Stocker Steers Research Articles

Monensin supplementation increases weight gain in stocker steers, but higher doses reduce essential mineral intake

Monensin is known to improve feed efficiency in cattle. At higher doses, however, monensin reduces the palatability of mineral supplements, which may reduce consumption of essential minerals such as selenium. The main objective of this study was to compare weight gain, while evaluating the impact on blood selenium concentrations, among treatment and control groups of stocker calves supplemented with a self-fed mineral supplement designed to deliver different amounts of monensin, while the control group received the same mineral without monensin. A secondary objective was to compare the presence of pathogenic and total coccidia oocysts. At study end, all monensin treatment groups weighed more than the control group but were not different from each other. No effect was detected on coccidia oocysts. In sum, there is a production gain from providing monensin in a mineral supplement to weaned calves on pasture. However, too high a dose may lead to insufficient trace mineral consumption. This is a concern in areas where forage is deficient in these nutrients.

148 Supplementing Bovacillus to newly weaned beef steers during a 90-d grazing period

Abstract This experiment compared performance, health, and physiological responses of high-risk stocker cattle receiving a Bacillus subtilis derivative during a 90-d grazing period. Crossbred steers (n = 120) were obtained from an auction yard and transported to the experimental facility. Steer shrunk body weight (BW) was recorded at arrival (d -1). This value was averaged with BW recorded on d 0 to represent initial BW (236 ± 2 kg). On d 0, steers were ranked by BW and allocated to 1 of 12 pastures (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers’ grains at 1% of BW containing either: 1) Bacillus licheniformis and B. subtilis ingredient (BOV; 2 g/steer daily of Bovacillus, Chr Hansen A/S, Horsholm, Denmark) or 2) no additive (CON). Cattle received treatments from d 0 to 90 while housed in pastures containing stockpiled grass forage, as well as free-choice access to water and a commercial mineral + vitamin mix without ionophores. Steers were assessed for bovine respiratory disease (BRD) signs daily, and shrunk BW recorded on d 91. Blood samples were collected, and BW recorded on d 0, 14, 28, 56, and 90. No treatment differences were detected (P ≥ 0.19) for glucose, non-esterified fatty acids, β-hydroxybutyrate, haptoglobin, or insulin-like growth factor 1, whereas a treatment × day interaction indicated increased cortisol in BOV cattle on d 56 (P < 0.01). A treatment × day interaction was detected for serum concentrations of parainfluenza type 3 antibodies, which was greater in BOV steers on d 90 (P < 0.01). No treatment differences were detected (P ≥ 0.23) for serum concentrations of antibodies against other BRD pathogen. Average daily gain (ADG) tended to be increased (P = 0.09) in BOV compared with CON steers from d 56 to d 90 (0.858 and 0.760 kg/d, respectively, although did not impact overall ADG (P = 0.48). No treatment differences were detected for steer final BW (P = 0.43). Total BW change per pasture was greater in BOV compared with CON (790 vs. 550 kg BW change; P = 0.02). No treatment differences were detected (P = 1.00) for BRD incidence, although steers removed from the experiment for health reasons tended to be increased in CON compared with BOV (P = 0.08). Despite lacking differences in health or physiological responses, B. licheniformis and B. subtilis supplementation increased overall production of BW in high-risk stocker steers during a 90-d grazing period.

Effects of pre-finishing plane of nutrition of stocker steers grazing introduced pastures on finishing performance and efficiency

Effects of pre-finishing plane of nutrition of stocker steers grazing introduced pastures on finishing performance and efficiency

Evaluation of Implants, Clover, and Fescue Variety on Stocker Steers – Year 3

Sixty-four growing steers were used in a split-plot experiment, where the whole plot was pasture, and the split-plot was the implant level. Whole plot treatment was a 4 × 2 factorial with four levels of fescue (High Endophyte, Low Endophyte, Novel, or Endophyte Free) and two levels of legume (Legumes or No Legumes). The split-plot included four implant levels (No Implant, Synovex One Grass, Revalor-G, or Ralgro). Data collected were weights and ultrasound carcass characteristics when steers were coming off grass. Steers on High Endophyte had a lower average daily gain (ADG) and final weight than steers on novel endophyte, with those grazing pastures that had low endophyte and endophyte-free were intermediate. There was no difference in cattle gains or carcass measurements based on the addition of legumes or the type of implant the steers received. The drought restricted the days on grass and potentially reduced the positive effects of implants.

Effect of Corn Type and Form of Supplement on Grazing Steers – Year 2

Eighty stocker steers were grazed on bromegrass from the end of May to the middle of August and were provided five different feeds while on grass during the summer. Treatments evaluated included (1) mineral only; (2) free-choice supplementation in the form of liquid feed (MIX30) or (3) block format (Mintrate 40 Red); and hand-fed supplements of 60% corn:40% dried distillers grains at 0.5% of body weight on a dry matter basis offered daily where the corn was either an (4) isoline corn (ISO; parent genetic line) or (5) Enogen feed corn (ENO; includes alpha-amylase gene). Steers were weighed every 28 days while on grass and were measured for carcass quality by ultrasound prior to being sold. Hand-fed steers had greater gain than self-fed supplemented steers and these steers tended to have more backfat, marbling, and did have more muscle depth coming off grass than other supplemented steers. Steers that received free-choice mineral or self-fed supplements also had lower gains than steers being hand-fed supplement. During a drought year overall, supplemented steers had a greater gain than non-supplemented controls (receiving mineral only). This advantage became apparent after 56 days on grass when the drought was the most severe and the difference may have become more pronounced if the steers hadn’t been removed from the pasture due to limited biomass. Overall, hand-feeding is the method that maintained a more consistent gain, regardless of pasture quality and biomass production. Evaluation of operational costs of production need to be evaluated before determining if the hand-feeding management strategy is the best for returns to the operation.

104 Grazing Evaluation of Two Bermudagrass Bases Interseeded with Alfalfa for Stocker Production in Southeastern US

Abstract Alfalfa (Medicago sativa) has shown promise in the Southeastern United States when interseeded into bermudagrass (Cynodon dactylon) to reduce reliance on synthetic N fertilization while also providing a high-quality grazable forage. However, data is limited when grazing alfalfa interseeded into different bermudagrass bases with stockers in the Southeastern U.S. A two-year grazing evaluation was conducted in a randomized complete block design with two replications from June-October 2020 (Y1) and April-October 2021 (Y2) at the University of Georgia Tifton Campus Better Grazing Program in Tifton, GA, to compare stocker cattle performance when grazing ‘Bulldog 805’ alfalfa interseeded into either ‘Russell’ or ‘Tifton-85’ bermudagrass (RAG and TAG, respectively). Paddocks (1-ha) were split into 4 (0.25-ha) sections and rotationally grazed to 10 cm using the put-and-take stocking method with two tester steers for each treatment (Y1 BW=228.3±27.02 kg; Y2 BW=183.1±20.8 kg). Paddock sections were evaluated pre- and post-grazing for herbage availability, botanical composition, and nutritive value. Stocker steers were weighed at study initiation, conclusion, and on a 28d interval for calculation of ADG and gain/ha. Data were analyzed using the PROC MIXED procedure of SAS 9.4. Differences for herbage mass, gain/ha, and stocking density were not detected seasonally but were observed within grazing cycle with RAG being greater in the earlier season, TAG being greater in the later portion of the grazing season, and no difference during the grazing cycles that occurred in the hot summer months. This study suggests that the bermudagrass variety utilized in the alfalfa-bermudagrass mixture will influence stocking management decisions.

Evaluation of Implants, Clover, and Fescue Variety on Stocker Steers – Year 2

Sixty-four growing steers were used in a split-plot experiment, where the whole plot was pasture, and the split-plot was the implant level. Whole plot treatment was a 4 × 2 factorial with four levels of fescue (High Endophyte, Low Endophyte, Novel, or Endophyte Free) and two levels of legume (Legumes or No Legumes). The split-plot included four implant levels (No Implant, Synovex One Grass, Revalor-G, or Ralgro). Data collected were weights, hair coat scores, hair length, rectal temperature (every 28 days), and ultrasound carcass characteristics when steers were coming off grass. Steers on High Endophyte had the lowest average daily gain (ADG) and final weight and smallest loin muscle as compared to steers on all other fescue types. The gain differentiation was observed beginning at day 56 through the end of the study. Overall, ADG was not impacted by the addition of legume. Steers that were implanted with Synovex One Grass had a greater gain, final weight, and lower hair score as compared to non-implanted steers. For many of the other measures, steers implanted with Ralgro or Revalor-G resulted in changes between non-implanted steers and those receiving Synovex One Grass. Steers on high endophyte fescue had greater final weight and ADG than non-implanted steers or those receiving Ralgro, with Synovex One Grass being intermediate. Gains for steers on endophyte free pastures were also impacted by the type of implant where Synovex One Grass steers had greater gains than non-implanted and Revalor-G steers, with Ralgro being intermediate. In this second year of research, the use of low to no endophyte fescue and the addition of implants increased gains.

Effect of Corn Type and Form of Supplement on Grazing Steers

Eighty stocker steers were grazed on bromegrass from April to the beginning of November and were provided five different feeds while on grass during the summer. Treatments evaluated included (1) mineral only; (2) free-choice supplementation in the form of liquid feed (MIX30) or (3) block format (Mintrate 40 Red); and hand-fed supplements of 60% corn:40% dried distillers grains at 0.5% of body weight on a dry matter basis offered daily where the corn was either an (4) isoline corn (ISO; parent genetic line) or (5) Enogen feed corn (ENO; includes alpha-amylase gene). Steers were weighed every 28 days while on grass and were carcass quality measured by ultrasound prior to placement in the feedlot. Hand-fed steers had greater gain than self-fed supplemented steers and these steers also had more backfat and tended to have more muscle depth coming off grass than other supplemented steers. Steers that received free-choice mineral or self-fed supplements also had lower gains than steers being hand-fed supplement. Within the first 28 days of the study, the hand-fed steers began weighing more and weighed 125 pounds more than the free-choice supplemented and control steers. On average hand-fed steers had a 0.6 lb/d greater ADG than control steers and those consuming free-choice supplement. Cost of gain was the highest with hand-fed steers at $0.27/pound, but even so profit was greatest with the hand-fed cattle.

46 Effects of Implants, Clover, and Fescue Variety on Stocker Steers

Abstract Fescue thrives due to a symbiotic relationship with a fungus called endophyte. Endophyte releases ergot toxins leading to metabolic issues, such as vasoconstriction, rough hair coats and poor cattle gains. Developments have occurred to remove or limit the toxins. The objective of this project was to identify management practices while grazing fescue to improve production and toxicity issues. Sixty-four growing steers (283 ± 14 kg BW) were used in a split-plot experiment, where the whole plot was pasture and the split plot was implants. Whole plot treatment was a 4 x 2 factorial with four levels of fescue (High Endophyte, Low Endophyte, Novel, Endophyte Free) and two levels of legume (Legumes or No Legumes). Split plot included four implant levels (No Implant, Synovex One Grass, Revalor-G, Ralgro). Data collected were weights, hair coat scores, hair length, rectal temperature (every 28d) and ultrasound carcass characteristics last day on pasture. Data were analyzed using the Glimmix Procedure of SAS (v. 9.4, Cary, NC). Steers on high endophyte had the lowest ADG, longest hair, and highest temperature as compared to steers on all other fescue types (P < 0.05). The gain differentiation was observed beginning at D56 through the end of the study (P < 0.05). Overall ADG was not impacted by addition of legume nor implant type (P > 0.10). Steers that were not implanted had a longer hair length throughout many measurement dates (P < 0.05). Steers grazing pastures with legume tended (P < 0.10) to have a higher ultrasound measured marbling score and less muscle depth. This study found that the best management strategy for fescue toxicity is to use non-endophyte or non-toxic varieties of fescue pasture. Contrary to previous research, the addition of implants and legumes for this project showed no improvement in cattle gains.

Evaluation of Implants, Clover, and Fescue Variety on Stocker Steers

Evaluation of Implants, Clover, and Fescue Variety on Stocker Steers

Competition at an automated supplement feeder affects supplement intake and behavior of beef stocker steers

ABSTRACT Objective The objective of this study was to determine the effect of competition for a feeding station at an automated supplement feeder on supplement intake and behavior of beef stocker steers. Materials and Methods In each of 2 yr, 128 mixed-breed beef steers (initial BW = 245 ± 28 kg) were randomly assigned to 8 paddocks that had access to an automated supplement feeder with 4 individual feeding stations. One paddock each year (i.e., test paddock; n = 16 steers) was selected to have continuous access to the feeder for the duration of the 16-wk trial. Each week, various additional paddocks were commingled with the test paddock to increase competition for the feeder. Supplement intake and behavior of the test paddock steers were regressed on the number of steers using each feeding station (i.e., competition). Results and Discussion Tester steers consumed an average of 0.29 kg of supplement per day (as fed, 60% of maximum allocation). Competition for a feeding station reduced (P = 0.01) supplement intake by 4 g/d, per steer of additional competition. Steers spent 4.4% of the time within 15 m of the feeder regardless of competition (P = 0.54). As competition increased, steers took more steps (P ≤ 0.01) and spent more time walking. Implications and Applications These data illustrate that in similar scenarios, the feeder can be stocked with at least 20 animals per feeding station with a relatively small effect on supplement intake.

76 Evaluating Nitrogen Management Strategies to Improve Southern Bermudagrass Grazing Systems

Abstract Bermudagrass (Cynodon dactylon) is one of the most common perennial warm-season forage crops grown in the South. While prominent in the region bermudagrass management requires large amounts of fertility and forage quality is moderate at best. Incorporating a legume into bermudagrass pastures could serve as an alternative to the necessary applications of synthetic N, while also improving the nutritive value of the forage base. A two-year grazing evaluation was conducted from May-Sept. 2018 (Y1) and May-Aug. 2019 (Y2) at the University of Georgia Tifton Campus in Tifton, Georgia, to compare concurring production of alfalfa/bermudagrass mixed pastures (BGA) with bermudagrass monoculture pastures with (BGN) or without (BGZ) the application of synthetic nitrogen. The experimental design was a randomized complete block with three treatments and two replications. All paddocks were evaluated pre and post grazing event for herbage availability, botanical composition, forage species competitiveness, and nutritive value. Paddocks (0.8-ha) were rotationally grazed using put and take management with stocker steers (Y1 BW=195.9±22.9 kg; Y2 BW=228.5±30.0 kg), two testers per treatment. Steers were weighed at initiation, conclusion, and on a 28–30 day interval for calculation of ADG and gain/ha. Statistical analysis was conducted using the PROC MIXED procedure of SAS. Despite significant drought in Y2, year did not affect total gain/ha, however treatment did (P = 0.04), such that BGA was highest (383.6±35.1 kg/ha), and BGN and BGZ were not different (261.2±35.1 kg/ha and 239.0±35.1 kg/ha, respectively). This is likely due to the lower stocking density and inclusion of high-quality volunteer annual grasses in BGZ treatments which allowed for selective grazing. These data suggest that rotationally grazing alfalfa/bermudagrass mixtures can result in a higher gain/ha, than bermudagrass pastures that are supplemented with or without synthetic N in the South.

77 Evaluating Nitrogen Management Strategies to Improve Southern Bermudagrass Grazing Systems

Abstract Bermudagrass (Cynodon dactylon) is one of the most common perennial warm-season forage crops grown in the South. While prominent in the region bermudagrass management requires large amounts of fertility and forage quality is moderate at best. Incorporating a legume into bermudagrass pastures could serve as an alternative to the necessary applications of synthetic N, while also improving the nutritive value of the forage base. A two-year grazing evaluation was conducted from May-Sept. 2018 (Y1) and May-Aug. 2019 (Y2) at the University of Georgia Tifton Campus in Tifton, Georgia, to compare concurring production of alfalfa/bermudagrass mixed pastures (BGA) with bermudagrass monoculture pastures with (BGN) or without (BGZ) the application of synthetic nitrogen. The experimental design was a randomized complete block with three treatments and two replications. All paddocks were evaluated pre and post grazing event for herbage availability, botanical composition, forage species competitiveness, and nutritive value. Paddocks (0.8-ha) were rotationally grazed using put and take management with stocker steers (Y1 BW=195.9±22.9 kg; Y2 BW=228.5±30.0 kg), two testers per treatment. Steers were weighed at initiation, conclusion, and on a 28–30 day interval for calculation of ADG and gain/ha. Statistical analysis was conducted using the PROC MIXED procedure of SAS. Despite significant drought in Y2, year did not affect total gain/ha; however, treatment did (P = 0.04), such that BGA was highest (383.6±35.1 kg/ha), and BGN and BGZ were not different (261.2±35.1 kg/ha and 239.0±35.1 kg/ha, respectively). This is likely due to the lower stocking density and inclusion of high-quality volunteer annual grasses in BGZ treatments which allowed for selective grazing. These data suggest that rotationally grazing alfalfa/bermudagrass mixtures can result in a higher gain/ha, than bermudagrass pastures that are supplemented with or without synthetic N in the South.

150 The effect of competition for an automated supplement feeder on supplement intake behavior of stocker steers

Abstract The objective of this research was to determine the effect of competition for a feeding space at an automated supplement feeder on supplement intake behavior. A 2 yr study was conducted; each yr, 128 mixed-breed beef steers (n = 256, initial BW = 245 ± 27.5 kg) were randomly assigned to 8 paddocks. One paddock each yr (n = 16 steers) was selected to have continuous access to the feeder for the duration of the 16 wk trial; this paddock was designated the “tester” paddock. The automated feeder had 4 feeding stations that dispensed supplement after eligible animal’s RFID tags were read by the electronics of the feeder. Steers were limited to 0.50 kg supplement/d. Weekly, additional paddocks were commingled with the tester paddock to increase competition for the feeder. This resulted in a stocking density from 4 to 32 steers per feeding station. For yr 2, one feeding station was disabled, resulting in a stocking density of 5.3 to 42.7 steers per feeding station. Approximately 31% of the steers did not voluntarily use the feeder; therefore, effective competition was less than the study design. Mean weekly supplement intake and GPS location were recorded for steers in the tester paddock. Additionally, pedometer data were collected in yr 2. Weekly mean supplement intake and time spent near the feeder were regressed on actual feeder stocking density with yr as a random variable; wk was the experimental unit (n = 16 wk). Tester steers consumed an average of 0.27 kg supplement/d. Competition for a feeding station numerically reduced (P = 0.01) supplement intake by 5 g/d per steer of additional competition. Steers spent 4.4% of the time within 15 m of the feeder regardless of competition (P = 0.54). As competition increased, steers took more steps (P < 0.01). These data illustrate that in environments similar to this experiment, the feeder can be stocked with at least 20 animals per feeding station with minimal effects on supplement intake.

Effects of Interseeding Ladino Clover into Tall Fescue Pastures of Varying Endophyte Status on Grazing and Subsequent Finishing Performance of Stocker Steers

Effects of Interseeding Ladino Clover into Tall Fescue Pastures of Varying Endophyte Status on Grazing and Subsequent Finishing Performance of Stocker Steers

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue and is detrimental to growth and performance. Recent research has shown that supplementing protein has the potential to enhance growth performance in weaned steers. Therefore, the objective of this study was to evaluate the effect of supplemental CP on physiological parameters in stocker steers experiencing fescue toxicosis. Thirty-six weaned Angus steers (6 mo of age) stratified by weight (196.1 ± 3.6 kg) were assigned to a 2 × 2 factorial arrangement for 56 d: endophyte-free (EF) seed and 14% CP (EF-14; n = 9), EF seed and 18% CP (EF-18; n = 9), endophyte-infected (EI) seed and 14% CP (EI-14; n = 9), and EI seed and 18% CP (EI-18; n = 9). Steer growth and hemodynamic responses were collected weekly during ergot alkaloid exposure. On day 14 of the trial, iButton temperature data loggers were subcutaneously inserted in the lateral neck region to record hourly body temperature for 42 d. Data were analyzed using PROC MIXED of SAS with repeated measures. No differences were observed in DMI, BW, ADG, F:G, or BCS during the treatment period (P > 0.05). Hair shedding scores, rectal temperatures, surface temperatures, and respiration rates were greater in EI steers compared to EF steers regardless of supplemental CP (P < 0.05). However, subcutaneous body temperature was greater in EI-14 steers (37.94 °C) compared to other steer groups (37.60, 37.68, 37.72 ± 0.04 °C for EF-14, EF-18, and EI-18, respectively; P < 0.05). Prolactin concentrations tended to be greater in EF steers when compared to EI steers (P = 0.07). Heart rate and hematocrit were reduced for EI-18 steers compared to other steer groups (P < 0.05). Caudal artery diameter was reduced in EI-18 steers compared to EI-14 steers (2.60 vs. 2.75 ± 0.05 mm, respectively; P < 0.05) and caudal vein diameter was reduced in EI-18 steers (3.20 mm) compared to all other steer groups (3.36, 3.39, 3.50 mm for EF-14, EF-18, and EI-14, respectively; P < 0.05). However, there was no difference observed in systolic or diastolic blood pressure during the treatment period (P > 0.05). Based on the data, exposure to low to moderate levels of ergot alkaloids during the stocker phase had a negative impact on hemodynamic responses and supplemental CP had minimal impact to alleviate symptoms. Therefore, feeding additional protein above established requirements is not expected to help alleviate fescue toxicosis.

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: II. Adaptive and innate immune function.

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue that affects performance; however, little information is available pertaining to its effects on immunity. Recently, it has been shown that supplemental CP can improve performance in weaned steers postvaccination. Thus, the objective of this study was to evaluate the effect of supplemental CP on innate and adaptive immune responses in stocker steers chronically exposed to ergovaline. Angus steers (n = 12 pens; 3 steers/pen) were stratified by weight and assigned to a 2 × 2 factorial arrangement to examine crude protein levels of supplement (14% or 18%) and ergovaline exposure (0 or 185 μg ergovaline/kg BW/d via ground endophyte-free (EF) or endophyte-infected (EI) tall fescue seed, respectively) on immune response. Consumption of low to moderate concentration of ergovaline from EI tall fescue seed was sufficient to induce mild symptoms associated with fescue toxicosis. Blood samples were collected at day 0, 42, and 56 to evaluate infectious bovine rhinotracheitis (IBR) and bovine viral diarrhea virus (BVDV) type 1b titers following vaccine challenge. Additionally, serum cytokine concentrations were evaluated using Quantibody Bovine Cytokine Arrays on day 0, 28, and 42. Data were analyzed using PROC MIXED of SAS with repeated measures. Regardless of treatment, no differences were observed in IBR and BVDV-1b seroconversion following vaccine challenge (P > 0.05). Regardless of crude protein concentration, EI steers had greater concentrations of proinflammatory cytokines (TNF-α, IFN-γ, IL-1α), chemokines (CCL2, CCL4, MIG), anti-inflammatory cytokines (IL-2, -13, -15, -21), and various growth factors (FGF-1, IGF-1, VEGF-A) when compared to EF steers (P < 0.05). Furthermore, VEGF-A and IGF-1 concentrations were greater in EI-14 steers on day 28 compared to EI-18, EF-14, and EF-18 steers (P < 0.05), however, this difference was not observed on day 0 or 42 (P > 0.05). Based on these data, steers exposed to ergovaline have an increase in pro- and anti-inflammatory cytokines and supplemental CP had minimal impact to mitigate this response. However, in the current study, exposure to ergovaline had little to no effect on adaptive immunity and response to vaccination. Together, chronic exposure to ergovaline results in a hyperactive innate immune response, which may lead to an immuno-compromised animal.

6 The effect of competition for an automated supplement feeder on supplement intake behavior of stocker steers

Abstract Interest in automated, precision feeding equipment is increasing, and users need information about how to effectively use this new approach. Our objective was to determine the effect of competition for a feeding space at an automated supplement feeder on supplement intake behavior. Mixed breed beef steers (n = 128, initial BW = 257 ± 29.2 kg) were randomly assigned to 8 paddocks. One paddock (16 steers) was selected to have continuous access to the feeder for the duration of the 16-wk trial; this paddock was designated the “tester” paddock. The automated feeder consisted of a large bin that dispensed supplement into 4 feeding stations. Supplement dispense was triggered by the presence of an eligible animal’s RFID tag; each steer was limited to 0.50 kg supplement/d by the electronics of the feeder. Weekly, additional paddocks were commingled with the tester paddock to increase competition for the feeder, resulting in a stocking density from 4 to 32 steers per feeding station in various weeks. Approximately 30% of the steers did not voluntarily use the feeder; therefore, effective competition was less than the study design. Supplement intake and GPS location were recorded for steers in the tester paddock, and averaged for each wk; week was the experimental unit (n = 16). Weekly mean supplement intake and time spent near the feeder were regressed on feeder stocking density. Tester steers consumed an average of 0.36 kg supplement/d. Competition for a feeder space numerically reduced (P = 0.15) supplement intake by 0.002 kg/d per steer of competition. Steers spent 6% of the time within 15 m of the feeder regardless of competition (P = 0.82). These data illustrate that in scenarios similar to these experimental conditions, the feeder can be stocked with at least 80 animals with minimal effects on supplement intake.

179 The effect of competition for an automated supplement feeder on supplement intake behavior of stocker steers

Abstract Interest in automated, precision feeding equipment is increasing, and users need information about how to effectively use this new approach. Our objective was to determine the effect of competition for a feeding space at an automated supplement feeder on supplement intake behavior. Mixed breed beef steers (n = 128, initial BW = 257 ± 29.2 kg) were randomly assigned to 8 paddocks. One paddock (16 steers) was selected to have continuous access to the feeder for the duration of the 16-wk trial; this paddock was designated the “tester” paddock. The automated feeder consisted of a large bin that dispensed supplement into 4 feeding stations. Supplement dispense was triggered by the presence of an eligible animal’s RFID tag; each steer was limited to 0.50 kg supplement/d by the electronics of the feeder. Weekly, additional paddocks were commingled with the tester paddock to increase competition for the feeder, resulting in a stocking density from 4 to 32 steers per feeding station in various weeks. Approximately 30% of the steers did not voluntarily use the feeder; therefore effective competition was less than the study design. Supplement intake and GPS location were recorded for steers in the tester paddock, and averaged for each wk; week was the experimental unit (n = 16). Weekly mean supplement intake and time spent near the feeder were regressed on feeder stocking density. Tester steers consumed an average of 0.36 kg supplement/d. Competition for a feeder space numerically reduced (P = 0.15) supplement intake by 0.002 kg/d per steer of competition. Steers spent 6% of the time within 15 m of the feeder regardless of competition (P = 0.82). This data illustrates that in scenarios similar to these experimental conditions, the feeder can be stocked with at least 80 animals with minimal effects on supplement intake.

Short Communication: Evaluation of 2 implants for growing steers grazing tall-grass prairie when using intensive early stocking

ABSTRACT Commercial implants can have different coating technologies, carriers, and hormone amounts that result in different payout characteristics and effects on cattle growth. Therefore, the objective of this study was to evaluate 2 implants in stocker steers on a 90-d grazing season. Implants were Revalor-G (REV), which contains 40 mg of trenbolone acetate and 8 mg of estradiol, is uncoated, and has a cholesterol carrier, or Synovex One Grass (SYN), which contains 150 mg of trenbolone acetate and 21 mg of estradiol benzoate and has a porous polymer coating. Steers (n = 242) were weighed with an overnight shrink on d 0, 44, and 91. Steers were implanted on d 0 and assigned to 1 of 7 pastures in a completely randomized complete block design with pasture as block. Total gains and gains in each half of the grazing season were evaluated. Average daily gain was not different based on implant type (P = 0.35; 1.16 kg/d for REV and 1.13 kg/d for SYN; SEM = 0.02) nor was total BW gain (P = 0.65; 101 kg for REV vs. 100 kg for SYN; SEM = 2.3). Additionally, BW gain and ADG were not different between implants in both sections of the grazing period (P ≥ 0.45). Overall, cattle performance was not different regardless of hormone amount and coating technology in implants in a short-duration grazing period with stocker steers, and these data do not support a price premium for SYN over REV in this grazing system.