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ARS Home » Midwest Area » West Lafayette, Indiana » Livestock Behavior Research » Research » Research Project #432941

Research Project: Protecting the Welfare of Food Producing Animals

Location: Livestock Behavior Research

2022 Annual Report

The long-term objective of this project is tightly focused to optimize animal welfare and productivity under modern farming conditions. The approach is to focus on animal behavior and the cumulative effects of internal biological changes, to assess where challenges may exist and to develop alternative management strategies; and to determine how changes in behavior relate to physiology and productivity. We will focus on the following objectives: Objective 1: To develop measures of animal welfare that are science-based and informative under industry conditions and practices. 1.A. Determine the thermal preference of sows and their physiological response during a heat stress event. 1.B. Assess the use of non-linear methods of measuring heart rate variability to determine if they can be used to assess pain in pigs and calves. 1.C. Expand chronic pain markers in dairy cow and sow leukocyte mRNA that create a profile of chronic pain that may be attributed to housing. 1.D. Evaluate tear staining as a welfare indicator in pigs. Objective 2: To determine the impact of production practices and environmental factors on animal welfare. 2.A. Determine the influence of the auditory environment of sows and its influence on maternal behavior and crushing. 2.B. Simultaneously enhance the thermal environment of sows and piglets to increase sow comfort and piglet survivability. 2.C. Evaluating the impact of in utero heat stress on postnatal behavior and stress response in pigs. Objective 3: To optimize animal husbandry to improve animal welfare and farm productivity. 3.A. To evaluate the effects of a dietary synbiotic (Lactobacillus + FOS + ß- glucan) in combination with a nutraceutical substrate (L-glutamine) on pig health and productivity after weaning and transport stress. 3.B. Probiotics to support development of dairy calf respiratory immunity. 3.C. Determine if probiotics prevent osteoporosis in laying hens. 3.D. Reduce heat stress in broiler chickens by activating the microbiota-gut- brain axis using synbiotics. 3.E. Reduce social stress in laying hens by prenatal modification of the serotonergic system with tryptophan. 3.F. Determine the effects of environmental enrichment on welfare and productivity of swine at all stages of production.

The long-term objective of this project is to optimize animal welfare and productivity. The approach is to focus on animal behavior, the outward expression of the cumulative effects of internal biological changes, to assess where challenges may exist and to develop alternative management strategies to solve these challenges. This project will examine animal agricultural practices, using behavior, physiology, immunology, and neurobiology. The project’s focus is on 3 significant areas of concern: 1) instances in which animals may experience pain or distress, 2) morbidity or mortality, and 3) the deleterious effects caused by climate variability. The varying expertise of the ARS scientists will be utilized to work together on multiple projects to address the primary challenges to animal welfare that are characteristic of the production systems for dairy cattle, swine and poultry. Our ultimate goal is to: 1) identify objective measures of distress, pain, and morbidity, 2) determine how specific production practices impact animal welfare, and 3) develop production practices to optimize welfare in a manner that also sustains and promotes productivity.

Progress Report
This is the final report for this project which terminated in August 2022. Future progress will be reported on the replacement project, 5020-32000-014-000D, “Optimizing Welfare for Food Producing Animals". During the past 5 years significant progress has been made in advancing the objectives as laid out in the original plan (5020-32000-013-000D). Under Objective 1, it was discovered that non-pregnant and gestating sows prefer to be housed under lower temperatures than what are currently used by commercial swine producers and that they become heat stressed at lower temperatures than previously thought. These data will help producers better manage the environment their pigs are raised under to improve welfare metrics and reduce the negative effects of heat stress on pig health and productivity. Additionally, non-linear measures of heart rate variability were observed to be an accurate predictor of pain in swine, which could be used by researchers to measure pain more precisely in pigs. Immune system biomarkers may be used to measure chronic pain in dairy cows, which could be used to assess chronic pain in dairy cows by both veterinary providers and researchers. Finally, tear staining was determined to be a predictor of increased swine stress and reduced pig welfare. Under Objective 2, it was observed that lactating sows in commercial systems may suffer from hearing loss that could negatively influence piglet crushing and increase pre-weaning piglet death loss. It was also determined that providing neonatal piglets with a warmer heating mat and brighter heating lamps could play a role in reducing pre-weaning death loss, but more research is needed in this area. Furthermore, in utero heat stress was determined to reduce post-weaning piglet growth rate and alter post-weaning stress response, which may contribute to reduced welfare. Finally, under Objective 3, it was discovered that supplementing pig diets with a conditionally essential amino acid (L-glutamine) could reduce behavioral indicators of stress and improve pig welfare throughout their lifetime. To address concerns regarding antibiotic resistance in animal agriculture, a combination of prebiotics and probiotics was included in the diets of neonatal dairy calves. It was determined that a combination of prebiotics and probiotics could improve dairy calf health, which could provide an alternative to antibiotic treatments in animal agriculture. Finally, because broiler chickens are heat stress sensitive, a nutritional supplement that combined prebiotics and probiotics was tested to determine whether it could reduce heat stress sensitivity. It was discovered that this nutritional supplement could reduce measures of heat stress in broiler chickens and could be a solution for poultry producers to improve broiler chicken welfare.

1. Developed a smartphone application that allows swine producers to predict thermal comfort and stress in their sows. Although several thermal indices have been proposed for swine to improve health, productivity, and welfare, none differentiate by gestation stage or predict thermal comfort using both behavioral and physiological information gathered from sows with current genetics. It is known that physiological changes brought on by gestation can alter the temperature thresholds at which pigs are comfortable or stressed and that advances in swine genetics have increased temperature sensitivity of pigs. Unfortunately, as a result of climate change, heat stress events are becoming more frequent thereby putting the health, productivity, and welfare of pigs at risk. Therefore, it is important that thermal indices are developed and/or re-defined to allow swine producers to manage the in-barn environment more precisely. To address this concern, ARS researchers in West Lafayette, Indiana, in collaboration with researchers from the University of Illinois and Purdue University developed a behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant, mid-gestation, and late-gestation sows. This decision support tool has the ability to accurately identify temperatures that modern sows find to be cool, comfortable, warm, mild heat stress, moderate heat stress, and severe heat stress. The decision support tool has been integrated into a smartphone application known as HotHog that will be freely available to the general public through either the Apple App Store or Google Play. It is expected that this tool will allow swine producers to more effectively manage their herds to improve sow comfort and reduce the negative effects of heat stress on both sow and offspring health, productivity, and welfare.

2. Determined that dietary additives (synbiotics) reduce the negative effects of heat stress on broiler chicken immune function leading to improved health and welfare during hot seasons. Ambient temperature that is elevated beyond the thermoneutral zone can lead to heat stress which is a common environmental stressor facing the poultry industry. To combat the negative effects of heat stress on broiler health and well-being, adequate ventilation has been used. However, as cooled air moves down the length of the chicken house, air temperature increases from internal heat loads, and thus birds furthest away from the inlets are not cooled as effectively. This can lead to increased stress which impairs immune status and can increase morbidity and mortality as a result of greater disease susceptibility. Therefore, ARS researchers in West Lafayette, Indiana, performed a study to examine the effects of a dietary synbiotic supplement on the immunity of broiler chickens exposed to heat stress. Broilers were fed either a control diet or a synbiotic additive and then exposed to heat stress conditions. It was determined that the synbiotic additive reduced pathogenic bacteria, improved the regulation of stress reactions, and improved antioxidant status in heat stressed broilers. The results reveal that chicken immunity can be enhanced using beneficial bacteria via the microbiota-gut-immune and microbiota-gut-brain axes. As such, feeding a diet supplemented with synbiotics could be a useful management tool for the poultry industry to improve chicken health and welfare during hot seasons, especially in the tropical and subtropical areas. The results have been introduced to stakeholders and poultry producers through scientific publications, magazines, and workshops.

3. Developed methods for non-invasive quantification of intestinal health in calves and pigs. Intestinal disease is the leading cause of morbidity and mortality in neonatal female dairy calves with a majority of calf deaths occurring as a result of diarrhea or other digestive problems. In addition, intestinal disorders can reduce the health and productivity of weaned pigs often resulting in greater antibiotic use. To address this issue, researchers often seek to quantify changes in intestinal health when neonatal dairy calves or weaned pigs are provided nutritional supplements or managed under variable conditions. Unfortunately, methods to quantify intestinal disease often involve euthanizing the animal to collect intestinal tissue or invasive procedures that may result in distress. Therefore, developing non-invasive procedures that reduce the use of animal euthanasia in agriculture research and refine methods to quantify intestinal health are paramount to improving animal welfare during experimentation. To address this concern, ARS researchers in West Lafayette, Indiana, in collaboration with researchers at Purdue University and Mercy Hospital in St. Louis, Missouri, developed 1) a non-invasive procedure to place urinary catheters in neonatal female dairy calves at 1-week and 6-weeks of age in order to quantify measures of intestinal health through the oral administration of a non-digestible marker that presented in the urine, and 2) an orally-administered bolus that allows for the non-invasive collection of intestinal contents in pigs. It was determined that these methods could safely and effectively allow researchers to quantify metrics of intestinal health while simultaneously eliminating the need to euthanize animals or implement invasive measures of intestinal health during research studies. These methods are expected to improve livestock welfare by eliminating the need to euthanize animals or implement invasive procedures during research studies.

4. Determined that in utero heat stress alters brain function in pigs and provides opportunities to develop effective strategies to improve swine welfare. Increasing global temperatures brought about by climate change threaten the sustainability and profitability of global animal agriculture and have been demonstrated to reduce swine health, productivity, and welfare during prenatal development and postnatal life. ARS researchers in West Lafayette, Indiana, have previously demonstrated that in utero heat stress can result in reduced postnatal welfare of pigs due to a greater behavioral and physiological stress response to common production stressors. However, the biological reason for why this occurs was previously unknown. Therefore, ARS researchers in West Lafayette, Indiana, conducted an experiment to determine whether in utero heat stress had an impact on brain function that could explain the previously observed reductions in postnatal welfare when pigs were subjected to common production practices. It was determined that in utero heat stressed pigs had an increase in size of a region of the brain (hypothalamus) that controls their physiological stress response. In addition, when pigs were subjected to a stress challenge, the in utero heat stressed pigs were observed to have a physiological response indicative of greater stress. These data indicate that in utero heat stress may alter brain development of pigs, putting them at a greater risk of reduced welfare when undergoing common production practices (e.g., transport, social mixing, etc.). This information is expected to enhance researcher understanding of how in utero heat stress influences the postnatal welfare of pigs so that they may develop more effective pharmaceutical, nutritional, and/or management-based mitigation strategies to improve swine welfare in the face of climate change.

5. Reduced lameness in laying hens through the provision of probiotics. In laying hens, there is a progressive decrease in the amount of mineralized structural bone resulting in osteoporosis, causing serious health and welfare issues as damaged bones cause chronic pain, inflammation, skeletal fragility and susceptibility to fracture in billions of laying hens globally. Several management strategies, such as modifying housing environments (e.g., the use of perches to increase physical activity), diets (such as omega-3 polyunsaturated fatty acid) or chemicals (such as strontium and photo-stimulation) have been used in an attempt to prevent osteoporosis by reducing social stress-associated physical and/or metabolic disorders. However, these methods have had limited success and provide no guarantee in preventing osteoporosis and lameness. Therefore, ARS researchers in West Lafayette, Indiana, performed a study to examine the effects of a dietary probiotic supplement on the skeletal health of laying hens. The results revealed that chicken bone health can be improved by providing probiotics to modify the gut microbiota composition and related the functions of the gut-brain-bone and gut-immune axes. As such, a dietary probiotic supplement may be an important management tool for the poultry egg industry to prevent or reduce the development of osteoporosis and related physical damage in laying hens, potentially safeguarding their health and welfare. The results have been introduced to stakeholders and poultry producers through scientific publications, magazines, and workshops.

6. Determined environmental enrichment can improve sow welfare. Group housing of sows in current U.S. commercial systems may challenge their welfare due to mixing aggression and boredom in barren environments. The introduction of environmental enrichment (e.g., commercially available rubber toys designed specifically for pigs) may help to address both of these. Therefore, ARS researchers in West Lafayette, Indiana, carried out a study to examine the short-term effects of an enrichment device on the behavior and welfare of sows that were group housed. Sows were mixed in pens provided with environmental enrichment, and behavior and welfare measures were recorded. Preliminary results suggest that the addition of environmental enrichment to group housed sow pens can improve sow welfare by decreasing injuries and fighting and improving cleanliness. Although confirmation by full data analysis is required, the environmental enrichment may have the potential to decrease group housing-induced aggression, which is important for sow welfare and productivity due to aggression-induced embryo loss, thereby addressing both consumer and producer concerns.

Review Publications
Freitas, P., Johnson, J.S., Chen, S., Oliveria, H., Tiezzi, F., Lazaro, S., Huang, Y., Gu, Y., Schinckel, A., Brito, L. 2021. Definition of environmental variables and critical periods to evaluate heat tolerance in large white pigs based on single-step genomic reaction norms. Frontiers in Genetics. 12. Article 717409.
Hu, J., Xiong, Y., Gates, R.S., Cheng, H. 2021. Perches as cooling devices for reducing heat stress in caged laying hens: A review. Animals. 11(11). Article 3026.
Hu, J., Mohammed, A.A., Murugesan, R.M., Cheng, H. 2022. Effect of a synbiotic supplement as an antibiotic alternative on broiler skeletal, physiological, and oxidative parameters under heat stress. Poultry Science. 101(4). Article 101769.
Huang, X., Hu, J., Peng, H., Cheng, H. 2022. Embryonic exposure to tryptophan yields bullying victimization via reprogramming the microbiota-gut-brain axis in a chicken model. Nutrients. 14(3):661.
Nejati, S., Wang, J., Heredia, U., Sedaghat, S., Woodhouse, I., Johnson, J.S., Verma, M., Rahimi, R. 2021. Small intestinal sampling capsule for inflammatory bowel disease type detection and management. Lab on a Chip. 22(1):57-70.
Johnson, J.S., Jansen, T.L., Galvin, M., Field, T.C., Graham, J.R., Stwalley, R.M., Schinckel, A.P. 2022. Electronically controlled cooling pads can improve litter growth performance and indirect measures of milk production in heat-stressed lactating sows. Journal of Animal Science. 100(2). Article skab371.
Byrd, C.J., Mcconn, B.R., Gaskill, B.N., Schinckel, A.P., Green-Miller, A.R., Lay Jr, D.C., Johnson, J.S. 2022. Characterizing the effect of incrementally increasing dry bulb temperature on linear and nonlinear measures of heart rate variability in nonpregnant, mid-gestation, and late-gestation sows. Journal of Animal Science. 100(1). Article skac004.
Ceja, G., Boerman, J.P., Neves, R.C., Johnson, N.S., Schoonmaker, J.P., Jorgensen, M.W., Johnson, J.S. 2022. Technical Note: A procedure to place urinary catheters in 1- and 6-week-old preweaned Holstein heifer calves for the in vivo evaluation of intestinal permeability. Journal of Animal Science. 100(8). Article skac213.
Sinclair, M., Lee, H., Chen, M., Li, X., Mi, J., Chen, S., Marchant, J.N. 2022. Opportunities for the progression of farm animal welfare in China. Frontiers in Animal Science . 3. Article 893772.
Maskal, J.M., Brito, L.F., Duttlinger, A.W., Kpodo, K.R., Mcconn, B.R., Byrd, C.J., Richert, B.T., Marchant, J.N., Lay Jr, D.C., Perry, S.D., Lucy, M.C., Safranski, T.J., Johnson, J.S. 2022. Characterizing the postnatal hypothalamic-pituitary-adrenal axis response of in utero heat stressed pigs at 10 and 15 weeks of age. Scientific Reports. 11. Article 22527.