Predicting Metabolizable Energy from Digestible Energy for Growing and Finishing Beef Cattle and Relationships to Prediction of Methane

Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. A previously developed database that included 87 treatment means from 23 respiration calorimetry studies has been updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926; r 2 = 0.99, root mean square prediction error [RMSPE] = 0.04, P < 0.01 for the intercept and slope). The slope did not differ from unity (95% CI = 0.936 to 1.065); therefore, the intercept (95% CI = -0.567 to -0.218) defines the value of ME predicted from DE. For practical use, we recommend ME = DE – 0.39. Based on the relationship between DE and ME, we calculated the citation-adjusted loss of methane, which yielded a value of 0.2433 Mcal/kg of DMI (SE = 0.0134). This value was also adjusted for the effects of dry matter intake (DMI) above maintenance, yielding a citation-adjusted relationship: CH4, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance; r 2 = 0.536, RMSPE = 0.0245, P < 0.01 for the intercept and slope). Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. These two approaches were evaluated using a second, independent database comprising 129 data points from 29 published studies. Four equations in the literature that used DMI or intake energy to predict methane production also were evaluated with the second database. The mean bias was substantially greater for the two new equations, but slope bias was substantially less than noted for the other DMI-based equations. Our results suggest that ME for growing and finishing cattle can be predicted from DE across a wide range of diets, cattle types, and intake levels by simply subtracting a constant from DE. Mean bias associated with our two new methane emission equations suggests that further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane.

Influence of crude protein content and flint maize processing methods on the performance of early-weaning Nellore calves

This study aims to determine the effects of dietary crude protein (CP) content of early-weaned calves; and the influence of flint maize processing methods on intake, total tract nutrient digestibilities and performance of Nellore heifer calves. Fifteen early-weaned Nellore female calves (4 ± 0.5 months; 108 ± 13.1 kg) were used. In phase 1, animals were fed one of the following diets for 112 days: 130, 145 or 160 g CP/kg dry matter (DM). In phase 2, animals received one of the two diets for 84 days: 0.60 dry ground maize grain, 0.30 whole-plant maize silage plus 0.10 mineral-protein supplement or 0.90 snaplage plus 0.10 mineral-protein supplement. In phase 1, intake and digestibility of dietary components were not affected (P > 0.05) by increasing dietary CP content. Daily total urinary nitrogen (N) and urinary urea N increased (P < 0.05) in response to increasing dietary CP content. Animal performance was not affected (P > 0.05) by dietary CP content. In phase 2, maize processing methods did not affect (P > 0.05) intake and digestibility of dietary components as well as animal performance, carcase characteristics and carcase composition. Therefore, based on the current experimental condition, we conclude that dietary CP concentrations of 130 g/kg DM can be indicated for early-weaned Nellore calves. However, more studies are recommended to validate this result and to evaluate concentrations below 130 g CP/kg DM for early-weaned Nellore calves. Moreover, snaplage could be used as an exclusive fibre and energy source for finishing cattle in feedlot.

Impact of Feeding Syngenta Enogen® Feed Corn Compared to Control Corn in Different Diet Scenarios to Finishing Beef Cattle

The objective of this pooled statistical analysis was to evaluate Syngenta Enogen® Feed Corn (EFC) versus conventional corn (CON) when fed as either dry-rolled corn (DRC) or high-moisture corn (HMC) for effects on finishing beef cattle performance and carcass characteristics. Corns were evaluated in diets with byproduct inclusion rates of 0, 15, 18, 20, and 30% distiller grains or 25 and 35% Sweet Bran® (a commercial corn gluten feed product). Seven trials (n = 1856) consisting of 200 pen means comparing 26 diet treatments were analyzed using regression in a pooled analysis. When EFC was processed as DRC, the gain efficiency (G:F) improved compared with CON, but the response to feeding EFC decreased from a 4.8% improvement to no improvement compared to CON as distiller grains increased from 0% to 30%, but was significantly improved due to feeding EFC in diets with 0 to 18% distiller grains. Feeding cattle EFC as DRC increased the average daily gain (ADG) and G:F by 4.5% compared with CON corn in diets containing Sweet Bran®. No improvements in animal performance were observed when cattle were fed EFC compared to CON when processed as HMC in any situation. Feeding Enogen® corn improved the gain efficiency of finishing cattle compared with conventional corn when processed as dry-rolled corn and fed in diets with less than 20% distillers or diets that include Sweet Bran®.

300 Effects of Associating Feed Additives on Rumen Ph Dynamics by Feedlot Cattle Fed a High-concentrate Diet

Our objective was to evaluate the effects of feed additives on ruminal pH of finishing cattle fed a 90%-concentrate diet. Twenty four 18-mo Angus-Nellore crossbred bulls (IBW, 456 ± 6,5 kg) were allocated in a completely randomized design to three treatments with eight replicates each, as follows: 1) Control (MON) - Sodium Monensin (26 mg/kg DM, Rumensin, Elanco Animal Health); 2) Crina® RumistarTM (CR) - a blend of essential oils, 90 mg/kg DM + exogenous α-amylase, 560 mg/kg DM) and 3) CR + HyD® (25-hydroxy-vitamin-D3 at 1 mg/animal/d, CRD, DSM Nutritional Products). The ruminal pH and temperature was monitored individually for 98 days, using a wireless bolus, (SmaXtec Animal Care, Austria). Data were analyzed using the Mixed procedure of SAS and means comparison evaluated by Tukey test at P&lt; 0.05. During adaptation period (i.e. first 14 days), bulls fed CR and CRD had increased rumen mean pH (6.40 and 6.36 vs. 6.16; P &lt; 0.01) and minimum pH (5.89 and 5.87 vs. 5.57; P &lt; 0.01) than bulls fed MON. In addition, rumen pH from bulls fed CR spent less time below 6.0 than bulls fed MON (256.07 vs. 452.62 min/d; P = 0.05). Regarding the total period, bulls fed MON had lower mean (6.22 vs. 6.51 and 6.42, P &lt; 0.01) and minimum rumen pH (5.60 vs. 5.92 and 5.85, P &lt; 0.01) than bulls fed CR and CRD. Additionally, feeding MON increased time duration of rumen pH (390.79 min/day, P &lt; 0.01) and had a larger area below 6.0 (81.52 min x pH units/day; P &lt; 0.01). Moreover, the addition of monensin increased pH time duration below 5.8 (161.10 vs. 121.13 and 122.56 min/day; P = 0.02) compared with CR and CRD, and increased ruminal temperature (39.60 vs. 39.51 and 39.5 °C; P &lt; 0.01). We conclude that feeding Crina® RumistarTM and Crina® RumistarTM HyD® increased the rumen pH of bulls.

PSIV-1 A comparison of chromatography methods to estimate ruminal VFA concentrations

The objective of this study was to describe two chromatography equipment and their methods (EM) and to evaluate their adequacy in estimating ruminal volatile fatty acid concentrations (VFA). Adequacy was assessed through precision and accuracy using three standard mixtures of known acetate, propionate, and butyrate concentrations. The standard mixtures were prepared for VFA analysis using high-performance liquid chromatography (HPLC) or gas chromatography (GC). Each mixture was injected ten times into each EM. The comparison was assessed with rumen fluid samples from four cannulated steers offered three diets at 2% BW. Diet A simulated a forage-based diet offered to cattle during the winter. Diet B simulated a grower-type diet offered to weaned calves. Diet C simulated a finisher-type diet offered to finishing cattle. Rumen fluid was collected three hours after the morning feeding for seven days for each diet and strained through 8 μm porosity fiberglass wool. Two 2-mL aliquots were stored at -20°C for HPLC analysis, while two 8-mL aliquots were diluted with 2 mL of 25% meta-phosphoric acid and stored at -20°C for GC analysis. Chromatograms without a flat baseline were removed from the analysis. For the adequacy evaluation, HPLC (R2 = 0.997; Cb = 0.874) was more precise and accurate at estimating total VFA than GC (R2 = 0.447; Cb = 0.763). When compared with the standards, HPLC estimated less (P &lt; 0.001) total VFA (98.8 ± 10.3 mM) than GC (110.5 ± 17.4 mM). Concentrations for acetate, propionate, and butyrate in rumen fluid samples were estimated for each EM and analyzed using a random coefficients model. Similarly, estimates for acetate, propionate, and butyrate were less for HPLC than GC (P ≤ 0.002). VFA estimation differs depending on EM chosen. Further research should identify the source of difference in VFA estimation from each EM.

PSXIV-11 Silage source, physically effective neutral detergent fiber, and undigested neutral detergent fiber concentrations affect eating behavior, ruminal pH and reticular motility of finishing heifers

This study evaluated the effects of silage source, physically effective neutral detergent fiber (peNDF), and undigested neutral detergent fiber (uNDF) concentrations on eating behavior, ruminal pH, and reticular contractions for finishing beef heifers. Six Hereford′Simmental heifers (579±51.2 kg) were used in a replicated 6×6 Latin square (21-d periods) balanced for carry-over effects with 2×2 + 2 factorial treatment arrangement. Barley grain-based diets included barley (BarS) or wheat silage (WhS) at 10% of dietary DM. Silages were harvested at two chop lengths to yield low (LpeNDF) vs. high peNDF (HpeNDF) silage. For both BarS and WhS, chopped wheat straw was included (5% of DM) by replacing an equal proportion of LpeNDF silages to evaluate low vs. high uNDF (7.3 vs. 8.2% dietary DM) concentrations. Heifers fed HpeNDF WhS had greater DMI (silage′peNDF; P &lt; 0.01) than those fed HpeNDF BarS, but DMI did not differ for LpeNDF treatments. Ruminating and eating time increased for heifers fed HpeNDF WhS relative to LpeNDF WhS, but were not different for BarS (silage′peNDF; P ≤ 0.02). Increasing uNDF increased eating and ruminating times for heifers fed WhS, but not BarS (silage′uNDF; P ≤ 0.03). Mean ruminal pH averaged 5.97 and was not affected by silage, peNDF, uNDF, or the interactions (P ≥ 0.12). Feeding BarS increased the duration (384 vs. 256 min/d; P = 0.02) and area (84.5 vs. 43.8 pH×min/d; P = 0.02) that pH was &lt; 5.5 relative to WhS. Increasing peNDF numerically reduced the frequency of reticular contractions when fed BarS but numerically increased them when fed WhS (silage′peNDF; P &lt; 0.01). Reticular contractions were not affected by dietary uNDF concentration (P ≥ 0.13). These data highlight that at a constant inclusion rate, silage source and chop length interact to affect DMI, eating behavior, ruminal pH, and reticular motility indicating the need to account for silage type, peNDF, and uNDF in diet formulation for finishing cattle.

299 Combination of Essential Oils, α-amylase and 25-hydroxy-vitamin-d3 Increases Carcass Production by feedlot Cattle

Our objective was to evaluate the effects of associating feed additives on feedlot performance of Nellore bulls. One hundred and sixtieth Nellore bulls (iBW, 380± 5.8 kg; age, 18 mo) were allocated in 20 pens (n = 8/pen), in a completely randomized block design, according to the treatments: 1) MON+VM - Sodium Monensin (MON, 25 mg/kg DM, Elanco Animal Health, Indianapolis, IN), + Virginiamycin (VM, 30 mg/kg DM, Phibro Animal Health Corporation, Guarulhos, São Paulo), and 2) CRD - Crina® RumistarTM + HyD® - a blend of essential oils, 90 mg/kg DM + exogenous α-amylase, 560 mg/kg DM + 25-hydroxy-vitamin-D3 at 1 mg/animal/d (DSM Nutritional Products, Basel, Switzerland). The initial BW was utilized as a criterion for block formation. Pens were considered experimental units (10 pens per treatment). Animals were adapted to the diets during 14 days with gradually increasing concentrate level from 70% to 86% of diet DM, and fed for 90 days. Weight assessments were performed at day 0 and 90 after 14h fasting. Data were analyzed using PROC MIXED of SAS and means were separated using the PDIFF statement, adopting P &lt; 0.05. Feeding CRD increased the DMI (12.13 kg vs. 10.52 kg, P &lt; 0.01), ADG (1.86 vs. 1.63 kg/d, P &lt; 0.01) and final BW (542 vs. 521 kg, P &lt; 0.01) compared to animals fed MON+VM. In addition, feeding CRD increased final HCW in 15 kg (311 vs. 296 kg; P &lt; 0.01), carcass ADG in 0,16 kg/d (1.31 vs. 1.15 kg/d; P &lt; 0.01) and dressing percentage in 0.48 percent points (57.34 vs. 56.86%; P &lt; 0.01) compared to MON+VM. The G:F (0.155, P = 0.53) and biological efficiency (137.9 kg DM/15 kg carcass, P = 0.87) were similar among treatments. Therefore, the inclusion of Crina® RumistarTM +HyD® can be used as a tool to increase carcass gain of feedlot finishing cattle.

304 Effects of Supplementing Phix-up® on Productive, Physiological, and Rumen Responses of Feedlot Cattle Consuming a Corn-based Finishing Diet

This experiment (d -14 to 118) compared rumen pH, productive, and physiological responses in finishing cattle supplemented or not with a rumen-buffering agent (pHix-up®; Timab, Dinard, France). Angus-influenced yearling cattle (58 heifers and 62 steers) were ranked by sex and body weight (BW) and allocated to 4 groups of 30 animals each (d -14). Groups were housed in 1 of 4 drylot pens equipped with GrowSafe automated feeding systems, and assigned to receive a corn-based diet containing monensin, and with the inclusion of pHix-up® at 0.00% (control) 0.25%, 0.50%, or 0.75% (d 0 to 118). Cattle BW was recorded twice monthly (d -14 to 118), and blood samples were collected on d 0, 28, 56, 84 and 112. Hair samples from the tail-switch were collected on d 0, 56 and 112. Cattle were slaughtered on d 119. Eight rumen-cannulated steers were also assigned to this experiment (d 42 to 98), with 2 steers housed with each group in a replicated 4 × 4 Latin Square design (4 periods of 14 d). Rumen pH was measured on d 7 and 14 of each period at 0800h, 1200h, 1600h and 2000h. No treatment effects were noted (P ≥ 0.13) for cattle BW gain, feed intake, and feed efficiency. Inclusion of pHix-up® linearly increased (P &lt; 0.01) plasma Mg concentrations and tended to linearly decrease (P = 0.09) plasma haptoglobin concentrations. Cattle receiving pHix-up® had greater (P &lt; 0.01) mean plasma cortisol concentrations compared with non-supplemented cattle. Hair cortisol concentration linearly decreased (P &lt; 0.01) as pHix-up® inclusion increased on d 112 (treatment × day interaction; P = 0.02). In rumen-cannulated steers, pHix-up® inclusion linearly increased (P = 0.03) mean rumen pH. Collectively, pHix-up® supplementation improved rumen pH and modulated stress-related physiological responses in finishing cattle, but without improving their productive responses.

543 Late-Breaking: Development of a Model to Predict Dietary Metabolizable Energy from Digestible Energy in Beef Cattle

We aimed to assess whether predicting the metabolizable energy (ME) to digestible energy (DE) ratio (MDR), rather than a prediction of ME with DE, is feasible and to develop a model equation to predict MDR in beef cattle. For this, we constructed a literature database based on published data. A meta-analysis was conducted with 306 means from 69 studies containing both dietary DE and ME concentrations measured by calorimetry to test whether the exclusion of the y-intercept is adequate in the linear relationship between DE and ME. A random coefficient model with study as the random variable was used to develop equations to predict MDR in growing and finishing beef cattle. The developed equations were evaluated with other published equations. The no-intercept linear equation represented the relationship between DE and ME more appropriately than the equation with a y-intercept. Within our growing and finishing cattle data, the animal’s physiological stage was not a significant variable affecting MDR after accounting for the study effect (P = 0.213). The mean (± SE) of MDR was 0.849 (± 0.0063). Two linear equations with the dry matter intake and content of several dietary nutrients were developed to predict MDR. When using these equations, the observed ME was predicted with high precision (R2 = 0.92). The model accuracy was also high, as shown by the high concordance correlation coefficient (&gt; 0.95) and small root mean square error of prediction (RMSEP), less than 5% of the observed mean. Moreover, a significant portion of the RMSEP was due to random bias (&gt; 93%), without mean or slope bias (P &gt; 0.05). We concluded that dietary ME in beef cattle could be accurately estimated from dietary DE and its conversion factor, MDR, using the two equations developed in this study.

254 Evaluation of Different Corn Milling Methods for High-moisture and Dry Corn on Finishing Cattle Performance and Carcass Characteristics

Steers (n=600; Initial BW = 402 ± 17 kg) were fed for134 day to evaluate the effect of milling method and corn type on performance and carcass characteristics. Treatments were evaluated as a 2 × 3 factorial with factors being milling method (Automatic Ag® roller mill or hammer mill) and corn type (100% high-moisture, 100% dry, or 50:50 blend of high-moisture and dry corn). High-moisture corn was processed at harvested based on respective treatment and ensiled until trial initiation. Both dry corn and HMC were processed using a 16-mm screen in the hammer mill and the roller mill was adjusted to ensure all kernels were broken. There were no interactions between milling method and corn type for final BW, daily gain (ADG), or dry matter intake (DMI; P ≥ 0.32), but there was a tendency for an interaction for G:F (P = 0.09). Cattle fed 100% high-moisture corn processed with the Automatic Ag roller mill were 4.7% more efficient (P ≤ 0.01) with 55% lower fecal starch (P &lt; 0.01) compared to high-moisture corn processed with the hammer mill. Cattle fed dry corn tended (P = 0.07) to have a greater live final BW regardless of milling type and had the greatest DMI (P ≤ 0.01) Intake decreased as high-moisture corn was increased in the diet. Due to no differences in ADG with lower DMI led to a 6% improvement (P ≤ 0.01) in G:F for steers fed HMC. There were no further effects (P ≥ 0.14) on performance or carcass traits regardless of milling method or corn type. Processing high-moisture corn using Automatic Ag roller mill improved feed efficiency compared to processing with a hammer mill when corn was included at 70% of the diet, but processing method had little effect when fed as dry corn or blended diets.