# Farm Lighting Management for Animal Housing ## Key Takeaways - Photoperiod manipulation is a critical tool for regulating reproduction, growth, and comfort in livestock, with specific day-length requirements varying by species and production stage, as guided by WOAH standards. - Light quality, encompassing intensity (lux), spectral composition (Kelvin), and uniformity, directly impacts animal vision, circadian rhythms, and behavior, with minimum lux levels of 100-200 generally recommended for housed livestock, and uniformity ratios above 0.6 to prevent behavioral issues. - Regular maintenance, including cleaning fixtures and replacing bulbs, is essential to prevent light loss, flicker, and potential fire hazards, with annual lux audits recommended to ensure optimal illumination levels. - Advanced computer vision technologies, leveraging deep learning algorithms, are increasingly used to monitor animal behavior in response to lighting, enabling data-driven adjustments to photoperiod and intensity for improved welfare and efficiency. - Adequate lighting is crucial for worker safety, reducing injury risk from slips and falls, and for food safety by facilitating thorough inspection and cleaning; UV disinfection systems require strict safety protocols to protect animals and handlers. - Species-specific lighting needs, such as extended photoperiods for increased milk yield in dairy cows or specific light cycles for poultry egg production, necessitate tailored management plans, often requiring consultation with veterinary or agricultural specialists. --- Lighting management in livestock barns directly influences animal welfare, productivity, and worker safety. Photoperiod goals, light quality, and maintenance schedules must be matched to species,specific physiology and housing systems to support natural behavior, health, and operational efficiency. This article summarizes the evidence,based planning decisions and core management framework for farm lighting, drawing on standards from the World Organisation for Animal Health (WOAH) and guidance from the Food and Agriculture Organization (FAO) of the United Nations. ## At a Glance | Aspect | Key Considerations | Reference | |--------|-------------------|-----------| | Photoperiod goals | Day,length manipulation used to regulate reproduction, growth, and comfort, requirements differ by species and production stage | [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/), [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) | | Light quality | Intensity (lux), spectral composition (color temperature), and uniformity affect vision, circadian rhythms, and behavior | [Effect of light intensity, spectrum, and uniformity on dairy cows navigating an obstacle course](https://api.elsevier.com/content/abstract/scopus_id/85174417809) (2023) | | Maintenance | Regular cleaning, bulb replacement, and system checks prevent light loss, flicker, and fire hazards | [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) | | Animal behavior | Consistent cues support feeding patterns, social interactions, and stress reduction, computer vision aids monitoring | [Deep learning algorithms to identify finishing pigs using 3D data](https://api.elsevier.com/content/abstract/scopus_id/105002863684) (2025), [Real,Time Livestock Activity Monitoring via Fine,Tuned Faster R,CNN](https://api.elsevier.com/content/abstract/scopus_id/85179754385) (2023) | | Worker safety | Adequate illumination and reduced glare lower injury risk, ultraviolet treatments may reduce pathogens but require careful handling | [Treatment of livestock odor and pathogens with ultraviolet light](https://api.elsevier.com/content/abstract/scopus_id/63149181615) (2008) | | Species,specific advice | Poultry, swine, cattle, and sheep each have distinct photoperiod and spectral requirements | [Merck Veterinary Manual](https://www.merckvetmanual.com/), [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) | ## System Context and Planning Decisions ### Environmental and Structural Factors Barn design,including insulation, ventilation, window placement, and artificial light fixture layout,determines how natural daylight is supplemented or replaced. The FAO Animal Production and Health guidance emphasizes that lighting systems must be integrated with overall climate control and hygiene protocols. Poor uniformity (e.g., zones below 50 lux in a barn designed for 200 lux) disrupts feeding behavior and can lead to injury, as shown in studies of dairy cows navigating obstacle courses under varying light conditions. The 2023 research on dairy cow obstacle navigation indicates that both intensity and spectrum affect a cow’s ability to detect obstacles, with implications for facility layout. ### Photoperiod Programming Photoperiod management is a primary tool for manipulating reproductive cycles in sheep, goats, and horses, and for optimizing growth in broilers and egg production in layers. The WOAH Terrestrial Animal Health Code notes that abrupt changes in day length can cause stress and should be avoided, gradual transitions (e.g., 15,30 minutes per week) are recommended where possible. For cattle, extended photoperiods (typically 16 hours light, 8 hours dark) have been associated with increased milk yield, but the underlying mechanisms involve both endocrine and behavioral responses. The PubMed record 42077479 provides foundational evidence on photoperiodic regulation in livestock. Exact thresholds depend on breed, age, and local climate, and producers should consult a veterinarian or extension specialist when establishing lighting schedules. ### Light Quality and Uniformity Light quality encompasses intensity (measured in lux at animal eye height), spectral composition (color temperature in Kelvin), and distribution. The Merck Veterinary Manual advises that most housed livestock require at least 100,200 lux during the light phase, though birds may require higher levels for proper feather pecking and foraging. Uniformity,the ratio of minimum to average illuminance across the barn,should not fall below 0.6 to avoid dark corners that encourage huddling or aggression. The 2023 obstacle course study demonstrated that cows perform worse under high,intensity, non,uniform lighting compared to moderate, uniform light. Workers benefit from color rendering indices above 80 to distinguish animal health cues and hazards. ## Core Management Framework ### Maintenance and Inspection Light output degrades over time due to lamp aging and dust accumulation on fixtures and lenses. The USDA APHIS Livestock and Poultry Disease resources recommend routine cleaning schedules and annual lux audits using a calibrated light meter. Flickering lights, which can cause stress and reduced feed intake, should be repaired immediately. For ultraviolet light systems used for pathogen reduction (e.g., in poultry litter or dairy parlors), the 2008 study on treatment of livestock odor and pathogens with ultraviolet light indicates efficacy but stresses the need for appropriate shielding and timer controls to prevent skin and eye injury to animals and handlers. ### Integration with Animal Behavior Monitoring Recent advances in computer vision enable automated detection of individual animals and their activity states, which can help assess lighting adequacy. The 2025 study on benchmarking YOLOv for cattle identification and the 2023 study on real,time pig behavior monitoring using Fine,Tuned Faster R,CNN illustrate how deep learning can track feeding, lying, and aggressive interactions under different lighting regimes. While these technologies are not yet standard, they offer a pathway to fine,tune photoperiod and intensity based on observed behavioral responses. Producers considering such systems should work with university extension or ag,tech advisors to validate data in their specific barn environment. ### Worker Safety Barn lighting must also meet occupational health standards. The WOAH code and FAO guidance stress that workers require well,lit walkways, handling areas, and emergency exits. Glare from poorly positioned fixtures reduces contrast and increases tripping risk. Where UV lights are used for disinfection, warning signs and automatic shutoff mechanisms are mandatory. Worker training on lighting system controls and emergency shutdown procedures should be documented as part of the farm’s safety plan. Professional escalation: Whenever lighting changes affect animal performance or behavior, consult a veterinarian with expertise in livestock environment or a lighting engineer familiar with animal housing. No single protocol fits all operations, adjustments should be monitored over at least two production cycles before being adopted permanently. ### Facilities and Environment The design of a lighting system in animal housing directly influences animal physiology and behavior. Light intensity, measured in lux, should be appropriate for the species and production stage. For example, dairy cattle require sufficient illuminance to navigate facilities safely and to detect feed and water sources. The study "Effect of light intensity, spectrum, and uniformity on the ability of dairy cows to navigate through an obstacle course" (https://api.elsevier.com/content/abstract/scopus_id/85174417809) demonstrates that both intensity and uniformity affect cow movement and comfort. Non-uniform lighting can cause hesitation or reluctance to enter certain areas, reducing access to resources. Spectrum, or the color temperature of light, also matters. Cool white light (higher kelvin) can promote alertness, while warmer light may be used during rest periods. The FAO Animal Production and Health guidelines (https://www.fao.org/animal-production/en/) emphasize that lighting should mimic natural daylight patterns to support circadian rhythms. Automated monitoring of animal behavior under different lighting conditions is now possible using computer vision. The research "Real-Time Livestock Activity Monitoring via Fine-Tuned Faster R-CNN for Multiclass Cattle Behaviour Detection" (https://api.elsevier.com/content/abstract/scopus_id/85179754385) highlights how deep learning algorithms can track behaviors such as feeding, ruminating, and resting, which can be correlated with lighting changes. The same approach is applied in "Computer vision in [precision livestock farming](/knowledge/animal-farming/farm-management/precision-livestock-farming-technologies-benefits-and-implementation-challenges): benchmarking YOLOv9, YOLOv10, YOLOv11, and YOLOv12 for individual cattle identification" (https://api.elsevier.com/content/abstract/scopus_id/105010871140) and "Deep learning algorithms to identify individual finishing pigs using 3D data" (https://api.elsevier.com/content/abstract/scopus_id/105002863684). These tools allow producers to adjust lighting based on real-time behavioral data instead of fixed schedules. Ultraviolet (UV) light can be used for environmental disinfection. The study "Treatment of livestock odor and pathogens with ultraviolet light" (https://api.elsevier.com/content/abstract/scopus_id/63149181615) reports that UV irradiation reduces airborne bacteria and odorous compounds. However, UV exposure must be controlled to prevent eye and skin damage to animals and workers. Enclosed UV fixtures or use during unoccupied periods are standard precautions. Air circulation and humidity affect UV efficacy, and professional guidance from a lighting engineer or agricultural engineer is recommended when integrating UV systems into existing barns. ### Nutrition and Water Lighting programs influence feeding behavior and water intake. Photoperiod manipulation can increase feed consumption in growing animals, but the relationship is species-specific. In dairy cattle, extended daylight (16 hours light, 8 hours dark) has been associated with increased dry matter intake, though the mechanism is not fully understood. The PubMed record 42077479 (https://pubmed.ncbi.nlm.nih.gov/42077479/) and record 41325192 (https://pubmed.ncbi.nlm.nih.gov/41325192/) provide early evidence of photoperiod effects on feed intake and growth in livestock. More recent reviews in the Merck Veterinary Manual (https://www.merckvetmanual.com/) confirm that lighting regimens should be combined with adequate nutrition to avoid metabolic disorders. For example, if lighting encourages greater feed intake, the diet must be balanced accordingly. Water consumption also responds to lighting. Animals tend to drink more during illuminated periods. Inadequate water access points or poorly lit water lines can reduce intake. The WOAH Terrestrial Animal Health Code (https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) includes recommendations for clean water provision, and lighting that ensures water troughs are visible supports this standard. In addition, placing lights near water sources can help maintain consumption levels during darker hours, especially in winter months when natural daylight is limited. ### Production-Stage Decisions Lighting management changes across production stages. For laying hens, photoperiod directly controls egg production. The USDA APHIS Livestock and Poultry Disease resources (https://www.aphis.usda.gov/livestock-poultry-disease) provide guidance on biosecurity and lighting for poultry, but specific photoperiod recommendations are often found in breed manuals. In broilers, shorter day lengths early in life promote leg health, while longer days later stimulate feed intake. The transition must be gradual to avoid stress. For swine, lighting affects reproduction. Gilts and sows housed under extended photoperiods (16 hours light) may have improved estrus expression and conception rates. However, boars may require shorter periods to maintain libido. The USDA National Animal Health Monitoring System (https://www.aphis.usda.gov/livestock-poultry-disease/nahms) conducts periodic studies on swine management, including lighting practices. These data are useful for benchmarking, but individual farm assessment is necessary. In dairy operations, dry cows and lactating cows have different photoperiod needs. The PubMed record 37980765 (https://pubmed.ncbi.nlm.nih.gov/37980765/) discusses how photoperiod manipulation affects milk yield and immune function. A common approach is to provide long days (16L:8D) for lactating cows and short days (8L:16D) for dry cows to prepare them for the next lactation. Abrupt changes should be avoided, a transition period of one to two weeks is advised. Veterinary consultation is recommended before implementing new lighting protocols, especially in herds with a history of metabolic or reproductive issues. ### Records and Monitoring Accurate recordkeeping of lighting schedules, intensity measurements, and animal responses is essential. Use lux meters to verify that light levels meet target ranges for each barn zone. Regular calibration of timers and photocells prevents unintentional photoperiod shifts. Computer vision systems can automate behavior monitoring, but the deep learning models require validation for each facility and species. The benchmarking of YOLOv9 through YOLOv12 for individual cattle identification (https://api.elsevier.com/content/abstract/scopus_id/105010871140) shows ongoing improvements in accuracy, but no single algorithm is universally best. Producers should work with precision [livestock farming](/knowledge/animal-farming/farm-management/livestock-farming-an-overview-of-modern-practices-and-challenges) specialists to select and maintain these systems. Failure patterns include bulbs dimming over time, inconsistent replacement schedules, and photocell sensor drift. Birds and insects may block fixtures, reducing uniformity. Regular inspection should be part of routine barn maintenance. Any unexpected change in animal behavior, such as increased resting or aggression, should trigger a lighting audit. ### Welfare Lighting directly affects animal welfare by influencing sleep, stress, and social behavior. The Merck Veterinary Manual (https://www.merckvetmanual.com/) notes that animals need periods of darkness for restorative rest. Continuous lighting can lead to chronic stress, reduced immunity, and ocular pathology. Conversely, prolonged darkness can depress feed intake and impair navigation. The WOAH Terrestrial Animal Health Code (https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) includes general principles on animal welfare that apply to housing environment, including lighting. If animals show signs of photophobia, squinting, or abnormal activity patterns, consult a veterinarian to rule out underlying disease and to evaluate the light regimen. In multi-species housing, consider dominance hierarchies: subordinate animals may avoid well-lit feeding areas, requiring adjustments to light placement or intensity. ### Worker and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Worker safety is improved by consistent, adequate lighting. Shadows and glare increase the risk of slips, trips, and falls, especially near wet areas or slurry pits. Emergency lighting should be tested regularly. The use of UV systems for pathogen control (https://api.elsevier.com/content/abstract/scopus_id/63149181615) must include protective measures. Workers should not be present during UV operation unless appropriate PPE is worn. Food safety also benefits from proper lighting. Carcass inspection, milk quality checks, and equipment cleaning depend on visibility. Poorly lit areas may hide contamination. Additionally, lighting that attracts insects can increase biosecurity risks in poultry houses. Insect control strategies should be integrated with lighting design. ### Failure Patterns and Practical Monitoring Common failure patterns include flicker from aging fluorescent tubes or LED drivers, which can cause stress in animals with high flicker sensitivity, such as poultry. Regular replacement before burnout and use of flicker-free drivers are recommended. Another pattern is photoperiod creep, where timers drift over weeks, gradually changing day length. Weekly verification of timer settings is a simple preventive measure. For computer vision systems, failure can occur due to changes in ambient light intensity or direction. The deep learning models cited (https://api.elsevier.com/content/abstract/scopus_id/105010871140, https://api.elsevier.com/content/abstract/scopus_id/105002863684, https://api.elsevier.com/content/abstract/scopus_id/85179754385) are sensitive to training data, if the lighting environment differs from the training set, performance degrades. Regular recalibration with new images is necessary. Practical monitoring includes conducting a walkthrough during both light and dark phases. Observe whether animals are feeding, resting, and moving normally. Use a lux meter to measure at animal eye level in multiple locations. Note any areas with shadows or glare. If using automated systems, review behavior reports daily. When abnormalities appear, first verify that the lighting system is functioning correctly before adjusting protocols. If issues persist, consult an agricultural lighting specialist or a [veterinary behaviorist](/knowledge/veterinary-medicine/anxiety-and-behavior-support/veterinary-behaviorist-when-to-refer). For UV disinfection systems, measure output with a UV meter and follow manufacturer maintenance schedules. In summary, effective lighting management requires integration of environmental design, species-specific photoperiods, regular monitoring, and collaboration with professionals. Each farm must adapt these principles to its unique conditions, with decisions supported by records and observation. ## Health Observation Properly managed lighting systems enable consistent observation of livestock health. Uniform illumination at recommended levels allows caretakers to detect early signs of disease, injury, or abnormal behavior. Research using dairy cows navigating obstacle courses demonstrated that light intensity and spectrum significantly affect animal movement and spatial awareness [Effect of light intensity, spectrum, and uniformity on the ability of dairy cows to navigate through an obstacle course](https://api.elsevier.com/content/abstract/scopus_id/85174417809). Uneven illumination or inappropriate spectra can mask lameness, skin lesions, or respiratory distress. Conversely, well-designed lighting highlights subtle changes in posture, gait, and feeding activity. Emerging precision livestock technologies integrate lighting with computer vision for continuous health monitoring. Deep learning algorithms trained to identify individual cattle or pigs using RGB or 3D data can track behavioral changes that precede clinical disease [Computer vision in precision livestock farming: benchmarking YOLOv9, YOLOv10, YOLOv11, and YOLOv12 for individual cattle identification](https://api.elsevier.com/content/abstract/scopus_id/105010871140) [Deep learning algorithms to identify individual finishing pigs using 3D data](https://api.elsevier.com/content/abstract/scopus_id/105002863684). Real-time multiclass behavior detection systems can flag reduced movement, altered feeding patterns, or withdrawal from social groups [Real-Time Livestock Activity Monitoring via Fine-Tuned Faster R-CNN for Multiclass Cattle Behaviour Detection](https://api.elsevier.com/content/abstract/scopus_id/85179754385). These tools do not replace direct observation but support early intervention when operated under consistent, appropriate lighting. ## Biosecurity Lighting management intersects with biosecurity through air quality and surface disinfection. Ultraviolet light in the UVC range has been shown to reduce airborne and surface pathogen loads in livestock settings [Treatment of livestock odor and pathogens with ultraviolet light](https://api.elsevier.com/content/abstract/scopus_id/63149181615). However, UVC exposure requires strict safety protocols to prevent eye and skin damage to animals and workers. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) provides general biosecurity guidance but does not specify UVC parameters. Producers considering UV disinfection should consult veterinary and safety specialists to design shielded systems that operate during empty periods or with remote control. Routine cleaning of light fixtures and lenses is essential for both biosecurity and light quality. Accumulated dust, cobwebs, and organic material reduce illuminance and can harbor pathogens. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resources emphasize cleaning and disinfection protocols for equipment in animal areas. Disinfectants must be compatible with fixture materials. ## Diagnostic and Veterinary Escalation When abnormal behavior or health indicators are noted under standard lighting, professional veterinary assessment is needed. Lighting conditions should be documented during diagnostic evaluations. For example, if a cow shows reluctance to move through a dim or unevenly lit alley, the problem may be optical discomfort instead of lameness. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) notes that cattle have reduced depth perception in low light, which can cause hesitation or falls. Veterinary escalation is required for signs such as prolonged photophobia, persistent squinting, corneal opacity, or head pressing. These may indicate toxicity, infection, or neurological disease unrelated to lighting. Sheep and goats with pregnancy toxemia or polioencephalomalacia may show odd photic responses. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides herd-level health monitoring frameworks that include environmental factors. Veterinarians can advise on photoperiod adjustments for reproductive management or to reduce aggression in group-housed pigs. ## Uncertainty Current knowledge gaps limit prescriptive recommendations for several aspects of lighting management. The optimal spectral composition for different livestock species is not fully established. Most commercial poultry guides recommend warm white light, but research on red or blue light for broiler growth remains inconsistent. Swine may prefer dimmer environments, but exact lux thresholds for welfare and production are debated. For dairy cattle, the [PubMed record 35765806](https://pubmed.ncbi.nlm.nih.gov/35765806/) and related reviews highlight that although prolonged photoperiods increase milk yield in lactating cows, effects on dry cows and heifers are less clear. Quantitative standards for light uniformity in animal housing are lacking. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) guidance emphasizes observation but does not specify uniformity coefficients. Producers should rely on empirical testing and professional engineering advice. Any lighting intervention should be trialed on a subset of animals before full implementation. ## Sustainability Lighting accounts for a significant portion of energy use in intensive livestock facilities. Transitioning to light-emitting diode technology reduces energy consumption by 50 to 70 percent relative to fluorescent or incandescent systems. LEDs also offer longer service life, reducing waste and maintenance labor. Dimmable and programmable controllers allow fine adjustment of photoperiod and intensity, supporting both animal needs and energy conservation. Sustainability also means designing lighting that does not compromise animal welfare. Rapid flicker or abrupt transitions between light and dark can cause stress. Gradual dawn and dusk simulations improve coping in many species. Photovoltaic integration with battery storage is feasible in remote barns, aligning with broader farm carbon reduction goals. ## Frequently Asked Questions **1. How often should light fixtures be cleaned in livestock barns?** At least quarterly, more often in dusty environments such as poultry houses or pig weaner rooms. Accumulated debris reduces light output and compromises biosecurity. **2. Can I use colored lights to calm pigs or increase egg production in layers?** Red light may reduce aggression in pigs and suppress cannibalism in layers, but effects vary by age and breed. Consult a poultry or swine veterinarian for specific protocols. **3. What is the best light intensity for a dairy free stall barn?** Typical recommendations are 150 to 200 lux at cow eye level during the light phase. Lower intensity may increase slips and falls. Measure with a lux meter at multiple locations. **4. Should I leave lights on at night for newborn lambs or calves?** Continuous light immediately after birth may help bonding and reduce disorientation. Transition to a natural or stepwise photoperiod within a few days to support circadian development. **5. How do I know if my lighting is causing stress in my flock or herd?** Signs include head shaking, persistent squinting, huddling away from light sources, reduced feeding, or increased aggression. Compare behavior under dimmed and bright light using controlled observation. **6. Is UVC disinfection safe to use while animals are present?** No. UVC can cause corneal burns and skin erythema. Use only in empty facilities or with fail-safe interlocks. Consult [USDA APHIS](https://www.aphis.usda.gov/livestock-poultry-disease) biosecurity guidelines. **7. What are the signs of poor light uniformity in a barn?** Animals clustering only in well-lit areas, reluctance to enter darker alleys, and increased stepping or vigilance. Measure uniformity using the ratio of minimum to average lux, a value below 0.6 indicates poor distribution. **8. Can automated lighting systems replace manual health checks?** No. Cameras and sensors aid surveillance but cannot substitute for hands-on examination. Veterinary diagnosis requires direct assessment of temperature, heart rate, respiration, and clinical signs. ## Educational Veterinary Notice This article provides general guidance derived from published research and official standards. Lighting management must be tailored to individual farm conditions, species, and local regulations. Consult a licensed veterinarian or agricultural engineer for specific advice on photoperiod programming, fixture selection, and integration with health monitoring systems. Sudden changes in lighting should be introduced gradually to avoid animal distress. ## Related Farming Guides - [How To Write A Farm Biosecurity Plan](/knowledge/animal-farming/farm-management/how-to-write-a-farm-biosecurity-plan) - [Livestock Farm Record Keeping System](/knowledge/animal-farming/farm-management/livestock-farm-record-keeping-system) - [Livestock Emergency Preparedness Plan](/knowledge/animal-farming/farm-management/livestock-emergency-preparedness-plan) - [Farm Health Intelligence Observation Records Biosecurity Diagnostics And Veterinary Escalation](/knowledge/animal-farming/farm-management/farm-health-intelligence-observation-records-biosecurity-diagnostics-and-veterinary-escalation) - [Animal Welfare Audits Building A Useful Farm Program](/knowledge/animal-farming/farm-management/animal-welfare-audits-building-a-useful-farm-program) ## Related Clinical & Scientific Guides * [Animal Welfare Audits: Building a Useful Farm Program](/knowledge/animal-farming/farm-management/animal-welfare-audits-building-a-useful-farm-program) * [Total Mixed Ration (TMR) for Dairy: Mixing and Feeding Management](/knowledge/animal-farming/farm-management/total-mixed-ration-dairy-mixing-feeding) * [Feed Additives for Livestock: Probiotics, Enzymes, and More](/knowledge/animal-farming/farm-management/feed-additives-livestock-probiotics-enzymes) ## References and Further Reading - [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) - [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) - [Merck Veterinary Manual](https://www.merckvetmanual.com/) - [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.