Steam-flaked Grain Research Articles

Effects of steam-flaked grains on foals\u2019 growth and faecal microbiota

BackgroundThere is little objective information concerning the effect of steam-flaked grains on foal’s growth performance and faecal microbiota. To determine the effects of steam-flaked grains on foal’s growth performance and faecal microbiota, faecal samples were collection from 18 foals which had been fed either corn, oat or barley diets over the 60 days of the experiment. Body weight and conformation measurements were collected. Next-generation sequencing of the V3 + V4 region of the 16 S rRNA gene was used to assess the microbial composition of faeces. Alpha diversity, Venn graph, Relative abundance and beta diversity are presented.ResultsThere was a significantly higher larger increase in the body weight of those foals fed barley compared to either corn or oats. There were also significant changes in the Alpha diversity of the gut microbiota. The Shannon and Simpson indices were significantly higher in the barley fed group than those fed corn or oats. The Chao1 index was significantly higher in the oat fed group than the corn or barley fed groups. There were significant changes in the relative abundance of bacteria in the microbiota in terms of phylum, family and genus. The histogram of LDA value distribution showed that the 12 statistically different biomarkers of the bacteria were present. Tax4Fun function annotation clustering heat map showed that functional information was detected from 26 species of bacteria in faecal samples from the foals.ConclusionsDifferences by starch sources were found in overall growth of the foals and in the faecal microbiota if either supplementary corn, oat or barley was fed. Further studies are required to determine the potential impact of the changes in the microbiota on the health and development of foals fed cereal starch of different sources.

Feeding Complete Concentrate Pellets Containing Ground Grains or Blend of Steam-Flaked Grains and Other Concentrate Ingredients in Ruminant Nutrition – A Review

Abstract The feed industry has attempted to encourage the animal husbandry sector to feed complete concentrate pellets containing ground grains in ruminant nutrition and thus prevent farmers from making concentrate in their farms. Reducing particle size using pre-pelleting grinding and pressing materials during pellet formation, plus starch gelatinization by heat treatment in the conditioner are key factors determining the extent and rate of starch digestion in ingested pellets. If prepelleting grinding of corn and barley grain for using in the pelleted concentrate results in ground materials of less than 1.8 mm mean particle size (especially in the case of barley grain which is highly fermentable), then it increases the rate of fermentability in the rumen which in turn increases the acidosis risk. Such situation and dissatisfaction from pellets feeding to ruminant have directed farmers to produce homemade mash concentrate which may include steam-flaked form of grains in the concentrate mixture. Pelleting process increases the time needed to collapse the pellet in the rumen so delays the access of microbes to fermentable organic matter. This counterbalance property highly depends on pellet size with highest effect obtained using 10 mm diameter pellets for cattle. Feeding separately steam-flaked grains (plus other pelleted/mash non-grain ingredients of concentrate) may give results similar to the complete concentrate pellets having ground grains prepared according to optimized recommendations (pellet diameter and grain mean particle size). Nonetheless cost benefit studies are necessary to adopt one of the above two optimized technologies that has higher starch utilization and lower fecal starch excretion by animal. In the situation where consuming steam-flaked grains has priority of application in the diet, it is strongly recommended to pellet non-grain portions of concentrate for obtaining numerous pellet advantages such as reducing transportation cost, dust, sorting and bird removal.

343 Feedlot performance and carcass characteristics of steers fed diets containing steam-flaked grain and corn silage from Enogen® Feed Corn

Abstract Enogen Feed Corn (EFC; Syngenta Seeds, LLC) is genetically modified to express high concentrations of amylase. Our objective was to evaluate EFC as corn silage and as steam-flaked corn in diets fed to finishing cattle. A 2 x 2 factorial experiment was conducted with steers (n = 960; 388 ± 7.4 kg initial body weight), with factors consisting of silage source (Control or EFC) and grain source (Control or Enogen). Steers were blocked by initial body weight, assigned randomly within block to treatments, housed in 48 pens with 15 or 25 cattle per pen, and harvested after 138, 152, or 166 days on feed. Grains were steam flaked to densities of 360 or 386 g/L for Control and EFC, respectively. Diets (dry basis) consisted of 8% corn silage, 2% alfalfa hay, 74.5% flaked corn, 12% Sweet Bran, and supplement. Incidences of liver abscesses and carcass weights were recorded at harvest, and longissimus muscle area, 12th-rib subcutaneous fat thickness, marbling score, and USDA yield and quality grades were determined after 36 h of refrigeration. There were no interactions between grain source and silage source (P > 0.05) for feedlot performance. Cattle fed diets containing EFC silage consumed less dry matter (P < 0.01) and efficiency of gain was improved by approximately 5.3% (P < 0.01) compared to cattle fed Control silage. Average daily gain and dry matter intake were unaffected by grain source, but cattle fed EFC grain were less efficient (P = 0.02) compared to cattle fed control grain. Carcass weight was greater for cattle fed the combination of EFC silage and Control grain compared to other treatments (P < 0.05), but liver abscess incidence and other carcass measurements were unaffected by grain or silage source. Feeding Enogen Feed Corn as corn silage, but not as grain, improved feedlot performance of steers. Keywords: Enogen, corn silage, amylase

Effects of partial replacement of corn grain with lactose in calf starters on ruminal fermentation and growth performance.

The objective of this study was to evaluate effects of partial replacement of dry ground corn with lactose in calf starters on dry matter intake, growth rate, ruminal pH, and volatile fatty acid profile. Sixty Holstein bull calves were raised on a high plane of nutrition program until 55 d of age. Calves were fed texturized calf starters containing 30.1% steam-flaked grains and lactose at 0 (control), 5, or 10% (n = 20 for each treatment) on a dry matter basis. All calves were fed treatment calf starters ad libitum from d 7 and kleingrass hay from d 35. Ruminal pH was measured continuously immediately after weaning (d 55-62) for 15 calves (n = 5 per treatment), and 3 wk after weaning (d 77 to 80) for the other 45 calves (n = 15 per treatment). Dry matter intake, growth performance, and ruminal pH variables were not affected by treatment. However, according to Spearman's correlation coefficient (rs) analyses, lactose intake was positively correlated with dairy minimum ruminal pH (rs = 0.306) for the data collected from d 77 to 80. Similarly, hay intake was not affected by treatment, but positively correlated with daily mean (rs = 0.338) and maximum ruminal pH (rs = 0.408) and negatively correlated with duration pH <5.8 (rs = -0.329) and area pH <5.8 (rs = -0.325), indicating that the variation in hay intake among animals might have masked treatment effects on ruminal pH. Ruminal molar ratio of acetate was higher (45.2 vs. 40.6%), and that of propionate was lower in 10% lactose than control (35.3 vs. 40.2%) for ruminal fluid collected on d 80; however, molar ratio of butyrate was not affected by treatment. These results indicate that lactose inclusion in calf starters up to 10% of dry matter might not affect dry matter intake and growth performance of calves, but that greater lactose and hay intake might be associated with higher ruminal pH.

Lactation and digestion in dairy cows fed ensiled total mixed ration containing steam-flaked or ground rice grain.

The objective of this experiment was to investigate the effect of feeding ensiled total mixed ration (TMR) containing steam-flaked (SF) or ground brown rice (Oryza satira L.; BR) on feed intake, lactation performance, digestion, ruminal fermentation and nitrogen (N) utilization in dairy cows. Eight multiparous Holstein cows were used in a crossover design with two dietary treatments: diets containing either SF or fine ground (FG) BR at 24% of dietary dry matter. Dietary treatment did not affect dry matter intake or milk yield and composition. The whole-tract digestibility of organic matter and fiber decreased, and the digestibility of starch increased with the replacement of SF with FG in ensiled TMR, but these differences were small between diets. Crude protein digestibility was not different between diets. The processing method of BR did not affect ruminal pH, total volatile acid concentration, or volatile fatty acid proportion in cows. The N intake, milk N secretion, fecal and urinary N excretion and N retention were not influenced by dietary treatment. These results show that feeding ensiled TMR containing FG instead of SF reduces fiber digestibility but has little impact on lactation and N utilization when diets contained 24% on a dry matter basis.

Effect of steam-flaking on chemical compositions, starch gelatinization, in vitro fermentability, and energetic values of maize, wheat and rice

Intact and steam-flaked grains of maize, wheat and rice (with whole hulls) were analyzed for chemical composition, starch gelatinization degree (SGD) and in vitro fermentation characteristics to investigate the influence of cereal type and steam-flaking (SF) processing on their nutritive values. The treatments were arranged in a 3×2 factorial design. Obvious differences (P<0.001) in chemical composition and energetic values were observed among the different cereal types. SGD and gas production (GP) rate was significantly increased (P<0.001) by SF processing. SF processing also increased (P<0.01) the proportion of propionic acid and decreased the acetic:propionic acid ratio in vitro. Steam-flaking also increased organic matter digestibility and the energetic value of the cereal grains, especially rice. Based on these results, rice probably is more amendable to SF processing than maize and wheat. In conclusion, it is feasible to partially substitute maize grain with wheat or rice in ruminant diets, and steam-flaking can significantly improve the nutritional value of wheat and rice grains.

Effect of substituting brown rice for corn on lactation and digestion in dairy cows fed diets with a high proportion of grain

The effects of the substitution of brown rice (Oryza sativa L.; BR) for corn (Zea mays L.) in ensiled total mixed ration (TMR) that had a high proportion of grain on feed intake, lactation performance, ruminal fermentation, digestion, and N utilization were evaluated. Nine multiparous Holstein cows (51±9 d in milk) were used in a replicated 3 × 3 Latin square design with 3 dietary treatments: a diet containing 0, 20, or 40% steam-flaked BR and 40, 20, or 0% steam-flaked corn (dry matter basis). Cows were fed ad libitum an ensiled TMR consisting of 40.7% alfalfa silage, 11.8% grass silage, 7.1% soybean meal, and 40.0% steam-flaked grain (dry matter basis). The ensiled TMR was prepared by baling fresh TMR, and then sealed by a bale wrapper and stored outdoors at 5 to 30°C for over 6 mo. Dry matter intake and milk yield were lower for cows fed 40% BR than for cows fed 40% corn. The ruminal pH and total volatile fatty acid concentrations were not affected by dietary treatment. The ruminal ammonia-N concentration decreased as the percentage of BR in the diets was elevated. The proportion of acetate decreased, and that of propionate and butyrate increased with the increasing levels of BR. Plasma urea-N concentrations was lower and glucose and insulin concentrations were higher for cows fed 40% BR than for cows fed 40% corn. The whole-tract apparent digestibility of dry matter, organic matter, and starch increased, and the digestibility of neutral detergent fiber and acid detergent fiber decreased with the increasing BR level in the diet, with no dietary effect on crude protein digestion. As a proportion of N intake, the urinary N excretion was lower and the retention of N was higher for cows fed 40% BR than for cows fed 40% corn, with no dietary effect observed on N secretion in milk and fecal N excretion. These results show that substituting BR for corn decreases urinary N losses and improves N utilization, but causes adverse effects on milk production when cows are fed high-grain diets at 40% of dietary dry matter.

Dry-rolled or steam-flaked grain-based diets and fecal shedding of Escherichia coli O157 in feedlot cattle1

Hindgut is a major colonization site for Escherichia coli O157 in cattle. In this study, diets were formulated to effect changes in hindgut fermentation to test our hypothesis that changes in the hindgut ecosystem could have an impact on fecal shedding of E. coli O157. Feedlot heifers (n = 347) were prescreened for the prevalence of E. coli O157 by fecal and rectoanal mucosal swab cultures. A subset of 40 heifers identified as being positive for fecal shedding of E. coli O157 was selected, housed in individual pens, and randomly allocated to 4 dietary treatments. Treatments were arranged as a 2 x 2 factorial, with factor 1 consisting of grain type (sorghum or wheat) and factor 2 being method of grain processing (steam-flaking or dry-rolling). Four transition diets, each fed for 4 d, were used to adapt the animals to final diets that contained 93% concentrate and 7% roughage. The grain fraction consisted of dry-rolled sorghum, steam-flaked sorghum, a mixture of dry-rolled wheat and steam-flaked corn, or a mixture of steam-flaked wheat and steam-flaked corn. Wheat diets contained 52% wheat and 31% steam-flaked corn (DM basis). Fecal and rectoanal mucosal swab samples were obtained 3 times a week to isolate (enrichment, immunomagenetic separation, and plating on selective medium) and identify (sorbitol negative, indole production, and agglutination test) E. coli O157. The data were analyzed as repeated measures of binomial response (positive or negative) on each sampling day. Method of processing (dry-rolled vs. steam-flaked), sampling day, and the grain type x day interaction were significant (P < 0.05), but not the method of processing x grain type interaction. The average prevalence of E. coli O157 from d 9 was greater (P < 0.001) in cattle fed steam-flaked grains (65%) compared with those fed dry-rolled grains (30%). Average prevalence in cattle fed sorghum (51%) or wheat (43%) were similar (P > 0.10) on most sampling days. Results from this study indicate that feeding dry-rolled grains compared with steam-flaked grains reduced fecal shedding of E. coli O157. Possibly, dry-rolling allowed more substrate to reach the hindgut where it was fermented, thus making the hindgut inhospitable to the survival of E. coli O157. Dietary intervention to influence hindgut fermentation offers a simple and practical mitigation strategy to reduce the prevalence of E. coli O157 in feedlot cattle.

Effects of Proportions of Steam-Flaked Corn and Grain Sorghum and Switching Grain Sources During the Finishing Period on Performance and Carcass Characteristics of Finishing Beef Steers

Three studies were conducted to determine effects of proportions of steam-flaked corn (SFC) and steam-flaked grain sorghum (SFGS) in the finishing diet (Exp. 1), effects of switching grain sources on d 56 of the finishing period on performance and carcass characteristics of finishing beef steers (Exp. 2), and effects of these two dietary ingredients on in vitro DM disappearance (IVDMD) (Exp. 3). For Exp. 1, 180 medium-framed beef steers (British × Continental) were used. Treatments included (DM basis) 100% SFC:0% SFGS, 75% SFC:25% SFGS, 50% SFC:50% SFGS, 25% SFC:75% SFGS, and 0% SFC:100% SFGS. Increasing the proportion of SFGS in the finishing diet increased (P<0.01) feed:gain for the overall experiment and resulted in a linear decrease (P<0.01) in calculated NE, NE, and ME values of the diet. No differences (P>0.10) were noted among treatments for carcass characteristics. In Exp. 2, 144 medium-framed beef steers (British × Continental) were used. Treatments were SFC fed from d 0 to end (Treatment 1), SFC fed from d 0 to 56 and SFGS fed from d 57 to end (Treatment 2), SFGS fed from d 0 to 56 and SFC fed from d 57 to end (Treatment 3), and SFGS fed from d 0 to end (Treatment 4). Experiments 1 and 2 were conducted concurrently, and steers on Treatments 1 and 4 were the same steers used in Exp. 1 and fed 100:0 and 0:100, respectively. Average daily gain was decreased (P<0.10), and feed:gain was increased (P<0.05) for the average of Treatments 2 and 3 vs Treatment 1 for the overall experiment. In vitro DM disapperance of diets used in Exp. 1 was similar (P>0.10) among treatments after 4, 12, 24, and 48 h of incubation. Results suggest no benefit from mixing SFC and SFGS in finishing diets, and switching grain sources during the finishing period may adversely affect performance.

Splanchnic nitrogen metabolism by growing beef steers fed diets containing sorghum grain flaked at different densities.

The objective of this study was to determine effects of processing method, dry-rolled (DR) vs steam-flaked (SF), and degree of processing (flake density, FD) of SF sorghum grain on splanchnic (gut and liver) N metabolism by growing steers. Diets contained 77% sorghum grain either DR or SF at densities of 437, 360, and 283 g/L (SF34, SF28, and SF22, respectively). Eight crossbred steers (340 kg initial BW), implanted with indwelling catheters into portal, hepatic, and mesenteric veins and the mesenteric artery, were used in a randomized complete block design. Blood flows and net output or uptake of ammonia N, urea N (UN), and alpha-amino N (AAN) were measured across portal-drained viscera, hepatic, and splanchnic tissues. Plasma arterial, portal, and hepatic concentrations of individual amino acids were also measured. Decreasing FD linearly increased (P = .04) net absorption of AAN (51, 73, and 78 g/d for SF34, SF28, and SF22, respectively) and transfer (cycling) of blood UN to the gut (49, 48 and 64 g/d; P = .02). Net UN cycling averaged 38% of N intake across all diets. Hepatic uptake of AAN or UN synthesis, and splanchnic output of AAN and UN, were not altered by FD. Lowering FD linearly increased (P < or = .02) portal-arterial concentration differences for blood AAN and UN and plasma arterial concentrations for alanine. Steers fed SF compared to DR tended to have greater (P = .11) blood UN cycling (percentage of hepatic synthesis; 64 vs 50%) and decreased (P = .03) net splanchnic UN output (30 vs 50 g/d), but other net fluxes of N were not altered across splanchnic tissues. Steam-flaking compared to dry-rolling tended to decrease (P = .12) portal, but not hepatic, blood flow and increased (P < .01) hepatic-arterial concentration differences for blood UN. Except for a decrease (P = .01) in hepatic-arterial concentration differences of glutamine, plasma amino acid concentrations were not altered by feeding SF vs DR sorghum. Processing method (steam-flaking vs dry-rolling) or increasing the degree of processing (by decreasing FD) of SF sorghum grain resulted in greater transfer of blood UN to the gut. Reducing FD also linearly increased the absorption of AAN by growing steers, which explains (in part) published responses of superior performance by steers fed SF grains.

Effects of grain type on growth and performance of steers limit-fed grain-based diets (1999)

Five hundred fifty two steers were used in a growth experiment designed to evaluate the use of grain sorghum in a limit-feeding program. Dry-rolled corn, dry-rolled grain sorghum, steam-flaked grain sorghum, or combinations of grains totaled 70% (dry matter basis) of the diet. Daily intakes were restricted to 2% of body weight (dry matter basis). Cattle were fed their assigned diet for 95 days followed by a 5- day period on a common diet to compensate for differences in gut fill. Steam-flaked grain sorghum and dry-rolled corn yielded similar gain efficiencies and average daily gains. Dry-rolled grain sorghum, however, had 71% the value of dry-rolled corn and 72% the value of steamflaked grain sorghum. These values became 80% and 83% when the 5 days on a common diet were considered. No significant associative effects were observed for the combinations of grains. The data clearly indicate that grains that are slowly fermented (i.e. dry-rolled grain sorghum) are less desirable in a limit-feeding program. Differences among grains observed in full-fed, finishing diets will likely be as great or greater with high-grain, limit-fed diets. Consequently, extensive processing of grain sorghum would be as beneficial in a limit-fed ration for growing cattle as it is perceived to be in a fullfed, finishing diet.

Flake density of steam-processed sorghum grain alters performance and sites of digestibility by growing-finishing steers.

The effect of several flake densities (FD) of steam-processed sorghum grain on performance, and site and extent of nutrient digestibilities by steers fed growing and finishing diets was determined. The effectiveness of common laboratory methods of starch availability (enzymatic hydrolysis or gelatinization) to provide target specifications for quality control of steam-flaked grains was also measured. In vitro starch availability of the processed grains increased (P < .05) linearly in response to decreased FD. Flake density was more highly correlated with enzymatic measures than with percentage gelatinization (R2 = .87 to .93 vs .36). Using 140 crossbred beef steers (181 kg initial weight), feedlot performance was determined for 112 d with a growing diet (50% grain), followed by 119 d with a finishing diet (78% grain). Each FD treatment (412, 360, 309, and 257 g/L or 32, 28, 24, and 20 lb/bu) was randomly assigned to five pens of seven steers each. Intake of DM by steers decreased linearly (P < .05) as FD decreased (7 and 13%, respectively, for growing and finishing diets). Decreasing FD reduced linearly (P < .05) ADG in the finishing phase and for the entire 231-d trial. With the growing diet only, feed efficiency and estimated diet NEm and NEg responses to decreasing FD were curvilinear (P < .05), with the 360 g/L (28 lb/bu) flake being most efficient. Electrical energy requirements for processing increased linearly (P < .05) as FD decreased. Using four multi-cannulated crossbred steers (275 kg), starch digestibility increased linearly (P < .05) in the rumen (82 to 91%) and total tract (98.2 to 99.2%) as FD decreased. Digestibilities within the small (74%) and large intestines (62%) were not altered by FD. Decreasing FD increased (P < .05) total CP digestibility, but did not consistently alter fiber digestibility or DE content of the diets. In conclusion, enzymatic laboratory methods to evaluate starch availability in processed grains can be used satisfactorily to establish FD criteria for quality control of the steam-flaking process. The greatest improvements in efficiency, estimated diet NE, and starch and protein digestibilities usually occurred when FD was decreased from 412 to 360 g/L (32 to 28 lb/bu). Based on these measures and processing costs, the optimal FD was 360 g/L (28 lb/bu).

Effects of feeding combinations of steam-flaked grain sorghum and steam-flaked, high-moisture, or dry-rolled corn on growth performance and carcass characteristics in feedlot cattle.

The objective of these two feeding trials was to determine the associative effects of feeding steam-flaked grain sorghum (SFGS) in combination with steam-flaked (SFC), dry-rolled (DRC), or high-moisture (HMC) corn on growth performance and carcass characteristics in feedlot cattle. In Trial 1, 200 yearling heifers were blocked by weight, allotted to 25 pens, and fed one of five finishing diets (77% grain, 15% corn silage, and 8% supplement on a DM basis) for an average of 137 d. The grain combinations were 100:0, 75:25, 50:50, 25:75, and 0:100 SFC:SFGS, respectively. Treatment had no effect on DMI (P > .05), but ADG, gain efficiency, and final live and hot carcass weights decreased linearly (P < .05) as the proportion of SFGS increased in the diet. Carcass backfat, quality grade, and liver abscess score were not affected (P > .05) by treatment. In Trial 2, 306 yearling steers were blocked by weight, allotted to 30 pens, and fed diets that contained 74.5% grain, 10% corn silage, 7.5% soybean meal, 4% tallow, and 4% supplement (DM basis) for an average of 139 d. The grain and grain combinations were 100% DRC, HMC, SFC, or SFGS and a 67%:33% combination of SFGS: DRC or SFGS:HMC. For steers fed diets containing a single source of grain, those fed SFC gained 7% more live weight and had a 7% higher gain efficiency (P < .05) than those fed DRC or HMC. Growth performance of steers fed SFGS was intermediate. Feeding grain combinations (67% SFGS:33% HMC or DRC) resulted in a 5 to 6% positive associative effect (P < .05) for ADG and gain efficiency. Carcass characteristics were not affected (P > .05) by treatment. We concluded that there were significant benefits (positive associative effects) when SFGS was fed in combination with DRC or HMC, but the effects were smaller when SFGS was fed in combination with SFC.

Processed grain sorghum and grain sorghum combinations for dairy cows (1998)

Twenty-four Holstein cows were used to evaluate the effects of processing methods on grain sorghum utilization by lactating dairy cows. No difference was observed in the utilization of steam-flaked grain sorghum and pelleted grain sorghum obtained by adding water to finely ground grain sorghum prior to extrusion and oven drying at a temperature of 200EF. Extensive processing (pelleting or steam-flaking) improved feed efficiency relative to dry rolling. Cows fed diets containing more extensively processed grains ate less feed but produced the same amount of milk as cows fed diets containing dry-rolled grain.; Dairy Day, 1998, Kansas State University, Manhattan, KS, 1998;

Effect of Fiber Source and Ruminal Starch Degradability on Site and Extent of Digestion in Dairy Cows

Four duodenally cannulated Holstein cows (166 DIM) were used in a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments to study effects of forage fiber source and ruminal starch degradability on digestion events. Forage NDF (21% of dietary DM) was from either alfalfa hay or a 1:2 (substituted on an NDF basis) ratio of alfalfa hay to wheat straw. Low and high ruminal starch degradabilities were achieved by use of either dry-rolled or steam-flaked sorghum grain, respectively. Dry matter intake did not differ among treatments (21 kg/d). Ruminal and total tract digestibilities of dietary OM, N, NDF, and ADF and flow of N fractions to the duodenum were not affected by fiber source. Diets with steam-flaked grain had higher ruminal (74 vs. 48%) and total tract (98 vs. 83%) starch digestibilities than did those diets with dry-rolled grain. Digestibilities of feed OM (63 vs. 51%) and CP (61 vs. 53%) and duodenal flows of nonammonia N (120 vs. 110% of intake) and bacterial N (.45 vs. .35 kg/d) also were higher, but microbial yield efficiency was not influenced by degradability of starch. Steam-flaked sorghum grain improved ruminal and total tract digestion of starch by lactating dairy cows and enhanced bacterial protein synthesis. Wheat straw NDF was substituted for two-thirds of the alfalfa hay NDF in diets for midlactation cows without adversely affecting digestion events or nument flow to the duodenum.

Response of Lactating Holstein Cows to Diets Varying In Fiber Source and Ruminal Starch Degradabllity

Twenty-two Holstein cows near peak lactation were used in an 8-wk experiment to study the effects of forage fiber source and ruminal starch degradability on lactational performance. High and low digestibility forages (alfalfa hay and wheat straw) and sorghum grain processed to give low and high ruminal starch degradability (dry-rolled and steam-flaked) were factorially arranged in four treatments. Diets contained 30% total NDF and 22% forage NDF; consequently, forage to concentrate ratio decreased from 52:48 to 31:69 when straw was substituted for alfalfa hay. Source of forage fiber did not influence production characteristics. Ruminal passage rates for liquid and diet ingredients were slower when diets contained wheat straw, but chewing time and digestibility of NDF were not affected. Total tract digestibility of starch increased from 80 to 97% when grain was steam-flaked, but digestibility of NDF was not influenced. Diets containing more ruminally degradable starch resulted in higher yields of milk (+3.4 kg/d) and milk protein (+110 g/d), milk protein percentage (+.08%), and improved efficiency and persistence of milk yield. Milk fat percentage decreased from 3.6 to 3.2% when steam-flaked grain was fed, but daily yield of milk fat was not decreased. Increasing ruminal degradability of starch has the potential to improve lactational performance when the proper balance of ruminally degradable starch and forage fiber is maintained.

Dual Implantation of Feedlot Steers with Commercial Estradiol and Trenbolone Acetate Implants

Recent introduction of the trenbolone acetate (TBA, Finaplix, Hoechst-Roussel Agri-vet Co., Somerville, NJ) implant into the U.S. market has stimulated interest in additive performance by implanting TBA along with commercial estradiol (E2) implants. Crossbred steers (Bos taurus; n = 168; initial wt = 759 lb) were implanted with one of six treatments in a 2 × 3 factorial arrangement with four pens of seven steers per treatment. The factors were: 0 (without) or TBA implant and either 0, STEER-oid (ST) or Synovex-S (SS), which are E2 based implants. Trenbolone acetate was reimplanted at 63 d. Steers were fed a steam-flaked grain sorghum based finishing diet for 115 or 153 d (final wt = 1100 lb). No interactions existed (P > 0.1) between TBA and E2 treatments over the experiment. Trenbolone acetate improved average daily gain (ADG; 2.68 vs. 2.44 lb, P < 0.01) and gain efficiency (lb gain/100 lb dry matter intake; 15.8 vs. 14.0, P < 0.001) over non-TBA implanted cattle. The ST and SS increased ADG (2.64 and 2.77 vs. 2.27 lb, P < 0.001), dry matter intake (15.1 and 15.8 vs. 13.8 lb/d, P < 0.05) and gain efficiency (15.1 and 15.8 vs. 13.8) over non-E2 implanted steers. Average daily gain for the SS steers tended to be greater (P = 0.09) than for ST steers. Trenbolone acetate addition improved ADG 13% (P < 0.05), 11% (P = 0.11) and 6% (P < 0.05) compared to non-E2, ST, and SS implanted steers, respectively. The response to all implant treatments declined after 115 d on trial. Carcass characteristics did not differ (P > 0.1) among treatments. Implantation with either ST of SS improved performance over nonimplanted steers and dual implantation with TBA and ST or SS improved steer performance over either implant alone.

Effect of grain processing on in sacco digestibility and degradability in the rumen

Effect on nylon-bag digestibility of rolling and steam-flaking as such or followed by grinding through a 1-mm screen was studied in wheat, barley and maize grains. Digestibilities of ground grains were not different, irrespective of rolling or steam-flaking, except flaked and ground barley, which was less digestible than ground barley. Rolled and flaked grains were less digestible than ground grains, except for rolled wheat which was not different from ground wheat. These results suggest that particle size due to grinding is more important than other methods of processing. Dry matter and protein degradabilities of steam-flaked grains were investigated by in sacco technique and compared with unprocessed grains. Dry matter degradability during incubation periods up to 24 h was reduced for steam-flaked wheat and barley, but increased for flaked maize. Protein degradability was lower for flaked grains.