Performance Of Steers Research Articles

Partial state-constrained integrated guidance and control for an STT missile with self-adjusting prescribed performance via non-barrier Lyapunov function method

A state-constrained guidance and control law is vital to the flight safety of an aerial interceptor against a maneuvering target. Taking the flight angle limitations, manipulation saturation, and terminal constraints into consideration, a novel integrated guidance and control (IGC) schema with a self-adjusting prescribed performance is proposed. To avoid the feasibility condition via the conventional barrier Lyapunov function-based method, a new state-dependent nonlinear mapping function is designed, based on which the state-constrained IGC system is converted into a constrained-free model. A novel prescribed performance with a self-tuning mechanism is proposed to guarantee satisfied transit and steady guidance performances. The backstepping technique combined with super-twisting integral sliding modes and newly defined predefined-time disturbance observers is implemented to generate state-constrained virtual command signals. All the signals in the closed-loop system are strictly proven to be bounded by Lyapunov stability theory. The simulation results show the effectiveness of the proposed IGC schema.

Dietary effects of protected fat, soybean meal, and heat-treated soybean meal on performance, physiological parameters, and behavioral measurements of early-fattening Hanwoo steers under heat stress conditions.

This study evaluated the effects of increased levels of dietary total digestible nutrient (TDN) and crude protein (CP) using protected fat (PF), soybean meal (SB), and heat-treated soybean meal (HSB) on performance, physiological parameters, and behavioral measurements of early-fattening Hanwoo steers under heat stress conditions. Thirty-six steers (480.9 ± 58.6 kg, 15.9 ± 1.4 months) were assigned to 4 treatments: Control (TDN 75%, CP 15%, rumen degradable protein [RDP]:rumen undegradable protein [RUP]=62:48), PF (TDN 82.5%, CP 15%, RDP:RUP=62:48), PF+SB (TDN 82.5%, CP 16.5%, RDP:RUP=62:48), and PF+SB+HSB (TDN 82.5%, CP 16.5%, RDP:RUP=48:52) for a total of 16 weeks with division of 4 weeks. The average temperature-humidity index (THI) was 82.9 (1st; Moderate), 76.9 (2nd; Mild), 70.9 (3rd; Comfort), and 65.8 (4th period; Comfort). Dry matter intake during whole period did not differ among treatments but decreased by 34% and 19%, respectively during 1st and 2nd compared to 4th. Average daily gain (ADG) of PF+SB+HSB was higher (p<0.05) than that of Control during the 1st period, and those of both PF+SB and PF+SB+HSB were higher (p<0.05) than Control during the 2nd. The ADG during whole period was in the order of PF+SB+HSB (1.23), PF+SB (1.18), PF (1.11), Control (0.98 kg/d) (p<0.05). As THI increased, rectal temperature and all blood parameters increased, while blood glucose levels decreased (p<0.05). Behavioral changes during 1st period compared to 3rd included decreases in Lying (24%), Walking (48%), and Eating (40%), and increases in Total standing (50%) and Drinking (43%) (p<0.05). Rumination during standing was 38% higher, and Rumination during lying was 32% lower (p<0.05). This study demonstrates 10% of increased levels of dietary TDN using PF and CP considering RUP can prevent performance reduction in early-fattening of heat-stressed Hanwoo steers and have positive effects on performance recovery from post-heat stress.

System Integration Design of High-Performance Piezo-Actuated Fast-Steering Mirror for Laser Beam Steering System

This paper presents an innovative piezo-actuated fast-steering mirror (FSM) that integrates control design and system operation to improve the tracking performance of laser beam steering (LBS) systems. The proposed piezoelectric FSM is centered on two pairs of stacked actuators functioning in the tip-tilt direction via novel flexible hinges with strain-gauge sensors for position measurement. The suggested flexible hinge scheme allows the first fundamental resonance mode with the optical mirror to exceed 400 Hz while achieving an actuation range of ±5 mrad. Thus, the design offers a wider mechanical actuation range than conventional piezoelectric FSMs. Moreover, LBS systems that use fast-steering motion controllers should be robust against dynamic disturbances, such as periodic external vibrations. Such disturbances, inherently associated with the operating conditions for LBS systems, typically reduce the stability of the tip-tilt motion. To attenuate the effects of such disturbances, a high-precision control system is necessary for the tip-tilt motion. Therefore, a control method integrating a proportional–integral controller with an adaptive feedforward control (AFC) algorithm is outlined to enhance tip-tilt tracking performance during high-speed scanning, compared with conventional LBS systems. Based on experimental findings, the AFC algorithm boosted control performance under dynamic disturbances, such as sinusoidal vibrations with multiple frequencies.

Numerical simulation and experimental study on guidance performance of hypersonic seeker under aerodynamic optical transmission effects

When a hypersonic seeker flies at high speed within the atmosphere, intense interaction with the incoming flow gradually develops into a complex turbulent flow field. This interaction results in complex thermal responses at the seeker window, causing aerodynamic optical effects such as image shift, jitter, and blur of the target image, thereby restricting the seeker's detection capability and accuracy. This paper uses a numerical simulation model for the guidance performance of a hypersonic seeker under aerodynamic optical transmission effects. The study focuses on an ellipsoidal seeker, with its supersonic flight simulation on the basis of the Reynolds-Averaged Navier-Stokes (RANS) equations to get a non-uniform gradient flow field. The correctness of the flow filed results can be verified by wind tunnel experiments. The transient temperature field of the seeker is solved using an unsteady thermal conduction-radiation coupled fluid-solid heat transfer method. Finally, the guidance performance of the hypersonic seeker under aerodynamic optical effects is predicted using the ray tracing method, which employs wavefront aberration, point spread function, degraded images, and image shift.

Improving the steering performance of microrobots by using a magnetically actuated technique

Mobile microrobots show the significance of potential medical procedures and challenge areas within the human body. An applied electromagnetic field is used as a precise magnetic actuation system for controllable steering mobility, and positioning is used. In this work, an adaptable microrobot is developed with an effective technique to enhance steering. An electromagnetic system is employed to produce an external magnetic field that guides a microrobot to improve its steerability. In particular, a driving system of eight coils creates a magnetic field that actuates the microrobot and enables upward and downward motion. Accordingly, three types of microrobot designs are proposed. Consequently, an efficient variation of steering in terms of deformation angle is achieved. The corresponding performance is determined mathematically in terms of the main system parameters, such as external magnetic field and microrobot geometry. In addition, finite element model is used for comparison and validation. Simulation results show that for a relatively high value of magnet field, namely, 15 mT and 90°, the deformation angles were 36.98° for the first design, 39.11° for the second design, and 34.48° for the third design in upward deformation. By contrast, the downward deformation ranges were –40.42°, –39.46°, and –37.04° for the first, second, and third designs, respectively, at –90° The error between the upward and downward steering of the second design had the lowest value of 0.35° The second design of the microrobots has the least error between the upward and downward deformation ratio at 0.89 %. In comparison, the first design has a 9.3 % error, and the third design has a 7.42 % error, with a relatively high value of magnetic field density (15 mT). Simulations have shown that the proposed second design is suitable for navigating narrow artery branches with the least error ratio and more precise control. This work verifies that the model could accurately control the steering of microrobots.

Growth performance, carcass characteristics and meat quality of Northern Finncattle steers compared to Holstein steers offered grass silage‐grain‐based ration

Growth performance, carcass characteristics and meat quality of Northern Finncattle steers compared to Holstein steers offered grass silage‐grain‐based ration

PSIV-25 Utilization of rumen protected lysine and methionine in beef feedlot diets: Impacts on steer performance

Abstract Our objective was to compare intake, gain, and feed efficiency of steers fed rumen protected lysine and/or methionine in 10% crude protein diet relative to performance of steers fed a diet with 13% crude protein without added amino acids. Beef steers [n = 161; body weight (BW) = 429.7 ± 44.5kg] were used in this experiment. Calves were randomly assigned to treatments consisting of 1) positive control diet (POS), formulated to contain 13.0 to 13.5% CP, 2) negative control (NEG) diet containing 10.2% CP, which also forms the basal diet for the remaining treatments, 3) rumen protected methionine (RPMet) 10.2% CP basal diet and 7.2 g/d supplemental methionine, 4) rumen protected lysine (RPLys) 10.2% CP basal diet and 18.5 g/d supplemental lysine, and 5) the combination of rumen protected lysine and methionine (RPMet+Lys) 10.2% basal diet with 7.2 and 18.5 g/d supplemental methionine and lysine, respectively. Initial and final BW were unaffected by treatment (P ≥ 0.24). Average daily gain for POS (1.93 kg/d P ≤ 0.02) was greater than those of NEG, RPLYS, and RPMET+LYS, but was similar to RPMET (1.86 kg/d; P = 0.17). Dry matter intake was greater in RPMET (12.1kg/d; P ≤ 0.10) compared with all other treatments. Gain-to-feed ratio was greatest in POS (0.170 kg gain:kg DMI; P ≤ 0.04). The impacts of rumen-protected amino acids on performance (intake, gain, and efficiency) of beef steers fed high-concentrate diets were inconsistent. Evaluating both lysine and methionine supplied independent of each other in various concentrations is critical before moving forward with recommendations for beef cattle. USDA is an equal opportunity provider and employer.

PSVII-14 Influence of dam parity and weaning strategy in previous lactation on feedlot performance of Nellore steers

Abstract In tropical beef cattle production systems, the impact of seasonality may be particularly challenging for young cows (primiparous or secondiparous) due to their increased nutritional requirements, encompassing maintenance, growth, gestation, and, in the case of secondiparous cows, lactation. Literature indicates that extending the duration of lactation during gestation is associated with decreased performance of progeny in their postnatal life. Therefore, implementing an early weaning approach can be an effective strategy to alleviate the nutritional demands of lactation in dams, thereby allocating more nutrients for fetal growth. This study aimed to evaluate the effect of early weaning on the feedlot performance of progeny that were in utero at the time of weaning intervention. To create experimental units, secondiparous and multiparous Nellore cows were assigned to one of two weaning strategies, where suckling calves were either; 1) early weaned 150 d (EW); or 2) conventional weaned at 240 d (CW). All calves were weaned at 150 d of lactation in 2022. Three bulls were used: Bull 1: had 13 calves with multiparous cows, had 7 calves with secondiparous cows, comprising 11 EW and 9 CW; Bull 2: had 10 calves with multiparous cows, had 6 calves with secondiparous cows, comprising 6 EW and 10 CW; and Bull 3: had 7 calves with multiparous cows, had 15 calves with secondiparous cows, comprising 11 EW and 11 CW. All cows were managed similarly after weaning, and through parturition, and weaning of subsequent calf, with resulting calves used for the current experiment. Nellore bulls (n = 57) with an initial body weight (BW) of 417.23 ± 9.12 kg and 18 mo of age were allocated to feedlot pens (equipped with Intergado equipment) and fed a common total mixed ration (80:20; concentrate:corn silage) for 97 ± 1.60 d. Bulls were distributed in a randomized complete block in a 2 × 2 factorial arrangement, considering dam weaning strategy in the previous lactation (EW and CW) and dam parity at subsequent calving (multiparous or secondiparous cows, MC and SC, respectively). Data were analyzed using PROC MIXED of SAS 9.4, with a model including the effects of dam weaning strategy, dam parity, and their interaction. Data were considered significant when P values were less than 0.05 and indicated a trend when 0.05 &amp;lt; P ≤ 0.10. There was an interaction between weaning strategy and cow parity, with calves born to SC-CW having reduced initial (P = 0.04) and final BW (P = 0.01) compared with all other groups (Figure 1 and 2). Steers from MC had greater dry matter intake (P = 0.003), and greater biological efficiency (P = 0.03; Table 1). Early weaning improved the final BW of steers born to secondiparous cows, suggesting it could be a strategy to enhance the performance of offspring and the reproductive performance of both secondiparous and multiparous cows.

PSXIII-7 Effects of whole corn on gain and subsequent feedlot and carcass traits of Brahman steers stocked on Tifton 85 bermudagrass

Abstract Supplementation (SUP) of stocker calves is used to enhance gain and/or adjust for stocking rates (SR). Our objective was to determine the influence of whole corn on performance of steers stocked on Tifton 85 bermudagrass [Cynodon dactylon (L.) Pers. X Cynodon nlemfuensis Vanderyst] (T85) that has documented forage crude protein ranging from 18.5% in June to 13.5% in September. For a 3-yr period, Brahman (Bos indicus) steers, 15 mo old and 275 kg body weight (BW), were stocked on T85 and received daily whole corn at 0 (PAS), 0.3% BW (SUP3), or 0.6% BW (SUP6). A fourth treatment included SUP6 at an increased stocking rate (SUP6SR). The 3-yr average SR of 275 kg steers was 11 steersּ ha-1 on PAS, SUP3, and SUP6, and 15 steersּ ha-1 on SUP6SR. Average daily gain (ADG) was similar for SUP steers at 0.98 kgּ d-1 (SUP6), 0.92 kgּ d-1 (SUP3), and 0.92 kgּ d-1 (SUP6SR), but greater (P = 0.002) than PAS steers at 0.84 kgּ d-1. Steer gainּ ha-1 was greatest (P = 0.001) for SUP6SR at 1230 kgּ ha-1. Gain ha-1 was similar for SUP6 and SUP3 at 1,010 kgּ ha-1 and 941 kgּ ha-1, respectively, and similar for SUP3 and PAS (860 kg-1). Body weights off pasture tended to be greater (P = 0.083) for all SUP steers at 370 kg than PAS steers at 354 kg. Body condition score off pasture was similar for all SUP steers at 5.7 and different (P = 0.001) from PAS steers at 5.2. At termination of stocking, steers were shipped 700 km to a commercial feedlot in South Texas. Each year, steers were fed in the same pen until a visual assessment of about 1.25 cm backfat was attained. Days on feed were similar for all steers at 190 d. Feedlot ADG was similar for steers on SUP3 (1.36 kgּ d-1), PAS (1.34 kgּ d-1), and SUP6SR (1.29 kgּ d-1), but greater (P = 0.045) than steers on SUP6 (1.24 kg d-1). These feedlot ADG exhibited some compensatory gain effects from pasture treatments. Off feedlot weights were similar at 620 kg. Steers were transported 60 km to an abattoir for harvest and carcass trait evaluations. There were no differences across treatments for steer hot carcass weight, 367 kg; 12th rib fat thickness, 1.13 cm; marbling score, 395; calculated yield grade, 3.10; longissimus dorsi area, 85.02 cm2; or internal fat (kidney-pelvic-heart), 1.92%. With SUP:extra gain at 12.5:1 for SUP3 and 13.8:1 for SUP6, supplementation of whole corn for Brahman steers stocked on T85 was not as efficient as previous T85 x SUP experiments with DDGS, but may offer management options for specific cattle classes and ownership-stocking strategies.

485 Impact of annual and perennial forage systems on forage biomass and quality, steer performance, and enteric methane emissions

Abstract Beef producers require forage options that provide adequate yield and high nutritive value, optimizing the production and sustainability of grazing operations. Few multiple year studies within Canada compare novel perennial and annual grass legume blends under grazing. This study evaluated the effects of perennial and annual forage systems on forage biomass and quality, grazing animal performance, and enteric emissions. Forage treatments included 1) AC Success hybrid bromegrass (Bromus riparius Rehm. × Bromus inermis Leyss.) + PS3006 alfalfa (Medicago sativa L.; HBG-ALF), 2) AC Armada meadow bromegrass (Bromus riparius Rehm.) + AAC Mountainview sainfoin (Onobrychis viciifolia Scop.; MBG-SF), 3) AC Hazlet fall rye (Secale cereale L.) + Frosty berseem clover (Trifolium alexandrinum L.; FR-CLOV), and 4) Winfred forage brassica (Brassica oleracea L.× Brassica rapa L.) + Gorilla forage brassica (Brassica napus L.) + 4010 pea (Pisum sativum L.) + CDC Austenson barley (Hordeum vulgare L.; BR-PE-BRAS). Yearling beef steers [n = 120, body weight (BW) = 397 ± 10 kg] were randomly allocated to 1 of 4 replicated (n = 3) forage systems for an average of 65 d grazing period amongst the 12 paddocks. Dry matter yield (DMY) was similar (P = 0.33) between BR-PE-BRAS (2,170 kg/ha) and HBG-ALF (1938 kg/ha), which were greater (P &amp;lt; 0.0001) than both MBG-SF (1030 kg/ha) and FR-CLOV (700 kg/ha) systems. Total digestible nutrient content (TDN) of FR-CLOV (63.6%) and BR-PEA-BRASS (62.0%) was greater (P &amp;lt; 0.0001) than both MBG-SF (51.7%) and HBG-ALF (49.3%) forages. Crude protein (CP) was greatest in FR-CLOV (15.2% P = 0.0012) intermediate in BR-PEA-BRASS (10.0%) and HBG-ALF (8.5%), and least in MBG-SF (6.6%). Steer performance was greatest when grazing HBG-ALF (87 kg/ha) paddocks, which was similar (P = 0.31) to FR-CLOV (62 kg/ha) and similar (P = 0.10) MBG-SF (51 kg/ha), but greater (P = 0.01) than BAR-PEA-BRASS (26 kg/ha). Enteric methane concentration from steers was the least when grazing BR-PE-BRAS (19.7g/kg DMI), followed by FR-CLOV (22.4g/kg DMI), MBG-SF (23.4g/kg DMI) and finally HBG-ALF (28.1g/kg DMI). In summary, BR-PE-BRAS and HBG-ALF forage systems provided the greatest DMY, while steer average daily gain (ADG) grazing HBG-ALF forage outperformed steers on BR-PE-BRAS paddocks. Forage energy and protein was greater in annual forage systems FR-CLOV and BR-PE-BRAS, compared with perennial forage systems. Enteric methane levels were the lowest in the steers grazing BR-PE-BRAS forage.

64 Effects of alternative finishing methods on performance and carcass quality of beef feeder steers

Abstract There has been an interest in directly locally marketing finished beef end products in Arkansas; however, most beef operations do not have the infrastructure to finish cattle conventionally. The objective of this study was to evaluate two non-traditional finishing methods (pasture-based with supplement) compared with a conventional finishing method on live performance and carcass quality of feeder steers. Crossbred beef steers (n = 63; 363.9 ± 28.7 kg) were blocked by body weight (BW) and assigned to pens (n = 3 steers/pen) with 7 pens randomly allocated to each treatment: conventional feedlot finishing diet with roughage included in the ration (FDLT); high starch supplement fed at 2 to 2.25% of BW with ad libitum access to bermudagrass pasture (STCH); or high by-product supplement fed at 2-2.25% of BW with ad libitum access to bermudagrass pasture (BYPD). Steers were fed their respective diets once daily and weighed on d 0, 28, 56, 84, 112, 140, and 161. Once cattle reached their targeted endpoint, they were transported to and harvested at a commercial slaughter facility in Arkansas City, Kansas. Carcass data were collected including hot carcass weight (HCW), preliminary yield grade (PYG), yield grade (YG), quality grade (QG), dressing percentage (DP), and final carcass value. Data were analyzed using PROC GLIMMIX and MIXED (SAS 9.4); pen was the experimental unit, treatment was a fixed effect, and block was considered a random effect. Cattle fed FDLT and BYPD had a greater BW on d 84, 112, and 140 (P ≤ 0.02) and greater overall carcass-adjusted BW (P = 0.03) compared with STCH. Average daily gain (ADG) was greater on d 84 (P = 0.03) for FDLT compared with STCH and BYPD. Overall carcass-adjusted ADG tended (P = 0.09) to be greater for FDLT and BYPD compared with STCH. As expected, cattle fed FDLT had greater dry matter intake (DMI) compared with STCH and BYPD for the entire study (P ≤ 0.0005). Both STCH and BYPD had a more efficient feed-only feed conversion on d 28, 56, 112, 140, and 0-161 (P ≤ 0.05) and were more economical (P &amp;lt; 0.0001) than FDLT. In this study, cattle fed BYPD were more profitable (P ≤ 0.04) compared with STCH and FDLT. Hot carcass weight tended (P = 0.13) to be greater and final carcass value (P = 0.01) was greater for BYPD and FDLT compared with STCH. No differences (P ≤ 0.78) were noted for PYG, YG, QG, or DP. Data from this study suggests feeding supplemental diets to beef cattle grazing pasture could successfully be used as an alternative finishing method without affecting carcass quality.

417 Impact of virtual fence technology on yearling steer behavior and performance

Abstract Virtual fencing (VF) has the capacity to transform the landscape of livestock management within extensive rangeland systems. The objective of this study was to evaluate the effect of Vence (Merck &amp; Co., Inc., Rahway, NJ) VF technology on yearling steer behavior and performance. Steers were allocated into one of two grazing systems [continuous grazing (CG) or rotational grazing (RG) managed using VF] across three different stocking rates (light, moderate, and heavy, 0.32, 0.40, and 0.72 animal unit months, respectively) for three grazing seasons. Based on initial body weight, steers were randomly blocked into six pastures (346 ± 39, 273 ± 34, and 319 ± 29 kg, respectively) at the South Dakota State University Cottonwood Field Station (n = 127, 135, and 127, in 2021, 2022 and 2023, respectively). Steers assigned to the CG treatment had free access to the entire pasture for the duration of the grazing season. Steers assigned to the RG treatment were rotated among virtual ‘paddocks’ for the duration of the grazing season. The days spent grazing in each paddock for the RG treatment were determined based on bi-weekly clip plots for biomass estimation. The VF collars were used to track steer location at 5-min intervals; only steers assigned to the RG treatment were managed with VF boundaries and exposed to auditory and electrical cues from the collars. Raw data was downloaded from Vence Herd Manager through an automatic programming interface and cleaned by removing messages that failed to transmit correctly or were outside the bounds of study site pastures. Animal behavior metrics of daily distance traveled (DDT), daily grazing time, daily resting time, and daily walking time were calculated for each individual animal and averaged by pasture using Program R. Steer weights were collected using SmartScales (C-Lock Inc, Rapid City, SD). Average daily gain (ADG) was calculated using a linear model to develop a regression equation for each individual animal using weight as the dependent variable and day of trial as the independent variable. The slope of the regression line was used to estimate ADG. Individual DDT, behavior, and performance metrics were analyzed using a mixed model analysis of variance (ANOVA) to compare the impact of grazing treatment and stocking rate (fixed effects) with year as the random effect. Treatment did not influence (P &amp;gt; 0.05) grazing, walking, or resting behavior. Similarly, no differences were detected in DDT between treatment groups or across different stocking rates. Furthermore, there were no differences (P &amp;gt; 0.05) in ADG across treatment groups. Implementation of VF had no impact on animal behavior or performance, justifying its use in grazing settings; however, financial and cattle finishing aspects still need to be evaluated to determine its overall benefits and costs.

511 Assessing the carry-over effects of precision livestock technology on steer performance and carcass characteristics

Abstract Our objective was to evaluate how virtual fencing grazing management during the stocker phase influences steer growth performance, carcass traits, and enteric emissions during the finishing phase. Angus steers [n = 96; initial body weight (BW) = 375 ± 7.2 kg) grazed native rangeland from 07 June 2023 to 31 August 2023 in Cottonwood, SD at South Dakota State University’s Cottonwood Field Station. Following summer grazing, steers were transported to Brookings, SD and fed for 130-d at the South Dakota State University Cow-Calf Education and Research Facility. During the summer grazing season, steers were assigned to different stocking rates (Light, Moderate, and Heavy, at 0.32, 0.42, and 0.72 animal unit months, respectively), and grazing strategies [continuous (CG) or virtual fencing rotational (RG)] in a 2 × 3 factorial design. Steers were transitioned from a 30% roughage to a 10% roughage diet over 21-d. The finishing diet (13.7% CP, 17.2% NDF, 1.36 Mcal/kg NEg, and 30 g/907-kg monensin sodium) was manufactured twice daily and provided ad libitum. Feed consumption was tracked using precision monitoring equipment (Insentec, The Hague, Netherlands). Steers were individually weighed on d 1 (entry BW), 21, 63, 90, and 130 and administered a steroidal implant (200 mg trenbolone acetate and 20 mg estradiol; Revalor-200, Merck Animal Health, DeSoto, KS) on d 21. Enteric emissions, including methane and carbon dioxide, were monitored using the GreenFeed trailer system (C-Lock Inc., Rapid City, SD), growth performance, carcass traits, and categorical carcass traits were analyzed in a factorial design using a randomized complete block design with individual steer considered the experimental unit. Final BW was determined from hot carcass weight divided by 0.625. Steers from heavy-CG had greater feedlot entry BW (P ≤ 0.05) compared with all treatments except light-CG and light-RG. Light-CG and light-RG had greater entry BW compared with heavy-RG (P ≤ 0.05). Gain efficiency was greater for light-CG compared with light-RG, moderate-CG, and heavy-CG (P ≤ 0.05), while moderate-RG and heavy-RG were intermediate (P ≤ 0.05). Steers from moderate-RG had greater marbling scores compared with heavy-RG (P = 0.05), and all other treatments were intermediate. Neither stocking density (P ≥ 0.15) nor grazing management strategy (P ≥ 0.13) had any influence on other measures of growth performance, emissions (CH4 and CO2) production rate, or carcass traits. These findings suggest that stocking density and grazing-management strategy (CG vs. virtual fencing-RG) influence gains on pasture and alter feedlot entry BW, highlighting the need for further investigation into their implications for greenhouse gas emissions, as well as for determining optimal stocking densities and management strategies for ranchers

354 Zinc supplementation prior to transit and transit duration effects on feedlot performance and muscle fatigue of beef steers: Part II – Feeding Behavior

Abstract This study assessed the effects of supplemental Zn on cattle feeding behavior after varying transit duration. Angus crossbred steers (80; 265 ± 18 kg) were used in a 2 × 2 factorial design. Steers were assigned to a dietary Zn treatment (DIET) and transit duration (DUR; d 0): Zn0 (no supplemental Zn) or Zn100 (100 mg Zn/kg DM; supplemented as ZnSO4, starting d -42 relative to transit) and short duration (8H; 8 h transit; 707 km) or long duration (18H; 18 h transit; 1608 km). Steers were fed ad libitum via GrowSafe bunks (GrowSafe Systems Ltd., Airdrie, AB, Canada), and steer was experimental unit (n = 1 bunk/pen; n = 5 steers/pen). On d 0, steers were stratified to trailer compartments across diets. The 8H and 18H groups departed at 1000 and 1300 h and returned at 1800 and 0700 h to pre-transit pens, respectively. Following transit, all steers received Zn100. Utilizing GrowSafe Behavior module, a feed event was characterized as a reading with &amp;lt; 300 s interruption with head down (FE-HD; recorded in seconds) and count (number of HD events). Intake rate (g/s) was feed consumed per FE-HD divided by FE-HD duration. Data for the 6-d post transit were analyzed as a complete randomized design utilizing PROC MIXED of SAS 9.4 (SAS Inst. Inc., Cary, NC) with fixed effects DIET, DUR, and DAY as repeated. Pre-transit values served as a covariate. During the week prior to transit, there was a DUR effect for FE-HD average and intake rate (P ≤ 0.03) where 8H had longer FE-HD but reduced intake rate than 18H. There was also a tendency for Zn100 to consume more feed per FE pre-transit (P = 0.07). Post-transit, both average intake and FE-HD average increased with days post-transit (DAY; P ≤ 0.01). Additionally, a DIET × DUR effect was observed for FE-HD count (P = 0.01) where 100 was greater than 0 within 18H and 0 was greater than 100 in 8H. A tendency for a TRT × DAY effect was noted for FE-HD count (P = 0.07) driven by Zn0 decreasing from d 3 to 4. A DUR × DAY effect (P = 0.02) was also noted for FE-HD count where 18H was greater on d 2, 4, and 5. A DUR × DAY effect was observed for FE-HD average (P = 0.01) driven by a d 3 difference where 8H was greater than 18H. Conversely, a DUR × DAY effect was observed for intake rate (P = 0.01) where 18H was greater on d 2, 3, and 6. These data indicate both transit duration and dietary Zn concentration influenced animal behavior post-transit.

353 Zinc supplementation prior to transit and transit duration effects on feedlot performance and muscle fatigue of beef steers: Part I – Performance and Muscle Fatigue

Abstract This study investigated zinc (Zn) as a mitigation strategy for transit-induced muscle fatigue. Recently weaned Angus-cross steers (n = 80) were stratified by body weight (BW = 265 ± 18.0 kg) to a 2×2 factorial. Dietary (DIET) treatments of no supplemental Zn (Zn0) or 100 mg supplemental Zn/kg DM (Zn100; Zn as ZnSO4), were fed for 42 d before transit. Along with a transit duration (DUR) of 8 h (~707 km; 8H) or 18 h (~1,608 km; 18H) on d 0. Upon return, and for 56 d post-transit, all steers received Zn100. Individual feed disappearance was monitored using GrowSafe bunks (1 bunk/pen; 5 steers/pen). Body weights were collected on d -42, -41, -1, 0 (on truck), 1 (off truck), 2, 7, 28, 55, and 56. Blood samples for analysis of non-esterified fatty acid (NEFA) and serum L-lactate were collected on d -1, 1, 2, and 7. Data were analyzed via ProcMixed of SAS (experimental unit = steer; 15 to 20/treatment) as a 2 × 2 factorial, with fixed effects of DIET, DUR, and the interaction. Individual initial (d -42) BW was used as a covariate in BW analysis. Average DMI of d -11 to d -2 (pre-trucking) was used as a covariate in post-transit DMI analysis. Blood parameters were log-transformed and analyzed as repeated measures with repeated effect of day. Pre-transit (d -1) concentrations were used as a covariate. Pre-transit average daily gain (ADG) and dry matter intake (DMI) were greater (P ≤ 0.02) and feed efficiency (gain to feed; G:F) tended to be greater (P = 0.10) in Zn100 vs. Zn0. BW on d -1 and 7 (P = 0.01) was greater for Zn100 than Zn0. There was a DIET effect and DUR tendency on post-transit G:F where Zn0 was greater than Zn100 (P ≤ 0.01) and 18H tended to be greater than 8H (P = 0.05). 56-d post-transit ADG was least for Zn100-8H (DIET×DUR, P = 0.02). Post-transit DMI was greatest for Zn0-8H with Zn100-8H being the lowest and other treatments being not different (DIET × DUR, P = 0.04). Diet did not affect L- lactate or NEFA concentrations (P &amp;gt; 0.13). NEFA was greater for 18H vs. 8H on d 1 and 2 but less on d 7 (DUR×DAY, P &amp;lt; 0.01). There was a DUR×DAY effect (P ≤ 0.01) for L-Lactate where 8H tended to be greater than 18H on d 1, but by d 2 8H was lesser than 18H, and on d 7 they were not different. In conclusion, longer transit duration increases some indicators of muscle fatigue and Zn supplementation improved pre-transit performance. Receiving Zn supplementation after trucking also improved the post-transit performance of those not previously supplemented with Zn.

22 Effects of trace mineral source and chromium propionate supplementation on rumen fermentation, growth performance, and carcass characteristics in finishing beef steers

Abstract Crossbred beef steers [n = 400; body weight (BW) = 370 ± 8 kg] were used to evaluate the effects of trace mineral (TM) source and chromium propionate (Cr) on rumen fermentation characteristics, plasma glucose and mineral concentrations, performance, and carcass characteristics in feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW and randomly assigned within block to 1 of 4 treatments (10 steers/pen) with 10 pens per treatment. The experimental design was a randomized complete block design with a 2 x 2 factorial arrangement of treatments. Factors included: 1) TM source [sulfate or hydroxychloride (IntelliBond] Cu, Mn, and Zn TM supplemented at 18, 40, and 90 mg/kg DM, respectively) and 2) with or without supplemental Cr (KemTRACE) at 0.0 or 0.25 mg/kg DM. Steers were individually weighed on d -1 and 0 and every 28 d throughout the experiment. Jugular blood samples and rumen contents were collected from 10 steers per treatment on d 28 and 84 of the experiment for plasma glucose and TM concentration and volatile fatty acid analysis, respectively. On d 154 of the experiment, steers were harvested at a commercial abattoir and carcass data was collected. Data were analyzed on a pen mean basis for a randomized complete block design using PROC MIXED of SAS. There was no TM source by Cr supplementation interactions for any of the response variables measured, therefore only main effects are reported. Overall ADG (P = 0.03) and gain:feed (P = 0.02) were greater in steers receiving supplemental Cr when compared with steers not supplemented with Cr. Hot carcass weight (P = 0.04), dressing percentage (P = 0.01), longissimus muscle area (P = 0.03), and USDA yield grades (P = 0.04) were greater in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had a greater dressing percentage (P = 0.01) and longissimus muscle area (P = 0.04) compared with steers not supplemented with Cr. On d 28 of the experiment, ruminal acetate concentrations were lesser (P = 0.01) and ruminal propionate concentrations tended to be greater (P = 0.12) in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had greater ruminal acetate concentrations (P = 0.04) and plasma glucose concentrations (P = 0.05) on d 28 of the experiment when compared with non-supplemented controls. These data indicate the Cr supplementation and TM source can influence feedlot steer performance, carcass characteristics, and rumen fermentation characteristics.

Enhancing dynamic stability of HTS maglev systems with preloading method

High temperature superconducting (HTS) bulks have strong flux pinning capabilities and are widely used in various fields. Their self-stabilizing characteristics also provide new ideas for ultra-high-speed rail transit. For HTS maglev systems, operational stability, curve negotiation and safety when subjected to external forces are very important. Due to the hysteresis effect of superconducting bulks, they do not always return to their initial positions after deviating from the levitated position in an alternative external magnetic field. In some cases, the levitation system can be destroyed. Studies have shown that preloading can enhance quasi-static levitation performance. Therefore, this paper conducts a detailed analysis of the quasi-static levitation and guidance forces of HTS bulks above a Halbach permanent magnet guideway (PMG) under conditions with and without preloading. Additionally, the dynamic responses of the HTS bulks under lateral or vertical pulsed excitations are studied, with a particular focus on the final equilibrium position offset after disturbance. The results indicate that preloading can suppress the attenuation of the levitation force, enhance the guidance performance, and raise stiffness in both lateral and vertical directions. It also effectively suppresses position deviation from disturbance and increases the maximum excitation force threshold for system instability. This study provides practical insights for HTS maglev applications.

395 The effect of forage allocation on steer performance when grazing cereal rye

395 The effect of forage allocation on steer performance when grazing cereal rye

Orientation optimization of the Halbach PMG for the levitation and guidance performance of the HTS maglev system

High-temperature superconducting maglev technology has great application potential in rail transit applications due to its advantages such as passive stable levitation and green environmental protection. As one of the key components of the HTS maglev system, the Halbach-type permanent magnet guideway (PMG) enhances the magnetic field on one side of the guideway and weakens that on the other side. Optimizing the PMG, including the geometry and magnetic properties of the magnet, is an effective method to improve the levitation and guidance performance of the system. In addition, since NdFeB permanent magnets are expensive, optimizing the design of the PMG for the HTS maglev system is also an important work to reduce the application cost. In this paper, the Nelder–Mead Simplex method (NMS) in the optimization solver in COMSOL software is used to optimize the geometric parameters of the Halbach PMG according to the different objective requirements of the HTS maglev system. The optimization objectives include the maximum levitation force and guidance force under the constraint of the maximum cross-sectional area of the PMG, as well as the minimum cross-sectional area of the PMG with a minimum levitation force constraint. The results indicate that the NMS method is effective. By comparing four PMGs during the optimization process, it is found that this method can fully improve the utilization of the magnetic field by changing the geometric parameters of the Halbach PMG. This study can provide a valuable reference for the optimal design of the PMG for HTS maglev systems in the future.

自动驾驶拖拉机电液耦合转向特性研究

To solve the problem of poor steering performance of existing self-driving tractors based on electro-hydraulic coupled steering systems (E-HCSS) under multiple influencing factors, the research on electro-hydraulic coupled steering characteristics of self-driving tractors was carried out in this paper. Taking the electro-hydraulic coupled steering system as the research object, the E-HCSS test bench of the tractor was built, and the influencing factors affecting the responsiveness of the steering process were obtained through theoretical analysis: hydraulic fluid temperature, oil supply pressure and driving speed. The hydraulic fluid temperature, oil supply pressure and driving speed were taken as the test factors, and the steering system response time and response error were taken as the performance indexes for the single-factor steering test and orthogonal test. By establishing the regression mathematical model between the influencing factors and the indexes, the interactive influence of the factors on the indexes was analyzed, the optimal parameter combination was obtained, and the optimization results were verified. The test results indicated that the tractor electro-hydraulic coupling steering system could achieve good steering performance under the optimal parameter combination, and the optimal parameter combination was: hydraulic oil temperature 60°C, hydraulic oil pressure 15 MPa and driving speed 8 km/h. The study's results were as follows: hydraulic oil temperature 60°C, hydraulic oil pressure 15 MPa and driving speed 8 km/h. The study's results could provide a reference for the steering control of the self-driving tractor, the design of the self-driving steering system and the optimization of the parameters.