Steam-flaked Corn Research Articles

Effects of corn processing and cattle size on total tract digestion and energy and nitrogen balance.

This study used 18 calves (295 ± 29 kg) and 18 yearlings (521 ± 29 kg) fed whole, cracked, or steam-flaked corn (SFC) to evaluate nutrient digestion and energy balance across different types of processed corn and sizes of cattle. Cattle were fed a diet comprised of 75% corn (dry matter [DM]-basis) from whole, cracked, or SFC to 2.5-times maintenance energy requirements. Subsequently, cattle were placed in individual stanchions, and urine and feces were collected together with measures of gas production via indirect calorimetry. Data were analyzed using the MIXED procedure of SAS. There was no interaction between corn processing and cattle size (P ≥ 0.40). Time spent ruminating (min/d) and rumination rate (min/kg DM intake [DMI]) were not affected by corn processing or cattle size. The eating rate (min/kg DMI) was faster (P < 0.01) for yearlings compared with calves. Total tract starch digestion was greatest (P = 0.01) for cattle fed SFC (97.5%), intermediate in cattle fed cracked (92.4%), and least in cattle fed whole corn (89.5%). Dietary digestible energy and metabolizable energy (Mcal/kg DMI) were greater (P ≤ 0.05) for cattle fed SFC compared with cracked or whole. A greater proportion of digestible energy was lost to heat production (P = 0.01) in cattle fed whole corn compared with cracked and tended to be greater (P = 0.08) in cattle fed SFC than cracked. Conversion of digestible energy to metabolizable energy in this study was more closely related to a dynamic model used to estimate metabolizable energy of feeds to dairy cows than to a linear model used to predict metabolizable energy of feeds to beef cattle. If library estimates of net energy for maintenance are correct, then retained energy (Mcal/d) should have been similar between each type of processed corn; however, retained energy was greater (P < 0.01) for cattle fed cracked compared with whole corn and tended to be greater (P = 0.06) compared with SFC. Yet, observed amounts of net energy based on measures of retained energy were not different (P ≥ 0.60) between cracked and SFC. Nitrogen balance was not affected (P ≥ 0.30) by corn processing or cattle size, although cattle fed cracked had numerically greater (P ≤ 035) N retention. These data indicate that physical processing of corn provides greater net energy to cattle in comparison to whole corn.

Flake density and starch retrogradation influence in situ ruminal degradability characteristics of steam-flaked corn and predicted starch digestibility and energetic efficiency.

Five ruminally cannulated steers (body weight = 390 ± 7.86 kg) were used in two experiments to evaluate the effects of flake density and starch retrogradation on in situ ruminal degradation of steam-flaked corn. In experiment 1, sifted flakes with flake densities of 257, 296, 335, 373, and 412 g/L (enzymatic starch availabilities: 87%, 76%, 66%, 43%, and 49%, respectively) were evaluated in a randomized complete block design experiment. In experiment 2, the experimental design was a randomized complete block design with a 3 × 2 factorial arrangement of treatments. Three steam-flaked corn fractions corresponding to different particle sizes were used: flakes + fines (not sifted; >4 and <4 mm), sifted flakes (>4 mm), and sifted fines (<4 mm). Particle size fractions were stored for 3 d at either 23 °C or 55 °C (starch availabilities averaged across particle sizes: 53.3% and 25.5%, respectively) in heat-sealed foil bags. Samples were ruminally incubated for 0, 3, 6, 12, 24, 48, 72, or 96 h. Degradation data were modeled to obtain the rate and extent of degradation and passage rate was set to 6% per hour. In experiment 1, the rate of degradation decreased linearly (P < 0.01) and in situ ruminal dry matter (DM) degradability decreased linearly (P < 0.01) from 78.9% to 57.3% as flake density increased from 257 to 412 g/L. In experiment 2, storage of steam-flaked corn samples at 55 °C for 3 d decreased (P < 0.01) the rate of degradation by 37.6% across all particle sizes. Storing samples at 55 °C for 3 d decreased (P < 0.01) in situ ruminal DM degradability of flakes + fines, sifted flakes, and sifted fines by 20.9%, 22.6%, and 14.7%, respectively. Using data from experiment 1 and 2, enzymatic starch availability of sifted flakes was positively correlated (R2 = 0.97; P < 0.01) with in situ ruminal DM degradability. The results demonstrate that decreased starch availability resulting from either starch retrogradation or increased flake density is associated with decreased ruminal digestibility. Decreases in starch availability and in situ ruminal degradability may indicate that increasing flake density or starch retrogradation could potentially alter the site of digestion in cattle. Using prediction equations, decreases in ruminal starch digestibility of steam-flaked corn caused by increasing flake density or increasing starch retrogradation could increase energetic efficiency, depending on the rate of passage and if small intestinal starch digestibility is maintained.

522 Late-Breaking: Effects of Corn Processing and Age on Energy Balance, Nutrient Digestion and Rumination in Cattle

Abstract Current library values for energy content in whole or dry-rolled corn (DRC) are identical and do not differ for cattle of different age (NASEM, 2016). Calves (295 ± 29 kg) and yearlings (521 ± 29 kg) were fed whole, DRC or steam-flaked corn (SFC) to evaluate library values of energy content in different types of processed corn among cattle of different age. Cattle were fed diets comprised of 75% corn (DM-basis) to 2.5-times maintenance energy requirements using estimates of NEm in corn and SFC (NASEM, 2016). Data were analyzed using the MIXED procedure of SAS. There was no observed interaction of corn processing and cattle age (P ≥ 0.40). Time spent ruminating (min/d) was not different between dietary treatment or age. Total tract starch digestibility was greatest (P = 0.01) for cattle fed SFC (97.5%), intermediate in cattle fed DRC (92.4%) and least in cattle fed whole corn (89.5%). Nitrogen balance was not affected (P ≥ 0.30) by corn processing or age. Digestible and metabolizable energy (Mcal/kg-DMI) were greater (P ≤ 0.05) for cattle fed SFC compared to DRC or whole. A greater proportion of DE was lost to heat production (P = 0.01) in cattle fed whole corn compared to DRC and tended to be greater (P = 0.08) in cattle fed SFC than DRC. Retained energy (Mcal/d) should have been similar if current library values correctly reflect energy content in each type of processed corn. However, retained energy was greater (P &amp;lt; 0.01) for cattle fed DRC compared to whole corn and tended to be greater (P = 0.06) compared to SFC indicating that library values for DRC underestimate energy available to growing cattle. Measures of retained energy for cattle fed DRC indicated that energy available for gain from DRC was 42% greater than library values (NASEM, 2016).

PSIV-9 Effective ruminal degradability of steam-flaked corn is influenced by flake density and starch retrogradation

Abstract The objective of this study was to evaluate in situ ruminal digestion characteristics of steam-flaked corn with large differences in starch availability (SA) using two different models: 1) increasing flake density and 2) exposure to 55°C temperatures to induce starch retrogradation. Five ruminally-cannulated steers (body weight = 390 ± 7.86 kg) were pen-fed a starter diet. In Exp. 1, sifted flakes with flake densities of 257, 296, 335, 373, and 412 g/L (SA: 87%, 76%, 66%, 43%, and 49%, respectively) were evaluated. In Exp. 2, three steam-flaked corn fractions were evaluated: flakes + fines (not sifted), sifted flakes (&amp;gt;4-mm), and sifted fines (&amp;lt; 4-mm). Feed fractions were stored for 3-d at either 23°C or 55°C (average SA across steam-flaked corn fractions: 53.3% and 25.5% respectively). Treatments of Exp. 2 were arranged with a 3 × 2 factorial. Both experiments were duplicated and analyzed as randomized complete block designs. In Exp. 1, the fractional rate of degradation linearly decreased (P &amp;lt; 0.001) and effective ruminal dry matter degradability (ERD) linearly decreased (P &amp;lt; 0.001) from 80.8% to 60.3% as flake density increased from 257 to 412 g/L. In Exp. 2, storage of steam-flaked corn samples at 55ºC for 3-d decreased (P &amp;lt; 0.001) the fractional rate of degradation and ERD by 38.6% and 21.7% across all feed fractions, respectively. Using data from Exp. 1 and 2, SA of sifted flakes was positively correlated (Pearson = 0.8435; R2 = 0.71; P &amp;lt; 0.001) to ERD. The results of the current study demonstrate that decreased SA resulting from starch retrogradation or increased flake density is associated with decreased ERD. Decreases in SA and ERD may indicate that increasing flake density or starch retrogradation could potentially alter the site of digestion in cattle, by increasing postruminal starch flows.

518 Late-Breaking: Effect of Feedlot Diets on Environmental Emissions from Four Representative U.S. Feedlots and the Beef Production System

Abstract Our objective was to evaluate effects of feedlot dietary management strategies on environmental impacts and net returns of feedlot operations in the United States. Representative feedlots were simulated with the Integrated Farm System Model (IFSM 4.6; USDA-ARS, University Park, PA) to quantify baseline environmental impacts of feedlot production and full US beef cattle production systems. The simulated dietary strategies included: 10% increase in feed efficiency, use of less water intensive forages, 10% increase in byproduct inclusion, 10% improvement in water use efficiency of corn, and steam-flaking of corn. Days on feed and head finished per year were held constant for all strategies to have equal comparisons to baseline results. Dietary management strategies were individually modeled and simulated in IFSM for each feedlot operation to obtain intensities (expressed per kg gain) for greenhouse gas (GHG) emissions, fossil energy use, blue water consumption, and reactive nitrogen loss. Feedlot operations were then linked with cow-calf, stocker, and backgrounding operations to estimate environmental intensities (expressed per kg CW) for full cattle production systems. Improving feed efficiency had the greatest effect on reducing carbon emission intensities (6%), energy use intensity (8%), blue water use intensity (9%), and reactive N loss intensity (4%) for feedlot operations. Increasing corn byproduct inclusion resulted in 9% reduction in blue water use intensity. However, byproduct inclusion increased reactive N loss intensity by 11% as a result of greater protein concentrations in the diet. Switching from rolled corn to steam flaked corn increased energy use intensity by 9%, but little to no changes (1% increase to 3% reduction) were observed for other environmental intensities. Improved feed efficiency was the most effective strategy to reduce environmental footprints of beef cattle production (1 to 2% reductions). Overall, feedlot dietary strategies were less pronounced for the full beef production system compared with feedlot results.

295 Effects of Live Yeast and Ruminal Environment on Beef Cattle Diet Digestibility: An in vitro Approach

Abstract The effects of live yeast (Saccharomyces cerevisiae) and ruminal environment on in vitro true digestibility of dry matter, organic matter, and fiber components were evaluated. Ruminally-cannulated beef steers (n = 4; BW = 520 ± 30 kg) were used in a cross-over design to serve as donors of ruminal content. In vitro substrates (6 grower and 6 finisher diets) and individual ingredients (steam-flaked corn, wet corn gluten feed, and old-world bluestem hay) were dehydrated (55o C), ground (1 mm), and incubated using a 2 × 2 factorial arrangement of treatments: a) the presence or not of yeast (8×109 CFU/animal-daily adjusted to a 70 L ruminal content volume), and b) two ruminal inoculums collected from donors fed a grower (50:50) or a finisher (92:08) diet (concentrate:forage). Four incubation batches (experimental unit) were performed, in which the initial two batches were performed followed by another two after animals switched diets and were adapted again during 21d. A Daisy in vitro incubation system was used, and samples incubated for 48h (39°C). The GLIMMIX procedure of SAS was used for the statistical analysis. No 3-way interactions (P ≥ 0.71) or 2-way interactions with substrate were observed (P ≥ 0.25). The in vitro true digestibility of DM, OM, NDF, and hemicellulose increased when yeast was added to the incubator containing a 50:50 ruminal content (Rumen × Yeast; P ≤ 0.02). The ADF digestibility increased (P = 0.02) with yeast addition regardless of ruminal content type (50:50 or 92:08). As expected, finisher substrate diets were more (P &amp;lt; 0.01) digestible than grower diets. The combination of live yeast and a specific ruminal environment seemed to be more important than substrate type, in which live yeast improved in vitro digestion within a 50:50 ruminal inoculum more evidently.

308 Effects of Roughage Source on Growth Performance, Carcass Characteristics, and Rumination Time of Beef Steers Fed Steam-flaked Corn Finishing Diets

Abstract We hypothesized that roughage source would not impact rumination time and growth performance if the different sources provided a similar concentration of dietary neutral detergent fiber (NDF) and physically effective NDF (peNDF). This experiment’s objective was to evaluate rumination time, and growth performance steers consuming finishing diets with differing roughage sources (corn stalks, cotton burrs, or wheat silage). Beef steers (n = 49; BW = 317 + 5.6 kg) were used in a completely randomized design with 3 dietary treatments. Steers consumed a steam-flaked corn-based diet containing corn stalks (CS), cotton burrs (CB), or wheat silage (WS) included at 7% (DM basis). Dietary NDF was similar (P = 0.36) across treatments. Each steer was fitted with a sensory collar to record daily rumination. Weekly ingredient and dietary samples were estimated for physically effective NDF (epeNDF) using the Penn State Particle Separator. Actual physically effective NDF (apeNDF) was calculated based upon rumination time. Neither initial nor final body weight (BW) differed between treatments (P &amp;gt; 0.52); nor did average daily gain (ADG), dry matter intake or carcass adjusted variables of FBW, ADG, empty BW, or empty body fat (P &amp;gt; 0.31). However, gain to feed (G:F) tended to differ (P = 0.06) between treatments. The CS diet had the greatest G:F with no difference (P = 0.75) between CB and WS. Dietary NDF and epeNDF were similar (P &amp;gt; 0.35) among roughage sources; however, CB had the least apeNDF, consistent with lower rumination time (P &amp;lt; 0.01). When energy values were calculated from animal performance, the CS diet had the greatest observed energy values, followed by WS and CB having the least. These results indicate roughage source impacted rumination time, although steers were fed a steam-flaked corn-based finishing diet with similar dietary roughage and NDF inclusions.

Effects of duration of zilpaterol supplementation on growth-performance, dietary energetics, carcass characteristics, and meat quality of crossbred yearling heifers slaughtered at lighter, less-than-mature final body weight (460 kg)

Our objective was to examine the effects of duration of zilpaterol hydrochloride (ZH) supplementation on growth performance, estimated dietary energetics, carcass characteristics, and meat quality in crossbred yearling heifers when slaughtered at lighter, less-mature final weight. Treatments consisted of a finishing diet based on steam-flaked corn supplemented with (1) 0 ZH (negative control); (2) 0.15 mg of ZH/kg of live weight supplemented for 20 of the final 23 d of the finishing period; (3) 0.15 mg of ZH/kg of live weight supplemented for 25 of the final 28 d of the finishing period, or (4) 0.15 mg of ZH/kg of live weight supplemented for 30 of the final 33 d of the finishing period. Duration of ZH supplementation did not affect ( P ≥ 0.15) any of the variables measured. Compared with the control, ZH increased ( P ≤ 0.02) carcass-adjusted weight gain, G:F, and apparent dietary NE. Zilpaterol supplementation also increased ( P ≤ 0.05) hot carcass weight, carcass DP, and LM area without effects on USDA QG, fat thickness, or KPH fat. Zilpaterol supplementation increased ( P < 0.01) gross retail cuts by 3.6%, when adjusting to a constant carcass weight. There were no treatment effects ( P ≥ 0.11) on shear force or meat color. Zilpaterol hydrochloride supplementation in heifers slaughtered at a final weight that was less than was estimated to be mature (460 kg) improved growth performance, hot carcass weight, carcass DP, LM area, and retail cuts in a manner consistent with results of previous studies in which heifers were slaughtered at heavier (>550 kg) BW. Effects of ZH on meat quality was not significant. Reducing ZH feeding duration from 30 to 20 d may not adversely affect growth performance, carcass characteristics, and meat quality.

Effects of replacing steam-flaked corn with shredded sugar beet pulp on feed sorting, behavior, blood metabolites, and growth performance of dairy calves.

This experiment was conducted to investigate the effects of partial replacement of steam-flaked corn (SFC) with shredded sugar beet pulp (SBP) in the starter diet on selective intake (sorting), feeding and chewing behavior, blood biochemical parameters, and growth in newborn female Holstein dairy calves. A total of 48 calves (3 d old; 40.1 ± 0.84 kg body weight; mean ± SE) were randomly assigned to 1 of 2 feeding treatments containing 0 or 25% SBP (percentage of dry matter [DM]) in the starter diet. Calves were weaned on d 61 and remained in the study until d 81. Intake of starter feed and total intake of DM (milk DM + starter feed DM), crude protein, and neutral detergent fiber were increased (P < 0.05) by feeding SBP; however, intake of starch (P < 0.01) and total intake of ether extract (P = 0.03) were decreased with no apparent effect on total intake of ME. Average daily gain, feed efficiency, final weight, and skeletal growth also showed no significant changes. Circulating concentrations of glucose, total protein, and albumin were not affected by partial replacement of SBP with SFC; however, higher concentrations of blood urea-N (P = 0.01) and a lower albumin-to-globulin ratio (P = 0.03) were observed in SBP- vs. SFC-fed calves. Calves fed SBP sorted more for particles retained on the 4.75-mm sieve (P = 0.02) and against particles retained on the 0.6-mm sieve and bottom pan (P < 0.01). Intake of neutral detergent fibers and starch from particles retained on all sieve fractions was increased and decreased (P < 0.01), respectively, by replacing SFC with SBP. Replacement of SBP with SFC was associated with increased meal length and meal size and increased rumination frequency and length, but decreased intervals between rumination (P ≤ 0.01). Calves fed SBP spent more time eating, rumination, and standing and less time lying and non-nutritive oral behaviors (P < 0.01). In general, 25% replacement of SFC with SBP did not affect calf performance but increased time spent rumination and eating and decreased non-nutritive oral behaviors.

Influence of air equilibration time, sampling techniques, and storage temperature on enzymatic starch availability of steam-flaked corn.

Measuring enzymatic starch availability is commonly used as a quality control method to ensure steam-flaked corn manufacturing consistency in commercial cattle feeding operations. However, starch availability estimates can be variable. We conducted five experiments to evaluate factors influencing starch availability estimates of steam-flaked corn. In Exp. 1, sample handling methods were evaluated. Sifted flakes were immediately placed into a plastic bag, air equilibrated for 240 min, oven-dried, or freeze-dried. Directly oven-drying samples at 55°C decreased (P < 0.01) starch availability compared to other sample handling methods. In Exp. 2, sifted flakes were air equilibrated for 0, 15, 30, 60, 120, or 240 min. Air equilibration time did not influence (P ≥ 0.54) starch availability. In Exp. 3, samples were evaluated for effects of sifting through a 4-mm screen (flakes + fines vs. sifted flakes) and air equilibration time (0 vs. 240 min). Both sifting steam-flaked corn samples and air equilibration for 240 min increased starch availability (P < 0.01 and P = 0.02, respectively). In Exp. 4, we evaluated the effects of air equilibration time (0 vs. 240 min) on the two sifted portions (sifted flakes vs. sifted fines). There was an air equilibration time × sifted portion interaction for starch availability because air equilibration time increased (P < 0.01) starch availability of sifted fines but did not influence starch availability of sifted flakes. Concentrations of crude protein, soluble crude protein, neutral and acid detergent fiber, ether extract, and acid-hydrolyzed fat, Ca, P, K, Mg, S, Fe, Zn, Mg, and Cu were greater (P < 0.01) for sifted fines compared to sifted flakes. Starch availability and total starch concentration were greater (P < 0.01) for sifted flakes compared to sifted fines. In Exp. 5, effects of air equilibration time (0 vs. 240 min) and storage temperature (23°C vs. 55°ºC) on flakes + fines were evaluated. Storage of flakes + fines in heat-sealed foil bags at 55°C for 3-d decreased (P < 0.01) starch availability by 40.7%. Sifted flakes contained less moisture, greater total starch concentrations, and greater starch availability than sifted fines. Moisture, sifting, air equilibration time, and storage temperature influence starch availability of steam-flaked corn. Adoption of the strategies discussed in the current study will lead to more consistent estimates of starch availability.

Feeding high amounts of almond hulls to lactating cows

California is the leading state for the production of almonds, with more than 400,000 bearing hectares of orchards that produced approximately 1 billion kilograms of shelled nuts in 2017. Almond hulls (AH) are a regional by-product feedstuff fed predominantly to dairy cattle in California. A 2012 study surveyed 40 dairy farms in California and found that 39 out of 104 total mixed rations contained AH, with a mean daily feeding rate of 1.45 kg/cow. In 2017, approximately 2 billion kilograms of AH was produced. At a feeding rate of 1.45 kg/cow daily, even if all 1.7 million lactating cows in California are consuming AH, there will be a surplus of AH on the market as the approximately 130,000 nonbearing hectares come into nut production. Therefore, the potential of feeding varying amounts of AH to lactating dairy cows was investigated using 12 Holstein cows with 4 primiparous and 8 multiparous cows. The dietary treatments were 4 total mixed rations containing 0, 7, 13, or 20% AH. The AH used contained 12.8% crude fiber (as-is basis), which was below the 15% legal limit set by state feed regulations. Diets were formulated so that as the inclusion rate of AH increased, the amount of steam-flaked corn and soyhull pellets decreased and soybean meal inclusion increased. Experimental design was a replicated 4 × 4 Latin square. Diet had a cubic effect on actual milk yield, energy-corrected milk yield, and dry matter intake, with the 7% AH diet having the highest values and the 13% AH diet having the lowest. The percent and yield of total solids and the yields of lactose and fat did not differ with diet, but percent and yield of protein declined linearly with increased AH inclusion, and fat percent increased linearly. Apparent total-tract digestibilities of dry matter and organic matter were higher with the inclusion of AH in the diet. Total percentage of the day spent ruminating increased linearly with higher amounts of AH. Overall, this work demonstrated that AH can be fed at varying amounts, up to 20% of the diet, to lactating dairy cows to support high levels of milk production and that increasing amounts of AH (up to 20%) in the diet could lead to improved digestibility and milk fat percentage but decreased milk protein production.

250 Effects of Bunk Management and Bulk Density of Steam-flaked Corn on Growth Performance, Carcass Characteristics, and Liver Score of Finishing Beef Cattle Fed Diets Without Tylosin Phosphate

Abstract One hundred ninety-two beef steers (BW = 332 ± 8.2 kg) were used in a randomized complete block design to evaluate the effects of differing bunk management and bulk density of steam-flaked corn (SFC) in a randomized complete block design. A factorial arrangement of treatments was used with: 1) slick bunk management (SBM) + 335 g/L SFC; 2) modified ad libitum bunk management (MAL) + 335 g/L SFC; 3) SBM + 425 g/L SFC; 4) MAL+ 425 g/L SFC. Steers were randomly assigned to treatment within BW block, with 12 pen replications per treatment. Data were analyzed using a mixed model with fixed effects of bunk management, SFC bulk density, and their interaction. Block was included as a random effect. Bunk management strategy did not affect growth performance, carcass characteristics, or liver abscess score (P &amp;gt; 0.10). The average daily gain (ADG) of steers fed 425 g/L SFC was greater (P = 0.05) from days 35 to 105 than those fed 335 g/L SFC; however, overall ADG did not differ (P = 0.36). The DMI of steers fed 425 g/L SFC was greater (P ≤ 0.05) than those fed 335 g/L SFC. Gain-to-feed of steers fed 425 g/L SFC tended (P = 0.10) to be lesser from days 0 to 35 but did not differ overall (P ≥ 0.12). Steers fed 425 g/L SFC tended to have greater backfat and calculated empty body fat (P ≤ 0.07) than those fed 335 g/L SFC and had a greater calculated yield grade (P = 0.05). Steers fed 425 g/L SFC had 43.51% fewer (P = 0.04) liver abscesses. Bunk management strategy did not impact growth performance or carcass characteristics; whereas, SFC processed to 425 g/L increased DMI, fat thickness, and yield grade while resulting in a decreased proportion of liver abscesses.

33 Comparison of Monensin Sodium Sources for Finishing Beef Cattle

Abstract The objective of this study was to evaluate the digestive characteristics of ruminally cannulated beef steers consuming a steam-flaked corn (SFC) or dry-rolled corn (DRC) based diet containing either Rumensin 90 (R) or Monovet 90 (MV). Six ruminally fistulated steers (657.7 kg ± 72.6) housed individually were used in a 6 × 6 Latin square design with a factorial treatment arrangement. Each of the 6 periods were 15 d with 14 d for diet adaptation and 1 d of rumen fluid collections. Six 15-d periods consisted of 14 d diet adaptation prior to rumen fluid collections. Dietary treatments were DRC without monensin sodium (DRC-C), SFC without monensin sodium (SFC-C), DRC with Rumensin 90 (DRC-R), DRC with Monovet 90 (DRC-MV), SFC with Rumensin 90 (SFC-R), and SFC with Monovet 90 (SFC-MV). Rumen contents and fluid were collected through the fistula of each animal at 0, 3, 6, 12, and 24 h on d 15 of each period. Rumen fluid was collected 6 h postfeeding each period for in vitro analyses. Steer was the experimental unit and the model included fixed effects of grain processing, additive, and grain processing × additive. Total gas produced was composited from each in vitro bottle into a gas collection bag for the 48-h determination of methane concentration. No differences were detected for DMI (P = 0.81). Ruminal pH did not differ for the control or additive treatments (P = 0.33). However, ruminal pH was lower (P &amp;lt; 0.01) with SFC relative to DRC There was a significant difference in acetate to propionate ratio for both additive (P = 0.04) and grain type (P ≤ 0.01). Additive inclusion reduced methane proportion of total gas relative to control treatments (P ≤ 0.01). Monensin sodium reduced methane concentration though source had no effect on DMI or ruminal pH.

278 Effect of Feeding CARS on Digestibility in Finishing Cattle Diets

Abstract An experiment was conducted to evaluate the digestibility of a novel liquid feed, Condensed Algal Residue Solubles (Veramaris, Blair, NE) in finishing cattle diets. Mass production of algae to harvest omega-3 fatty acids results in byproduct production of CARS (25.4% DM, 19.3% CP, 8.3% Fat, 9.96% Na on DM basis), made up of the de-oiled algae cells and residual fermentation substrates. The CARS product has generally recognized as safe (GRAS) status. Six ruminally and duodenally cannulated crossbred steers were assigned randomly to 1 of 3 treatments over 3 collection periods, for a 3 x 3 replicated Latin Square design. Treatments differed by increasing inclusion of CARS (0, 2.5, and 5% of diet DM) fed with CARS replacing steam flaked corn (72, 69.5, and 67% of diet DM as CARS inclusion increased). All diets contained 15% dry distillers grains, 8% alfalfa haylage, and 5% supplement. Cattle were dosed with 10 g of titanium dioxide per day. Duodenal and fecal samples were collected four times per day across four days and composited by period for each animal. Fecal samples were analyzed for titanium dioxide concentration to determine fecal output and diet digestibility. Data were analyzed with CARS inclusion and period as fixed effects and animal as a random effect. Orthogonal contrasts were used to test linear and quadratic effects of CARS inclusion. There were no significant differences for DM intake and OM intake between the different CARS inclusions (P ≥ 0.17), averaging 7.76 kg DM/d and 6.94 kg OM/d. Total tract DM digestibility was not affected by treatment (P ≥ 0.71) and averaged 73.0%. Total tract OM digestibility was also not different between treatments (P ≥ 0.93) and averaged 71.1%. Replacing steam flaked corn with CARS up to 5% of diet DM in finishing cattle diets did not affect diet digestibility.

251 Effects of Roughage Source on Rumination Time and Ruminal Ph in Steers Fed a Steam-flaked Corn Finishing Diet

Abstract Research is limited on how physically effective fiber from various roughage sources aids in rumination time and ruminal pH of finishing beef cattle. This experiment’s objective was to evaluate rumination time and ruminal pH of beef steers consuming finishing diets with varying roughage sources (corn stalks, cotton burrs, or wheat silage). We hypothesized that roughage type would not impact rumination time and ruminal pH if different sources provide similar dietary neutral detergent fiber (NDF). Ruminally cannulated steers (n = 6; average BW = 644.56 + 13.15 kg) were used in a 3 × 3 replicated Latin square with 3 dietary treatments and 3, 21-d periods (20-d diet adaptation, 1-d sampling). Steers consumed a steam-flaked corn-based finishing diet containing corn stalks (CS), cotton burrs (CB), or wheat silage (WS) included at 7% (DM basis) of the diet. Dietary NDF was similar across treatments. Steers were fitted with a sensory collar to record daily rumination (Allflex Livestock Intelligence). Ruminal pH was measured using a handheld pH probe on d-21 at 0, 3, 6, 12, 24 hr postprandial. The NDF and dry matter intake (DMI) were greatest for steers consuming the WS diet (P &amp;lt; 0.01) while CS and CB diets did not differ (P = 0.81). While dietary NDF and estimated physically effective NDF (peNDF) were similar among roughage sources, CB had the lowest actual peNDF, consistent with lower rumination time (P &amp;lt; 0.01) and lower ruminal pH (P = 0.29). This experiment’s results indicate that roughage source impacted rumination time despite feeding steers a steam-flaked corn-based finishing diet with similar roughage and NDF levels. Using rumination time (min/d) to determine peNDF was a better indicator of rumen function parameters than particle size measured via the Penn State Particle Separator equation.

148 Analysis of purported insulin modulators on glycemic and insulinemic responses to various feeds in mature horses

Understanding the insulinemic and glycemic responses to common equine feeds and the efficacy of purported insulin modulators, such as aloe vera and grape seed extract, is valuable in designing appropriate equine diets. Using a repeated 5 × 5 Latin square design, dehydrated alfalfa (DA), beet pulp (BP), oats (O), steam-flaked corn (C), and steam-flaked corn with an insulin modulator consisting of combined aloe vera and grape seed extract (CIM) were tested for glycemic and insulinemic response in 10 mature horses aged 6 to 25 years with an average of 11.5 years. The various feeds were fed at the rate of 1.5 g/kg of body weight on an as-fed basis. The aloe vera and grape seed extract were fed at the rates of 150 mg/kg and 20 mg/kg of body weight respectively. Horses were maintained on a forage-only diet consisting of pasture grazing and hay, except once per week, when they were stalled and subjected to a glycemic response test. For testing, hay was removed the evening before, and a 12-h fasted blood sample was taken at time 0 before providing the assigned treatments. Horses were allowed 30 min to consume each treatment before any ORTS were removed. Additional blood samples were taken via jugular catheter at 30, 60, 90, 120, 150, and 180 min post-feeding. Blood glycemic and insulinemic responses were evaluated by maximum concentrations and time to peak response (minutes). Peak glucose and insulin were determined by Proc Mixed function in SAS 9.4 with the main effect of treatment and the random variables of horse and week. Results are presented as lsmeans ± SEM. Both DA and BP had lower peak glucose and insulin concentrations (P < 0.05) than the 3 high starch concentrate treatments (O, C, and CIM). The addition of insulin modulators to steam-flaked corn had no effect on the response for peak glucose [C: 128 ± 5 mg/dL, CIM: 133 ± 5 mg/dL, P = 0.39] or insulin [C: 54.5 ± 15.6 µIU/mL, CIM: 58.6 ± 15.6 µIU/mL; P = 0.78]. Likewise, the addition of the insulin modulators did not impact time to peak glucose concentrations [C: 93 ± 9 min, CIM: 108 ± 9 min, P = 0.23], nor the time to peak insulin concentrations [C: 81 ± 13 min, CIM: 87 ± 13 min, P = 0.73]. The results support that feeds with greater starch concentrations produce higher maximal blood glucose and insulin concentrations, but that, in this study, the addition of insulin modulators to steam-flaked corn did not result in a detectable change in the horses’ insulinemic and glycemic response.

Comparison of monensin sodium sources for finishing beef cattle.

The objective of this study was to evaluate the ruminal fermentation characteristics of ruminally fistulated beef steers consuming a steam-flaked corn (SFC) or dry-rolled corn (DRC) based diet containing either Rumensin 90 (RUM; Elanco, Greenfield, IN), or Monovet 90 (MV; Huvepharma, Peachtree City, GA). Six ruminally fistulated steers (657.7 kg ± 72.6) housed individually were used in a 6 × 6 Latin square design with 2 × 3 factorial treatment arrangement. Each of the 6 periods were 15 d with 14 d for diet adaptation and 1 d of rumen fluid collections. Dietary treatments were DRC without monensin sodium (DRC-C), SFC without monensin sodium (SFC-C), DRC with Rumensin 90 (DRC-R), DRC with Monovet 90 (DRC-MV), SFC with Rumensin 90 (SFC-R), and SFC with Monovet 90 (SFC-MV). Rumen contents and fluid were collected through the fistula of each animal at 0, 3, 6, 12, and 24 h on d 15 of each period. Rumen fluid collected at 6 h post-feeding each period was used for in vitro analyses. Steer was the experimental unit and the model included fixed effects of grain processing, additive, and grain processing × additive. Total gas produced was composited from each in vitro bottle into a gas collection bag for the 48-h determination of methane concentration. No differences were detected for DMI (P = 0.81). Ruminal pH did not differ for the control or additive treatments (P = 0.33). However, ruminal pH was lower (P < 0.01) with SFC compared to DRC. There was a significant difference in acetate to propionate ratio for grain type (P = 0.01) and a tendency for additive inclusion (P = 0.06). Additive inclusion reduced methane proportion of total gas compared to control treatments (P ≤ 0.01). Overall, monensin sodium reduced methane concentration though source had no effect on DMI or ruminal pH.

Evaluation of whole corn substitution in diets based on steam-flaked corn containing different concentrations of wet distillers grains with solubles for beef cattle

Our objective was to determine effects of substituting steam-flaked corn (SFC) with whole shelled corn (WSC) in finishing diets containing wet distillers grains with solubles (WDGS) on cattle performance, carcass characteristics, digestion, and rumen microbial ecology. The study used 642 Angus-cross heifers (411.7 ± 18.0 kg of initial BW) assigned to 36 pens. Treatments (2 × 3 factorial) were 6 SFC-based finishing diets with 0 or 20% WSC and 0, 15, or 30% WDGS (DM basis). Ruminal fluid was collected to evaluate ruminal characteristics, and feces and manure were collected to determine nutrient digestion and losses. Heifers fed 20% WSC diets had greater ( P < 0.01) DMI, but ADG and G:F were not affected ( P ≥ 0.11) by WSC concentration. The percentage of carcasses grading USDA Choice tended to be lower ( P = 0.07) for cattle fed diets with 20 versus 0% WSC. Increasing dietary WDGS decreased G:F ( P < 0.01) and tended to decrease ADG ( P = 0.10), increased DMI ( P = 0.08), and decreased hot carcass weight ( P = 0.09). Dietary WSC affected ruminal pH ( P < 0.01) and VFA molar concentrations ( P = 0.05). Ruminal acetate:propionate decreased (quadratic, P < 0.03) with increasing WDGS. Bacterial diversity was not affected by WSC ( P = 0.63) but increased with increasing WDGS ( P = 0.01). Substituting SFC with 20% WSC in cattle finishing diets did not affect animal performance but decreased carcass quality. In contrast, increasing dietary WDGS decreased animal performance but did not affect carcass characteristics.

Effects of ground, steam-flaked, and super-conditioned corn grain on production performance and total-tract digestibility in dairy cows

This study aimed to evaluate the effects of feeding ground, steam-flaked, or super-conditioned corn on production performance, rumen fermentation, nutrient digestibility, and milk fatty acid (FA) profile of lactating dairy cows. Twenty-four lactating Holstein cows (130 ± 12 d in milk) in a completely randomized block design experiment were assigned to 1 of 3 treatments that contained 31% of one of the following corn types: (1) ground corn; (2) steam-flaked corn; and (3) super-conditioned corn. Actual milk yield was greater in the super-conditioned corn diet than in the steam-flaked and ground corn diets. Dry matter intake, 3.5% fat-corrected milk and energy-corrected milk remained unaffected by treatments; however, milk fat concentration decreased in the super-conditioned corn diet compared with the ground and steam-flaked corn diets. The molar proportion of ruminal acetate decreased in the super-conditioned corn diet compared with the ground and steam-flaked corn diets, whereas the molar proportion of propionate spiked in the super-conditioned corn diet. Ruminal pH dropped in cows fed super-conditioned corn compared with the other 2 diets. A similar pattern was observed for ruminal NH3-N and acetate-to-propionate ratio. Total-tract starch digestibility increased the most in the super-conditioned corn diet followed by the steam-flaked and ground corn diets (96.8, 95.1, and 92.5%, respectively). The neutral detergent fiber digestibility declined in cows fed the super-conditioned corn diet as opposed to other diets (~3.9%). The concentrations of 16:0 and mixed-FA in milk fat dropped in the super-conditioned corn-based diet compared with the ground corn diet. Milk trans-10 18:1 FA increased, whereas trans-11 18:1 FA decreased in cows fed the super-conditioned diet. We concluded that super-conditioned corn has the potential to increase milk yield and starch digestibility in lactating dairy cows; however, reduced milk fat output caused by altering ruminal pH and ruminal FA biohydrogenation pathways may not be desirable in certain markets. Future research is warranted to investigate how super-conditioned corn affects feed efficiency.

Concentrate allowance and corn grain processing influence milk production, body reserves, milk fatty acid profile, and blood metabolites of dairy cows in the early postpartum period

The study goal was to determine the effects of a fast (FAS) or slow (SLW) incremental rate of concentrate feeding and corn processing method during the early postpartum period on lactational performance, body reserves, blood metabolites, and milk fatty acid (FA) profile. Forty multiparous Holstein cows were used in a randomized block design with a 2 × 2 factorial arrangement of treatments. Treatment diets were either a FAS [1.0 kg of dry matter (DM)/d] or SLW (0.25 kg of DM/d) incremental rate of concentrate feeding (up to 12 kg of DM/d) with either dry ground corn (DGC) or steam-flaked corn (SFC) as the primary starch source in concentrate. Treatments were fed from 5 to 64 d postpartum. The basal diet consisted of forage, soybean meal, and 5 kg/d concentrate in the postpartum period. Throughout the experiment, dry matter intake (DMI) and milk yield were measured daily, and milk components, body condition score, and body weight were recorded at 16-d intervals, whereas blood metabolites and milk FA profile were measured at 16 and 32 d in milk. The incremental rate of concentrate feeding interacted with corn processing method to affect plasma concentration of glucose with greater glucose in SFC treatment compared with DGC in cows fed with the FAS strategy. Cows fed FAS and SFC had a greater total DMI than those fed SLW and DGC counterparts (22.8 versus 22.1 kg and 22.7 versus 22.1 kg, respectively), and also SFC increased yield of actual milk compared with the DGC counterpart (42.7 versus 41.6 kg). The milk fat and energy-corrected milk yields were not different among treatments whereas milk protein yield was greater when SFC was fed. Greater incremental rate of concentrate feeding tended to increase milk lactose yield during the first 64 d of lactation. The loss of body condition score increased when cows were fed SLW for the entire period and plasma nonesterified fatty acids and β-hydroxybutyrate concentrations increased with the SLW strategy. The proportions of total trans 18:1 and trans-11 18:1 FA in milk fat were higher in cows fed FAS. However, feeding SLW enhanced milk de novo and mixed FA proportions compared with FAS, whereas the proportions of milk FA were not affected by corn grain processing method. The incremental rate of concentrate feeding had significant effects on DMI, milk yield, and body reserve changes. Although feeding SFC instead of DGC had benefits on DMI and milk yield at 48 and 64 d postpartum, treatments did not interact to affect production responses when cows were fed with the SLW strategy.