses of nitrogen (milligrams per duck per 54 h) were 292 (Experiment 1) and 461 (Experiment 2) and energy (kilocalories per duck per 54 h) were 12.12 and 22.26 in feed-deprived group. The determined AMEn and TMEn for corn were 3.245 and 3.407, and 3.210 and 3.517 kcal/g for Experiments 1 and 2, respectively. For dehulled oats, wheat, and sorghum, the determined AMEn and TMEn were 3.464 and 3.625, 3.150 and 3.312, and 3.363 and 3.670 kcal/g, respectively.

The influence of different cereal grains on iron absorption from infant cereal foods.

Iron absorption from various cereal grains was evaluated in the present study to identify possible preferences for the preparation of infant weaning foods. In six separate studies, four radioiron absorption tests were performed in each of 57 volunteer subjects by using a sequential double-isotopic method. Serum ferritin concentration was used to adjust for the effect of differences in the iron status of subjects participating in separate studies. Identical commercial processing and test meal composition were used to evaluate iron absorption from 50 g cooked cereal prepared from rice, wheat, maize, oats, millet, and sweet or bitter quinoa. In an initial evaluation of cereals fortified with 2.5 mg Fe as FeSO4, geometric mean absorption values were uniformly < 1% for all cereals and were not significantly different. In subsequent studies, percentage iron absorption was enhanced by either eliminating the fortifying iron or adding 50 mg ascorbic acid to the test meal. The effect was similar for most of the cereals tested with a composite mean increase in absorption of 37% when fortifying iron was removed and 270% when ascorbic acid was added. There was a strong inverse correlation between iron absorption and the phytate content of different cereals. Except for a modestly lower absorption of iron from quinoa and a remarkably higher absorption from one lot of maize, we conclude that the type of cereal grain has little influence on iron bioavailability of infant cereals. On the other hand, modification in the milling and processing methods for cereal grains that reduce their content of phytic acid is likely to improve iron availability significantly.

The effect of grain source and grain processing on performance of feedlot cattle: a review.

Effects of grain species and grain processing method on DMI, rate and efficiency of gain, and feeding value for cattle fed high concentrate diets were appraised by statistically compiling results from 605 comparisons from feeding trials published in North American journals and experiment station bulletins since 1974. Metabolizable energy (ME) values for each grain and processing method were calculated by quadratic procedures from DMI and animal performance. Averaged across processing methods, ME values for corn, milo, and wheat grain (3.40, 3.22, and 3.46 Mcal/kg DM) fell within 9% of ME estimates from NRC (1996) for beef cattle. In contrast, ME values for barley and oats grain (3.55 and 3.46 Mcal/kg DM) were 24% and 17% greater than NRC (1996) estimates. Compared with the dry rolled forms, high moisture corn and milo resulted in lower ADG and DMI. Compared with dry rolling, either steam rolling or flaking of corn, milo, and wheat decreased DMI without decreasing ADG and improved feed efficiency by 10, 15, and 10%, respectively. Compared with dry rolled grain, steam flaking increased (P < .05) body weight-adjusted ME of corn and milo grain by 15 and 21%, respectively; body weight-adjusted ME for whole corn was 9% greater (P < .05) than for rolled corn grain. Steam flaking was surprisingly effective (13%) at increasing (P < .05) the body weight-adjusted ME of wheat, but steam flaking failed to increase the ME of barley and oats. Higher moisture content of high-moisture corn decreased dry matter intake without depressing ADG and improved efficiency and increased ME of the grain. Compared with steam flakes of moderate thinness, processing milo or barley to a very thin flake tended to reduce ADG and failed to improve feed efficiency. The ideal roughage source and roughage moisture content for maximum ME and ADG varied with grain processing method. Feeding corn silage rather than alfalfa and wet rather than dry roughage depressed (P < .01) ADG of cattle and reduced (P < .01) body weight-adjusted ME of cattle fed high-moisture corn grain but tended to increase both with steam-flaked corn or wheat.

Effect of high-amylose starch and oat bran on metabolic variables and bowel function in subjects with hypertriglyceridemia.

We compared the effects of a diet in which approximately 25% of the carbohydrate was replaced by high-amylose starch with those of a similar diet high in oat bran or low-amylose starch in 23 hypertriglyceridemic subjects who were overweight mostly because of abdominal adiposity. Each diet was consumed for 4 wk in random order and in a crossover fashion. Overall, the diets were high in carbohydrate (> 55% of energy) and low in fat (< 30% of energy); the amount of resistant starch in the foods containing high-amylose starch was 17 g in women and 25 g in men. The metabolic effects of specific starches on plasma lipids, fasting and postprandial glucose and insulin profiles, and bowel function were assessed at the end of each intervention. Plasma triacylglycerols (triglycerides) were significantly lower after the oat bran diet than after the other two diets (P < 0.02). No other effects on fasting plasma lipids, glucose, or insulin were noted. However, when the high-amylose starch comprised 33% of the carbohydrate content in a test meal, there was a significant but biologically small reduction in the overall postprandial plasma insulin concentration by 17% relative to the low-amylose diet (P < 0.01). Both the oat bran and the high-amylose diet resulted in an increased frequency of bowel actions and lower fecal pH (P < 0.02) relative to the low-amylose diet. However, unlike the oat bran diet, the high-amylose diet increased short-chain fatty acid concentrations in fecal water by 32% (P < 0.001).

Preexercise meal composition alters plasma large neutral amino acid responses during exercise and recovery.

This study was designed to determine the effect of ingesting three preexercise meals on energy metabolism during exercise and recovery and to relate metabolic perturbations to subjective and objective measurements associated with central fatigue. Twelve subjects consumed isoenergetic meals consisting of oat, wheat, or corn cereals 90 min before cycling. A fasting trial served as the control. Blood samples and cognitive function, perceived hunger, and sleepiness measurements were obtained before and after feeding and during recovery when self-selected food intake was also measured. After meal ingestion, plasma insulin was lower for oat than for wheat or corn whereas the ratio of tryptophan to large neutral amino acids (LNAAs) for corn was less than for all others. During exercise, the tryptophan-LNAA ratio increased from preexercise values for the fasting and wheat trials, but exercise performance was unaffected. During recovery, tryptophan:LNAA increased from postexercise values in fasting trials. Also, hunger and fatigue ratings were greater in fasted subjects, but self-selected food intake measured at the end of the recovery period was not different among groups. We conclude that preexercise meal consumption affected tryptophan:LNAA before, during, and after exercise, but these changes were not sufficient to alter physical and cognitive performance.

Persistence of the effects of early experience on consumption of low-quality roughage by sheep.

The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wethers (IW) grazed fresh oats (initial exposure). Then both EW and IW were fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after completion of the initial exposure EW and IW were offered sorghum hay (low-quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P < .02) sorghum than IW. When given sorghum simultaneously with alfalfa at different levels of availability, EW ingested more (P < .10) sorghum than IW when only sorghum was freely available. Nitrogen retention was negative in both groups, but it was less negative in EW than in IW per unit of metabolic weight (P < .09) and per wether (P < .04). The results show that early dietary experience can have profound and persistent effects on consumption of foods low in nutritional quality, apparently through changes in critical physiological mechanisms.

Products based on a high fiber barley genotype, but not on common barley or oats, lower postprandial glucose and insulin responses in healthy humans.

Postprandial blood glucose and insulin responses to cereal products made from common barley, oats or a barley genotype containing elevated levels of beta-glucans were evaluated in nine healthy subjects. Porridges were made from commercial Swedish whole-meal barley or oat flours, and a mixed whole-meal porridge using the high fiber barley genotype and commercial Swedish common barley (50:50). Also studied were two types of flour-based bread products composed of high fiber barley and common barley in ratios of 50:50 or 80:20, respectively. The common oat and barley porridges produced postprandial glucose and insulin responses similar to the white wheat bread reference, suggesting that the naturally occurring dietary fiber in these whole-meal flours has no impact on the glucose tolerance. In contrast, all high fiber barley products induced significantly lower responses than did the reference product, with the glycemic and insulin indices ranging from 57 to 72 or 42 to 72%, respectively. It is concluded that "lente" products of high sensory quality can be prepared from a barley genotype with an elevated content of soluble dietary fiber. The glycemic index of these products compares favorably with that of products made from common cereals, suggesting their use as a potential component of diets for patients with diabetes and hyperlipidemia, and for individuals predisposed to metabolic disease.

Effects of excess dietary leucine and leucine catabolites on growth and immune responses in weanling pigs.

Two experiments with weanling pigs were conducted to study the effects on growth and immune responses of excess dietary L-leucine (LEU) and dietary supplementation with the LEU catabolites, alpha-ketoisocaproic acid (KIC) and beta-hydroxymethyl butyrate (HMB). In Exp. 1, 80 pigs were randomly allocated according to initial BW and ancestry to five replications of four dietary treatments (four pigs/pen). The control diet contained wheat, oat groats, menhaden fish meal, and dried whey and provided 1.12% LEU. Treatment diets were the control plus 1.12% LEU, 1.12% KIC, or .4% HMB. The experiment lasted 6 wk. In Exp. 2, 36 pigs were randomly allocated to nine replications of four dietary treatments in a 2 x 2 factorial arrangement. Treatments consisted of two concentrations of dietary LEU and a daily i.m. injection of dexamethasone (DEX) or saline. Pigs were fed a control corn-soybean meal and dried whey diet (1.56% LEU) or the control diet plus 1.56% of crystalline LEU. Pigs were individually penned and the experiment lasted 4 wk. Growth performance, plasma free amino acids, plasma urea nitrogen, and humoral and cellular immune responses were measured. Results indicated that LEU concentrations in practical diets and supplementation with KIC and HMB (Exp. 1) did not detrimentally affect growth and immune response. The high LEU concentration and DEX injection used in Exp. 2, however, were detrimental to both growth and immune response.