# Stocker Cattle Management: Grazing, Health, and Marketing Decisions ## Key Takeaways - Bovine Respiratory Disease (BRD) is the primary health concern, responsible for over 90% of morbidity and mortality in stocker operations, necessitating arrival processing within 24 hours, including vaccination against IBR, BVD, PI3, and BRSV, and parasite control. - Rotational grazing is critical for optimizing forage utilization and plant recovery, with cattle moved when cool-season grasses reach 4-6 inches or warm-season grasses reach 3-5 inches, allowing 21-30 days for regrowth. - Supplementation is essential as forage alone rarely meets nutrient requirements; protein supplementation is critical when forage crude protein drops below 7-8%, and energy supplementation may be needed as digestibility declines. - Monensin, an ionophore, can improve feed efficiency by altering rumen fermentation to favor propionate production, potentially increasing average daily gain by 3-5%, but requires careful intake monitoring and a 7-14 day adaptation period. - Marketing decisions should consider weight targets (typically 700-850 lb), price seasonality, and feedlot demand, with options including auction sales, direct sales, retained ownership, or forward contracting to manage price volatility. - Comprehensive record-keeping, including performance (ADG, cost of gain), health (vaccinations, treatments, withdrawal periods), and financial data, is fundamental for evaluating profitability and identifying areas for operational improvement. --- Stocker cattle operations bridge the gap between weaning and feedlot entry, using forage-based or limit-fed growing programs to add frame and weight before finishing. This article covers grazing system design, health risk mitigation, and marketing timing for producers managing stocker calves. The content draws on peer-reviewed veterinary and animal science literature, USDA technical resources, and industry proceedings to support practical decision-making. ## At a Glance: Stocker Enterprise Decision Framework | Decision Area | Primary Consideration | Common Approach | Key Limitation | |---------------|----------------------|-----------------|----------------| | Grazing system | Forage quality and availability | Rotational grazing on cool-season or warm-season pastures | Seasonal growth patterns require supplementation planning | | Health protocol | Bovine respiratory disease (BRD) risk | Vaccination upon arrival, metaphylaxis for high-risk calves | No single protocol fits all source-origin groups | | Marketing window | Weight gain target and price seasonality | Sell at 700-850 lb or retain ownership through feedlot | Price risk and feed cost volatility affect margin | ## Grazing Systems for Stocker Cattle ### Forage Species Selection Forage selection depends on regional climate, soil type, and intended grazing season. Cool-season grasses such as tall fescue, orchardgrass, and ryegrass provide high-quality growth in spring and fall. Warm-season grasses including bermudagrass and bahiagrass support summer grazing but decline in nutritive value as they mature. Legume incorporation, such as clover or alfalfa, can improve protein content and extend the grazing window. The USDA Natural Resources Conservation Service provides technical guides for forage species adapted to specific soil and climate conditions across the United States [1]. ### Rotational Grazing Implementation Rotational grazing involves moving cattle between paddocks based on forage height and regrowth stage. This system improves forage utilization, reduces selective grazing pressure, and allows rest periods for plant recovery. Stocking rate must match forage production capacity. Overstocking leads to reduced average daily gain and increased soil compaction. Understocking results in forage waste and reduced profit per acre. Practical steps for implementing rotational grazing include: 1. Divide pasture into at least four paddocks using permanent or temporary fencing. 2. Measure forage height before each move using a rising plate meter or grazing stick. 3. Move cattle when forage height reaches 4-6 inches for cool-season grasses or 3-5 inches for warm-season grasses. 4. Allow 21-30 days of regrowth before returning cattle to a paddock. 5. Adjust paddock size based on herd weight and desired intake. ### Supplementation Strategies Forage alone rarely meets the nutrient requirements of stocker calves for maximum gain. Protein supplementation is most critical when forage crude protein falls below 7-8%. Energy supplementation, typically from grain or byproduct feeds, may be needed when forage digestibility declines. The Veterinary Clinics of North America publication "Nutritional Management of Beef Stocker Calves in Grazing Systems" addresses supplementation timing and composition for grazing stockers [3]. Supplementation decisions should be based on: - Forage quality test results from each paddock - Target average daily gain (typically 1.5-2.5 lb/day) - Cost per pound of gain for supplement versus forage - Labor and equipment available for feeding ### Water Access and Quality Cattle require clean, accessible water for optimal performance. Water consumption varies with temperature, humidity, feed intake, and dry matter content of forage. The invited review "Water consumption, and drinking behavior of beef cattle, and effects of water quality" published in Applied Animal Science provides guidance on water intake patterns and quality thresholds [12]. Producers should test water sources annually for total dissolved solids, sulfates, nitrates, and bacterial contamination. Trough placement should allow at least 2 inches of linear trough space per animal and be located within 800 feet of grazing areas. ## Health Management Protocols ### Bovine Respiratory Disease Risk Assessment Bovine respiratory disease (BRD) is the most common and costly disease affecting stocker cattle. Recent studies show that BRD is responsible for more than 90% of all morbidity and mortality on stocker operations [9]. Risk factors include commingling from multiple sources, transport stress, weaning stress, and inadequate passive immunity transfer. High-risk calves typically come from auction markets, are weaned at sale, and have unknown vaccination history. Low-risk calves come from single-source herds with documented preconditioning programs. The publication "High-Risk Cattle Management and Stocker Calf Health: Modulation of the Bovine Respiratory Microbiome from a Systems Perspective" discusses microbiome-based approaches to reducing BRD susceptibility [10]. ### Arrival Processing Protocol Processing upon arrival should occur within 24 hours of delivery. The protocol should include: 1. Individual identification with ear tags or electronic identification 2. Body weight recording 3. Vaccination against respiratory pathogens (IBR, BVD, PI3, BRSV) and clostridial diseases 4. Parasite control with an appropriate anthelmintic 5. Implant administration if growth promotion is desired 6. Metaphylaxis with an approved antimicrobial for high-risk calves The Merck Veterinary Manual provides detailed guidance on vaccination schedules and product selection for stocker cattle [2]. Producers should consult with a veterinarian to develop a written protocol specific to their operation and source cattle. ### Monitoring and Treatment Protocols Daily observation is essential for early BRD detection. Clinical signs include depression, nasal discharge, ocular discharge, cough, and reduced feed intake. Treatment protocols should be established with veterinary guidance and include: - Case definition criteria for treatment - First-line antimicrobial selection - Withdrawal period documentation - Retreatment criteria for non-responders - Record-keeping requirements The American Association of Bovine Practitioners proceedings "Management of bovine respiratory disease in beef stocker calves - an overview of current evidence and recommendations" emphasizes that treatment success depends on early detection, appropriate antimicrobial selection, and supportive care [9]. ### Parasite Control Internal and external parasites reduce gain and increase disease susceptibility. Fecal egg counts should be performed at arrival and periodically during the grazing season to guide deworming decisions. Anthelmintic resistance is a growing concern, and rotational use of drug classes may help preserve efficacy. Pour-on products are convenient but may have variable efficacy against certain parasites. Injectable and oral formulations provide more consistent dosing. ## Marketing Decisions ### Marketing Timing and Weight Targets Stocker calves are typically sold when they reach 700-850 lb, depending on forage availability, price outlook, and feedlot demand. The publication "Southern Section Interdisciplinary Beef Cattle Symposium: Carryover effects of stocker cattle systems on feedlot performance and carcass characteristics" describes how stocker management affects subsequent feedlot performance and carcass quality [6]. Calves that gain weight rapidly on high-quality forage may have different carcass characteristics than those grown more slowly on lower-quality forage. Marketing options include: - Sale at auction barn - Direct sale to feedlot - Retained ownership through finishing - Forward contract with a feedlot or packer ### Price Risk Management Price volatility affects stocker profitability. Producers can manage price risk through: - Futures and options contracts on feeder cattle - Livestock Risk Protection (LRP) insurance - Forward contracting with buyers - Diversified marketing windows The publication "Stocker/feeder cattle standardized performance analysis" provides a framework for evaluating economic performance of stocker enterprises [8]. Producers should track cost of gain, breakeven price, and net return per head. ### Retained Ownership Considerations Retained ownership allows producers to capture finishing and carcass value but increases financial risk and management complexity. The publication "Effect of stocker management program on beef cattle skeletal muscle growth characteristics, satellite cell activity, and paracrine signaling impact on preadipocyte differentiation" indicates that stocker nutrition affects muscle development and marbling potential [4]. Producers considering retained ownership should evaluate their ability to manage feedlot health, nutrition, and marketing. ## Records and Measurements ### Performance Records Accurate records are essential for evaluating stocker enterprise profitability. Key measurements include: - Average daily gain (ADG) calculated from start and end weights - Total weight gain per head - Cost per pound of gain - Mortality rate - Morbidity rate and treatment cost The publication "Backgrounding beef cattle" in The Veterinary Clinics of North America discusses record-keeping systems for stocker operations [5]. Records should be maintained for each group of cattle and used to compare performance across years and management systems. ### Health Records Health records must include: - Individual animal identification - Vaccination dates and products - Treatment dates, products, and doses - Withdrawal periods for antimicrobials and implants - Mortality dates and necropsy findings These records support veterinary oversight, regulatory compliance, and marketing claims for preconditioned cattle. ### Financial Records Financial records should track: - Purchase price per head - Feed and supplement costs - Veterinary and pharmaceutical costs - Labor and equipment costs - Interest on operating capital - Sale price per head The standardized performance analysis framework helps producers calculate net return and identify areas for improvement [8]. ## Common Failure Patterns ### Overstocking Pastures Overstocking reduces forage availability, increases soil erosion, and decreases average daily gain. Producers should calculate carrying capacity based on forage production data and adjust stocking rates seasonally. Signs of overstocking include reduced forage height, increased weed pressure, and cattle losing body condition. ### Inadequate BRD Prevention Failure to implement a comprehensive BRD prevention program leads to high morbidity and mortality. Common errors include: - Delaying processing after arrival - Using inappropriate vaccine combinations - Skipping metaphylaxis for high-risk calves - Inadequate observation during the first 21 days ### Poor Marketing Timing Selling cattle during seasonal price lows reduces profitability. Producers should monitor feeder cattle futures and local auction prices to identify favorable marketing windows. Forward contracting can lock in prices but limits upside potential. ## Welfare and Safety Context ### Handling and Transport The publication "The Role of Early Handling Experiences on the Welfare of Beef Stocker Cattle" emphasizes that early handling experiences affect stress response and welfare outcomes [7]. Low-stress handling techniques reduce cortisol levels, improve immune function, and enhance weight gain. Producers should train all personnel in low-stress cattle handling methods. Transport stress contributes to BRD susceptibility. Transport duration, stocking density, and ventilation affect stress levels. Calves should be transported during cooler hours and provided with rest stops on long hauls. ### Worker Safety Cattle handling presents injury risks including kicks, bites, and crushing. Safety protocols should include: - Use of well-designed handling facilities - Training in cattle behavior and flight zone principles - Use of personal protective equipment - Emergency response procedures ### [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Stocker producers must comply with withdrawal periods for all pharmaceuticals. Records of treatment dates and withdrawal periods must be maintained and provided to buyers. The Merck Veterinary Manual provides withdrawal period information for approved products [2]. Producers should verify withdrawal periods with their veterinarian and follow label instructions exactly. ## Professional Escalation Criteria Producers should consult a veterinarian when: - Morbidity exceeds 10% in any group within 30 days of arrival - Mortality exceeds 2% in any group - Treatment response rate falls below 80% - Diagnostic testing is needed to identify pathogens - Antimicrobial resistance is suspected Producers should consult a nutritionist when: - Average daily gain falls below target for more than 14 days - Forage quality testing indicates deficiencies - Supplement costs exceed budget - Body condition scores decline Producers should consult an agricultural economist when: - Breakeven prices exceed market projections - Financing options need evaluation - Risk management strategies require assessment ## Rumen Microbiome Management and Monensin Use in Stocker Programs The rumen microbiome plays a central role in feed efficiency, gain consistency, and health outcomes for stocker cattle. Recent research published in the Journal of Animal Science and Biotechnology examined how diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle [11]. This work underscores that microbial community shifts occur rapidly when cattle transition from forage-based to concentrate-based diets, and that management interventions can either stabilize or disrupt these populations. For stocker operators, understanding rumen microbiome dynamics provides a practical framework for managing feed transitions, optimizing gain, and reducing digestive disturbances. ### Monensin as a Management Tool Monensin is an ionophore approved for use in beef cattle to improve feed efficiency and alter rumen fermentation patterns. In stocker programs, monensin is typically delivered through mineral supplements, protein blocks, or complete feeds. The publication "Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle" provides evidence that monensin shifts the rumen microbial community toward populations that produce more propionate and less methane, improving energy retention [11]. This shift can increase average daily gain by 3-5% when forage quality is adequate and intake is not limited by other factors. Practical considerations for monensin use include: - Delivery method: Mineral mixes, protein supplements, or complete feeds - Intake monitoring: Target consumption of 100-200 mg per head per day for stocker calves - Adaptation period: Allow 7-14 days for rumen microbial populations to adjust - Withdrawal period: Follow label requirements for slaughter withdrawal Producers should verify that monensin-containing products are compatible with other feed additives and that intake is consistent across all animals in the group. Inadequate intake reduces the expected gain response, while excessive intake can cause toxicity, particularly in horses or other non-target species that may access supplements. ### Transition Management Between Forage and Supplement Stocker calves often experience multiple diet transitions: from milk and creep feed to forage, from forage to supplement, and eventually from forage to finishing rations. Each transition stresses the rumen microbiome and can reduce intake and gain for 7-21 days. The publication "Nutritional Management of Beef Stocker Calves in Grazing Systems" addresses the importance of gradual transitions to maintain rumen health and avoid acidosis [3]. A practical transition protocol includes: 1. Introduce supplement at 0.5% of body weight per day for the first 7 days 2. Increase to 1.0% of body weight per day for days 8-14 3. Target final inclusion rate based on desired gain and forage quality 4. Monitor for signs of acidosis: reduced intake, loose manure, lethargy 5. Reduce supplement level if digestive upset is observed For calves transitioning from stocker programs to feedlot entry, the carryover effects of rumen microbiome management can influence feedlot performance and carcass characteristics. The publication "Southern Section Interdisciplinary Beef Cattle Symposium: Carryover effects of stocker cattle systems on feedlot performance and carcass characteristics" describes how stocker nutrition and management affect subsequent finishing outcomes [6]. Calves with stable, adapted rumen microbiomes at feedlot entry experience fewer digestive upsets and achieve target gain more quickly. ### Practical Decision Framework for Rumen Health Management Producers can use the following decision framework to manage rumen microbiome stability and optimize monensin use: **Step 1: Assess Current Diet and Transition Risk** - Record current forage type and quality - Determine supplement type and inclusion rate - Identify upcoming transitions (new pasture, supplement change, feedlot entry) - Calculate days until next transition **Step 2: Select Monensin Delivery Method** - Mineral supplement: Best for low-intake, consistent delivery - Protein block: Useful when forage quality is low and protein is needed - Complete feed: Appropriate for limit-fed or drylot stocker programs - Consult with a nutritionist to determine appropriate concentration **Step 3: Monitor Intake and Response** - Weigh supplement disappearance weekly - Adjust feeder placement to ensure all cattle have access - Observe individual cattle for signs of reduced intake - Record average daily gain for the group **Step 4: Evaluate and Adjust** - Compare actual gain to target gain - Assess supplement cost per pound of gain - Adjust monensin concentration if intake is inconsistent - Document outcomes for future transition planning ### Records and Measurements for Rumen Health Specific records for rumen microbiome management include: - Supplement type and monensin concentration - Daily supplement disappearance per group - Transition dates and duration - Observed digestive upset events (bloat, acidosis, loose manure) - Average daily gain during and after transitions - Feedlot entry health and performance data for retained ownership cattle These records allow producers to identify patterns and refine transition protocols over time. The publication "Stocker/feeder cattle standardized performance analysis" provides a framework for evaluating the economic impact of management changes, including feed additive use and transition management [8]. ### Common Failure Patterns in Rumen Health Management **Abrupt Diet Changes** Moving cattle from high-quality pasture to a high-concentrate supplement without an adaptation period can cause acidosis, reduced intake, and weight loss. Signs include cattle going off feed, diarrhea, and lethargy. Prevention requires gradual introduction over 7-14 days. **Inconsistent Monensin Intake** When monensin delivery is uneven, some cattle receive subtherapeutic doses while others may receive excessive amounts. This reduces the expected gain response and increases the risk of toxicity. Solutions include using palatable carriers, providing adequate feeder space, and monitoring supplement disappearance daily. **Ignoring Forage Quality Changes** As forage matures, its digestibility declines and the rumen microbiome must adapt. Failure to adjust supplement type or inclusion rate when forage quality changes can result in reduced gain and increased supplement cost per pound of gain. Regular forage testing and supplementation adjustment are essential. ### Welfare and Safety Context for Rumen Health Rumen health directly affects cattle welfare. Acidosis causes pain, reduces feed intake, and increases the risk of laminitis and liver abscesses. The publication "The Role of Early Handling Experiences on the Welfare of Beef Stocker Cattle" emphasizes that stress from handling and transport can compound digestive disturbances [7]. Low-stress handling during processing and transition periods reduces cortisol levels and supports normal rumen function. Worker safety considerations include proper storage and handling of monensin-containing products. Monensin is toxic to horses, dogs, and other species. Feeders and supplements must be placed where non-target animals cannot access them. Spills should be cleaned immediately, and equipment used for monensin delivery should be labeled and stored separately. ### Professional Escalation Criteria for Rumen Health Producers should consult a veterinarian or nutritionist when: - More than 5% of cattle show signs of digestive upset within 14 days of a diet transition - Average daily gain drops below 1.0 lb/day for more than 7 days with no identifiable cause - Supplement intake varies by more than 20% from target for three consecutive weeks - Bloat occurs in more than 2% of the group - Cattle show signs of monensin toxicity (incoordination, muscle tremors, recumbency) Consultation with a nutritionist is particularly important when designing transition protocols for high-risk calves or when incorporating novel feed ingredients. The publication "High-Risk Cattle Management and Stocker Calf Health: Modulation of the Bovine Respiratory Microbiome from a Systems Perspective" notes that rumen health and respiratory health are interconnected, and that managing the rumen microbiome may reduce BRD susceptibility [10]. ## Frequently Asked Questions ### What is the ideal stocking rate for stocker cattle on pasture? Stocking rate depends on forage species, soil fertility, rainfall, and management intensity. Producers should calculate carrying capacity based on forage production data from their specific location. The USDA Natural Resources Conservation Service provides technical guides for determining appropriate stocking rates [1]. A starting point is 1-2 head per acre for cool-season grasses under rotational grazing, but this varies widely. ### How long should stocker calves be held before marketing? The holding period typically ranges from 90 to 180 days, depending on starting weight, target weight, and forage availability. Calves entering at 400-500 lb may need 120-150 days to reach 700-800 lb at 1.5-2.0 lb/day gain. Producers should monitor weight gain and market conditions to determine optimal sale timing. ### What vaccines are essential for stocker calves? Core vaccines include those against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), parainfluenza-3 (PI3), [bovine respiratory syncytial virus](/knowledge/viruses/livestock-viruses/bovine-respiratory-syncytial-virus) (BRSV), and clostridial diseases. The Merck Veterinary Manual provides vaccination schedules for stocker cattle [2]. Producers should work with a veterinarian to select products appropriate for their region and cattle source. ### How can I reduce BRD risk in high-risk stocker calves? Risk reduction strategies include sourcing from preconditioned herds, minimizing transport stress, processing within 24 hours of arrival, using metaphylaxis for high-risk groups, and providing clean water and high-quality feed immediately. The American Association of Bovine Practitioners proceedings emphasize that early detection and treatment are critical for BRD management [9]. ### What is the best marketing strategy for stocker cattle? The best strategy depends on price outlook, risk tolerance, and management capacity. Options include selling at auction, direct sale to feedlots, retained ownership, or forward contracting. The publication "Southern Section Interdisciplinary Beef Cattle Symposium: Carryover effects of stocker cattle systems on feedlot performance and carcass characteristics" describes how stocker management affects finishing outcomes [6]. Producers should evaluate their breakeven price and market projections before choosing a strategy. ### How do I calculate cost of gain for stocker cattle? Cost of gain is calculated by dividing total feed and supplement costs by total weight gain. Include all costs: purchased feed, pasture rent or ownership cost, supplements, labor, veterinary, and pharmaceuticals. The standardized performance analysis framework provides a comprehensive method for calculating cost of gain [8]. ### What records should I keep for stocker cattle? Essential records include purchase weight and date, vaccination and treatment records, feed and supplement consumption, weight gain data, mortality and morbidity rates, and financial records. Health records must include withdrawal periods for all pharmaceuticals. The publication "Backgrounding beef cattle" discusses record-keeping systems for stocker operations [5]. ### How does stocker nutrition affect feedlot performance? Stocker nutrition affects muscle development, marbling potential, and feedlot gain. The publication "Effect of stocker management program on beef cattle skeletal muscle growth characteristics, satellite cell activity, and paracrine signaling impact on preadipocyte differentiation" indicates that stocker nutrition influences muscle and fat development [4]. Rapid gain on high-quality forage may improve feedlot performance, while compensatory gain after slower growth may reduce efficiency. ## Related Farming Guides - [Dairy Cow Cooling System Management](/knowledge/animal-farming/dairy-cattle/dairy-cow-cooling-system-management) - [Beef Cattle Backgrounding Management](/knowledge/animal-farming/beef-cattle/beef-cattle-backgrounding-management) - [Beef Cattle Manure Management](/knowledge/animal-farming/beef-cattle/beef-cattle-manure-management) - [Beef Cattle Marketing Records](/knowledge/animal-farming/beef-cattle/beef-cattle-marketing-records) - [Beef Cattle Mud Management](/knowledge/animal-farming/beef-cattle/beef-cattle-mud-management) ## Related Clinical & Scientific Guides * [Cattle Head Gate Selection and Adjustment](/knowledge/animal-farming/beef-cattle/cattle-head-gate-selection-and-adjustment) * [Beef Cattle Handling Facility Flow](/knowledge/animal-farming/beef-cattle/beef-cattle-handling-facility-flow) * [Beef Cattle Maternity Pen Design: Comfort and Monitoring](/knowledge/animal-farming/beef-cattle/beef-cattle-maternity-pen-design-comfort-monitoring) ## References and Further Reading - [www.nrcs.usda.gov](https://www.nrcs.usda.gov/) - [www.merckvetmanual.com](https://www.merckvetmanual.com/management-and-nutrition) - [Nutritional Management of Beef Stocker Calves in Grazing Systems.](https://pubmed.ncbi.nlm.nih.gov/42342481). The Veterinary clinics of North America. Food animal practice, 2026. - [Effect of stocker management program on beef cattle skeletal muscle growth characteristics, satellite cell activity, and paracrine signaling impact on preadipocyte differentiation.](https://pubmed.ncbi.nlm.nih.gov/31602304). Journal of animal science and technology, 2019. - [Backgrounding beef cattle.](https://pubmed.ncbi.nlm.nih.gov/16814023). The Veterinary clinics of North America. Food animal practice, 2006. - [Southern Section Interdisciplinary Beef Cattle Symposium: Carryover effects of stocker cattle systems on feedlot performance and carcass characteristics.](https://pubmed.ncbi.nlm.nih.gov/23048147). Journal of animal science, 2013. - [The Role of Early Handling Experiences on the Welfare of Beef Stocker Cattle.](https://pubmed.ncbi.nlm.nih.gov/42303481). The Veterinary clinics of North America. Food animal practice, 2026. - [Stocker/feeder cattle standardized performance analysis.](https://pubmed.ncbi.nlm.nih.gov/7584818). The Veterinary clinics of North America. Food animal practice, 1995. - [Management of bovine respiratory disease in beef stocker calves - an overview of current evidence and recommendations](https://doi.org/10.21423/aabppro20249078). American Association of Bovine Practitioners Conference Proceedings, 2025. - [High-Risk Cattle Management and Stocker Calf Health: Modulation of the Bovine Respiratory Microbiome from a Systems Perspective.](https://doi.org/10.1016/j.cvfa.2022.03.001). The Veterinary clinics of North America. Food animal practice, 2022. - [Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle](https://doi.org/10.1186/s40104-023-00967-5). Journal of Animal Science and Biotechnology, 2024. - [INVITED REVIEW: Water consumption, and drinking behavior of beef cattle, and effects of water quality](https://doi.org/10.15232/aas.2021-02136). Applied Animal Science, 2021. > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.