Fundamental study on the influence of Fusarium infection on quality and ultrastructure of barley malt.

Barley infection with Fusarium species has been a long standing problem for the malting and brewing industries. In this study, we evaluate the impact of Fusarium culmorum infected raw barley on the final malt quality. Barley grains were infected for 5 days at optimum fungal growth conditions. Grains were fully characterized and compared to standard barley grains. Due to fungal infection, germinative energy of infected barley grains decreased by 45%; its water sensitivity increased dramatically, and grains accumulated 199 µg/kg of deoxynivalenol (DON). Barley grains were subsequently malted for 8 days, fully characterized and compared to standard malt grains. Fungal growth behavior was evaluated during malting using a PCR-based assay and mycotoxins were measured using HPLC. Fungal biomass increased in grains, during all stages of malting. Infected malt accumulated 8-times its DON concentration during malting. Kernel ultrastructure was evaluated using scanning electron and confocal laser scanning microscopy. Infected malt grains were characterized by extreme structural proteolytic, (hemi)-cellulolytic and starch deterioration with increased friability and fragmentation. Infected grains had higher protease and ß-glucanase activities, lower amylase activity, a greater proportion of free amino and soluble nitrogen, and a lower ß-glucan content. Malt loss was over 27% higher in infected malt in comparison to the control. The results of this study revealed that 20% F. culmorum infected barley kernels lead to a significant reduction in malt quality as well as mycotoxin formation.

Effect of ozone treatment on the safety and quality of malting barley.

Molds and their mycotoxins are an expensive problem for the malting and brewing industries. Deoxynivalenol (DON) is a mycotoxin that is associated with Fusarium spp. These fungi frequently cause Fusarium head blight in wheat and barley in the midwestern region of the United States; Manitoba, Canada; Europe; and China. Barley growers and malt producers would benefit from a postharvest control method for mold growth and DON production. We evaluated the use of gaseous ozone (O(3)) for preventing Fusarium growth and mycotoxin production while maintaining malt quality characteristics. Micromalting was performed in three replications under standard conditions. Ozone treatment was applied to malting barley during steeping via a submerged gas sparger. Ozone treatment conditions were 26 mg/cm(3) for 120 min after 2 and 6 h of steeping. The effects of gaseous ozone on DON, aerobic plate counts, Fusarium infection, and mold and yeast counts of barley throughout the malting process were measured. Various quality parameters of the malt were measured after kilning. Statistical tools were used to determine the significance of all results. Ozonation of malting barley during steeping did not lead to significant reductions in aerobic plate counts but did lead to a 1.5-log reduction in mold and yeast counts in the final malt. The influence of gaseous ozone on DON concentration was inconclusive because of the low initial concentrations of DON in the barley. Ozone significantly reduced Fusarium infection in germinated barley. Gaseous ozone did not negatively influence any aspect of malt quality and may have subtle beneficial effects on diastatic power and ß-glucan concentrations.

Occurrence of ochratoxin A and citrinin in Czech cereals and comparison of two HPLC methods for ochratoxin A detection.

The aims of the study were to obtain information about the occurrence of ochratoxin A (OTA) and citrinin (CIT) in cereals harvested in the Czech Republic and to compare two analytical procedures for detecting OTA. A total of 34 cereal samples, including two matrix reference materials (R-Biopharm, Germany), were analysed. The results were compared with the limit for raw cereal grains used as a foodstuff according to Commission Regulation No. 1881/2006, which allows a maximum OTA level of 5 µg kg(-1). Compared were two methods based on the high-performance liquid chromatography principle, one using the immunoaffinity columns OchraTest (VICAM) and the second based on solvent partition (PART), both followed by fluorescence detection. The highest OTA contents were found in two barley samples. According to the method employed, the results for the first sample (malting barley) were VICAM = 31.43 µg kg(-1) and PART = 44.74 µg kg(-1). For the second sample (feeding barley) they were VICAM = 48.63 µg kg(-1) and PART = 34.40 µg kg(-1). Two samples of bread wheat had an OTA content approaching the legal limit (VICAM = 4.71 µg kg(-1) and PART = 6.03 µg kg(-1); VICAM = 4.12 µg kg(-1) and PART = 3.95 µg kg(-1)). CIT was analysed using the PART method only, and its highest content (93.64 µg kg(-1)) was found for the malting barley sample with high OTA content (44.74 µg kg(-1) as analysed using PART).

Effect of hot water treatments on the safety and quality of Fusarium-infected malting barley.

Utilization of Fusarium-infected barley for malting may lead to mycotoxin contamination of malt and decreased malt quality. Hot water treatments may prevent or reduce safety and quality defects and allow use of otherwise good quality barley. We evaluated hot water treatments for preventing Fusarium growth and mycotoxin production while maintaining barley-malt characteristics. Four barley lots with varying deoxynivalenol (DON) concentrations were hot water-treated at 45 or 50 degrees C for 0, 1, 5, 12, and 20 min. Treated barley was malted in a pilot-scale malting unit. Barley and malt were analyzed for Fusarium infection (FI), germinative energy (GE), aerobic plate count (APC), mold and yeast count (MYC), and DON. Malt quality parameters included malt extract, soluble protein, wort color, wort viscosity, free amino nitrogen, alpha-amylase, and diastatic power. Significant decreases in FI occurred within 1 min at both 45 degrees C (41-66%) and 50 degrees C (51-69%) in all barley samples. Significant reductions in APC (1.0-1.8 log) and MYC (1.7-1.8 log) in barley were observed after 5 min at both temperatures. The largest reductions for DON were observed in malts prepared from barley treated with hot water at 45 degrees C (79-93%) and 50 degrees C (84-88%) for 20 min. GE and most of the malt quality parameters were only affected when barley was treated at 50 degrees C for 12 and 20 min. The results suggest that hot water treatments may offer the potential for treating mildly FHB infected malting barley.

Effect of electron-beam irradiation on the safety and quality of Fusarium-infected malting barley.

Utilization of Fusarium-infected barley for malting may lead to mycotoxin production during malting and decreased malt quality. Electron-beam irradiation may prevent safety and quality defects and allow use of otherwise good quality barley. We evaluated electron-beam irradiation for preventing Fusarium growth and mycotoxin production while maintaining barley-malt quality characteristics. Four barley lots with varying deoxynivalenol (DON) concentrations were irradiated at 0, 2, 4, 6, 8, and 10 kGy. Treated barley was malted in a pilot-scale malting unit. Barley and malt were analyzed for Fusarium infection (FI), germinative energy (GE), aerobic plate counts (APC), mold and yeast counts (MYC), and DON. Malt quality parameters included malt extract, soluble protein, wort color, wort viscosity, free amino nitrogen, alpha-amylase, and diastatic power. FI, APC, and MYC decreased in barley with an increase in dosage. The APC and MYC for malts from barley exposed to 8-10 kGy were slightly higher than in other malted samples indicating that irradiation-resistant microflora could flourish during malting. Barley GE significantly decreased (3-15%) at 8-10 kGy. Although irradiation had no effect on DON in raw barley, DON decreased significantly (60-100%) in finished malts prepared from treated barley (6-10 kGy). Malt quality parameters were slightly affected by electron-beam radiation. The results suggest 6-8 kGy may be effective for reducing FI in barley and DON in malt with minimal effects on malt quality.

Evaluación de la calidad física de diferentes variedades de cebada (Hordeum sativum jess) cultivada en los estados de Hidalgo y Tlaxcala, México / Evaluation of physical quality from different barley varities (Hordeum sativum jess) produced in the states of Hidalgo and Tlaxcala from Mexico

La cebada es el cuarto cereal de mayor importancia a nivel mundial, así como también a nivel nacional en México. Hidalgo y Tlaxcala son dos de los estados de mayor producción de cebada en grano de temporal. Entre los cereales existen variaciones en sus características y propiedades físicas, aún siendo de la misma variedad. Es por eso que existen sistemas de clasificación, para darle al grano de cebada determinada calidad y grado. Con la finalidad de determinar la calidad de siete variedades de cebada producidas en Hidalgo y Tlaxcala, las muestras se sometieron a diferentes análisis: sensorial y temperatura, impurezas y sanidad, densidad, dureza y selectivo. De los análisis mencionados se determinó que sólo la variedad Pastor Ortiz tiene el grado México de acuerdo a la norma mexicana NMX-FF-043-SCFI-2003, las otras seis variedades obtienen el grado México no clasificado.

Barley is the fourth cereal of greater importance at world-wide level, as well as at national level in México. Hidalgo and Tlaxcala are two of the states of greater production of barley. Between cereals, physical variations in their characteristics and properties exist, even in those of the same variety. A classification systems exist to give to the grain from certain barley regarding quality and degree. With the purpose of determining the quality of seven produced varieties of barley in Hidalgo and Tlaxcala, samples were put under different analyses: sensorial and temperature, impurities and sanitary, density, hardness and selectivity. From the analyses mentioned it was determined that only the Pastor Ortiz variety has the Mexico degree according to Mexican norm NMX-FF-043-SCFI-2003, the other six varieties received the Mexico rank of none classified.

Evaluation of gaseous ozone and hydrogen peroxide treatments for reducing Fusarium survival in malting barley.

The use of Fusarium-infected barley for malting can lead to mycotoxin production and decreased malt quality. Methods for treatment of Fusarium-infected barley might prevent these safety and quality defects and allow use of otherwise good-quality barley. Gaseous ozone and hydrogen peroxide (HP) were evaluated for effectiveness in reducing Fusarium survival while maintaining germinative energy (GE) in barley. Gaseous ozone treatments (GOT) included concentrations of 11 and 26 mg/g for 0, 15, 30, and 60 min. HP treatments included 0, 5, 10, and 15% concentrations with exposure times of 0, 5, 10, 15, 20, and 30 min. For GOT, in naturally Fusarium-infected barley, a statistically significant (P < 0.05) decrease (24 to 36%) of Fusarium survival occurred within 15 min of exposure at either concentration. GE was significantly (P < 0.05) affected by 30 min at both concentrations in naturally Fusarium-infected barley, but not in sound barley. GOT did not cause any significant (P > 0.05) effect on GE in sound barley at either concentration over the full 30-min exposure time. For HP, Fusarium survival was significantly decreased (50 to 98%) within 5 min of exposure. With the exception of two treatments (10 and 15% HP agitated for 20 min), GE was not statistically significantly different from the control in naturally Fusarium-infected barley. In sound barley, HP had no significant (P > 0.05) effect on GE. The results suggest that GOT and HP might have potential for treatment of Fusarium-infected malting barley.

Evaluation of hot water and electron beam irradiation for reducing Fusarium infection in malting barley.

The use of Fusarium-infected barley for malting may lead to mycotoxin production and decreased product quality. Physical methods for the treatment of Fusarium-infected barley may prevent these safety and quality defects and allow the use of otherwise good quality barley. Hot water and electron beam irradiation were evaluated for their effectiveness in reducing Fusarium infection while maintaining germinative energy in barley samples. Hot-water treatments involved temperatures of 45, 50. 55, and 60 degrees C and treatment times of 0, 1, 5, 10, and 15 min. Electron beam irradiation involved doses ranging from 0 to 11.4 kGy. Treatment with water at 45 degrees C for 15 min resulted in a reduction in Fusarium infection from 32 to 1% after 15 min, with only a very slight reduction in germination. Treatment with water at 50 degrees C for 1 min resulted in a reduction in Fusarium infection from 32 to 2%, and no effect on germination was observed for up to 5 min of treatment. At higher water temperatures. Fusarium infection was essentially eliminated, but germination was also severely reduced. Electron beam irradiation of Fusarium-infected barley reduced Fusarium infection at doses of >4 kGy, and a slight increase in germination for dry samples was observed with doses of 6 to 8 kGy. Doses of >10 kGy significantly decreased germination. Physical methods may have potential for the treatment of Fusarium-infected malting barley.

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.

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.

The relationship among dietary undetermined anion, acid-base balance, and nutrient metabolism in swine.

Dietary undetermined anion (dUA) reflects, in part, the net acid load contributed by the diet. Although dUA is known to influence performance and nutrient metabolism of swine, a lack of knowledge impairs its application to diet formulation. This study was undertaken to separate the effects of dUA from the individual electrolytes that constitute its calculation. Eighteen 35-kg pigs were fitted with indwelling venous catheters and fed one of three barley and soybean meal-based diets: a control diet (C), an acidogenic diet containing calcium chloride (A), or a compensated acidogenic diet containing alkaline salts of sodium and potassium, as well as calcium chloride (CA). Compared with diet C, diet A lowered (P < .05) blood pH, bicarbonate, and base excess and increased (P < .05) urinary ammonium, titratable acid (TA), and net acid excretion (NAE). Diet CA returned blood acid-base values to normal and reduced urinary ammonium, TA, and NAE relative to diet A. Total nitrogen balance was unaffected by diet. Diet CA increased (P < .05) water intake and urine output. Diet A, but not CA, increased (P < .05) serum ionized Ca and C1. Apparent Ca and S digestibility and retention were reduced by diet A, but not by CA. Sodium retention was enhanced (P < .05) by diets A and CA; potassium retention was impaired (P < .05) by CA. Dietary UA altered systemic and renal acid-base balance in pigs. Mineral, but not nitrogen, metabolism was affected by both dUA and specific ion effects.

Preference of sheep and goats for extracts from high-grain concentrate.

Appetite stimulants were extracted and partially isolated from high-grain concentrate. The stimulants were fed daily and were palatable to sheep and goats used in the experiments. The stimulative effects were tested by comparing the intake of two types of hay: with or without the extracts. Diethylether and n-pentane extracts of the concentrate stimulated feeding in sheep (P < .01 and P < .05, respectively). However, methanol extracts had no significant stimulative effect on selective feeding in sheep. Goats also preferentially fed on hay sprayed with the diethyl ether extracts (P < .01). The diethyl ether extracts were divided into acid, neutral, and basic fractions. Sheep and goats had a marked preference for the acid fraction only (P < .01 and P < .05, respectively). These results suggest that specific chemicals to increase palatability of hay are present in high-grain concentrate and that the chemical are nonpolar, acidic substances.

Factors affecting phosphorus and calcium digestibility in diets for growing-finishing pigs.

In two experiments, we investigated various factors that affect the estimation of the apparent total tract digestibility (ATTD) of DM, Ca, and total P in diets for growing-finishing pigs. In Exp. 1, the effects of age, housing, and calculation method (indicator [Cr2O3] vs 10-d total collection) were determined. Eighteen barrows and gilts (40 to 95 kg BW) were housed in six pens, and ATTD was estimated using the indicator method. Twelve barrows were housed in metabolic crates, and ATTD was estimated using both calculation methods. Dietary treatments were 1) a tapioca-soybean-barley-based diet, 2) Diet 1 supplemented with 400 FTU microbial phytase/kg of diet, and 3) a corn-soybean meal-based diet: In Exp. 2, six barrows (95 to 120 kg BW) were fed a phytase-deficient diet to investigate the effects of coprophagy (40 g fresh feces/kg of diet) and movement. Pigs were fed at 2.8 times maintenance requirement (418 kJ ME/BW.75); water supply was 2.5 L/kg of feed. The ATTD increased as BW increased. Phytase enhanced total P ATTD by an average of 18.1 percentage units. The ATTD of DM was higher and the ATTD of Ca and total P (P < .001) were lower in pigs housed in pens than in pigs housed in metabolic crates. Fecal consumption and movement led to numerical increases in Ca (P = .217) and total P (P = .103) ATTD. Estimates of Ca and total P ATTD using pigs in metabolic crates are lower than estimates in practice.

Effect of feeding blends of Fusarium mycotoxin-contaminated grains containing deoxynivalenol and fusaric acid on growth and feed consumption of immature swine.

Experiments were conducted to determine the effect of feeding diets containing combinations of the Fusarium metabolites deoxynivalenol (DON) and fusaric acid (FA) to starter swine. In all experiments, pigs of approximately 8.2 kg initial weight were fed diets containing blends of mycotoxin-contaminated corn, wheat, and barley for 21 d with growth and feed consumption determined weekly. In the first experiment, diets were determined to contain 0 microgram DON/g + 58.9 micrograms FA/g (control), 4.4 micrograms DON/g + 57.1 micrograms FA/g, 6.0 micrograms DON/g + 48.6 micrograms FA/g, and 7.5 micrograms DON/g + 57.4 micrograms FA/g. The feeding of all diets containing DON caused significant linear depressions in growth and feed intake after only 1 wk. Lower concentrations of DON and FA were fed in the second experiment with diets containing 0 microgram DON/g + 16.3 micrograms FA/g (control), .5 microgram DON/g + 14.3 micrograms FA/g, 1.1 micrograms DON/g + 14.1 micrograms FA/g, and 1.9 micrograms DON/g + 13.6 micrograms FA/g. There was a significant linear reduction in feed intake after 1 wk with increasing levels of dietary DON. Weight gains declined significantly only after 3 wk. Increasing amounts of FA combined with relatively constant amounts of DON were fed in the third experiment. By analysis, diets contained .5 micrograms DON/g + 2.9 micrograms FA/g (control), 2.2 micrograms DON/g + 12.2 micrograms FA/g, 2.5 micrograms DON/g + 15.6 micrograms FA/g, and 2.4 micrograms DON/g + 15.9 micrograms FA/g. In the 1st wk, the feeding of increasing amounts of fusaric acid combined with a relatively constant amount of DON caused a significant linear depression in weight gain. We concluded that a toxicological synergism exists between DON and FA when fed to immature swine and that FA concentrations in feeds should be determined whenever DON analysis is conducted.

Effect of forage:concentrate ratio on digestion and reproduction in primiparous beef heifers.

We evaluated the effects of high- (HF) and moderate- (MF) forage diets on digestive and reproductive characteristics in beef heifers. Thirty primiparous beef heifers were allotted by weight and backfat thickness to receive either 80:20 (HF) or 50: 50 (MF) forage:concentrate ratio diets from parturition to at least 90 d postpartum. Alfalfa hay and wheat straw were the forage sources and barley was the concentrate source. Equal daily amounts of ME were provided to all heifers by restricting intake of the MF diet. Digestibility of DM was greater (P < .001) for MF compared with HF diets, whereas NDF digestibility was not different. Dry matter and NDF digested daily was lower (P < .001) for MF than for HF diets. Ruminal fluid pH was lower (P < .05) for MF diets; however, the acetate:propionate ratio was not different. Serum insulin concentrations were greater for MF diets for all hours (P < .001) and weeks (P < .05) of sampling. Changes in weight, backfat thickness, and body condition score at 90 d postpartum were not different between treatments. Calf gain to 30 d, however, was greater (P < .10) for the MF than for the HF treatment (25.5 vs 20.7 kg). Maximum size of the ovulatory follicle was greater (P < .10) for cows receiving the HF diet than for cows receiving the MF diet. However, other aspects of ovarian follicular growth and wave dynamics and the intervals from parturition to first and second ovulation, first estrus, first service, and conception were not different between treatments. Shifts in energy supply from forage to concentrate had minimal effect on digestion and reproduction in first-calf beef heifers in this study.

Energy evaluation of eight barley cultivars for poultry: effect of dietary enzyme addition.

Three experiments were conducted to study eight barley cultivars and the effect of enzyme addition on their energy value for poultry. In Experiment 1, the AMEn of a reference barley (Beka cultivar) was calculated by increasing barley concentrations (30, 40, 50, and 60%) that replaced a high protein basal diet. In Experiment 2, eight barley cultivars (four spring and four winter cultivars) replaced the reference barley in the diet with 50% barley inclusion. Two of the winter cultivars were two-rowed and two were six-rowed cultivars. A commercial enzyme was added to these diets to study the effect of enzyme addition. Diets were consumed ad libitum by 27 and 145 21-d-old Arbor Acres broiler chicks, in Experiments 1 and 2, respectively. In Experiment 3, 66 adult roosters were used to determine the TMEn of the eight cultivars used in Experiment 2. Dietary AMEn decreased linearly (P < 0.05) with increasing barley (Beka cultivar) inclusion. Beka barley AMEn was calculated by extrapolation of the linear regression equation be equal to 2,980 kcal/kg DM. Barley energy value was influenced by cultivar (P < 0.001); the spring cultivars showed greater energy value than the winter cultivars (2,963 vs 2,852 kcal AMEn/kg DM; 3,192 vs 2,929 kcal TMEn/kg DM). Two-rowed cultivars showed higher TMEn than six-rowed winter cultivars, although no differences were found for AMEn. The correlation between AMEn and TMEn values of barley was relatively low (r = 0.69); therefore, barley TMEn cannot be extrapolated to AMEn for young chicks. Enzyme addition produced an average increase of 220 kcal/kg DM in barley AMEn (P < 0.001); there was a significant (P < 0.10) interaction between barley cultivar and enzyme supplementation. The increment of barley AMEn caused by enzyme addition was partly explained (47%) by an increase in barley viscosity. This relationship implies that enzyme supplementation significantly improves the feeding value of high as compared to low viscosity barley samples, which involved a decrease in AMEn variation among cultivars for enzyme-supplemented barley. No relationship was found between AMEn of unsupplemented barley cultivars and their chemical composition. Instead, a relationship was detected for enzyme-supplemented barley; therefore two equations were proposed for predicting the AMEn of enzyme-supplemented barley to be used directly in diet formulation.

Influence of flake density on the comparative feeding value of a barley-corn blend for feedlot cattle.

Ninety-six medium-frame crossbred steers (209 kg) were used in an 86-d feeding trial. Dietary treatments consisted of a 92% concentrate diet containing 76.15% (DM basis) grain as 1) steam-flaked barley (SFB), flake density (FD) = .26 kg/L; 2) blend of 2/3 barley and 1/3 corn steam-flaked (SFBLEND), FD = .36 kg/L; 3) SFBLEND, FD = .31 kg/L; 4) SFBLEND, FD = .26 kg/L. There were no treatment effects (P > .10) on growth performance of feedlot steers or NE value of the diet. Weight gain averaged 1.46 kg/d. Feed efficiency was in close agreement (101%) with expected values based on observed DMI and tabular dietary NE values. Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (280 kg) with cannulas in the rumen and proximal duodenum in a 4 x 4 Latin square design. Ruminal digestibility of OM (P < .01), starch (P < .01), and feed N (P < .10) increased, and ruminal N efficiency (duodenal nonammonia N/N intake, P < .01) decreased (linear component) with decreasing FD. Net microbial N flow to the small intestine was greater (P < .05) for SFB than for the SFBLEND. Total tract digestion of OM (P < .01), starch (P < .05), and DE (P < .05) was greater for the SFBLEND than for SFB. There were no treatment effects (P < .10) on postruminal and total tract digestibility of N. We conclude that blending barley and corn before flaking will have very little impact on the feeding value of the grains compared with flaking the grains separately.

Influence of level of concentrate allocation and fermentability of forage fiber on chewing behavior and production of dairy cows.

Nine midlactation dairy cows were offered one of three mixed silage rations with neutral detergent fiber (NDF) that was similar in concentration but different in fermentability. Differences in fermentability were achieved by substituting a high quality alfalfa silage for a low quality alfalfa silage and substituting a combination of ryegrass and timothy silages for a barley silage. In addition, concentrate was allocated at 0.30, 0.82, or 1.37 kg of dry matter/kg of dry matter intake (DMI) from the mixed silage ration. As expected, the NDF content of the mixed silage ration did not differ, although fermentability of NDF increased numerically as forage quality increased. Intake of NDF increased linearly, and DMI tended to increase linearly, as fiber fermentability of the mixed silage ration increased. In addition, cows produced more milk, milk fat, and milk protein and generated more total and milk energy. The calculated concentration of net energy for lactation of the total diet also increased. Results support the concept that NDF quality influences and can be used to predict voluntary feed intake, at least in relatively high producing dairy cows. The DMI increased, and intake of NDF and crude protein declined, as the allocation of concentrate increased. In addition, as concentrate allocation increased, cows spent less time eating and ruminating and more time resting and produced more milk, milk protein, and milk lactose. Cows also generated more total energy and milk energy, although, despite a sharp decrease in the forage proportion of the diet, the calculated energy density of the diet did not differ among concentrate levels. The lack of significant interactions between concentrate level and fiber fermentability for any parameter measured supports the contention that high quality forage is critical to a successful dairy ration, regardless of the proportion of forage in the diet.

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.

Influence of energy supplementation on grazing ruminants: requirements and responses.

Energy requirements of grazing livestock seem to be poorly defined. Requirements generated from measurements in pen-fed animals present both theoretical and practical concerns when they are applied to grazing situations. In mature ruminants a majority of energy used for maintenance seems to be consumed by visceral tissues. Moreover, factors that affect visceral energy use are poorly understood. Energy supplementation to meet requirements and production demands is often practiced during periods of summer dormancy and in winter months. Source of supplemental energy varies widely and includes grains, readily digestible fiber sources, and high-quality forages. Intake and digestibility can be reduced or unaffected by energy supplementation. In some cases, lower levels of energy supplementation have been shown to increase utilization of grazed forage. Reductions in ruminal pH, often cited as the major cause of reduced fiber digestion, may not always explain reductions in intake and digestibility associated with energy supplementation. Livestock production is usually either enhanced or unaffected by energy supplementation. Additional research regarding energy requirements of grazing ruminants, visceral energy use, and mechanisms associated with reductions in intake and digestibility of grazed forage resulting from energy supplementation is warranted.