Feed preference in pigs: effect of cereal sources at different inclusion rates

The palatability of different cereals was studied in 2 two-way choice (preference) experiments using pigs of 56 d of age and 17 kg of BW. In Exp. 1, the effect of 24 cereals vs. a common reference diet containing white rice on feed preference in pigs was studied. Pigs were offered free choice between the reference diet and a diet with the cereal under study for 4 d. Barley, corn (2 sources), wheat, cassava meal, biscuit meal, rye, sorghum, and 1 source of oats were tested at inclusion rates of 300 and 600 g x kg(-1). Short-grain rice (whole, brown, or extruded white), long-grain white rice (raw and cooked), extruded barley, extruded corn, extruded wheat, oats (2 sources), thick rolled oats, cooked oats, and naked oats (raw, extruded, or micronized) were tested at inclusion rates of 150, 300, and 600 g x kg(-1). Relative preference of cereals (% of total feed intake) was affected by type of cereal and by rate of inclusion. The diets containing extruded rice (150 g x kg(-1)), extruded naked oats (150, 300, and 600 g x kg(-1)), or naked oats (150 and 300 g x kg(-1)) were preferred (P < 0.05) by pigs to the reference diet. However, the reference diet was preferred (P < 0.05) to the diets containing 150, 300, and 600 g x kg(-1) of cooked long-grain rice, oats, or cooked oats, 300 and 600 g x kg(-1) of extruded wheat, wheat, corn, sorghum, or unhulled short-grain rice, and 600 g x kg(-1) of thick rolled oats, extruded corn, rye, extruded barley, micronized naked oats, barley, cassava, or biscuit meal. Extrusion improved (P < 0.05) preference values for corn and naked oats by pigs, but had no effect on barley, rice, or wheat. In Exp. 2, the preferences of pigs for oats and barley were studied using mash and pelleted diets. Diet form did not affect preference in oats diets. However, for barley, greater preference values were obtained when measured in pelleted form compared with mash form. Additionally, direct 2-way choices were also performed between oats and barley diets and between diets presented in mash and pelleted forms. Pigs preferred barley to oats, and preferred diets presented in pelleted form to those presented in mash form. In conclusion, cereal type, inclusion rate, and diet form affected feed preference in pigs. Using cereals with greater preference values may contribute to the formulation of more palatable feeds, which enhance feed intake of piglets at critical stages such as weaning time.     

Effects of Three Different Liquid Additives Mixed with Whole Oats or Rolled Oats on the Generation of Airborne Particles from an Experimental Simulating Horse Feeding

This study was designed to analyze the reduction potential of three different liquid additives (water, rapeseed oil, and molasses) in three different concentrations mixed with cleaned whole or rolled oats on the generation of airborne particles under standardized laboratory conditions. In addition, the influence of two different drop heights (20 and 40 cm) was analyzed. Airborne particle concentrations were detected online with the gravimetrically measuring analyzer TEOM 1400a that was equipped successively with different inlets to measure the particle fractions PM₂₀, PM₁₀, and PM_2.5. The mixing of oats with just 1% (w/w) of each of the liquid additives led to a significant reduction in airborne particle generation in all three particle fractions with respect to the samples without additives (P < .0001). By the addition of 1% oil, a reduction in the PM₂₀ fraction of 90.6% (120.3 μg/m³) could be achieved. The same dosage of water or molasses only resulted in a reduction of 60.4% (504.6 μg/m³) or 69.1% (393.2 μg/m³), respectively. In general, the highest significant reduction in the PM₂₀ fraction was achieved using 3% rapeseed oil: 96.5% as compared with 75.6% for 3% water and 81.9% for 3% molasses. The drop height only had a significant effect on the generation of the PM₁₀ fraction, with it being lower at 20 cm than at 40 cm (P = .0261).     

Effect of feeding whole cereals on performance,starch digestibility and duodenal particle size distribution in broiler chickens

1. An experiment was conducted to study the effects of whole wheat, oats and barley at different inclusion levels on performance, starch digestibility, duodenal particle size distribution, gizzard weight and pH of gizzard contents for broiler chickens. 2. Feed consumption and weight gain were significantly reduced when ground cereals were replaced by whole cereals (P < 0.05). However, feed conversion efficiency was not affected by inclusion of up to 440 g/kg of whole wheat, and up to 300 g/kg of whole oats and barley. 3. Duodenal particle size was measured by laser diffraction to below 1 micron in size. A remarkably large proportion of particles were below 100 microns, with as much as 50% of the particles in the duodenum being below 40 microns in size. Inclusion of moderate amounts of whole cereals reduced the duodenal mean particle size. Large inclusions of whole cereals decreased (P < 0.05) the proportion of particles up to 40 microns in size, and increased (P < 0.05) the proportion with size between 100 and 300 microns. 4. Starch digestibility was improved (P < 0.05) by replacing ground wheat or barley with whole wheat or barley. 5. There was no consistent effect of cereal species or feed form on the pH value of the gizzard contents.     

The effect of grain species, processing and time of feeding on the efficiency of feed utilization and microbial protein synthesis in sheep

This study investigated the effect of cereal grain species (sorghum, wheat, oats and barley), extent of processing (cracked barley, finely ground barley, and wet whole barley) and time of feeding (barley grain mixed with ryegrass hay or fed 2 h before hay was fed), on whole tract dry matter digestibility (WTDMD), and microbial protein synthesis (MPS), as a supplement to ryegrass hay when fed to rumen-cannulated sheep.Expected dry matter digestibility (EDMD) in mixtures of cereal grain and ryegrass hay was calculated by interpolation between in vitro dry matter digestibility (DMD) of each grain and the ryegrass hay. These were compared with measured actual WTDMD to detect positive or negative associative effects. Among grain species, the percentage difference in digestibility between actual WTDMD and EDMD was negative at − 6.6% units for wheat but positive at + 2.3%, + 4.3% and + 5.7% units for sorghum, oats, cracked or finely ground barley, respectively.As expected, the supplementation of sheep fed ryegrass hay with different sources of carbohydrates increased urinary allantoin output (as an indicator of MPS) when compared to sheep fed ryegrass hay alone. The concentration of urinary allantoin was significantly higher in sheep supplemented with sorghum (1916 mg/sheep/day) than wheat, oats or cracked barley ([mean ± S.E.M.] 1451 ± 24 mg/sheep/day) grain. There was a significantly higher urinary allantoin concentration in sheep fed cracked barley compared to finely ground barley or wet whole barley (1479 vs. 1095 vs. 1031 mg/sheep/day, respectively). There was no significant (P > 0.05) difference in urinary allantoin output, expressed as output/kg DM intake, when cracked barley was mixed and fed with the hay or fed 2 h before hay. However, in terms of total output of allantoin this was significantly higher (P < 0.05) (1479 vs. 1209 mg/sheep/day).In sacco degradability characteristics of organic matter and nitrogen for sorghum, oats, wheat, barley at different levels of processing and for ryegrass hay were also measured in the rumen of cannulated sheep.Among grain species, wheat had the highest effective organic matter degradability in the rumen (78.1%) while sorghum had the lowest. The effective degradability of protein of finely ground barley in the rumen was found to be higher than cracked barley or wet whole barley.Wheat grain, being highly degradable in the rumen, had a negative effect on WTDMD. In contrast, sorghum grain, being more slowly degradable in the rumen, would be expected to provide a substantially increased supply of energy to microbes over time in the rumen for MPS.Both cracked barley and finely ground barley also had a positive associative effect on WTDMD when fed with ryegrass increasing it by 5.7% units. The MPS was significantly higher (P < 0.05) in sheep fed cracked barley compared to finely ground barley or wet whole barley. This supports the hypothesis that slowly degrading carbohydrate sources synchronise more closely with available N from degradation of forage in the rumen.     

Feeding of Unground Pearl Millet to Laying Hens

The use of new varieties of pearl millet (PM) as an alternative feed ingredient for poultry has gained increased interest due to the favorable nutritional characteristics of this grain. However, its incorporation into poultry feeds has been limited because commercial availability of PM in the United States is currently low and also because many feed mills lack the capacity to store more than 1 ground grain. Previous studies have demonstrated the advantages of the inclusion of moderate levels of whole grains in poultry feeds. A series of 3 experiments was conducted to investigate whether unground PM would be a satisfactory feed ingredient for laying hens. In Experiment 1, diets containing 5, 10, 20, 30, and 40% unground PM were fed. At the end of a 7-d feeding period, it was determined that the percentage of whole seed disappearance was equal to or greater than 98% at all levels of inclusion. No significant differences in whole seed disappearance were detected among treatments, indicating that laying hens have the capacity to break down whole PM seeds. In Experiment 2, diets containing 0 or 15% inclusion of either ground or unground PM were fed to laying hens for a 7-d feeding period. Starch digestibility of the diets was determined to be >97% for all treatments. Significantly greater starch digestibility was observed in the hens fed the 15% unground PM as compared with the hens receiving the ground PM diet. In Experiment 3, after a 4-wk feeding period, it was determined that the inclusion of 10% unground PM does not have a negative or positive effect on feed consumption or egg production. These results indicate that PM is a satisfactory feed ingredient for laying hens that can be included in the unground form at moderate levels.     

Feed preferences of ponies

Preference trials were conducted with mature ponies. In Trial 1, oats were compared with oats plus sucrose. Four of six pony geldings selected oats plus sucrose, but one pony demonstrated a dislike for sucrose and one selected from the bucket on the right side regardless of content. Oats, maize, barley, rye and wheat were compared in Trial 2 using six mature pony mares. Oats were the preferred grain, with maize and barley ranking second and third respectively. Wheat and rye were the least preferred. Even though the ponies demonstrated preference, the total intake at a given meal was not greatly depressed when only the less palatable grains were fed. In Trial 3, pony mares selected a diet containing 20 per cent dried distillers' grain and 80 per cent of a basal mixed diet of maize, oats, wheat bran, soybean meal, limestone and molasses over 100 per cent basal mixed diet, but selected the basal diet over diets containing 20 per cent blood meal, beet pulp or meat and bone meal and 80 per cent basal diet. They did not differentiate against diets containing 20 per cent alfalfa meal or 10 or 5 per cent meat and bone meal when the diets were compared to the basal mixed diet.     

Effects of moisture,roller setting,and saponin-based surfactant on barley processing,ruminal degradation of barley,and growth performance by feedlot steers

Two experiments were conducted to study the effects of six processing techniques for barley grain in a 3 x 2 factorial arrangement of grain conditions and roller settings on ruminal degradation of the grain (Exp. 1) and on growth performance by 138 feedlot steers (n = 23 per treatment; Exp. 2). Dry barley (11% moisture, D barley), barley tempered to 20% moisture (M barley), and barley tempered with 60 mL/t of surfactant-based tempering agent (GrainPrep, Agrichem, Inc., Anoka, MN; MS barley), were each rolled at two roller settings selected from preliminary tests. The settings selected for the study were RD, the roller position that had yielded optimally processed D barley, and RMS, the setting that had yielded optimally processed MS barley. Setting RMS was tighter than RD. Barley rolled at the RMS setting was more extensively processed (i.e., had a lower [P < 0.001] processing index, PI), had lighter (P < 0.001) volume weight, thinner (P < 0.001) kernels, and fewer (P < 0.001) whole kernels compared with setting RD. Tempering did not affect (P > 0.05) PI, percentage of whole kernels, or kernel thickness at either roller setting. The processing characteristics of tempered barley were unaffected (P > 0.05) by surfactant. The extent of in situ DM disappearance (ISDMD) was higher (P < 0.01) in grain rolled at setting RMS compared with RD. At both roller settings, tempering reduced (P < 0.05) ISDMD between 4 and 24 h of ruminal incubation. Steers fed RMS-rolled barley had lower (P < 0.001) DMI, slightly lower (P = 0.084) ADG, but increased (P < 0.05) gain:feed (G:F) compared with steers fed RD-rolled barley. Tempering did not affect (P > 0.05) ADG, DMI, or G:F during backgrounding, but improved (P < 0.01) these variables during finishing. Surfactant improved (P < 0.05) G:F but not DMI or ADG. The improvement in G:F was most pronounced when setting RMS was used. The optimal PI values calculated from performance data were numerically greater for the backgrounding diet than for the finishing diet. Steers fed M or MS barley had heavier (P < 0.01) hot carcasses and thicker (P < 0.05) fat cover but lower (P < 0.05) dressing percentages than steers fed D. When the feed barley was rolled at setting RMS, steers fed MS barley produced heavier (P < 0.05) carcasses than those fed M. Tempering with or without surfactant increased performance by feedlot steers compared with not tempering. Diet composition and degree of barley processing mediated this effect.     

Effect of grain processing degree on intake, digestion, ruminal fermentation, and performance characteristics of steers fed medium-concentrate growing diets

Three trials were conducted to evaluate the effects of degree of barley and corn processing on performance and digestion characteristics of steers fed growing diets. Trial 1 used 14 (328 +/- 43 kg initial BW) Holstein steers fitted with ruminal, duodenal, and ileal cannulas in a completely randomized design to evaluate intake, site of digestion, and ruminal fermentation. Treatments consisted of coarsely rolled barley (2,770 microm), moderately rolled barley (2,127 microm), and finely rolled barley (1,385 microm). Trial 2 used 141 crossbred beef steers (319 +/- 5.5 kg initial BW; 441 +/- 5.5 kg final BW) fed for 84 d in a 2 x 2 factorial arrangement to evaluate the effects of grain source (barley or corn) and extent of processing (coarse or fine) on steer performance. Trial 3 investigated four degrees of grain processing in barley-based growing diets and used 143 crossbred steers (277 +/- 19 kg initial BW; 396 +/- 19 kg final BW) fed for 93 d. Treatments were coarsely, moderately, and finely rolled barley and a mixture of coarsely and finely rolled barley to approximate moderately rolled barley. In Trial 1, total tract digestibilities of OM, CP, NDF, and ADF were not affected (P > or = 0.10) by barley processing; however, total tract starch digestibility increased linearly (P < 0.05), and fecal starch output decreased linearly (P < 0.05) with finer barley processing. In situ DM, CP, starch disappearance rate, starch soluble fraction, and extent of starch digestion increased linearly (P < 0.05) with finer processing. In Trial 2, final BW and ADG were not affected by degree of processing or type of grain (P > or = 0.13). Steers fed corn had greater DMI (P = 0.05) than those fed barley. In Trial 3, DMI decreased linearly with finer degree of processing (P = 0.003). Gain efficiency, apparent dietary NEm, and apparent dietary NEg increased (P < 0.001) with increased degree of processing. Finer processing of barley improved characteristics of starch digestion and feed efficiency, but finer processing of corn did not improve animal performance in medium-concentrate, growing diets.     

Correlation between median and mean irregular particle sizes and degradation kinetics in barley genotypes

Barleys, a major source of feed, are all coarsely dry‐rolled before feeding beef and dairy cattle in North America. The shapes of coarsely dry‐rolled barley particles are not round but very irregular. The model for geometric mean is not suitable for determining irregular barley particle size. In a previous study, we tested four different published models to determine the mean and median particle sizes of coarsely dry‐rolled barley with irregular particle size shapes and found that the Pond’s model with 0 mm = 100% was the best model to compute mean and median particle sizes of the coarsely dry‐rolled barley samples expressed as per cent cumulative weight oversize. However, we still did not know which parameter, median or mean particle size, was the best indicator to predict rumen nutrient degradation and availability. This information is badly needed. The objective of this study was to study the relationship between the mean and median irregular particle sizes and nutrient availability of various barley varieties which were coarsely dry‐rolled. The results revealed a stronger correlation between the median irregular particle size (not mean particle size) and the rate (K_d) and extent (ED) of rumen degradation of dry matter (K_d: R = ?0.78, p = 0.065; EDDM: R = ?0.89, p = 0.016), starch (K_d: R = ?0.96, p = 0.003; EDST: R = ?0.95, p = 0.003) and crude protein (K_d: R = ?0.59, p = 0.215; EDCP: R = ?0.89, p = 0.019). In conclusion, it is the median but not mean particle size that has stronger correlation with rumen degradation kinetics. The 79.9%, 78.3% and 91.0% of variation of effective degradability of dry matter, crude protein and starch, respectively, could be explained by the median irregular particle size.     

Glycemic Index of Ten Common Horse Feeds

Two 6 × 6 Latin-square designed experiments examined the glycemic responses to 10 common equine feeds in six Quarter Horse mares. At 8:00 am of the sampling days, horses were offered a meal of 1 of 10 common feeds. The amount of feed offered was calculated on an isocaloric basis at 4 Mcal digestible energy per meal. Jugular blood samples were collected for 300 minutes after feeding, and plasma was analyzed for glucose concentration. The results showed that plasma glucose values peaked approximately 90 to 120 minutes after eating, whereas glycemic index (GI) values ranged from 7 to 129 based on a standard of oats set at a GI of 100. The four feeds with the highest GI values (sweet feed, corn, jockey oats, and oats) were greater (P < .05) than the four feeds with the lowest GI values (beet pulp, alfalfa, rice bran, and soy hulls). Barley and wheat bran had intermediate GI (55–69) values, but were not significantly different from either the high or low group. Whereas large variations in the data were found, conservative utilization of the ranking or categories of GI values of the 10 common horse feeds examined may be useful for formulating rations with different glycemic objectives.     

Nitrogen metabolism in dairy cows fed restricted amounts of grass–clover silage supplemented with seeds from narrow-leafed lupin or pea

Twelve dairy cows in mid to late lactation were fed iso-nitrogenous diets (161 g CP/kg DM, forage:concentrate ratio 65:35) where rolled barley and coarsely ground seeds from either narrow-leafed lupin or field pea supplemented grass–clover silage. Feed allowance was individually restricted and fixed (18.8 ± 0.6 kg dry matter/day) throughout the experiment to avoid refusals. The experiment was of 2 × 2 change-over design and utilized a previous change-over experiment with 3 periods as covariate. Nitrogen balance was assessed by quantitative urine sampling and fecal spot sampling in eight cows whereas rumen metabolism was studied in four cannulated cows. Production of energy corrected milk was 24.3 kg/day with the lupin diet and 23.2 kg/day with the pea diet (P < 0.05). Daily milk fat yield was also higher (P < 0.05) with the lupin diet. Proportion of feed N excreted in milk did not differ between diets. Milk urea concentration, as well as the amounts of total urinary N and urinary urea were higher (P < 0.05) for the lupin diet, while urinary N proportion of feed N only tended (P = 0.08) to be higher with the lupin diet. N balance was lower with the lupin diet. Digestibilities of organic matter, neutral detergent fiber and crude protein did not differ between diets and neither did ruminal pools of these constituents. In addition, there were no differences between the diets with respect to the ruminal concentrations of NH₃-N and total volatile fatty acids, and only minor differences in ruminal pH and ruminal concentrations of iso-acids and α-amino-N. It is concluded that the higher fat content in lupins compared to peas is an advantage in typical Scandinavian home-grown rations and probably explains the higher milk yield in this experiment. Differences in protein utilization between lupins and peas are of small magnitude when fed ground without thermal processing. In practical feeding, ad libitum forage allowance may create response differences between lupin seeds and peas not observed in this experiment.     

Effects of cereal grain supplementation on apparent digestibility of nutrients and concentrations of fermentation end-products in the feces and serum of horses consuming alfalfa cubes

Twenty geldings (five groups; similar age and BW) were used in a completely randomized design experiment to determine effects of grain supplementation of an alfalfa-cube diet on apparent nutrient digestibility and hindgut fermentation. The geldings were housed individually, fed their diets in two equal meals (0600 and 1800), and adapted to five dietary treatments over 6 wk. The treatments were alfalfa cubes (1% of BW; DM basis) without (control) or with one of four rolled cereal grains (i.e., barley, corn, naked oats, or oats) to provide a target level of 0.4% of BW as total nonstructural carbohydrates (TNC). Due to acute laminitis, three geldings (one in the control group and two in the barley group) were excluded. Because of this and multiple incidents of gas colic, TNC level was decreased to 0.2% of BW to ensure the geldings' health throughout the adaptation (7 d) and sample collection (5 d) periods. Grain intakes varied (P < 0.05) and reflected the different TNC concentrations. Apparent digestibilities of DM, OM, CP, NDF, ADF, and cellulose were not affected (P > 0.05) by grain supplementation and averaged 63.2, 63.1, 79.5, 42.7, 39.9, and 50.3%, respectively. Regardless of the source, grain supplementation increased (P < 0.05) apparent digestibility of TNC (from 85.6 to 94.6%) and decreased (P < 0.05) fecal pH (from 7.04 to 6.74). Fecal concentrations of total VFA (mg/g of DM) were greatest for the barley and naked oats diets (averaging 11.73), intermediate for the oats diet (8.00), and least for the control and corn diets (averaging 5.00; P < 0.05). Fecal concentrations of lactate (microg/g of DM) were greatest for the barley diet (254), intermediate for the oats diet (138), and least for the remaining diets (averaging 100; P < 0.05). Fecal concentrations of NH3 N (mg/g of DM) were greatest for the naked oats diet (1.68), intermediate for the barley and oats diets (averaging 0.86), and least for the remaining diets (averaging 0.63; P < 0.05). Serum concentration of lactate was 46% higher (P < 0.05) for the control than for the grain diets (averaging 0.05 mg/100 mL). Feeding barley, corn, naked oats, and oats contributed to 13, 15, 8, and 20% higher (P < 0.05) serum NH3 N concentrations than the control diet (0.25 mg/100 mL). Higher (P < 0.05) serum concentrations of urea N (mg/100 mL) were detected for the control, barley, and naked oats diets (averaging 25.28) than for the corn or oats diets (averaging 22.21). Results suggest that horses consuming alfalfa cubes could be supplemented with rolled barley, corn, naked oats, or oats at levels not exceeding 0.2% of BW as TNC without affecting nutrient digestion or overall health negatively.     

Effects of barley grain processing on the site and extent of digestion of beef feedlot finishing diets

Effects of extent of barley rolling on chewing activities, ruminal fermentation, and site and extent of digestion were evaluated for feedlot finishing cattle diets in a 4 x 4 Latin square design. Four Jersey steers (452 kg), cannulated in the rumen and duodenum, were used. Barley grain was temper-rolled to four extents: coarse, medium, medium-flat, and flat, which were expressed as processing index (PI, volume weight of barley after processing expressed as a percentage of its volume weight before processing, DM basis) and equivalent to 82, 75, 70, and 65%, respectively. Diets consisted of 9.7% barley silage, 86% temper-rolled barley, and 4.3% other ingredients (DM basis). Steers were offered ad libitum access to a total mixed ration once daily. Dry matter intake was not affected (P > 0.15) by PI of barley. Digestibility of OM in the rumen and in the total tract were numerically lower (P = 0.13) for steers fed coarsely rolled barley than for steers fed more extensively processed barley. Digestibility of starch in the total tract was linearly increased (P = 0.02) with grain processing, but NDF digestion was not affected by processing (P > 0.15). Digestibility of CP did not differ in the rumen but tended (P = 0.08) to increase in the total tract with increased processing of barley. Flow of microbial nitrogen to the duodenum was approximately one-third lower (linear effect, P = 0.06) for steers fed coarsely rolled barley than for steers fed further rolled barley. Increased grain processing tended to decrease (linear effect, P = 0.08) rumination time without affecting eating time. These results indicate that optimal degree of rolling for barley fed to feedlot cattle corresponded to a PI of 75% or lower. Coarsely rolled barley is not recommended because it resulted in the lowest digestibility and lowest microbial protein synthesis. Processing barley to attain a PI less than 75% resulted in marginal improvements in feed digestion, but rumination time decreased, which could lead to problems associated with acidosis if lower-fiber diets are used.     

Energy requirements of cattle for standing and for ingestion, estimated by a ruminal emptying technique

Energy requirements for ingestion and standing were determined in open-circuit respiration chambers with four ruminally cannulated German Red Pied steers weighing 617 +/- 53 kg of BW (mean +/- SD). The requirement for standing over lying was derived by regressing heat production on time spent standing within 2-h periods when no feed was offered to avoid any interference with eating activity, and amounted to 14 kJ/(d x kg of BW). The energy requirement for ingestion was determined by calculating the difference between heat production during a 2-h period without feed and during a consecutive 2-h period in which straw of different particle sizes, fresh and conserved grass, or rolled barley were offered for ad libitum intake. Before measurements, the rumens of the steers were emptied, washed, and filled with a buffer solution to avoid heat production by metabolism of absorbed nutrients from the feed ingested during the experimental periods. The mean value for all feeds tested was 20 J/(min of ingestion x kg BW). Relating heat production to the amount of DM or fiber ingested did not decrease variation among feeds. This confirms the observations of earlier studies, that energy requirement for ingestion is mainly determined by time spent eating. Results of additional measurements, in which the same amounts of the respective feeds ingested in preceding periods were put into the emptied rumens via the cannulas, showed that the presence of the feed in the rumen did not increase heat production, indicating that the increment of heat production during eating is mainly caused by ingesting and chewing the feed. Further measurements in the same animals with an ingesta-filled rumen showed that ingestion of straw led to an increase in heat production per minute of chewing similar to those with emptied rumens, which confirms the validity of the experimental procedure using ruminally emptied animals to determine the energy requirement for ingestion.     

Generation of Airborne Particles from Different Bedding Materials Used for Horse Keeping

Among other factors (eg, feed), bedding material has an important effect on stable air quality with respect to airborne particle formation. This study was designed to establish which material is suited to create an improved stable environment for horses. First, the following materials were analyzed under standardized conditions in a laboratory experiment: wheat straw, dry wood shavings, hemp shives, linen shives, wheat straw pellets, paper cuttings (unprinted newspaper). The second investigation was carried out under in situ conditions in which three of these bedding materials (wheat straw, wood shavings, and straw pellets) were analyzed under practical conditions. In both experiments, airborne particle concentrations were detected online with the gravimetrically measuring analyzer TEOM 1400a (Rupprecht & Patashnick Co., Franklin, MA). In the laboratory experiment, the TEOM was equipped successively with different inlets to measure the particle fractions PM₁, PM_2.5, PM₁₀, and PM₂₀. During the in situ experiment, only the fraction PM₁₀ was detected. In the laboratory experiment, hemp and linen had the highest generation of airborne particles in all fractions. The lowest particle generation was detected with straw pellets. Results of the in situ investigation supported results of the laboratory experiment with respect to mean particle generation of straw pellets. With an average of 111.2 ± 149.2 μg/m³, it was significantly lower than the mean particle generation of wheat straw with 227.5 ± 280.8 μg/m³. The particle generation of wood shavings had an average of 140.9 ± 141.9 μg/m³ and also was significantly lower than the generation by wheat straw. An activity-correlated variation of particle concentrations was found. In conclusion, taking both experiments into consideration, straw pellets seemed to be suitable for horse stables, to promote an improvement in the stable climate in relation to airborne particle formation.     

The effect of mixing and changing the order of feeding oats and chopped alfalfa to horses on: glycaemic and insulinaemic responses, and breath hydrogen and methane production

The aim of this study was to investigate the effects of feeding oats alone before or after feeding chopped alfalfa or, in admixture with the alfalfa on the glycaemic and insulinaemic responses of horses as well as post-prandial breath hydrogen and methane excretion. Horses were fed in a randomized order, chopped alfalfa as a source of dietary fibre and unprocessed oats as a source of starch. Chopped alfalfa intake was adjusted to a crude fibre intake of 0.5 g/kg bodyweight (BW) per meal and the oats intake was adjusted to a starch intake of 2 g/kg BW per meal. The feeds were offered in three different ways: (i) alfalfa followed by oats (A/O), (ii) oats followed by alfalfa (O/A) or (iii) a mixture of alfalfa and oats (A + O). Oats alone were used as a control. Blood and breath were collected after the test meal was fed at the end of a 11.5-h overnight fast following a 10-day acclimatization period. The highest glycaemic and insulinaemic responses were measured when the A/O and O/A diets orders were fed, whereas most hydrogen was produced after feeding oats alone. It was concluded that adding alfalfa chaff to a meal of oats prolonged the pre-caecal digestion of starch, but there was no evidence for any effect on pre-caecal starch digestibility.     

Fermentation Pattern in the Bovine Rumen after Feeding Straight Feeds

The influence of straight feeds on the fermentation pattern in the bovine rumen was investigated by feeding with hay, grass pellets, dried beet pulp with molasses and rolled oats. The study comprised 3 rumenfistulated dairy heifers, and the parameters measured were ammonia, pH and volatile fatty acids (VFA) in the rumen fluid, and non-glucogenic/glucogenic ratio (NGGR) in the VFA mixture.Typical differences related to the structure and chemical composition of the diets were demonstrated by the parameters measured. Fermentation of the easily digestible feeds resulted in so extensive variations that representative means could be obtained only by analyzing samples collected frequently throughout the feeding cycle.Rumen pH was found highly correlated to total VFA concentration for all the feeds examined, and the regression coefficients showed that diets, based upon beets and oats, were fermented under low buffering capacity.     

不同淀粉源饲料的瘤胃降解特性研究初探

通过尼龙袋法测定了5种淀粉源饲料在瘤胃的降解率。结果显示,玉米和荞麦在瘤胃的有效降解率(60.0%和61.6%)低于燕麦、小麦和大麦(78.9%、75.4%、69.8%)(P<0.05);燕麦的可溶性淀粉含量比较高,大麦和小麦表现出在9h内已经达到大部分被降解。     

Barley grain for ruminants: A global treasure or tragedy

Barley grain (Hordeum vulgare L.) is characterized by a thick fibrous coat, a high level of ß-glucans and simply-arranged starch granules. World production of barley is about 30 % of that of corn. In comparison with corn, barley has more protein, methionine, lysine, cysteine and tryptophan. For ruminants, barley is the third most readily degradable cereal behind oats and wheat. Due to its more rapid starch fermentation rate compared with corn, barley also provides a more synchronous release of energy and nitrogen, thereby improving microbial nutrient assimilation. As a result, feeding barley can reduce the need for feeding protected protein sources. However, this benefit is only realized if rumen acidity is maintained within an optimal range (e.g., > 5.8 to 6.0); below this range, microbial maintenance requirements and wastage increase. With a low pH, microbial endotoxines cause pro-inflammatory responses that can weaken immunity and shorten animal longevity. Thus, mismanagement in barley processing and feeding may make a tragedy from this treasure or pearl of cereal grains. Steam-rolling of barley may improve feed efficiency and post-rumen starch digestion. However, it is doubtful if such processing can improve milk production and feed intake. Due to the need to process barley less extensively than other cereals (as long as the pericarp is broken), consistent and global standards for feeding and processing barley could be feasibly established. In high-starch diets, barley feeding reduces the need for capacious small intestinal starch assimilation, subsequently reducing hindgut starch use and fecal nutrient loss. With its nutritional exclusivities underlined, barley use will be a factual art that can either matchlessly profit or harm rumen microbes, cattle production, farm economics and the environment.     

Effect of a short duration feed withdrawal followed by full feeding on marbling fat in beef carcasses

The effect of feed withdrawal for 48 h, prior to initiation of the finishing (fattening) period (75 d) on carcass marbling fat was studied in 120 European × British cross-bred heifers with an average weight of 585 ± 39 kg. Heifers were randomized in a 2 × 2 factorial design experiment with two dietary management treatments, where half the heifers were provided the feed components of steam rolled barley and barley silage either free choice or as a total mixed ration (TMR) containing 87% steam rolled barley and 13% barley silage with ad libitum vitamins and minerals via salt blocks for all animals. Within each dietary management treatment, 30 heifers were denied feed (water was available) for 48 h prior to the two week adaptation to the high grain diet preceding the 75 d finishing period. At the end of the 48 h feed denial blood samples were collected from the jugular vein prior to feeding for determination of glucose and insulin concentrations, which indicated that 48 h feed withdrawal consistently decreased (P = 0.0001) plasma concentrations of both glucose and insulin but the ratios of the concentrations of glucose to insulin were not affected. At slaughter samples of subcutaneous fat from the brisket (BF) and skirt muscle (pars costalis diaphragmatis; PCD) were procured for determination of chemical fat content, fat dissected from the muscle and for enumeration of adipocytes, less than 35 μm in diameter and to determine the average cell size in the dissected fat and from the BF by flow-cytometry of adipocytes fixed in osmium tetroxide. The carcass characteristics were also obtained. Although no differences due feed withdrawal for 48 h were evident for carcass weight, percent lean (saleable) meat yield, rib eye area, average fat cover, fat content of PCD or BF, the US marbling score was increased (P = 0.048) and the amount of dissected fat from the muscle tended to be higher (P = 0.107), thus 81% of the carcasses graded “US Choice” or “Canada AAA,” or displayed at least a “small” amount of intramuscular fat as compared (P = 0.0807) to 68% of the heifers not denied feed. Based on more than three years of weekly prices of carcasses that graded “Canada AAA” and “Canada AA,” these experimental results suggested that the expected price of a finished heifer could increase by $4.61 Canadian if a 48 h feed withdrawal was imposed prior to initiation of the finishing phase. Although significant differences in adipocyte numbers due to a single time 48 h feed withdrawal prior to initiation of the finishing phase were not detected, the carcass quality factors were affected leading to an odds ratio of 1.84 times in favour of cattle carcasses to grade “Canada AAA” than if fed continuously.