Steam-flaked Corn Research Articles

A survey of starch availability of steam-flaked corn in commercial feedlots evaluating roll size and flake density

<h2>ABSTRACT</h2> The quality of steam-flaked corn (SFC) in feedlot diets can affect animal performance and the incidence of digestive disorders. Therefore, this study was conducted to define important and relevant measures used to determine SFC quality in commercial feedyards. Commercial feedlots (n = 17) located in Kansas, Nebraska, Texas, New Mexico, Arizona, and California were asked to participate in a survey to evaluate SFC manufacturing practices implemented, equipment used, and parameters targeted to measure flake quality. Manufacturing practice parameters evaluated included dry corn moisture, grain water addition, tempering time, steaming time, steam-cabinet temperature, mill electrical load, steam-conditioned corn moisture content, SFC moisture content, and SFC flake thickness. Equipment evaluated included roll size and steam-cabinet dimensions and capacity; flake quality parameters evaluated included hot and cooled SFC flake density, SFC volumetric flake weight, and starch availability of SFC samples. Samples of steam-conditioned corn and SFC were collected from each flaker (n = 49) within each feedlot. Flake density was measured on hot (immediately from below the rolls) and cooled flakes, and volumetric weight was measured only on cooled flakes. Steam-flaked corn samples were evaluated for starch availability using enzymatic hydrolysis. Enzymatic starch availability (ENZ) averaged 50.6 ± 8.02, with a range of 37.0 to 65.0%. Significant (<i>P</i> < 0.10) variables contributing to the final multiple linear regression model using ENZ as the dependent variable were SFC moisture, cooled flake density (CFD), and roll diameter [ENZ = 119.72 − (1.22 × SFC moisture) − (2.42 × CFD) + (0.47 × roll diameter); R² = 0.5276; <i>P</i> < 0.10].

Effects of wet distillers grains with solubles in diets based on steam-flaked corn containing moderate or high roughage levels on nutrient digestibility in feedlot cattle and in vitro fermentation

ABSTRACT Previous research with roughage and wet distillers grains with solubles (WDGS) concentrations in feedlot diets based on steam-flaked corn has not extensively evaluated measurements of digestibility. Two experiments were conducted to evaluate the effects of concentrations of alfalfa hay (AH) and WDGS on apparent total-tract nutrient digestibility by finishing cattle and in vitro fermentation characteristics. In both studies, treatments were arranged in a 2 × 3 + 1 factorial and consisted of diets based on steam-flaked corn including AH (6 or 12% of DM) and WDGS (15, 30, or 45% of DM), and a control diet without WDGS that contained 9% AH. In Exp. 1, 56 beef steers (initial BW = 395 ± 7 kg) were used in a randomized complete block design and fed for 28 d. Intakes of DM, OM, NDF, ADF, and CP were greater (P ≤ 0.048) by steers fed 12 versus 6% AH. Increasing the dietary concentration of WDGS increased NDF, ADF, and CP intakes (P ≤ 0.046), and an AH × WDGS interaction (P ≤ 0.02) was detected for starch intake. Digestibility of DM and OM was greater for control steers than for the average of all treatments containing WDGS (P

Effects of ruminally degradable starch levels on performance, nitrogen balance, and nutrient digestibility in dairy cows fed low corn-based starch diets

ObjectiveThis trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows.MethodsEight multiparous Holstein cows (body weight [BW]: 717±63 kg; days in milk [DIM]: 169±29) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component.ResultsThe results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR.ConclusionResults of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.

Effect of feeding brown rice instead of corn on lactation performance and blood metabolites in periparturient dairy cows

The objective of this study was to evaluate the effect of replacing corn with brown rice (BR) on dry matter intake (DMI), milk production, blood metabolites and energy balance (EB) in cows during the periparturient period. Twenty-four nonlactating multiparous Holstein cows in late gestation were studied from 3 week before the expected calving date through 6 week after parturition. The cows were divided into one of two dietary treatment groups based on parity and the expected calving date. The treatments were a diet containing steam-flaked corn and a diet containing steam-flaked BR. Prepartum DMI and body weight (BW) and postpartum DMI, BW, milk yield, milk protein and lactose yield were not affected by the dietary treatment. However, the milk fat content and fat yield were higher (P=0.02 and P=0.01) for cows fed BR than for cows fed corn. Thus, cows fed BR-based total mixed ration (TMR) tended to have more negative EB in early lactation (P=0.06) compared with cows fed corn-based TMR. During the prepartum period, the plasma concentrations of glucose, insulin, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), aspartate transaminase (AST) and Ca were not affected by dietary treatments. On the other hand, the postpartum plasma glucose and insulin concentrations were decreased (P<0.01 and P=0.02) and the BHBA and AST concentrations were increased (P<0.01 and P=0.02) by replacing corn with BR with no dietary effect on postpartum plasma NEFA and Ca concentrations. These results show that feeding BR instead of corn does not affect DMI or milk yield, but increases milk fat production and leads to a more negative EB state in early lactation. Replacing corn with BR during the periparturient period has adverse effects on the metabolism and energy status in early lactating cows.

Carcass and meat traits of feedlot Nellore bulls fed different dietary energy sources

The objective of this experimental study was to evaluate the effects of different dietary energy sources on the carcass and meat traits of feedlot Nellore bulls. A total of 48 Nellore bulls at 32 months of age with 354.35±19.56 kg body weight were studied for 85 days. The bulls were allotted to four groups of 12 individuals: Whole corn grain - diet based on whole corn grain; Ground corn - diet based on ground corn grain; Citrus pulp - diet based on citrus pulp; and Steam-flaked corn - diet based on steam-flaked corn. Diets did not influence carcass quality or meat quality. Average values for fat depth, rib eye area, shear force, total cooking losses, and carcass yield were 4.97 mm, 74.71 cm2, 5.85 kgf, 26.82%, and 52.0%, respectively. Based on the quantitative and qualitative analysis of this study, there is no restriction for the adoption of any of the tested diets in feedlots with Nellore bulls and the evaluated energy sources may be used to replace ground corn grain.

Effect of ensiling process of total mixed ration on fermentation profile, nutrient loss and in situ ruminal degradation characteristics of diet.

This experiment aimed to determine the changes in chemical composition, fermentation profile, in situ disappearance characteristics, and nutrient losses of ensiled total mixed ration (TMR) containing steam-flaked corn or brown rice (BR) during storage. TMRs for dairy cows, containing either steam-flaked corn or BR at 31.9% with 15.2% rye silage, 40.5% alfalfa silage, 5.0% beet pulp and 7.0% soybean meal, were prepared (dry matter (DM) basis). Each TMR was placed in a plastic drum silo, stored at 23°C in an air-conditioned room and sampled 0, 7, 14, 30, 90 and 210 days after preparation. In both grain sources, the fermentation products increased, while DM and starch storage losses increased and starch content greatly decreased during storage. The rapidly degradable fraction and effective ruminal degradability of DM, crude protein and starch increased during storage. These changes of dietary characteristics were large during 30 days of storage, but small after 90 days of storage. Replacing corn with BR led to increased fermentation products, starch loss and effective ruminal degradability of the ensiled TMR. These results indicate that the ensiling process of TMR changes the dietary characteristics and replacing corn with BR in TMR had a large impact on these dietary characteristics.

Skeletal muscle and hepatic insulin signaling is maintained in heat-stressed lactating Holstein cows

Multiparous cows (n=12; parity=2; 136±8 d in milk, 560±32kg of body weight) housed in climate-controlled chambers were fed a total mixed ration (TMR) consisting primarily of alfalfa hay and steam-flaked corn. During the first experimental period (P1), all 12 cows were housed in thermoneutral conditions (18°C, 20% humidity) with ad libitum intake for 9 d. During the second experimental period (P2), half of the cows were fed for ad libitum intake and subjected to heat-stress conditions [WFHS, n=6; cyclical temperature 31.1 to 38.9°C, 20% humidity: minimum temperature humidity index (THI)=73, maximum THI=80.5], and half of the cows were pair-fed to match the intake of WFHS cows in thermal neutral conditions (TNPF, n=6) for 9 d. Rectal temperature and respiration rate were measured thrice daily at 0430, 1200, and 1630 h. To evaluate muscle and liver insulin responsiveness, biopsies were obtained immediately before and after an insulin tolerance test on the last day of each period. Insulin receptor (IR), insulin receptor substrate 1 (IRS-1), AKT/protein kinase B (AKT), and phosphorylated AKT (p-AKT) were measured by Western blot analyses for both tissues. During P2, WFHS increased rectal temperature and respiration rate by 1.48°C and 2.4-fold, respectively. Heat stress reduced dry matter intake by 8kg/d and, by design, TNPF cows had similar intake reductions. Milk yield was decreased similarly (30%) in WFHS and TNPF cows, and both groups entered into a similar (−4.5 Mcal/d) calculated negative energy balance during P2. Insulin infusion caused a less rapid glucose disposal in P2 compared with P1, but glucose clearance did not differ between environments in P2. In liver, insulin increased p-AKT protein content in each period. Phosphorylation ratio of AKT increased 120% in each period after insulin infusion. In skeletal muscle, protein abundance of the IR, IRS, and AKT remained stable between periods and environment. Insulin increased skeletal muscle p-AKT in each period, but the phosphorylation ratio (abundance of phosphorylated protein:abundance of total protein) of AKT was decreased in P2 for TNPF animals, but not during WFHS. These results indicate that mild systemic insulin resistance during HS may be related to reduced nutrient intake but skeletal muscle and liver insulin signaling remains unchanged.

The effects of dry-rolled corn particle size on performance, carcass traits, and starch digestibility in feedlot finishing diets containing wet distiller's grains.

Crossbred yearling steers ( = 360; 395 ± 33.1 kg initial BW) were used to evaluate the effects of dry-rolled corn (DRC) particle size in diets containing 20% wet distiller's grains plus solubles on feedlot performance, carcass characteristics, and starch digestibility. Steers were used in a randomized complete block design and allocated to 36 pens (9 pens/treatment, with 10 animals/pen). Treatments were coarse DRC (4,882 μm), medium DRC (3,760 μm), fine DRC (2,359 μm), and steam-flaked corn (0.35 kg/L; SFC). Final BW and ADG were not affected by treatment ( > 0.05). Dry matter intake was greater and G:F was lower ( < 0.05) for steers fed DRC vs. steers fed SFC. There was a linear decrease ( < 0.05) in DMI in the final 5 wk on feed with decreasing DRC particle size. Fecal starch decreased (linear, < 0.01) as DRC particle size decreased. In situ starch disappearance was lower for DRC vs. SFC ( < 0.05) and linearly increased ( < 0.05) with decreasing particle size at 8 and 24 h. Reducing DRC particle size did not influence growth performance but increased starch digestion and influenced DMI of cattle on finishing diets. No differences ( > 0.10) were observed among treatments for any of the carcass traits measured. Results indicate improved ruminal starch digestibility, reduced fecal starch concentration, and reduced DMI with decreasing DRC particle size in feedlot diets containing 20% wet distiller's grains on a DM basis.

Effect of level and source of supplemental tannin on growth performance of steers during the late finishing phase

ABSTRACTTwo trials were conducted to evaluate the effect of tannin supplementation of steers during the feedlot finishing phase. In Trial 1, 96 Holstein steers (478 ± 6.5 kg) were used to evaluate the effects of level of supplemental condensed tannin (0%, 0.2%, 0.4%, and 0.6% of dry matter basis) on growth performance. Supplemental tannin increased (6.5%, P = 0.05) weight gain, gain efficiency (5.5%, P = 0.04), and tended to increase dietary net energy (3.2%, P = 0.06). In Trial 2, 96 Holstein steers (392 ± 4 kg) were used to evaluate the effect of tannin sources on growth performance. Treatments consisted of a steam-flaked corn diet supplemented with (1) no supplemental tannin, (2) 0.6% condensed tannin, (3) 0.6% hydrolysable tannin, and (4) a blend of 0.3% condensed and 0.3% hydrolysable tannin. Tannin supplementation tended to increase average daily gain (ADG, 6.8%, P = 0.08) and dry matter intake (DMI, 4%, P = 0.04). It is concluded that tannin supplementation promotes greater DMI, and hence, ADG of steers during the finishing feedlot phase. The basis for this effect on feed intake is not certain, but is apparently independent of potential tannin effects on metabolizable protein supply. Source of supplemental tannin (condensed vs. hydrolysable) have minimal effects on overall growth performance response to supplementation.

Effects of physical form of starter and forage provision to young calves on blood metabolites, liver composition and intestinal morphology

This study evaluated the effects of physical form of starter feed and forage provision on the performance, blood metabolites, liver composition and intestinal morphology of dairy calves. Individually housed calves (n=52; body weight=41.5±2.5kg) were randomly allocated (n=13 per treatment) to one of the following four treatments: (i) ground starter feed (GS; mean particle size=0.72mm in diameter), (ii) textured starter feed (TS; mean particle size=3.61mm in diameter, including steam-flaked corn and barley), (iii) pelleted starter feed (PS; mean particle size=4.53mm in diameter) and (iv) ground starter feed with chopped alfalfa hay (GS+AH; mean particle size=1.02mm in diameter). The calves fed GS+AH diets had greater (p<0.01) starter intake, final body weight and average daily gain compared with the other groups, while GS and TS groups both had greater (p<0.01) starter intake than the PS group. Feed efficiency was found to be better (p<0.05) in the TS group than in the GS or PS group, but not different from the GS+AH one. Compared with the other groups, the GS+AH group had the highest (p<0.01), while the PS one had the lowest (p<0.01) concentrations of blood glucose and triglyceride. The calves fed GS+AH had the highest blood concentrations of total protein, globulin, triiodothyronine (T3), thyroxin (T4), T3:T4 ratio (p<0.05) and levels of fat and glycogen in the liver (p<0.01) compared with the other groups. The highest (p<0.05) liver glycogen contents were observed in the GS+AH and TS groups. The duodenum, ileum and jejunum in the calves fed GS+AH exhibited a greater muscle layer thickness (p<0.05) compared with the other groups. Based on the results obtained, the addition of dietary forage to starter diets positively influenced performance, liver composition and intestinal morphology in developing calves.

Flint corn grain processing and citrus pulp level in finishing diets for feedlot cattle.

Four trials were conducted to evaluate the effects of flint corn processing and the replacement of corn with citrus pulp (CiP) in diets for Nellore feedlot cattle. In a 103-d finishing trial, 216 Nellore bulls (350 ± 24 kg initial BW) were used in a randomized complete block design with a 2 × 4 factorial arrangement of treatments. Factors included 2 processing methods, either ground corn (GC) or steam-flaked corn (FC), with CiP replacing each corn type at 4 levels (0, 25, 50, and 75% of DM). All diets contained 12% sugarcane bagasse and 88% concentrate (DM basis). Treatments were also evaluated in metabolism trials, in which 10 ruminally cannulated Nellore steers (389 ± 37 kg) were assigned to 2 independent but simultaneous 5 × 5 Latin squares, each using 1 method of corn processing (GC and FC). Interactions ( < 0.05) between corn processing and CiP inclusion level were observed for final BW, DMI, ADG, G:F, and HCW. With FC-based diets, added CiP linearly decreased final BW ( = 0.04), whereas with GC-based diets, added CiP quadratically increased final BW ( = 0.002). With FC-based diets, the inclusion of CiP linearly increased DMI ( = 0.03) and linearly decreased ADG ( = 0.03) and G:F ( = 0.001). Increasing CiP in GC-based diets quadratically increased DMI ( = 0.001), ADG ( = 0.005), and HCW ( = 0.003). In FC-based diets, CiP inclusion had no effect on HCW ( = 0.21). Dressing percent, LM area, and 12th-rib fat were not affected by diet ( ≥ 0.05). For steers fed GC diets, CiP inclusion in the diet quadratically decreased the molar proportion of isovalerate ( = 0.001) but linearly increased ruminal butyrate ( = 0.006). No differences ( ≥ 0.16) were observed for total VFA concentrations, acetate:propionate ratio, and ruminal NH-N as CiP replaced GC. For steers fed FC diets, the molar proportion of acetate linearly increased ( = 0.002) whereas the proportion of propionate was linearly decreased ( < 0.001), resulting in a linear increase ( = 0.001) in the acetate:propionate ratio. Replacing corn with CiP linearly reduced NEm ( = 0.001) and NEg ( < 0.001) of FC-based diets but did not affect ( = 0.15) NE values of CG-based diets. Steam flaking flint corn improved cattle performance in this trial more than has been reported for dent corn in the published literature.

Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations before and after an endotoxin challenge.

English × Continental heifers ( = 180) were sourced in 2 loads (219.3 ± 16.0 and 221.4 ± 16.4 kg, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was used with BW nested within arrival load and blocked by BW into 3 dietary treatments (36 pens, 5 heifers/pen, 12 blocks, 3 pens/block, and 12 pens/treatment). Treatment diets contained 1) 0% DCP (control diet [CON]), 2) 10% DCP, or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steam-flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the 56-d trial period, as the amount of dietary DCP increased, DMI decreased ( = 0.01), ADG decreased ( < 0.01), and G:F decreased ( = 0.02). From d 0 to 28, there was no difference in the observed minus the predicted NEg of the diet ( = 0.73); from d 28 to 42, there was a linear increase in NEg favoring DCP treatments ( < 0.01); and from d 42 to 56, there was a linear decrease in NEg against the DCP treatments ( < 0.01). At the conclusion of the trial, a subset of heifers ( = 22; 307.89 ± 3.32 kg on d 63) were used to evaluate blood metabolite concentrations before and after a lipopolysaccharide (LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were intravenously challenged with LPS (0.5 μg/kg BW), and blood samples were collected every 0.5 h from -2 to 8 h and at 24 h relative to the LPS challenge (0 h). Serum glucose, serum urea nitrogen (SUN), and NEFA concentrations were determined. Cattle lost less weight at both 24 and 72 h after the LPS challenge with increasing DCP percentage ( < 0.01). Glucose ( = 0.12) and NEFA ( = 0.13) concentrations did not differ before the LPS challenge; however, there was a treatment effect for SUN, with elevated concentrations of SUN in CON cattle ( < 0.01). After the LPS challenge, DCP-fed cattle had reduced glucose, elevated NEFA, and reduced SUN concentrations ( ≤ 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge and affected feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase DMI or explore levels of DCP less than 10% in the diet of newly received heifer calves.

A comparison of via of administration of the injection of vitamin E in newly received feedlot calves

Fifty Holstein steers calves (121 ± 4 kg) were used in order to determine the effects of route of administration of vitamin E at the time of arrival of feedlot cattle on levels of plasma alpha-tocopherol concentrations during the initial 16 days following their arrival into the feedlot. Ten steers served as controls, the remaining 40 steers (20 steers/treatment) were injected either intramuscular (IM) or subcutaneous (SQ) with 1500 IU of vitamin E (d-alpha tocopherol). Vitamin E treatments were administered on days 1 and 8 of the arrival, while blood samples were obtained on days 1, 4, 8, 12 and 16. Injection sites were examined visually on day 16 to determine if route of administration affected incidence of injection-site inflammation. Steers were fed a steam-flaked corn based receiving diet with a 72:28 concentrate-to-forage ratio. Plasma alpha-tocopherol concentrations of control steers remained low (range from 0.06 to 0.10 mg/dL) throughout the 16-d period. Vitamin E injection increased (P&lt;0.01) 4-fold the plasma alpha-tocopherol concentration. Route of vitamin E administration did not influence (P &gt; 0.10) the incidence of injection site inflammation, averaging 17.5% (χ2, P&gt;0.05). Plasma alpha-tocopherol concentrations were not affected (P &gt; 0.30) by the presence of injection site inflammation. Since the risk of lesions in meat are considerably higher with intramuscular application and plasma alpha-tocopherol concentrations were not different between routes of application, it is concluded that subcutaneous administration is a practical alternative to the traditional intramuscular of administration of injectable vitamin E for feedlot cattle.

Comparative feeding value of steam-flaked triticale as a replacement for steam-flaked corn in finishing diets for feedlot cattle

ABSTRACTForty-eight crossbred steers (296 ± 5 kg) were used in a 155-day trial to compare the feeding value of steam-flaked triticale (SFT) with steam-flaked corn (SFC). Dietary treatments were: (1) basal finishing diet (BD), (2) 40% BD plus 60% SFT, and (3) 40% BD plus 60% SFC. Substitution of BD with SFT or SFC increased gain efficiency (P < .01), tended to increase average daily gain (ADG) (P = .07) and decrease dry matter intake (P = .11). The derived net energy for maintenance (NEm) and net energy for gain (NEg) values of SFT averaged 2.28 and 1.59 Mcal/kg, respectively. Four steers (442 ± 28 kg) were used in a 4 × 4 Latin square experiment to determine the effects of replacement of SFC with SFT on digestion. Treatments consisted of a SFC basal diet where SFT replaced 0, 32, 64, and 96% of SFC. Increasing level of SFT decreased total tract digestion of organic matter (OM) (linear component, P = .03), acid detergent fiber (ADF) (linear component, P < .01), and digestible energy (DE) (linear component, P < .01). The replacement DE value for SFT averaged 3.88 Mcal/kg, corresponding to NEm and NEg values of 2.18 and 1.50 Mcal/kg, respectively. It is concluded that the replacement net energy (NE) value of SFT is 92–96% that of SFC.

Influence of Wheat Straw Pelletizing and Inclusion Rate in Dry Rolled or Steam-flaked Corn-based Finishing Diets on Characteristics of Digestion for Feedlot Cattle.

Eight Holstein steers (216±48 kg body weight) fitted with ruminal and duodenal cannulas were used to evaluate effects of wheat straw processing (ground vs pelleted) at two straw inclusion rates (7% and 14%; dry matter basis) in dry rolled or steam-flaked corn-based finishing diets on characteristics of digestion. The experimental design was a split plot consisting of two simultaneous 4×4 Latin squares. Increasing straw level reduced ruminal (p<0.01) and total tract (p = 0.03) organic matter (OM) digestion. As expected, increasing wheat straw level from 7% to 14% decreased (p<0.05) ruminal and total tract digestion of OM. Digestion of neutral detergent fiber (NDF) and starch, per se, were not affected (p>0.10) by wheat straw level. Likewise, straw level did not influence ruminal acetate and propionate molar proportions or estimated methane production (p>0.10). Pelleting straw did not affect (p≥0.48) ruminal digestion of OM, NDF, and starch, or microbial efficiency. Ruminal feed N digestion was greater (7.4%; p = 0.02) for ground than for pelleted wheat straw diets. Although ruminal starch digestion was not affected by straw processing, post-ruminal (p<0.01), and total-tract starch (p = 0.05) digestion were greater for ground than for pelleted wheat straw diets, resulting in a tendency for increased post-ruminal (p = 0.06) and total tract (p = 0.07) OM digestion. Pelleting wheat straw decreased (p<0.01) ruminal pH, although ruminal volatile fatty acids (VFA) concentration and estimated methane were not affected (p≥0.27). Ruminal digestion of OM and starch, and post-ruminal and total tract digestion of OM, starch and N were greater (p<0.01) for steam-flaked than for dry rolled corn-based diets. Ruminal NDF digestion was greater (p = 0.02) for dry rolled than for steam-flaked corn, although total tract NDF digestion was unaffected (p = 0.94). Ruminal microbial efficiency and ruminal degradation of feed N were not affected (p>0.14) by corn processing. However, microbial N flow to the small intestine and ruminal N efficiency (non-ammonia N flow to the small intestine/N intake) were greater (p<0.01) for steam-flaked than for dry rolled corn-based diets. Ruminal pH and total VFA concentration were not affected (p≥ 0.16) by corn processing method. Compared with dry rolled corn, steam-flaked corn-based diets resulted in decreased acetate:propionate molar ratio (p = 0.02). It is concluded that at 7% or 14% straw inclusion rate, changes in physical characteristics of wheat straw brought about by pelleting negatively impact OM digestion of both steam-flaked and dry-rolled corn-based finishing diets. This effect is due to decreased post-ruminal starch digestion. Replacement of ground straw with pelleted straw also may decrease ruminal pH.

Effects of flaxseed encapsulation on biohydrogenation of polyunsaturated fatty acids by ruminal microorganisms: feedlot performance, carcass quality, and tissue fatty acid composition.

The objective of this study was to evaluate the efficacy of protecting PUFA within ground flaxseed against ruminal biohydrogenation by encapsulating them in a matrix consisting of a 1:1 blend of ground flaxseed and dolomitic lime hydrate (L-Flaxseed). Crossbreed heifers ( = 462, 346 ± 19 kg) were blocked by weight and randomly assigned to pens. Pens were assigned to 1 of 6 dietary treatments in a randomized complete block design. Treatment 1 consisted of a combination of 54.6% steam-flaked corn (SFC), 30.0% wet corn gluten feed, 8.0% roughage, and supplement (0% flaxseed). In treatments 2 and 3, a proportion of SFC was replaced with 3 and 6% flaxseed, respectively; in treatments 4, 5, and 6, SFC was replaced with 2, 4, or 6% L-Flaxseed, respectively. Cattle were fed for 140 or 168 d and then harvested in a commercial abattoir where carcass data were collected. Approximately 24 h after harvest, carcasses were evaluated for 12th-rib fat thickness, KPH, LM area, marbling score, and USDA yield and quality grades. Samples of LM were also obtained for determination of long-chain fatty acid profiles. Cattle that were fed diets with 4 and 6% L-Flaxseed consumed less feed than other treatments ( < 0.05), which adversely affected ADG. Compared with cattle fed 0% flaxseed, cattle in these treatments had lower final BW (18 and 45 kg less for the 4 and 6% L-Flaxseed treatments, respectively), less ADG (0.16 and 0.48 kg/day less for the 4 and 6% L-Flaxseed treatments, respectively), and lower carcass weights, dressing percentages, LM areas, backfat thicknesses, and marbling scores ( < 0.05). The addition of flaxseed or 2% L-Flaxseed did not affect performance or carcass traits ( > 0.05). Supplementation with flaxseed increased ( < 0.05) the concentration of α-linolenic acid (ALA) in meat (0.173, 0.482, 0.743 mg/g for 0, 3, and 6% flaxseed, respectively). Furthermore, proportionate increases in the ALA content of muscle tissue were 47% greater when flaxseed was encapsulated within the dolomitic lime hydrate matrix (0.288, 0.433, 0.592 mg/g for 2, 4, and 6% L-Flaxseed, respectively). Both products showed a linear response in ALA concentration ( > 99%; increases for Flaxseed and L-Flaxseed of 0.095 and 0.140 mg of ALA/g of tissue for each percentage of flaxseed added). This study indicates that a matrix consisting of dolomitic lime hydrate is an effective barrier to ruminal biohydrogenation of PUFA; however, adverse effects on DMI limit the amounts that can be fed.

Effect of dietary energy source and level on nutrient digestibility, rumen microbial protein synthesis, and milk performance in lactating dairy cows

This study was conducted to examine the effects of dietary energy source and level on intake, digestion, rumen microbial protein synthesis, and milk production in lactating dairy cows, using corn stover as a forage source. Eight multiparous Holstein cows, 4 of which were fitted with rumen cannulas, were evaluated in a replicated 4×4 Latin square design, with each period lasting 21 d. The cows were randomly assigned into 4 treatment groups: low-energy (LE) ground corn (GC), LE steam-flaked corn (SFC), high-energy (HE) GC, and HE SFC. Changes to ruminal energy degradation rates were induced by feeding the cows diets of either finely ground corn or SFC as components of diets with the same total energy level. Milk yield, milk protein content and yield, and milk lactose yield all increased in response to higher levels of dietary energy, whereas contents of milk fat and lactose were unaffected. Cows fed HE diets had a higher crude microbial protein yield and total-tract apparent digestibility than those receiving LE diets. Milk yield, milk protein yield, and microbial protein yield were also higher when SFC replaced GC as the main energy source for lactating cows fed LE diets. These results suggest that an increased dietary energy level and ruminal degradation rate are beneficial to milk protein production, which we suggest is due to increased yields of microbial proteins, when cows are fed corn stover as a dietary forage source.

Effects of glycerin concentration in steam-flaked corn-based diets with supplemental yellow grease on performance and carcass characteristics of finishing beef steers.

Forty-eight individually fed crossbred steers (initial BW = 381 ± 7.61 kg) were used to determine the effects of glycerin (GLY) concentration in steam-flaked corn (SFC)-based diets with added yellow grease on animal performance and carcass characteristics. Glycerin was included at 0, 2.5, 5, and 10% dietary DM replacing SFC. A completely randomized design was used with steers as the experimental unit, and the model included the fixed effects of diet. Contrast statements were used to determine linear and quadratic effects of GLY inclusion. Final BW and DMI were not affected (P > 0.27) by GLY concentration. Average daily gain and G:F based on live BW did not differ as GLY level increased in the diet from 0 to 10% of DM (P > 0.33). Carcass-adjusted final BW and carcass-adjusted G:F were also not affected by GLY concentration (P > 0.22); however, carcass-adjusted ADG tended to respond quadratically by decreasing from 2.5 to 5% GLY inclusion and increasing thereafter (P = 0.10). Calculated dietary NEm and NEg did not differ as GLY increased in the diet (P > 0.37). Hot carcass weight tended to respond quadratically, decreasing from 2.5 to 5% GLY and increasing thereafter (P = 0.10). Likewise, dressing percentage tended to respond quadratically by decreasing from 2.5 to 5% GLY inclusion and increasing to 10% GLY inclusion (P = 0.09). Fat thickness decreased linearly as GLY inclusion increased in the diet (P < 0.01); however, no differences were detected in marbling score and LM area (P > 0.21). Calculated yield grade (YG) decreased linearly as GLY increased in the diet from 0 to 10% of DM (P = 0.04). Based on our results, there was no animal performance benefit for replacing SFC with GLY in diets containing yellow grease, and the only change in carcass merit was a slight improvement in YG.

Fresh Steam-Flaked Corn in Cattle Feedlots Is an Important Site for Fecal Coliform Contamination by House Flies

House flies are a common pest at food animal facilities, including cattle feedlots. Previously, house flies were shown to play an important role in the ecology of Escherichia coli O157:H7; house flies in cattle feedlots carried this zoonotic pathogen and were able to contaminate cattle through direct contact and/or by contamination of drinking water and feed. Because house flies aggregate in large numbers on fresh ( # 6 h) steam-flaked corn (FSFC) used in cattle feed, the aim of this study was to assess FSFC in a cattle feedlot as a potentially important site of fecal coliform contamination by house flies. House flies and FSFC samples were collected, homogenized, and processed for culturing of fecal coliforms on membrane fecal coliform agar. Selected isolates were identified by 16S rRNA gene sequencing, and representative isolates from each phylogenetic group were genotyped by pulsed-field gel electrophoresis. Fecal coliforms were undetectable in FSFC shortly (0 h) after flaking; however, in summer, after 4 to 6 h, the concentrations of fecal coliforms ranged from 1.9 × 10(3) to 3.7 × 10(4) CFU/g FSFC (mean, 1.1 ± 3.0 × 10(4) CFU/g). House flies from FSFC carried between 7.6 × 10(2) and 4.1 × 10(6) CFU of fecal coliforms per fly (mean, 6.0 ± 2.3 × 10(5) CFU per fly). Fecal coliforms were represented by E. coli (85.1%), Klebsiella spp. (10.6%), and Citrobacter spp. (4.3%). Pulsed-field gel electrophoresis demonstrated clonal matches of E. coli and Klebsiella spp. between house flies and FSFC. In contrast, in winter and in the absence of house flies, the contamination of corn by fecal coliforms was significantly (∼10-fold) lower. These results indicate that FSFC is an important site for bacterial contamination by flies and possible exchange of E. coli and other bacteria among house flies. Further research is needed to evaluate the potential use of screens or blowers to limit the access of house flies to FSFC and therefore their effectiveness in preventing bacterial contamination.

Effects of corn and soybean meal types on rumen fermentation, nitrogen metabolism and productivity in dairy cows.

Twelve multiparous Holstein dairy cows in mid-lactation were selected for a replicated 4×4 Latin square design with a 2 ×2 factorial arrangement to investigate the effects of corn and soybean meal (SBM) types on rumen fermentation, N metabolism and lactation performance in dairy cows. Two types of corn (dry ground [DGC] and steam-flaked corn [SFC]) and two types of SBM (solvent-extracted and heat-treated SBM) with different ruminal degradation rates and extents were used to formulate four diets with the same basal ingredients. Each period lasted for 21 days, including 14 d for adaptation and 7 d for sample collection. Cows receiving SFC had a lower dry matter (DM) and total N intake than those fed DGC. However, the milk yield and milk protein yield were not influenced by the corn type, resulting in higher feed and N utilization efficiency in SFC-fed cows than those receiving DGC. Ruminal acetate concentrations was greater and total volatile fatty acids concentrations tended to be greater for cows receiving DGC relative to cows fed SFC, but milk fat content was not influenced by corn type. The SFC-fed cows had lower ruminal ammonia-N, less urea N in their blood and milk, and lower fecal N excretion than those on DGC. Compared with solvent-extracted SBM-fed cows, cows receiving heat-treated SBM had lower microbial protein yield in the rumen, but similar total tract apparent nutrient digestibility, N metabolism measurements, and productivity. Excessive supply of metabolizable protein in all diets may have caused the lack of difference in lactation performance between SBM types. Results of the present study indicated that increasing the energy degradability in the rumen could improve feed efficiency, and reduce environmental pollution.