Finishing Cattle Diets Research Articles

Feeding or pen surface application of clinoptilolite with different particle sizes: impact on nitrogen utilization and manure ammonia emissions in feedlot cattle.

This study investigated the effects of feeding clinoptilolite (CLN; 2.5% of diet dry matter) with a particle size of either 30- or 400-µm on ruminal fermentation characteristics, measures of nitrogen (N) utilization, and manure ammonia-N (NH3) emissions in feedlot cattle. The impact of directly applying 30- or 400-µm CLN to the pen surface (2,250kg/ha) on manure NH3-N emissions was also evaluated. Six beef heifers were used in a replicated 3 × 3 Latin square design with 21-d periods. Dietary treatments were 1) finishing ration with no supplement (CON), 2) CON + 30-µm CLN (CLN-30), and 3) CON + 400-µm CL (CLN-400). Intake was measured daily. To evaluate fermentation characteristics, ruminal fluid was collected on day 19. Indwelling pH loggers were used to measure ruminal pH from days 15 to 21. Blood was collected 3-h post-feeding on day 21 for metabolite analysis. Fecal grab and urine spot samples were also collected from days 19 to 21 to measure nutrient digestibility, route of N excretion, and in vitro NH3 emissions. There was no diet effect (P ≥ 0.12) on nutrient intake and apparent total tract digestibility, and ruminal short-chain fatty acid profile and pH. Ruminal NH3 concentration, which was lower (P = 0.04) for CLN-30 than CON heifers, did not differ between CON and CLN-400 heifers. Although there was no diet effect (P = 0.50) on plasma urea-N (PUN) concentration, proportion of urea-N excreted in urine was lower (P = 0.01) for CLN-30 than CON and CLN-400 heifers. Urinary NH3-N excretion, which was greater (P ≤ 0.04) for CLN-400 than CON heifers, did not differ between CLN-30 and CLN-400 heifers. Feeding CLN also increased (P ≤ 0.02) fecal excretion of potassium (K) and iron (Fe) and reduced (P = 0.01) urinary excretion of calcium (Ca). There was a treatment × time interaction (P = 0.01) for NH3 emission rate, which was greatest within the first 36h of incubation and was lower for manure from CLN-400 compared to CON and CLN-30 heifers and pen surface application treatments. Cumulative NH3 emissions were lower (P < 0.01) for manure from CLN-400 compared to CON and CLN-30 heifers and the pen surface application treatments. Although surface application was ineffective, feeding 400-µm CLN to finishing cattle could result in a beneficial decrease in manure NH3 emissions. However, changes in fecal and urine excretion of minerals like K and Ca, which suggest a decrease in bioavailability, need to be considered when feeding CLN in finishing cattle diets.

106 Using a Novel Direct-Fed Microbial as an Alternative for Tylosin Phosphate to Control Liver Abscesses and Decrease Antimicrobial Use in Finishing Beef Steers

Abstract Our objective was to evaluate the use of a novel direct-fed microbial as an alternative to antimicrobials to decrease liver abscesses in feedlot cattle. Angus beef steers (n = 240; initial BW = 263 ± 18.0 kg) were used in a randomized complete block design comprised of 3 BW blocks and 3 pen replications per treatment. Experimental treatments were randomly assigned to pen within BW block and consisted of: 1) negative control, dietary supplement contained no tylosin phosphate (NCON); 2) positive control, dietary supplement contained tylosin phosphate (PCON); 3) positive control with tylosin phosphate removed the last 65 d of the feeding period (PCONW); and 4) novel direct-fed microbial fed at 1 g mixture/animal with 1 × 1011 CFU/g (DFM). By design, initial BW did not differ (P = 0.79) among treatments, and at the end of the 59-d receiving period, there were no differences in final BW (P = 0.25). From d 0 to d 30, ADG, DMI, DMI as a percentage of BW, and G:F did not differ (P ≥ 0.21). Likewise, ADG, DMI, DMI as a percentage of BW, and G:F, from d 31 to d 59, were not different (P ≥ 0.30). From d 0 to d 59, there were no differences in ADG, DMI, DMI as a percentage of BW, nor G:F (P ≥ 0.20). During the finishing period, live- and carcass-adjusted final BW did not differ (P ≥ 0.57) among treatments. During the finishing period, there were also no differences in ADG, DMI, DMI as a percentage of BW, or G:F (P ≥ 0.17). Carcass-adjusted ADG, DMI as a percentage of BW, and G:F also did not differ (P ≥ 0.16). Across treatments, no differences in HCW were noted (P = 0.84). Dressing percentage, marbling score, longissimus dorsi (LM) area, 12th-rib fat thickness, and calculated yield grade (YG) were not different among dietary treatments (P ≥ 0.32). Liver abscess incidence and severity were not affected by dietary treatments (P ≥ 0.13). The inclusion of a novel direct-fed microbial in finishing cattle diets did not affect growth performance, carcass characteristics, nor the prevalence of liver abscesses. However, the removal of tylosin phosphate 65 d before harvest numerically resulted in the lowest frequency of severe liver abscesses when compared with steers not fed tylosin phosphate.

355 Effects of Processing Method of Hybrid Rye for Cattle Backgrounding Diets

Abstract Cereal rye is used to diversify crop rotations in the Northern Great Plains and can be harvested through grazing, processed as forage (hay or silage), or allowed to reach maturity for grain and straw. Although rye has not traditionally been used in growing and finishing cattle diets due to the occurrence of ergot. Recent hybrid germplasms have shown promise with increased yields and decreased ergot incidence. This study aimed to determine the effects of substituting dry-rolled or ground hybrid rye for dry rolled corn (DRC) on dry matter intake (DMI), growth performance and gain:feed (G:F) of growing beef steers. One-hundred-fifty crossbred steers [260 ± 22.3 kg, initial body weight (BW)] were transported to the Carrington Research Extension Center near Carrington, North Dakota, stratified by BW, and assigned to one of fifteen pens (n = 10 steers/pen) and three dietary treatments in a randomized block design. Hybrid rye was substituted on a dry matter basis for DRC as follows: a basal diet formulated 33.8% corn silage, 23.6% forage barley hay, 17.5% modified distillers grains and solubles (MDGS), and 3% supplement and limestone with either 22.1% DRC (CON), 22.1% dry rolled hybrid rye (RRYE), and 22.1% ground hybrid rye (GRYE) on a dry matter basis. Due to extreme cold windchill temperatures, steers were fed for a total of 64 days beginning October 24, 2022. Body weights were taken before feeding on Day 1, 2, 28, 63, and 64 with a 4% pencil shrink applied to the initial and final BW. Performance data including animal BW, average daily gain (ADG), DMI and G:F ratio were calculated. The monthly average of growth performance were analyzed using the repeated measures procedure of PROC MIXED in SAS 9.4 with pen serving as the experimental unit. Pre-planned contrasts (control vs rye; rolled rye vs ground rye, rolled rye vs control, and ground rye vs control) were analyzed. No differences in BW (P = 0.35), ADG (P = 0.19), DMI (P = 0.83), or G:F (P = 0.21) were detected due to the replacement of DRC with hybrid rye throughout the study (Table 1). Steers assigned to GRYE had increased G:F (P = 0.04) and tended (P = 0.05) to have greater ADG compared with RRYE throughout the study. Steers fed hybrid rye tended to have lesser BW (P = 0.06) than those fed DRC after the first 28-day weigh period. During the final 36 days, steer assigned to GRYE had increased ADG (P = 0.03) compared with RRYE and tended (P = 0.05) to have greater ADG than those assigned to CON. Results from the study suggest that steers fed processed hybrid rye grain in a high forage backgrounding diet performed similarly to calves fed DRC.

163 Effect of Enogen Feed Corn Inclusion in Conventional and Natural Finishing Cattle Diets

Abstract A finishing experiment was conducted to determine the effects of Enogen Feed Corn inclusion in comparison with a control corn hybrid within natural and conventional feeding programs on finishing performance. The experiment used 400 crossbred steers (initial BW = 384 ± 33 kg) and 200 crossbred heifers (initial BW = 330 ± 19 kg) in a 2×2 factorial arrangement of treatments with 10 replications of steers and 5 replications of heifers per treatment. Factors were Enogen Feed Corn (EFC) or control corn hybrid inclusion as dry-rolled corn and corn silage within conventional and natural feeding programs. Cattle assigned to the conventional program were fed rations that contained feed additives and received implants whereas cattle in the natural program received neither. Performance data were analyzed as a 2×2×2 factorial assessing interactions between sex, feeding program, and corn hybrid inclusion. A sex by feeding program by corn hybrid (P = 0.01) interaction was observed for dry matter intake (DMI). Interactions between sex and feeding program were observed for carcass adjusted final BW (final BW; P &amp;lt; 0.01), average daily gain (ADG; P &amp;lt; 0.01), feed efficiency (G:F; P &amp;lt; 0.01), and hot carcass weight (HCW; P = 0.01). No significant corn hybrid by sex interactions (P ≥ 0.12) or corn hybrid by feeding program interactions (P ≥ 0.13) were observed. Inclusion of EFC in natural heifer diets tended to increase DMI by 0.4 kg/d (P = 0.10), while hybrid inclusion had no impact on DMI of conventional heifers. Feeding EFC in conventional steer diets tended to increase DMI by 0.4 kg/d (P = 0.06) compared with steers consuming the control corn hybrid diet. Corn hybrid had no impact on DMI in natural steer diets (P = 0.15). Carcass adjusted final BW decreased by 75 kg in natural steers and 41 kg in natural heifers compared with conventional programs (P &amp;lt; 0.01). Natural heifers gained 0.24 kg/d less than conventional heifers (P &amp;lt; 0.01). Feeding steers in the natural program reduced ADG by 0.43 kg/d in comparison with conventional program steers (P &amp;lt; 0.01). Compared with natural cattle, G:F improved by 13.0% when heifers were fed in a conventional program (P &amp;lt; 0.01) and 19.4% when steers were fed in a conventional program (P &amp;lt; 0.01). Feeding program had no effect on marbling (P = 0.38) while conventional cattle had greater 12th rib fat than natural cattle (P &amp;lt; 0.01). Inclusion of EFC had no effect on ADG (P = 0.71), G:F (P = 0.22), or HCW (P = 0.57). The incorporation of implants and feed additives within the finishing period increased final BW, HCW, and ADG leading to improved G:F in steers and heifers, with the improvement being greater in steers.

312 Evaluation of Dietary Roughage Manipulation During the Feeding of Ractopamine Hydrochloride as a Method to Improve Ruminal Health and Control Liver Abscess Severity in Feedlot Steers

Abstract The objective of this study was to determine if additional roughage inclusion to feedlot steer finishing diets during the feeding of ractopamine hydrochloride (RH) is an effective method to improve rumen health and control liver abscess severity. Steers [n = 64; initial shrunk body weight (SBW) = 633 kg ± 35.1 kg] were sourced from an unrelated trial and remained in their previous study pens; pens (n = 8) were assigned to dietary treatment in a completely randomized design. All steers on trial were fed a common 7% [dry matter (DM) basis] roughage equivalent (RE) finishing diet composed of dry-rolled corn, dried distillers grains plus solubles, corn silage, and grass hay for the 58 d preceding study initiation. Steers were fitted with rumination tags to track daily rumination. Dietary treatments were CON: no diet change; and 12R: 5% (DM basis) RE addition to diet via grass hay during the feeding of RH. Steers were fed RH (300 mg/steer/d), finished on treatment diets for 28 d, and harvested at a commercial beef processor. Growth performance, efficiency of dietary net energy (NE) utilization, and continuous carcass data were analyzed with pen as the experimental unit (EU) and fixed effect of treatment. Minutes ruminating was analyzed as an analysis of covariance with individual animal as the EU, fixed effects of treatment, days on feed (DOF) and their interaction, and baseline minutes ruminating as a covariate in the model. Liver abscess prevalence, rumen health, and categorical carcass data were analyzed with the Fisher’s exact test to determine differences between treatments. No difference (P ≥ 0.19) was observed for final SBW, average daily gain, dry matter intake, feed conversion efficiency, dressing percentage, hot carcass weight, calculated yield grade, marbling score, 12th rib fat thickness, calculated empty body fat, observed dietary NE for maintenance and gain, observed-to-expected dietary NE for maintenance and gain, or distribution of liver abscess prevalence, ruminitis score, or USDA yield grade. Ribeye area tended (P = 0.10) to differ between treatments with 12R steers exhibiting a 3.5% larger ribeye. Distribution of USDA quality grade differed (P = 0.003) between treatments with 12R steers having 25% more carcasses grading USDA average choice or better. A treatment × DOF interaction (P = 0.045) was observed for minutes ruminating per day. Daily minutes ruminating was increased (P ≤ 0.05) for 12R on d 1, 2, and 20 and tended to be increased (P ≤ 0.10) for 12R on days 10, 13, 24, and 25. Inclusion of an additional 5% RE to finishing cattle diets during a 28 d RH feeding period can be a management strategy to decrease risk of digestive upsets without sacrificing growth performance or carcass quality.

Effect of substitution of distillers grains and glycerin for steam-flaked corn in finishing cattle diets on growth performance and carcass characteristics.

An experiment was conducted to determine the effect of substituting modified corn distillers grains with solubles (DGS) or crude soy glycerin (CG) for steam-flaked corn (SFC) in finishing diets on growth performance and carcass characteristics. Treatments were arranged as a 2 × 2 factorial with DGS (0% or 40%) and CG (0% or 10%) replacing dietary SFC in a basal diet. Growth performance and carcass traits were measured on 48 individually fed crossbred yearling cattle (21 steers and 27 heifers; 380 ± 37 kg). Cattle were randomly allotted to 48 Calan gate bunks. After the first 28 days, nine animals were removed from the study for health reasons or observed confirmation of consumption of feed from unassigned Calan gate bunk (n = 39). After the feeding period, cattle were harvested in two groups on day-124 and day-173. No DGS × CG interactions were observed (P > 0.10) for any dependent growth performance or carcass characteristic variable tested. Cattle-fed DGS as 40% of diet dry matter (DM) had greater (P< 0.01) dry matter intake (DMI), while CG inclusion at 10% of diet DM did not affect DMI (P = 0.16). Carcass-adjusted average daily gain (ADG) was not affected by DGS (P = 0.73) or CG (P = 0.28). Decreased (P = 0.03) carcass-adjusted gain-to-feed (G:F) was observed as the main effect of DGS. Greater DMI resulting from feeding DGS as 40% of diet DM appears to have driven the tendency for reduced G:F. Hot carcass weight, longissimus muscle area, 12th rib fat depth, yield grade, and marbling score were not (P> 0.10) influenced by DGS or CG. However, kidney, pelvic, fat (KPH) was increased (P = 0.01) when cattle were fed DGS as 40% of diet DM. Based on the findings presented, it is concluded that CG can substitute up to 10% of SFC in the diet without negatively affecting cattle growth performance or carcass characteristics, regardless of DGS inclusion as 40% of the diet DM.

Effects of hempseed cake on ruminal fermentation parameters, nutrient digestibility, nutrient flow, and nitrogen balance in finishing steers.

Five ruminally and duodenally cannulated red angus steers (n = 5; initial body weight [BW] = 542 kg, SD = 40 kg) were used in a three-period Youden square design consisting of three 21-d periods, three treatments, and five steers (one or two steers per treatment within each period) to evaluate the effect of feeding hempseed cake on ruminal fermentation parameters, organic matter (OM) intake, total tract nutrient digestion, and nitrogen (N) balance in steers fed finishing diets. The control (CON) diet contained 75% dry-rolled corn, 20% corn silage, and 5% supplement (DM basis). The dried corn distillers grains plus solubles (DDGS) and hempseed cake (HEMP) diets contained 55% dry-rolled corn, 20% corn silage, 20% dried corn distillers grains plus solubles or hempseed cake, and 5% supplement (DM basis). Total ruminal volatile fatty acid concentration was greater (P < 0.01) in steers fed the HEMP diet than in steers fed the DDGS or CON diets. Ruminal fluid pH was not influenced (P = 0.93) by treatment. Organic matter intake tended (P = 0.07) to be greater and OM total tract digestibility was less (P = 0.03) in steers fed the HEMP diet compared with steers fed the DDGS or CON diets. Ruminal true and total tract apparent N digestibility was greater (P < 0.01) in steers fed the HEMP diet than steers fed the DDGS or CON diets. Duodenal flow of essential, nonessential, and total amino acids was not influenced (P ≥ 0.37) by dietary treatment, but the lack of response was likely because ruminally degradable protein (RDP) supply exceeded the RDP requirement. Steers fed the HEMP diet had greater (P < 0.01) N retention (g/d) than steers fed the DDGS diet, which was greater (P < 0.01) than steers fed the CON diet, suggesting that feeding hempseed cake improved utilization of N. Although inclusion of hempseed cake decreased total tract OM digestibility compared with dried corn distillers grains or corn, improvements in N utilization suggest that hempseed cake could be a useful alternative feed ingredient for finishing cattle diets.

Inclusion of Grape Pomace in Finishing Cattle Diets: Carcass Traits, Meat Quality and Fatty Acid Composition.

Simple SummaryGrape pomace, a by-product of winemaking, could be used as feed for beef cattle as it provides essential nutrients like fiber and protein. Grape pomace also contains bioactive compounds like condensed tannins, which have been shown to improve meat quality primarily in lambs. Since this information was still lacking, the present study evaluated the effects of feeding a high amount of grape pomace to finishing cattle on quality attributes (e.g., shelf life) and the fatty acid composition of beef. Feeding a high amount of grape pomace to finishing cattle reduced lipid oxidation and increased the meat content of several fatty acids linked to positive health outcomes in humans (e.g., total polyunsaturated fatty acids). These findings suggest that dietary inclusion of grape pomace in finishing cattle diets could enhance the sensory quality of beef and the health value of beef lipids.Because of its high content of polyphenolic compounds, dietary inclusion of grape pomace (GP) in finishing cattle diet could possibly enhance product quality and the health value of beef lipids. Therefore, the aim of this study was to evaluate the effects of feeding a high amount of grape pomace in finishing cattle diets on carcass traits, product quality, and fatty acid (FA) composition of beef. Jersey × Holstein crosses (n = 24) were fed either a typical finishing diet (CON) or a finishing diet containing 58% grape pomace (DM basis; HGP). Following the feeding period, animals were harvested, and carcass traits measured. Longissimus lumborum (LL) and semimembranosus (SM) muscle were then collected from each carcass for sensory quality evaluation and FA profile analysis. Hot carcass weight, backfat thickness, and preliminary and final yield grades were greater (p ≤ 0.04) for CON than HGP steers. However, there was no diet effect on rib eye area (REA), kidney, pelvic, and heart (KPH) fat, and marbling. Feeding the HGP compared to CON diet reduced lipid oxidation of LL and SM steaks over time; the malondialdehyde (MDA) concentration, which did not differ on d 0 and 2 of 8-d simulated retail display, was lower on d 4, 6 and 8 for HGP than CON steers (treatment × day of simulated display interaction; p < 0.01). Brightness (L* values) and redness (b*) were greater for LL steaks from HGP than CON steers on most days of simulated display (treatment × day of simulated display interaction; p < 0.01). In addition, the LL and SM muscle content of several FA linked to positive health outcomes in humans including 18:2 n-6, 18:2 c9t11, total conjugated linoleic acid (CLA) and total polyunsaturated fatty acid (PUFA) was also greater (p ≤ 0.02) for steers fed the HGP compared to the CON diet. In summary, current findings suggest that although it could possibly limit growth performance, feeding a high amount of grape pomace to finishing cattle could enhance both the sensory quality and the health value of beef lipids, which are key in increasing consumer acceptability of beef.

PSII-B-20 Altering the Particle Size of Supplemental Zeolite (Clinoptilolite) in Finishing Cattle Diets: Manure Characteristics and Ammonia Emissions

Abstract A potential strategy to limit ammonia (NH3) emissions from feedlots is the feeding of supplemental clinoptilolite (CLN), which has a high affinity for ammonium (NH4+). The particle size of CLN could influence its efficacy in binding NH4+ in the rumen and manure. Therefore, our objective was to determine the effects of feeding CLN (2% of diet DM) of two different particle sizes (30 and 40 µm) on manure N profile and NH3 emissions. Six beef heifers were used in a replicated 3 × 3 Latin square design with 21 d periods. Dietary treatments were: 1) finishing ration with no supplement (CON), 2) CON + 30-µm CLN (CL-30), and 3) CON + 40-µm CLN (CL-40). Grab fecal and spot urine samples were collected (d 19 to 21) for analysis. To determine NH3 emissions, six rectangular vented, non-steady state, closed chambers interfaced with a Fourier Transform Infrared Spectroscopy analyzer were used. Soil was added to chambers to a depth of 10 cm before addition of manure and incubated over a 7-d period. Data were analyzed using SAS. There was no diet effect (P ≥ 0.78) on urinary total nitrogen (N) and urea-N concentrations. However, urinary NH3-N concentration, which was less (P = 0.03) for CON than CL-40 heifers did not differ between CON and CL-30 heifers. Fecal N concentration, which tended to greater (P = 0.07) for CL-30 than CL-40 heifers did not differ between CON and CL-40 heifers. However, there was no diet effect (P = 0.25) on fecal NH3-N concentration. Ammonia emissions, which were less (P = 0.02) for manure from CL-40 than CL-30 heifers, did not differ between CON and CL-30 heifers during the first 48 h of incubation. In summary, feeding CL with different particle sizes resulted in changes in the manure N profile and NH3 emissions.

Impacts of including Sweet Bran and wet distillers grains with solubles alone or in combination in finishing cattle diets on physically effective fiber concentrations and rumen buffering characteristics of feedlot cattle.

This study evaluated the effects of Sweet Bran (SB) and wet distillers grains with solubles (WDGS) in the diet alone or in combination on physically effective neutral detergent fiber (peNDF), ruminal pH, and rumination behavior of finishing beef cattle. For this study, 455 steers (373 ± 15.5 kg) were allocated to 48 pens in a randomized complete block design. Treatments (n = 12 pens per treatment) were one of four steam-flaked corn-based diets containing no corn-milling products (CON), 20% WDGS (WDGS20), 20% SB (SB20), or 20% SB and 10% WDGS (COMBO). Within each pen, two steers were randomly selected to receive an indwelling ruminal pH bolus to quantify ruminal pH and a 3-axis accelerometer tag to measure rumination for the first 92 d of the study. Diet samples were collected weekly to determine particle size, neutral detergent fiber (NDF) concentration, and peNDF. Physically effective NDF was calculated using both the proportion of particles > 4.0 mm (peNDF4.0) and the proportion of particles > 8.0 mm (peNDF8.0). The percentage of particles > 4.0 mm was greatest (P < 0.01) for CON, intermediate for SB20, and least for WDGS20 and COMBO. Both NDF (P < 0.01) and peNDF4.0 (P < 0.01) were greatest for COMBO, intermediate for WDGS20 and SB20, and least for CON. The percentage of particles > 8.0 was greatest (P < 0.01) for CON, intermediate for WDGS20 and SB20, and least for COMBO, but peNDF8.0 did not differ (P = 0.40). A diet × day interaction (P < 0.01) was observed for daily rumination minutes per kg of DMI, NDF, peNDF4.0, and peNDF8.0. A diet × hour interaction (P < 0.01) was observed where CON cattle spent less time ruminating at 0800 and 1000 h in a 24 h period. Daily ruminal pH was greatest (P < 0.01) for COMBO, intermediate for SB20 and WDGS20, and least for CON. A diet × hour interaction (P < 0.01) was also observed for circadian ruminal pH, where pH was least for CON from 0800 to 1800 h. Relationships between peNDF, rumination behavior, and ruminal pH observed in this study suggest that SB and WDGS similarly enhance rumen buffering capacity when steam-flaked corn is replaced in the diet.

51 Supplemental Lysine in Finishing Cattle Diets

Abstract Smartamine ML (Adisseo), a bioavailable (80%) source of lysine and methionine was used to evaluate effects of increasing lysine supply on performance of beef cattle. Crossbred steers (n=120, initial BW 261 kg) were individually fed a diet of 15% modified distillers grains plus solubles (MDGS), 68% blend of high moisture and dried rolled corn, 12% corn silage, and 5% supplement with Smartamine ML top-dressed daily. Steers were assigned to 8 inclusions of lysine, 0 to 7 g/d in 1 g increments, with 15 steers per treatment. Data were analyzed with MIXED procedure of SAS as a generalized randomized design with animal as experimental unit and treatment as fixed effect. Orthogonal contrasts evaluated linear, quadratic, and cubic responses. Contrast statements compared the control with 1, 2, and 3 g/d treatments. Feeding increasing amounts of bioavailable lysine linearly decreased DMI (P = 0.04), final live BW (P = 0.04), and ADG (P = 0.02) with no effect on G:F (P ≥ 0.27). Numerical differences in DMI and ADG (P ≥ 0.26) led to a trend (P = 0.06) for improved live G:F for the 1 g/d treatment compared with control (0.188 and 0.176, respectively). During the Optaflexx feeding period (d 163-195), DMI linearly decreased (P = 0.01) as lysine increased in the diet with no differences in ADG (P ≥ 0.13) or G:F (P ≥ 0.12), with a trend (P = 0.08) for improved live G:F for 3 g/d compared with control (0.163 and 0.131, respectively). Hot carcass weight tended (P = 0.07) to linearly decrease as Smartamine ML increased in the diet, with no effect on other carcass measures including longissimus muscle area, 12th rib fat, and marbling score (P ≥ 0.18). In finishing beef cattle diets with 15% MDGS, more than 3 g/d of supplemental lysine did not improve performance.

225 Effect of Increasing Doses of Encapsulated Butyric Acid and Zinc on Beef Feedlot Steer Growth Performance, Dietary Net Energy Utilization, and Carcass Characteristics

Abstract The objective of this study was to determine the effects that increasing doses of encapsulated butyric acid and zinc (BPZ) have on beef feedlot steer growth performance, dietary net energy utilization, and carcass characteristics. Steers (n = 272; shrunk BW = 360 kg ± 74 kg) were assigned to dietary treatment [0 (CON), 1, 2, or 3 g BPZ/kg diet DM] in a randomized complete block design (RCBD) with pen (n = 32) as experimental unit. Cattle were fed until visually assessed to have 1.27 cm rib-fat and were shipped for harvest at a commercial beef abattoir. Carcass and liver health data was recorded. Feedlot performance data was calculated on a carcass-adjusted basis (HCW/0.625). Data were analyzed as a RCBD with fixed effects of BPZ inclusion level and block was considered a random effect; pre-planned contrasts for CON vs. BPZ, plus linear, and quadratic responses were tested. No differences (P ≥ 0.14) were observed for final BW, DMI, ADG, feed conversion efficiency, observed dietary NEm and NEg, observed-to-expected dietary NEm and NEg, HCW, REA, rib-fat thickness, marbling score, estimated EBF, or distribution of USDA YG 1, 3, 4, 5, and USDA quality grade among treatments. A tendency (P = 0.10) was observed for CON vs. BPZ for calculated YG. Tendencies were detected for USDA YG 2 carcass distribution (linear; P = 0.07) and for normal and abscessed liver prevalence (quadratic; P = 0.08). Dressed yield tended to be greater (P = 0.08) for BPZ vs. Con and increased with dose (linear; P = 0.05). Supplementation of BPZ in finishing cattle diets does not appreciably influence growth performance, but increases dressed yield. Data from this study suggests that the addition of BPZ to feedlot finishing diets for decreasing the prevalence of abscessed livers should be further investigated.

Increasing dietary proportion of wheat grain in finishing diets containing distillers' grains: impact on nitrogen utilization, ruminal pH, and digestive function.

Because of its high crude protein (CP) content, dietary inclusion of corn dried distillers' grains with solubles (DDGS) in finishing cattle diets can increase the ruminal loss of ammonia-nitrogen (NH3-N), which ends up excreted as urine urea-N (UUN). Increasing dietary fermentable energy supply can enhance ruminal use of N; however, it could also lead to acidotic conditions that compromise digestive function and animal performance. We evaluated the effects of partially replacing dietary corn grain with 20% or 40% (dry matter [DM] basis) wheat grain in finishing diets containing 15% corn DDGS on N utilization, ruminal pH, and digestive function. Nutrient intake and digestion, ruminal fermentation characteristics, microbial protein synthesis, route of N excretion, and blood metabolites were measured. Six ruminally fistulated crossbred beef heifers (initial body weight ± SD; 797 ± 58.8 kg) were used in a replicated 3 × 3 Latin square design with 28-d periods. Dietary treatments were either corn (73% of diet DM; CON), 53:20 corn:wheat blend (20W), or 33:40 corn:wheat blend (40W) as the major fermentable energy source. Dry matter intake (DMI) tended to be lower for heifers fed the 40W than CON and 20W diets. Feeding diets containing wheat grain led to an increase (P = 0.04) in neutral detergent fiber (NDF) intake. However, there was no diet effect (P ≥ 0.60) on apparent total tract DM and NDF digestibility. Feeding wheat grain led to a decrease (P ≤ 0.03) in mean and minimum pH, an increase (P = 0.04) in pH < 5.8 duration, and a tendency for an increase in the area and acidosis index for pH < 5.8 and 5.5. Nitrogen intake, which was lower (P = 0.04) for 40W than 20W heifers did not differ between CON and 20W heifers. There was no diet effect (P = 0.80) on ruminal NH3-N concentration and estimated microbial N flow. However, feeding diets containing wheat grain led to a decrease (P = 0.045) in UUN excretion (% total urine N). Fecal and total N excretion (% of N intake) increased (P < 0.01) following the addition of wheat grain to the diet. Apparent N retention was lower (P = 0.03) for 40W than CON and 20W heifers. In summary, although it led to a desirable decrease in UUN excretion, feeding wheat grain in corn DDGS-containing diets increased acidotic conditions in the rumen, which possibly led to the tendency for a decrease in DMI. The negative apparent N retention at the 40% wheat grain inclusion also suggests a decrease in nutrient supply, which could compromise feedlot performance.

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.

Optimum grape pomace proportion in feedlot cattle diets: ruminal fermentation, total tract nutrient digestibility, nitrogen utilization, and blood metabolites.

Because of its high content of polyphenolic compounds, the dietary inclusion of grape pomace (GP) in ruminant diets can reduce reactive nitrogen (N) and methane emissions and enhance the shelf life and beneficial fatty acids (FAs) content of meat. However, the dietary inclusion of GP beyond a threshold that is still to be determined for feedlot cattle can also compromise nutrient supply and, thus, growth performance. This study investigated the optimum proportion of GP in finishing cattle diets. Nutrient intake and apparent total tract digestion, ruminal pH and fermentation, estimated microbial protein synthesis, route of N excretion, and blood metabolites were measured. Six ruminally fistulated crossbred beef heifers (mean initial body weight ± SD: 714 ± 50.7 kg) were used in a replicated 3 × 3 Latin square with 21-d periods. Dietary treatments were 0%, 15%, and 30% of dietary dry matter (DM) as GP, with diets containing 84%, 69%, and 54% dry-rolled barley grain, respectively. There was a linear increase (P = 0.07) in DM intake and quadratic change (P ≤ 0.01) in neutral detergent fiber (NDF) intake. There was a quadratic change (P ≤ 0.04) in apparent total tract DM, NDF, and crude protein digestibility as dietary GP content increased. However, there were no treatment effects (P ≥ 0.18) on total ruminal short-chain FA concentration and duration and area pH < 6.2, 5.8, and 5.5. Although N intake did not differ (269, 262, 253 g/d; P = 0.33) across dietary treatments, feeding GP led to a tendency for a quadratic change (P ≤ 0.07) in ruminal ammonia-N and plasma urea-N concentrations. Total N excretion also changed (quadratic, P = 0.03) because of changes (quadratic, P = 0.02) in fecal N excretion as urinary excretion of N and urea-N did not differ (P ≥ 0.15) across treatments. Feeding GP led to quadratic changes (P ≤ 0.01) in fecal excretion of fiber-bound N. Microbial N flow and apparent N retention also changed (quadratic, P ≤ 0.04) as dietary GP proportion increased. In conclusion, responses to dietary GP proportion were mostly quadratic with indications that nutrient supply as reflected by changes in apparent total tract nutrient digestibility, microbial N supply, and apparent N retention could be compromised beyond a 15% dietary inclusion level.

PSXII-2 Potential interactions between prior endophyte exposure and phytogenic supplementation for finishing steers with varying chute exit velocities

Abstract All-natural phytogenic supplementation has gained momentum in the feeding industry. Because mechanisms likely differ, these supplements could add benefit when combined with antibiotics in finishing cattle diets. Our objective was to determine influence of Actifor®Energy (ActEN) when fed with monensin and tylosin on performance and carcass measurements of finishing cattle with varying chute exit velocities (EV) and differing prior endophyte exposure (E). Crossbred steers (n = 118; 345 ± 33 kg BW) were utilized in a split plot design (whole plot: prior grazing toxic [EI] or nontoxic [EN] fescue × 6g·hd-1·d-1 dietary ActEN or control). Prior EV (PEV, subplot factor) from receiving, backgrounding, and grazing periods was included as a covariate. Weights and EV were recorded on d0, d28, d56, d112, and at slaughter when cattle were shipped to a commercial abattoir, harvested, and carcass measurements recorded. Starting weights were 22 kg lower (P = 0.10) for cattle previously grazing EI and 10 kg lower (P &amp;lt; 0.01) per 1m·s-1 increase in PEV. Intake (%BW) was unaffected (P &amp;gt; 0.10) by E or ActEN. Gain:feed (E×ActEN P = 0.09) was greater for EN/ActEN compared with EI/ActEN, most influenced by the first 28d. ADG was depressed by EI and increasing PEV (E×PEV P = 0.09) with greater PEV impact for EN compared with EI. Endophyte effects on ADG were most prominent in the first 56d. ActEN tended (P = 0.12) to interact with E status for ADG where gains were numerically greater for ActEN with EN compared with EI, especially during the first 28d. Carcass measurements were largely unaffected (P &amp;gt; 0.10) by E or ActEN. Decreased PEV (P ≤ 0.02) was associated with heavier HCW, increased backfat, and higher YG. Prior exit velocity and grazing regimen were the primary factors influencing performance and carcass traits. Indications of smaller effects of phytogenic supplementation on top of antibiotics, especially during the first 28 d of feeding, warrant further investigation.

Effects of essential oils and(or) benzoic acid in beef finishing cattle diets on the fatty acid profile and shelf life stability of ribeye steaks and ground beef

The effects of feeding essential oils and(or) benzoic acid to finishing steers on fatty acid profile and oxidative stability (color and lipid oxidation) of beef longissimus thoracis steaks and ground beef was determined in this study. Beef was procured from crossbred beef steers (n = 63) fed one of five dietary treatments: (1) control (no antibiotics fed); (2) monensin/tylosin (monensin supplemented at 33 mg/kg [DM basis]; tylosin supplemented at 11 mg/kg [DM basis]); (3) essential oils (supplemented at 1.0 g/steer/day); (4) benzoic acid (supplemented at 0.5% [DM basis]); and (5) combination (essential oils supplemented at 1.0 g/steer/day and benzoic acid supplemented at 0.5% [DM basis]). Although no improvements in shelf life stability were observed, feeding finishing cattle essential oils and(or) benzoic acid did not have detrimental impacts on beef color stability and lipid oxidation over a simulated retail display period.

PSIV-22 The effects of altering ruminal fermentable carbohydrate supply in finishing diets containing distillers grains on rumen fermentation characteristics and nitrogen utilization

Abstract This study examined the effects of altering ruminal fermentable carbohydrate (RFC) supply by feeding different amounts of corn and wheat in finishing cattle diets containing 15% corn dried distillers grains [DDGS; dry matter (DM) basis] on ruminal fermentation characteristics and nitrogen (N) utilization. Six ruminally-cannulated crossbred heifers were used in a replicated 3 × 3 Latin square design with 28 d periods. Dietary treatments were either corn (73% of diet DM; CON), 53:20 corn:wheat blend (20W) or 33:40 corn:wheat blend (40W) as the major fermentable carbohydrate source. Diets were isonitrogenous (12% CP; DM basis). Feed intake was measured daily. Indwelling pH logger were used to measure ruminal pH (d 22 to 28) and ruminal fluid was collected from d 26 to 28 to determine fermentation characteristics, as were feces and urine to measure N excretion. Data was analyzed using PROC MIXED in SAS. Dry matter and N intake tended to be lower (P ≤ 0.07) for heifers fed the 40W compared to the CON and 20W diets. There was no diet effect (P = 0.15) on total VFA concentration; however, the duration and area for pH &amp;lt; 5.5 tended to be longer (P = 0.07) and greater (P = 0.096), respectively, for heifers fed the 20W and 40W compared to the CON diet. There was no diet effect (P ≥ 0.44) on ruminal ammonia concentration and total urine N excretion (g and % of N intake). However, urine urea N (UUN) excretion as a percentage of total urine N tended to be lower (P = 0.05) in heifers fed the 20W and 40W compared to the CON diet. In summary, although altering RFC supply by feeding increasing amounts of wheat resulted in a decrease in UUN excretion, it also caused a decrease in ruminal pH that possibly compromised DM intake.

PSXIV-8 Inclusion of byproducts derived from the process of corn ethanol production in finishing cattle diets

Abstract Two experiments were conducted to evaluate the performance and metabolism responses of finishing cattle to dietary inclusion of corn ethanol byproducts. All diets were isonitrogenous and contained 15% corn silage, 12% soyhulls, 0.55 to 0.85% urea and 2.25% mineral supplement. Treatments were (dry basis): Control [8% whole cottonseed, 5% soybean meal and 56.9% ground corn (GC)]; High Protein Distillers Grains (HPDG; 10.3% HPDG and 59.65% GC); Dry Distillers Grains plus Solubles (DDBS; 30% DDBS and 39.65% GC); Wet Distillers Brain plus Solubles (WDGS; 30% WDGS and 39.65% GC). In Exp. 1, 268 Nellore bulls were blocked by initial body weight (423.3 kg ± 36.6 kg), assigned to 44 pens in a randomized complete block design and fed for 110 days. Dry matter intake (DMI) tended (P = 0.058) to be greater for DDBS compared with WDBS (11.2 vs. 10.3 kg, respectively). Average daily gain was greater (P &amp;lt; 0.05) for DDBS compared with HPDG (1.62 vs 1.45 kg respectively) and tended (P = 0.086) to be greater for DDBS compared with control (1.62 vs. 1.48 kg respectively). Hot carcass weight was greater (P &amp;lt; 0.05) for DDBS compared with the other treatments (332 vs. 321 kg respectively). Feed efficiency, carcass dressing, ribeye area and back fat thickness were not affected (P &amp;gt; 0.05) by treatments. In Exp. 2, four rumen cannulated Nellore steers (389 ± 37 kg) were used in a 4 × 4 Latin square design. Total tract digestibility of dry matter was greater (P &amp;lt; 0.05) for HPDG compared with DDBS (76.8 vs. 68.5% respectively). Rumen acetate:propionate ratio was less (P &amp;lt; 0.01) for HPDG and DDBS (2.01) compared to control and WDBS (2.72). The greater HCW of bulls fed DDBS may be the result of its positive effect on DMI and rumen VFA profile.

PSXIV-9 Effect of monensin, a blend of essential oils and Lithothamnium calcareum over two racial groups in finishing cattle diets

Abstract This study aimed the evaluation of the effects of three feed additives – sodium monensin (MON; 32 mg/kg DM), Lithothamnium calcareum plus sodium monensim (LC+MON; LithoNutri® 5g/kg DM + 32 mg/kg DM) or a blend of essential oils (BEO; BioPhitus® 0.3g/kg DM) – and its interaction with two ratial groups of beef cattle – Nellore (NEL) vs. Crossbreds (CROSS) – on a finishing diet. Ninety Nellore bulls (initial BW = 394 ± 34 kg) and ninety crossbreds (initial BW = 406 ± 31 kg), were fed for 112 days, diets containing 8.5% sugarcane bagasse, 42.2% of fine ground corn, 41.7% of citrus pulp, 5% of soybean meal, 1.3% of urea, 0.35% of sodium chloride and 0.95% of minerals and vitamins. Treatments were NEL+MON; NEL+LC+MON; NEL+BEO; CROSS+MON; CROSS+LC+MON; CROSS+BEO in a randomized complete block with a 2 x 3 factorial arrangement (2 racial groups and 3 feed additives). There were no interactions between racial groups and feed additives (P &amp;gt; 0.05). Regardless of the additive used there were no differences in final BW (P = 0.237), ADG (P = 0.610), HCW (P = 0.120) or dressing (P = 0.095). Animals fed LC+MON had lower DMI (P &amp;lt; 0.01) than animals fed MON or BEO (7.74 kg, 8.64 kg, 9.26 kg, respectively). However, feed efficiency (G:F) of LC+MON did not differ from MON. Animals fed diets with BEO had lower G:F than animals fed diets with MON or LC+MON (P &amp;lt; 0.01; 0.1382, 0.1469 and 0.1550 respectively). Animals fed diets with MON or LC+MON were 6.3% and 12% more efficient than animals fed with BEO. Crossbred bulls had higher DMI (P &amp;lt; 0.001), ADG (P &amp;lt; 0.001), FBW (P &amp;lt; 0.001) and HCW (P &amp;lt; 0.001) than Nellore bulls. In summary, LC reduced DMI not altering feed efficiency. Diets containing BEO reduced G:F of the animals when compared with animals receiving diets containing MON.