Roughage Inclusion Research Articles

PSIV-A-5 Effect of roughage inclusion in limit-fed cow rations on behavior, cow hygiene, and manure scores

Abstract The objective was to determine the effects of roughage inclusion in isocaloric total mixed rations (TMR) fed to drylot housed cow-calf pairs on behavior, manure score, and hygiene score. Spring-born Simmental x Angus cows (n = 72) and their calves were stratified by calf age, sex, and body weight (BW) and assigned to 12 pens with 6 pairs to pen. Pens were randomly assigned to one of two treatments: moderate roughage inclusion (40%) TMR targeting DMI of 1.7% of BW (LimitTMR) or high roughage inclusion (60%) TMR targeting DMI of 2.1% of BW (BulkyTMR). Concrete bunks (4.7 m; 0.8 m/cow). Cow-calf pairs were housed in concrete dry lots with open-front buildings. Buildings were bedded with straw once a week. Cow and calf behavior (standing, lying, at bunk, and eating bedding) was observed hourly from 1 h before feeding until 6 h post-feeding. Behavior assessments were done on 2 consecutive days (before new bedding and after new bedding) each week for 5 wk. Hygiene and manure scoring was conducted on d 40 and 75 by 2 trained evaluators. Hygiene was scored on a 1-4 scale; 1 – no manure, 4 confluent plaque of manure. Cow hygiene was evaluated on the lower leg, udder, and upper leg and flank. Manure from each pen was scored on a 1-5 scale; 1 – very liquid consistency, 5 – firm fecal balls. Data were analyzed using the MIXED procedure of SAS 9.4. On day prior to new bedding, there was a treatment × time interaction (P < 0.01) for cows at bunk. More cows on BulkyTMR were at the bunk at h 2, 3, 4, and 5 post-feeding. On day after new bedding, there was also a treatment × time interaction (P < 0.01) for cows at bunk. More cows on LimitTMR were at the bunk before feeding; however, more cows on BulkyTMR were at bunk at h 2 and 3 post-feeding. On both evaluation days there was a treatment × time interaction (P ≤ 0.05) for calves at bunk. More calves on BulkyTMR were at the bunk at h 1 and 2 post-feeding. Cows fed the LimitTMR had dirtier (P ≤ 0.02) lower leg (1.5 vs 1.2) and upper leg/flank (1.4 vs 1.1) hygiene scores on d 40 than cows fed the BulkyTMR; however, there were no treatment differences (P ≥ 0.31) on d 75. There were no treatment differences (P ≥ 0.26) for manure scores on d 40 or d 75. In conclusion, a bulkier TMR with more roughage inclusion resulted in more time at the bunk for cows and calves and cleaner hygiene scores for cows, but roughage inclusion did not affect manure scores.

165 Comparing corn earlage to a blend of corn silage and grain when fed at two different inclusions for finishing cattle

Abstract An experiment was conducted to evaluate the effects of feeding earlage as the sole source of roughage and grain in a finishing diet when compared with corn silage plus grain at equal forage NDF inclusions in the diet. Crossbred yearling steers [n = 216; initial body weight (BW) = 471 ± 14.1kg] were fed one of 4 experimental diets in a 2 × 2 factorial treatment arrangement with roughage type and forage inclusion being the 2 factors. Treatment diets were formulated for earlage to provide all the grain the diet (74%) which provided 14.8% forage and was compared with 29.6% corn silage and 44.4% corn as a 50:50 blend of dry rolled corn (DRC) and high moisture corn (HMC). The other two diets were formulated for corn silage to provide a standard roughage inclusion for finishing diets (i.e., corn silage at 15% to supply 7.5% forage in the diet). To match 7.5% roughage with earlage providing all the roughage, another diet included earlage at 37%, with an additional 37% corn included as the 50:50 blend of HMC and DRC. All diets included 20% wet distiller’s grains (WDGS) and 6% supplement. The two inclusions of forage were either 7.5 or 14.8% forage as either earlage or corn silage. Earlage was assumed to provide 20% forage and corn silage to provide 50% forage, on a DM basis. Cattle were stratified into 3 BW blocks, then assigned randomly assigned to pens within block, and treatment assigned randomly to pens. A total of 24 pens containing 9 steers in each were used with pen as the experimental unit. Feeding performance, carcass characteristics and liver abscess prevalence were evaluated using the MIXED procedure of SAS with BW block and treatment being fixed effects. No interactions between roughage type or forage inclusion were observed for performance or carcass traits (P > 0.13) except for marbling or liver abscesses (P < 0.09). When cattle were fed a diet with corn silage as the roughage source, greater dry matter intakes (DMI) and average daily gain (ADG) were observed (P ≤ 0.01), but feed efficiency was not significantly different (P = 0.35). However, when evaluating effects of NDF inclusion, cattle fed 7.5% forage in the diet were 6.8% more efficient than cattle fed 14.8% forage and tended to have greater gain (P = 0.10), but no significant differences were observed for intake (P = 0.11). These data suggest that cattle fed earlage will eat and gain less than cattle fed a blend of corn silage and grain when estimated forage is equivalent, and when earlage is fed as the sole source of grain, cattle will be less efficient than when conventional roughage inclusions are fed.

164 Impact of varying dietary inclusion of modified distiller’s grains plus solubles weekly compared with constant inclusion on feedlot cattle performance and carcass characteristics

Abstract The use of distiller’s grains in feedlot diets was abundant due to supply and price, but the availability to feedlots and greater prices of distiller’s grains has led to reduced inclusion and more variation in supply, and thus, inclusion within the feeding period for cattle. The hypothesis was that varying inclusion of modified wet distiller’s grains plus solubles (MDGS) in the diet would negatively impact cattle performance due to changing dietary starch concentration and risk of acidosis. One solution to help with ruminal acidosis concerns with variable MDGS inclusion would be increasing roughage inclusion. Therefore, our objective was to evaluate if varying the inclusion of MDGS at normal and 2X normal roughage inclusion influences performance of finishing cattle. In this study, crossbred steers (n = 576) with an initial body weight (BW) = 379 kg (SD= 11 kg) were evaluated for performance and carcass traits over the 143 d on study. Two inclusions of grass hay (6% and 12%) and three treatments related to MDGS (no inclusion, constant inclusion at 25% MDGS, and varying inclusion between 15 and 35% MDGS) were tested in a 2 × 3 factorial. Variable inclusion was accomplished by randomly selecting inclusions of 15, 20, 25, 30, or 35% each week with inclusion averaging 25% over the entire feeding period. There was no interaction between grass hay inclusion and MDGS inclusion (P ≥ 0.67) for performance data except a tendency (P = 0.09) for a gain to feed (G:F) interaction. In treatments fed 12% hay, G:F increased for cattle fed either MDGS inclusion (25% constant or varying inclusion) compared with 0% MDGS. In cattle fed 6% hay, G:F was similar between 0, 25 constant or variable 25% MDGS treatments. There was not an interaction due to a different response of variable versus constant inclusion of MDGS when more hay was included, as hypothesized. The 25% constant MDGS and 25% variable MDGS treatments did not differ (P ≥ 0.22) in average daily gain (ADG), hot carcass weight, or G:F. There was a tendency for cattle fed varying inclusion of MDGS to eat less (P = 0.10), but this difference was small (0.1 kg/d). In general, cattle fed MDGS (constant or varying) had greater dry matter intake and ADG, with greater fatness and marbling compared with cattle fed without MDGS (P ≤ 0.01). As for the degree of liver abscess severity, there was no interaction between treatments. Our results show that although varying supply of MDGS in diets is not recommended or desired, if it occurs and inclusions vary from 15 to 35%, these weekly adjustments did not negatively affect gain or feed efficiency in this study.

Activity and rumination of implanted Charolais × Angus feedlot steers versus non-implanted counterparts consuming 3 levels of roughage throughout a 361-day feeding duration

ObjectiveRumination and activity of growing feedlot steers were evaluated in response to growth-promoting implant administration, feeding duration, and dietary rough- age. Materials and MethodsCharolais × Angus steers (n = 80) were randomized to harvest (1, 42, 84, 126, 168, 210, 252, 294, 336, or 378 d on feed) and implant treatment (REV: Revalor-XS on d 0 and d 190; CON: no implant). Activity and rumination were objectively monitored via accelerometers attached to the left ear. Steers consumed 3 rations throughout the study: starter (38.5% roughage), intermediate (23% roughage), and finishing (8.5% rough- age). Data were logged in 2-h increments from 77 steers across 361 d and analyzed using mixed models. Results and DiscussionRumination and activity varied within 24-h, exhibiting bimodal patterns; rumination peaked at 0600 and 1400 h and troughed at 1000 and 1800 h. Activity peaked at 0800 and 1800 h and troughed at 0400, 1200 to 1400, and 2200 h. Steers administered REV ruminated less (331 vs. 354 min/d) than CON; however, activity was similar between treatments. Treatment × roughage interactions occurred for rumination and activity. Rumination tended to be greater for CON steers consuming 38.5% than CON steers consuming 23% roughage, furthermore, CON steers ruminated more than REV when consuming 8.5% roughage. Implanted and non-implanted steers ruminated less as roughage inclusion decreased from 38.5% and 23% to 8.5% (457 and 439 vs. 317 min/d, respectively) in the finishing ration. Activity was greatest for steers consuming 38.5% roughage and was similar between treatments; however, activity decreased upon transition to 23% and 8.5% roughage. Observed surges and declines in activity can be attributed to processing days and weather events. Implanted steers consuming 8.5% roughage were more active (342 vs. 337 and 333 min/d) than CON and REV steers consuming 23% roughage. Implications and ApplicationsIn conclusion, rumination and activity are responsive to hour of day, dietary roughage and growth-promoting implants.

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.

Custos de produção e indicadores econômicos no ciclo completo de bezerros mestiços leiteiros

Abstract The complete rearing cycle of dairy calves is not yet widely adopted by rural producers, possibly because they do not perceive these animals as potential meat producers or are unaware of their production capabilities. This study aimed to assess the economic viability of rearing dairy calves through their entire growth cycle. Sixteen Holstein × Gyr crossbred animals were assessed, originating from dairy farming, with an average initial weight of 40.67 ± 5.27 kg and slaughtered at 10 months of age, reaching a final weight of 320.4 ± 45.87 kg. These calves were reared in a feedlot system and received a mash diet without the inclusion of roughage. The experiment was conducted on a farm primarily focused on dairy farming, situated in the municipality of Turvânia, GO, Brazil. Economic evaluations were conducted at the conclusion of the production cycle, with the calculation of the value of the arroba (@ = 15 kg) produced. Data were analyzed using a production cost structure methodology, which included effective operating cost, total operating cost, and total cost. The following economic indicators were examined: gross revenue, gross margin, net margin, and the break-even point. Results were highly promising, demonstrating a profit from raising dairy male calves, with a net margin per animal of BRL 321.50. Additionally, these animals displayed noteworthy potential for weight gain and carcass quality. A total of 149.19 @ were produced, averaging 9.32 @ per animal, with a production cost of BRL 105.52, encompassing expenses such as milk consumption, concentrate diet, and labor, which amounted to BRL 1.18 per month per animal. These findings underscore the economic feasibility of this rearing system.

The effects of receiving diet roughage inclusion on performance, health, and serum metabolite characteristics of newly received beef calves.

Current dogma suggests increased dietary roughage may improve calf health at the expense of performance during receiving. In experiment 1, the effects of increasing dietary roughage on performance and clinical health of high-risk heifers was evaluated over a 56-d receiving period. Heifers (n = 589; initial body weight; BW = 230 ± 33 kg) were sourced from Oklahoma livestock auctions from April through October of 2019. Heifers were randomly assigned to pens, which were randomly assigned to 1 of 3 experimental dietary treatments in a randomized complete block design. Diets contained either: 1) 15% roughage (R15), 2) 30% roughage (R30), or 3) 45% roughage (R45) in the form of prairie hay. Orthogonal contrasts were used to test for linear and quadratic responses among experimental treatments. There was a linear decrease in overall average daily gain (ADG; P ≤ 0.0001) with increasing roughage inclusion which resulted in a linear decrease (P ≤ 0.0001) in heifer final BW. A linear increase (P ≤ 0.01) was observed for overall dry matter intake (DMI), and overall gain:feed (G:F) decreased linearly (P ≤ 0.0001) as dietary roughage concentration increased. A quadratic response to decreasing roughage was observed (P = 0.02) for the percent of calves treated three times for bovine respiratory disease (BRD). No other responses (P ≥ 0.11) were detected in animal health variables. In experiment 2, Angus steers (n = 12) and heifers (n = 6; BW = 272 ± 28 kg) were acquired from a single ranch in Oklahoma to evaluate the same experimental dietary treatments on serum metabolite concentrations. Animals were randomly assigned to experimental treatments, with animal serving as the experimental unit in experiment 2. Statistical models for serum metabolites in experiment 2 were analyzed using repeated measures with the effects of treatment, time, and treatment × time. In experiment 2, there were tendencies for treatment × time interactions for blood urea nitrogen (BUN; P = 0.07) and nonesterified fatty acid (NEFA; P = 0.06) concentrations. No metabolites were affected by treatment (P ≥ 0.11), while all metabolites were impacted by time (P ≤ 0.02). In summary, growth performance was improved in calves as dietary roughage concentration decreased with minimal impacts on health and serum metabolites. These results suggest that diets containing as little as 15% roughage can be used during receiving to improve calf performance without compromising calf health when fibrous byproducts are included in the diet.

Effects of increased dietary roughage during the late finishing period on beef cattle performance, carcass traits, and blood, ruminal, and faecal characteristics

Finishing cattle consume diets high in concentrates to efficiently deposit both muscle and adipose tissue while decreasing cost of gain during finishing. Concerns regarding liver abscesses and late finishing period morbidity and death loss have led to interest in increasing dietary roughage concentrations during late finishing. The objective of the current experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, blood, inflammation markers, ruminal, and fecal characteristics of feedlot steers. Crossbred beef steers (n = 60; initial body weight; BW = 289 ± 35.6 kg) were blocked by BW and assigned to experimental dietary treatments in a randomized complete block design during the final 58 d on feed. Experimental treatments included control (CON; 6% roughage DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets (CON = 5 pens and INT and HGH = 4 pens; 4 steers per pen). All experimental diets contained dry-rolled corn, prairie hay, Sweet Bran (Cargill, Inc., Blair, NE), dry supplement, urea, and a corn steep and molasses-based liquid supplement. The inclusion rate of roughage and dry-rolled corn were adjusted for each experimental treatment diet. Overall dry matter intake (DMI) tended to increase linearly (P = 0.02) with increasing roughage concentration. No differences in BW, overall average daily gain (ADG), or gain to feed (G:F) were observed (P ≥ 0.72). Rib eye area increased linearly with increasing roughage concentration (P = 0.02). Fat thickness, hot carcass weight (HCW), marbling, liver score, and kidney, pelvic, and heart fat (KPH) did not differ (P ≥ 0.29) among treatments. Steers consuming the HGH diet had a lower fecal pH at the end of the finishing period (P = 0.05) compared to CON and INT steers. Ruminal lactate was increased on d 14 for CON steers compared to other treatments (P < 0.001). No differences were observed for ruminal pH (P ≥ 0.11) among treatments at any collection. Results from the current experiment suggest that increasing roughage late in the finishing period may not negatively impact growth performance or carcass characteristics but does alter feed intake and may alter fermentation and digestion.

194 Evaluation of Dietary Roughage Inclusion in a Single or Two-Diet System for Backgrounding and Finishing Steers

Abstract The objective of this experiment was to determine the influence that equal cumulative roughage inclusion in a single diet or two-diet system during a 210-d growing-finishing period has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in beef steers. Pre-conditioned beef steers (n = 46; initial shrunk [4%] BW = 281 ± 40.4 kgs) were fed once daily, and bunks were managed according to a slick bunk management system at the Ruminant Nutrition Center in Brookings, SD. Treatments included: 1) A single diet program (targeted a 1.30 Mcal/kg NEg diet fed for 210-d; 1D) or 2) two diet program (targeted a 1.21 Mcal/kg NEg diet fed for 98-d, a 1.30 Mcal/kg NEg diet fed for 14-d, and a 1.39 Mcal/kg NEg diet fed for 98-d; 2D). All steers were implanted on d 1 with a 100 mg trenbolone acetate (TBA) and 14 mg estradiol benzoate (EB) implant and re-implanted with a 200 mg TBA and 28 mg EB implant on d 112. Average daily gain tended (P = 0.06) to be 9.5% greater for 1D compared with 2D during the backgrounding portion and ADG was increased (P = 0.01) for 2D compared with 1D by 11.3% during the finishing phase of the experiment. Cumulative ADG did not differ between treatments (1.61 vs. 1.62 ± 0.046 kgs) for 1D and 2D, respectively. Cumulative observed dietary NEm and NEg did not differ (P ≥ 0.96) between treatments. There were no differences (P ≥ 0.18) detected between treatments for HCW, DP, REA, RF, USDA marbling score, KPH, yield grade, retail yield, EBF, or body weight at 28% estimated EBF. In conclusion, Northern Plains feedlot producers can feed a single growing-finishing diet to preconditioned beef steers with minimal effects on overall growth performance or carcass traits.

Impacts of added roughage on growth performance, digestibility, ruminal fermentation, and ruminal pH of feedlot steers fed wheat-based feedlot diets containing 30% modified distillers grains with solubles.

Two experiments were conducted to evaluate the inclusion rate roughage in wheat-based diets containing modified distillers grains with solubles (MDGS) on feedlot performance (Feedlot Experiment), as well as digestibility, ruminal pH, and ruminal fermentation characteristics (Digestibility Experiment). The feedlot experiment utilized 72 Angus steers (392 ± 46.3 kg initial body weight) which were randomly assigned to 1 of 12 pens, 3 pens per treatment, to evaluate feedlot performance and carcass characteristics. Dietary treatments were 1) control; 10% roughage, 2) 12% roughage, 3) 14% roughage, and 4) 16% roughage. The digestibility experiment used four ruminally and duodenally cannulated steers (393 ± 33.0 kg) in a 4 × 4 Latin Square with either 10%, 12%, 14%, or 16% roughage as in the feedlot experiment. However, dietary roughage source was different between these two experiments and included a combination of grass hay and wheat straw (Feedlot Experiment), and corn silage (Digestibility Experiment). All data were analyzed with the Mixed Procedures of SAS. Feed intake was recorded, with duodenal and fecal output calculated using chromic oxide. Ruminal pH and fermentation were assessed. Growth performance and most carcass characteristics were not affected by increasing roughage (P ≥ 0.11). Marbling tended to decrease linearly (P = 0.10) with increasing roughage inclusion. Increasing dietary roughage content had no effect on organic matter intake (P = 0.60) in the digestibility experiment. Intake, duodenal flow, and digestibility of neutral detergent fiber and acid detergent fiber were not affected by treatment (P ≥ 0.16). Ruminal pH increased linearly (P < 0.01) as rate of roughage inclusion increased. Ruminal concentrations of acetate and butyrate increased, and propionate decreased in a linear fashion (P < 0.01) thereby increasing (P < 0.01) acetate and butyrate to propionate ratio with increasing dietary roughage. Our data indicate that increasing roughage inclusion in wheat-based diets including 30% MDGS increased ruminal pH and shifted ruminal fermentation patterns. Additionally, increasing roughage inclusion did not affect feedlot performance in steers fed wheat at 36% to 42% of dietary dry matter in combination with 30% MDGS.

Effects of changes in finishing diets and growth technologies on animal growth performance and the carbon footprint of cattle feeding: 1990 to 2020

Our objective was to estimate the effects of changes in feedlot diets and the availability of performance-enhancing technologies on growth performance and the carbon footprint of cattle feeding between 1990 and 2020. A model was developed to represent feedlot diets and technologies used in 1990 versus 2020 and evaluate changes in growth performance and carbon footprint. Byproduct feeds became more common between 1990 and 2020; thus, corn and dry roughage inclusion rates decreased. Estradiol-only implants and monensin were the available technologies in 1990, whereas in 2020 use of implants with combinations of trenbolone acetate and estradiol, monensin, and ractopamine hydrochloride (in the final 28 to 42 d) were common. In both 1990 and 2020 use of all available technologies increased final BW, ADG, G:F, and hot carcass weight compared with no technology. From 1990 to 2020 initial BW, final BW, ADG, G:F, hot carcass weight, and daily DMI increased. Total days on feed increased by 44 d from 1990 to 2020. Compared with no technology, use of technologies in both 1990 and 2020 decreased total greenhouse gas emissions per animal (CO 2 equivalent, CO 2 e). Because cattle had greater days on feed in 2020, all sources of greenhouse gas emissions per animal increased compared with the values estimated in 1990. However, when expressed as CO 2 e/kg of BW gain, emissions have decreased by 4.4% because of greater total BW gain in 2020 versus 1990. Feedlot cattle decreased relative emissions from 4.78 kg of CO 2 e/kg of BW gain in 1990 to 4.58 kg of CO 2 e/kg of BW gain in 2020. Overall, feedlots in 2020 produced 47.5% more BW gain with 1.4% less cattle, while only increasing total CO 2 e by 39.5%. Therefore, changes in available technologies and diet formulations have improved efficiency and reduced the carbon footprint of feedlot cattle production in the past 30 yr.

PSV-12 The impact of modern diets and growth technologies on animal growth performance and the carbon footprint of cattle feeding

Abstract Both dietary ingredients and technology used in the feedlot cattle industry have evolved in the past 30 years. As consumer concern for the sustainability of the feedlot cattle production increases, it is important to understand how production efficiency and greenhouse gas emissions have changed in this period. For this study, a model was developed to represent feedlot diets and technologies used in 1990 vs. 2020 and evaluate changes in growth performance and carbon footprint. Dietary changes from 1990 to 2020 included the use of byproduct feeds while decreasing corn and dry roughage inclusion rates. In 1990, available technologies included estradiol-only implants and monensin as a feed additive; whereas in 2020 use of combination implants including both trenbolone acetate and estradiol, monensin, and ractopamine hydrochloride (in the final 28 to 42 d) were common. In both 1990 and 2020 use of available technologies increased final body weight (BW), average daily gain (ADG), feed efficiency, and hot carcass weight (HCW) compared to no technology. From 1990 to 2020 initial BW, final BW, ADG, gain to feed ratio, and HCW increased, and dry matter intake decreased. Total days on feed (DOF) also increased by 43 days from 1990 to 2020. Compared to no technology, use of technologies in both 1990 and 2020 decreased total greenhouse gas emissions per animal (CO2e). Because cattle had greater DOF in 2020 than 1990, all sources of greenhouse gas emissions per animal increased. However, when expressed as CO2e/kg BW gain, emissions have decreased by 12.6% because of greater total BW gain in 2020. Feedlots in 2020 produced 48.15% more BW gain with 6.7% less cattle, while only increasing total CO2e by 23.42%, indicating changes in technologies and diet formulations have improved efficiency and reduced the carbon footprint of feedlot cattle production in the past 30 years.

PSI-2 Activity and rumination of implanted British × Continental steers vs. non-hormone treated counterparts consuming various levels of roughage throughout a 361-d growth window

Abstract A serial-harvest study was conducted to evaluate rumination and activity of growing steers in response to implant and dietary roughage. Charolais×Angus steers (n = 80) were randomized to harvest (0, 42, 84, 126, 168, 210, 252, 294, 336 or 378 DOF) and implant treatment (REV: Revalor-XS on d-0 and d-190 or CON: no implant). Activity and rumination were objectively monitored by SCR accelerometers attached to the left ear. Steers consumed 3 rations throughout the study: starter (38.5% roughage), intermediate (23% roughage), and finishing (8.5% roughage). Data was logged in 2-h increments from 77 steers across 361 d and analyzed using mixed models. Rumination and activity varied (P &amp;lt; 0.01) within 24-h, exhibiting bimodal patterns; rumination peaked at 0600 and 1400 h and troughed at 1000 and 1800 h. Activity peaked at 0800 and 1800 h and troughed at 0400, 1200–1400, and 2200 h. Steers administered REV ruminated less (364 vs 380 min/d; P = 0.04) than CON; however, 24-h activity was similar (P = 0.29) among treatments. Treatment×roughage interactions (P &amp;lt; 0.01) occurred for rumination and activity. Rumination tended to differ (P = 0.06) between CON consuming 38.5% and 23% roughage, however, CON steers ruminated (P &amp;lt; 0.01) more than REV when consuming 8.5% roughage. Implanted and non-implanted steers ruminated less (P &amp;lt; 0.01) as roughage inclusion decreased from 38.5% and 23% to 8.5% (457 and 439 vs 317 min/d) in the finishing ration. Activity was highest for steers consuming 38.5% roughage and was similar (P &amp;gt; 0.05) among treatments; however, activity decreased (P &amp;lt; 0.01) upon transition to 23 and 8.5% roughage. Activity peaks and troughs can be attributed to processing days and weather events. Implanted steers consuming 8.5% roughage were more active (342 vs. 337 and 333 min/d; P &amp;lt; 0.01) than CON and REV steers consuming 23% roughage. In conclusion, rumination and activity are responsive to hour, dietary roughage and growth-promoting implants.

194 Effects of feeding increased roughage to feedlot steers the last 56 days of finishing

Abstract Finishing cattle are fed high concentrate diets to increase deposition of both muscle and adipose tissue and decrease cost of gain. The objective of this experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, and ruminal and fecal characteristics of feedlot steers. Treatments included a control (CON; 6% roughage DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets. Crossbred beef steers (n = 54; BW = 289 ± 35.6 kg) were assigned to treatments for the late finishing period in a randomized complete block design (4 pens of INT and HGH, 5 pens of CON; 4 steers per pen). Experimental diets contained prairie hay, Sweet Bran, rolled corn, dry supplement, urea, and a corn steep and molasses-based liquid supplement. The inclusion rate of roughage and rolled corn were adjusted for each treatment diet. Steers in HGH tended to have increased overall DMI (P = 0.07). No differences in final BW, overall ADG, or gain:feed were observed among treatments (P ≥ 0.72). Steers fed HGH had the greatest REA (P = 0.03) and a tendency for a lower yield grade (P = 0.08). Fat thickness, HCW, marbling, liver scores, and KPH did not differ (P ≥ 0.29) among treatments. Steers fed the HGH diet had a lower fecal pH at the end of finishing (P = 0.05) compared to CON and INT steers. Ruminal lactate was increased on d 14 for CON steers compared to other treatments (P &amp;lt; 0.001). No differences were observed for ruminal pH (P ≥ 0.11). Results of this experiment suggest that increasing roughage late in the finishing period does not negatively impact growth performance or carcass characteristics, but may alter ruminal fermentation and post ruminal digestion.

Optimum roughage proportion in barley-based feedlot cattle diets: growth performance, feeding behavior, and carcass traits.

High grain diets are fed to finishing beef cattle to maximize animal performance in a cost-effective manner. However, a small amount of roughage is incorporated in finishing diets to help prevent ruminal acidosis, although few studies have examined optimum roughage inclusion level in barley-based diets. The objective of the study was to evaluate the effects of roughage proportion in barley-based finishing diets on growth performance, feeding behavior, and carcass traits of feedlot cattle. Crossbred beef steers (n = 160; mean body weight ± SD, 349.7 ± 21.4 kg) were allocated to 20 pens that were assigned randomly to four dietary treatments (five pens of eight steers per treatment). The treatment diets contained barley silage at 0%, 4%, 8%, and 12% of dietary dry matter (DM). The remainder of the diets (DM basis) consisted of 80%, 76%, 72%, and 68% barley grain, respectively, 15% corn dried distiller's grains, 5% mineral and vitamin supplement, and 32 mg monensin/kg diet DM. The diets were fed as total mixed rations for ad libitum intake (minimum of 5% refusal) once per day. Cattle were weighed on 2 consecutive days at the start and end of the experiment and on 1 d every 3 wk throughout the experiment (124 d). Two pens for each treatment group were equipped with an electronic feeding system (GrowSafe Systems Ltd., Calgary, Alberta) to monitor feed intake and feeding behavior of individual cattle. The data for dry matter intake (DMI), average daily gain (ADG), gain:feed (G:F) ratio, and carcass traits were analyzed as a completely randomized design with fixed effect of barley silage proportion and pen replicate as experimental unit. Feeding behavior data were analyzed similarly, but with animal as experimental unit. Averaged over the study, DMI increased linearly (11.1, 11.3, 11.7, 11.8 kg/d; P = 0.001) as barley silage proportion increased from 0%, 4%, 8%, and 12% of DM, but ADG was not affected (carcass-adjusted,1.90, 1.85, 1.87, 1.89 kg/d; P ≥ 0.30). Consequently, G:F ratio decreased linearly (carcass-adjusted, 168.9, 163.8, 158.5, 160.6 g/kg DMI; P = 0.023). When averaged over the study, proportion of barley silage in the diet had no linear or quadratic effects (P > 0.10) on meal frequency, duration of meals, intermeal duration, or meal size, but eating rate decreased linearly with increasing silage proportion (P = 0.008). There was no diet effect on liver abscesses (P ≥ 0.92), and effects on carcass characteristics were minor or nonexistent. We conclude that increasing the proportion of barley silage in a feedlot finishing diet at the expense of barley grain to minimize the incidence of ruminal acidosis may decrease feed conversion efficiency.

Effects of corn stalk inclusion rate on rumination and ruminal pH in finishing beef steers

ABSTRACT Objective The objective of this experiment was to measure feedlot performance, rumination, ruminal pH, and carcass characteristics of cattle consuming a finishing diet with increasing levels of corn stalks (CS). Materials and Methods Fifty cross-bred steers (initial BW = 302 ± 27 kg) were randomly allocated to 1 of 3 dietary treatments: 5% (5CS; n = 17), 10% (10CS; n = 17), or 15% (15CS; n = 16) CS in a finishing diet based on steam-flaked corn. Experimental design was a randomized complete block, and data were analyzed using generalized random coefficients models. Rumination (min/d) was recorded from all the steers, and half of the steers (n = 27) received an indwelling rumen bolus to monitor pH. Results As CS inclusion rate increased, ADG and G:F decreased (P ≤ 0.05) linearly, whereas DMI of cattle consuming 10CS and 15CS was greater (P ≤ 0.05) than those consuming 5CS. Ruminal pH tended (P Applications Results of this study indicate that optimal dietary roughage inclusion of CS should be between 5 and 10% to optimize feedlot performance while maintaining rumination and ruminal pH.

Survey of management practices used by Brazilian dairy farmers and recommendations provided by 43 dairy cattle nutritionists

This work aimed to survey management practices used by dairy farmers and to report nutritional recommendations adopted by 43 dairy cattle nutritionists in Brazil. The web-based survey consisted of 80 questions. Almost 50% of the participants had clients that produce &lt;1000 kg of milk daily and 48.8% had clients who own fewer than 100 dairy cows. Corn was the primary source of grain (97.4%), and 43.9% of the nutritionists included from 41% to 50% concentrate in lactation diets. The mean roughage inclusion in lactation diets was 50.5% and 79% of the nutritionists reported corn silage as the primary roughage source. Average crude protein and rumen-degradable protein concentrations recommended by the nutritionists for lactation diets were 15.7% and 9%, respectively. Average Ca and P concentrations recommended for lactation diets were 0.70% and 0.41%, respectively. The major health problem reported by 83.9% of the nutritionists was mastitis. The present survey provides an overview of management practices adopted by dairy farmers and nutritional recommendations currently applied by dairy cattle nutritionists in Brazil. The most critical points identified were low milk yield, mastitis as the major health problem, lack of proper mixing and delivery of rations, and destination of male calves.

Effects of reducing inclusion rate of roughages by changing roughage sources and concentrate types on intake, growth, rumen fermentation characteristics, and blood parameters of Hanwoo growing cattle (Bos Taurus coreanae).

ObjectiveReducing roughage feeding without negatively affecting rumen health is of interest in ruminant nutrition. We investigated the effects of roughage sources and concentrate types on growth performance, ruminal fermentation, and blood metabolite levels in growing cattle.MethodsIn this 24-week trial, 24 Hanwoo cattle (224±24.7 kg) were fed similar nitrous and energy levels of total mixed ration formulated using two kinds of roughage (timothy hay and ryegrass straw) and two types of concentrate mixes (high starch [HS] and high fiber [HF]). The treatments were arranged in a 2×2 factorial, consisting of 32% timothy–68% HS, 24% timothy–76% HF, 24% ryegrass–76% HS, and 17% ryegrass–83% HF. Daily feed intakes were measured. Every four weeks, blood were sampled, and body weight was measured before morning feeding. Every eight weeks, rumen fluid was collected using a stomach tube over five consecutive days.ResultsThe mean dry matter intake (7.33 kg) and average daily gain (1,033 g) did not differ among treatments. However, significant interactions between roughage source and concentrate type were observed for the rumen and blood parameters (p<0.05). Total volatile fatty acid concentration was highest (p<0.05) in timothy–HF-fed calves. With ryegrass as the roughage source, decreasing the roughage inclusion rate increased the molar proportion of propionate and decreased the acetate-to-propionate ratio; the opposite was observed with timothy as the roughage source. Similarly, the effects of concentrate types on plasma total protein, alanine transaminase, Ca, inorganic P, total cholesterol, triglycerides, and creatinine concentrations differed with roughage source (p<0.05).ConclusionDecreasing the dietary roughage inclusion rate by replacing forage neutral detergent fiber with that from non-roughage fiber source might be a feasible feeding practice in growing cattle. A combination of low-quality roughage with a high fiber concentrate might be economically beneficial.

226 Impact of corn silage level on finishing cattle nutrient digestion, ph characteristics, and feeding behavior

Abstract When used as a roughage source in a finishing diet, corn silage can have different effects on digestion compared to hay because of the presence of additional corn grain. The objective of this study was to determine the effects of corn silage inclusion level on cattle digestion and feeding behavior. In a digestion study, 3 ruminally cannulated steers (430 kg ± 0.20 kg) were utilized in a generalized randomized block design with 8 periods. Treatments consisted of 3 levels of corn silage included at 0, 7.5 and 15% of the diet DM and a control treatment with 15% alfalfa. Results showed DMD, OMD, NDF digestibility, and ADF digestibility were greatest for cattle fed CS0 followed by CS7.5, CS15, and Alf (P &lt; 0.01). Average ruminal pH was least for CS0, CS7.5 was intermediate, followed by Alf and CS15 with the greatest pH (P &lt; 0.01). Total VFA production was greatest in cattle fed CS0 followed by CS7.5 and Alf with CS15 having the least. Acetate to propionate ratio was least for cattle fed CS0, intermediate for CS7.5 and CS15 and greatest for Alf. Cattle ate the same number of meals which were similar in size as a % of total DMI (P ≥ 0.60). However, cattle fed Alf and CS0 spent more time eating compared to cattle fed CS7.5 and CS15 (P = 10). The rate of intake (kg/hr) was greatest for CS15 (9.55) and decrease linearly for CS7.5 (9.44), Alf (8.12) and least for CS0 (7.68; P = 0.04). These data suggest that cattle, typically at high risk for reduced performance, are susceptible to negative effects of high grain diets, like acidosis, when fed no or low inclusion of roughage. Feeding silage at 15% was similar to feeding alfalfa at 7.5%.

Alkali addition and roughage inclusion effect on performance and carcass characteristics of feedlot steers fed diets containing 60% dried distillers grains with solubles.

Three experiments were conducted to determine the effectiveness of calcium hydroxide (Ca(OH)2) addition and roughage inclusion on digestibility, performance, and carcass characteristics of steers fed 60% dried distillers grains with solubles (DGS). Statistical analyses for studies were conducted using the MIXED procedures of SAS. In experiment 1, 48 steers (353.5 ± 7.55 kg) were allotted to individual pens and fed 1 of 3 diets (dry matter [DM] basis) containing 60% dried DGS, 20% corn silage, and 4% supplement with: 1) 14.5% corn and no Ca(OH)2; 2) 14% corn and 2% Ca(OH)2; and 3) 14.5% additional corn silage and no Ca(OH)2. Steers fed Ca(OH)2 consumed the least (P = 0.03) and steers fed added corn silage consumed the most and had the least gain:feed (P = 0.02). Gain and carcass quality were not affected by treatment (P ≥ 0.48). In experiment 2, 112 steers (375.3 ± 19.25 kg) were allotted to pens (four pens per treatment; seven steers per pen) arranged as a 2 × 2 factorial (roughage × Ca(OH)2) and fed one of four diets (DM basis) containing 60% dried DGS, 17% corn silage, and 4% supplement with: 1) 17.5% corn silage and no Ca(OH)2; 2) 17% corn silage and 2% Ca(OH)2; 3) 17.25% corn stover and no Ca(OH)2; and 4) 17% corn stover and 2% Ca(OH)2. Added stover decreased average daily gain (ADG) compared to added corn silage (P = 0.04). Ca(OH)2 increased ADG when steers were fed stover, but not when steers were fed only corn silage (P = 0.05; interaction). In experiment 3, six ruminally cannulated steers (initial body weight = 352 ± 14.8 kg) were randomly allotted to a 6 × 6 Latin square design to determine the effects of roughage inclusion (corn, corn silage, stover) and Ca(OH)2 addition (0% or 2%) on ruminal characteristics. Feeding stover decreased total volatile fatty acid(s) (VFA) concentration and DM digestibility compared to corn silage or corn (P < 0.01), whereas Ca(OH)2 resulted in greater total VFA concentrations and DM digestibility (P ≤ 0.02). Stover increased rate of DM degradation (Kd) and rate of particle outflow from the rumen (P ≤ 0.04) but decreased extent of DM digestion and mean retention time (P ≤ 0.02) compared to corn or silage. Ca(OH)2 increased Kd (P < 0.01) and tended to increase (P = 0.06) liquid passage rate. In conclusion, added roughage did not improve performance of cattle fed 60% dried DGS. Ca(OH)2 may decrease intake and maintain performance of cattle fed 60% dried DGS with corn silage as the roughage source and increases ADG when corn stover replaces a portion of the corn silage.