Location: Livestock Behavior Research
2020 Annual Report
Objectives
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.
Approach
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
Sub-Objective 1.A. Determine the thermal preference of sows and their physiological response during a heat stress event. For the thermal preference testing, two thermoclines were constructed and sows at three reproductive stages (open, mid-gestation, late-gestation) were allowed free access to a thermal gradient. Sows were video-recorded to assess thermal preference over a 24-hour period. This project was in collaboration with researchers at Purdue University. Data collection and analysis for the thermal preference testing of sows has been completed and data has been written up for publication. Four abstracts have been submitted for scientific conferences based on the data from Sub-objective 1.A. For determining the physiological response of sows during a heat stress event, sows at three reproductive stages (open, mid-gestation, late-gestation) were catheterized and exposed to gradually increasing temperature levels for a total of 11 hours. During this time body temperature, heart rate, and blood samples were taken. All data collection from this experiment has been completed and data analysis and manuscript write-up is currently ongoing.
Sub-Objective 1.D. On-farm assessment of tear staining and Welfare Quality measures. A study was carried out on pigs from birth to slaughter, examining tear stains and a range of individual and group measures of welfare, including skin lesions, body condition scores, lameness, respiratory and gastrointestinal health. Preliminary results indicate a relationship with skin lesions and tear stain scores. Further analysis is ongoing.
Sub-Objective 2.A. The amino acid tryptophan can be used to decrease aggression and it has been suggested to use this dietary supplement when mixing groups of pregnant sows. However, it is not known if the high doses of tryptophan effect the development of the fetuses. Diets containing three different levels of tryptophan were fed to gestating sows and physiologic and behavioral responses to stress were measured. No effects on the fetus' physiology or behavior were found. Data have been analyzed and a manuscript is in preparation.
Sub-Objective 2.B. Piglet survival during their first few days of life can be decreased due to their inability to maintain their body temperature. A heating pad to cover 2/3 of the floor space of the farrowing pen was designed, leaving the sow area unheated. Behavior, physiology and productivity data were collected and analyzed, and a manuscript is in preparation.
Sub-Objective 2.C. Evaluating the impact of in utero heat stress on postnatal behavior and stress response in pigs. The study objective was to determine whether in utero heat stress negatively impacted the stress and performance response of newly weaned and transported piglets. Pregnant sows were exposed to either heat stress or thermoneutral conditions throughout the first half of pregnancy at the University of Missouri in Columbia, Missouri. Their offspring were then weaned and transported for 12 hours to West Lafayette, Indiana, and housed at the Purdue University swine farm. Behavioral and production measures were recorded and blood samples were taken to evaluate physiological indicators of stress and post-absorptive metabolism. This project was in collaboration with researchers at the University of Missouri and Purdue University. All animal testing has been completed for this objective, data have been analyzed, and the final manuscript has been submitted for publication.
Sub-Objective 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. Piglets were weaned and transported for 12-hours. Following transport, all pigs were group housed and provided one of five diet treatments for 14 days (antibiotic free, antibiotics, 0.20% L-glutamine, synbiotics, 0.20% L-glutamine + synbiotics). All live phase procedures, lab analyses, and statistical analyses have been completed. Data has been written and a paper has been submitted for publication.
Sub-Objective 3.C. Determine if probiotics prevent osteoporosis in laying hens. Behavioral and physiological analysis for the probiotic effect on skeletal health and related welfare was completed. Some of the data has been published and presented during scientific annual meetings. The remaining data is undergoing analysis and interpretation and will be prepared for submission next year.
Sub-Objective 3.E. Reduce social stress in laying hens by prenatal modification of the serotonergic system with tryptophan. Behavioral and physiological data are undergoing analysis and interpretation. Some of the results have been reported through a peer-reviewed journal publication.
Sub-Objective 3.F. Demonstrate that providing beneficial enrichment materials to swine will decrease problem behaviors and improve welfare and productivity. One longitudinal study was carried out to examine the effects of enrichment delivered to slaughter pigs over three phases of life, namely during lactation, nursery and grow-finish. All data have been collected and is being analyzed. Preliminary results suggest that the enrichment used conferred benefits in skin lesions, tear stains and cortisol concentrations, indicating improved welfare.
Accomplishments
1. Determined the role of stress in the efficacy of dietary antibiotics. Dietary antibiotics are often included in the diets of newly weaned and transported pigs to reduce the incidence of disease, improve intestinal health, and increase growth performance. However, anecdotal evidence exists demonstrating that dietary antibiotic efficacy may be reduced if pigs are not stressed. To determine whether the physiological stress response plays a role in the efficacy of dietary antibiotics on improving intestinal health of pigs, ARS researchers in West Lafayette, Indiana, conducted a study to evaluate the effects of providing dietary antibiotics or no dietary antibiotics to pigs that received an injection of a corticotropin releasing hormone antagonist or sterile saline and then were weaned and transported for 12 hours. The corticotropin releasing hormone antagonist inactivated the physiological stress response during the weaning and transport process. It was determined that providing the corticotropin releasing hormone antagonist with no dietary antibiotics improved biomarkers of intestinal health (morphology, gene expression) and inflammation (cytokines) to a similar extent as pigs given the antibiotics and sterile saline or antibiotics and the corticotropin releasing hormone antagonist and that providing no dietary antibiotics and a saline injection resulted in reduced intestinal health. These data suggest for the first time that there is a direct link between reducing the physiological stress response and eliminating the need for dietary antibiotics to improve intestinal health in pigs. Results from this project may be used to develop stress reducing management practices and/or nutritional supplements that can reduce or eliminate the use of prophylactic antibiotics in swine production and improve animal welfare and producer profitability.
2. Demonstrated that using nitrous oxide (laughing gas) to euthanize pigs is as effective as using carbon dioxide and may be more humane. Pig farmers are forced to euthanize a significant number of pigs due to injuries, hernias, or unthriftiness. Most pigs are euthanized using carbon dioxide gas asphyxiation. However, the humaneness of carbon dioxide is being increasingly questioned. ARS researchers in West Lafayette, Indiana, compared euthanizing pigs with either carbon dioxide or nitrous oxide. Pigs lost posture within the same duration and pigs in both treatments performed a similar amount of distress behaviors. However, pigs receiving carbon dioxide performed more distressful behaviors prior to losing posture, a sign of losing consciousness. Therefore, nitrous oxide is a suitable alternative to carbon dioxide which may improve the welfare of pigs that have to be euthanized.
3. Determined that a synbiotic (probiotics plus nutrients necessary for them to flourish) reduces the effects of heat stress in broiler chickens. 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. ARS researchers in West Lafayette, Indiana, performed a study in a controlled environment to examine the effects of a dietary synbiotic supplement on the behavioral patterns and growth performance of broiler chickens exposed to heat stress. The results suggest that the synbiotic supplement may prove to be an important management tool for the broiler industry to diminish the negative effects of heat stress, potentially safeguarding the welfare and production of broiler chickens, particularly in areas that experience hot climates.
4. Determined that the probiotic, Bacillus subtilis, reduces the development of osteoporosis in laying hens. In laying hens, there is a progressive decrease in the amount of mineralized structural bone resulting in osteoporosis, causing a serious health and welfare issue 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 the use of chemicals (such as strontium and photostimulation) have been used in attempts 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. ARS researchers in West Lafayette, Indiana, performed a study to examine the effects of a dietary probiotic supplement on skeletal health of laying hens. The results suggest that the probiotic supplement may prove to 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.
5. Investigated a contactless method of heart rate measurement based on video analysis. ARS researchers in West Lafayette, Indiana, carried out two experiments in which video-recorded data was collected from a) an anesthetized pig and b) a sleeping pig. Focusing on skin areas of the face, belly and foreleg, data were collected on color variations due to blood flow in the anesthetized pig, separating the pixels of the video frames into their red, green and blue channel values and deriving an algorithm which would enable them to estimate heart rate and comparing this against simultaneously collected electrocardiogram values. The derived algorithm was then also used to estimate heart rate in the sleeping pig. With the anesthetized pig, the mean accuracy of the video method was within 2.3 beats per minute. With the sleeping pig, this increased to six beats per minute. The belly was the best area to focus on and the green channel values provided the best accuracy. With further refinement and development, video data alone could be used to measure heart rate of pigs in a resting state within commercial production systems, which currently cannot be done, thereby improving on-farm welfare assessment.
6. Demonstrated that even minimal enrichment was beneficial to pig welfare in lactation and nursery phases. ARS researchers in West Lafayette, Indiana, found that during lactation, piglets with access to rubber toy enrichment had lower cortisol concentrations, which is an indicator of decreased stress levels, lower skin lesion scores and smaller tear stains than unenriched piglets. During the nursery phase, cortisol concentrations were highest in pigs who were housed without enrichment, but who had previously had enrichment during lactation. During the grow-finish phase, treatment did not affect measures. Results show that even minimal enrichment can have some positive effects, but more beneficial enrichment should be provided to maximize welfare benefits. Further data analysis is ongoing, and the second stage of this experiment is to introduce enrichment to commercial farms with our industry partners.
Review Publications
Yan, F., Mohammed, A.A., Murugesan, R., Cheng, H. 2019. Effects of a dietary synbiotic inclusion on bone health in broilers subjected to cyclic heat stress episodes. Poultry Science. https://doi.org/10.3382/ps/pey508.
Hu, J., Hestor, P.Y., Makagon, M.M., Xiong, Y., Gates, R., Cheng, H. 2019. Effect of cooled perches on performance, plumage condition, and foot health of caged White Leghorn hens exposed to cyclic heat. Poultry Science. https://doi.org/10.3382/ps/pez039.
Eicher, S.D., Chitko-McKown, C.G., Bryan, K. 2020. Variation in the response of bovine alveolar lavage cells to diverse species of probiotic bacteria. BMC Research Notes. https://doi.org/10.1186/s13104-020-4921-9.
Hu, J., Hester, P., Makagon, M.M., Xiong, Y., Gates, R., Cheng, H. 2019. Effect of cooled perches on physiological parameters of caged White Leghorn hens exposed to cyclic heat. Poultry Science. https://doi.org/10.3382/ps/pez012.
Jiang, S., Wu, X.L., Jin, M.L., Wang, X.Z., Tang, Q., Sun, Y.X., Cheng, H. 2019. Pathophysiological characteristics and gene transcriptional profiling of bone microstructure in a low calcium diet fed caged laying hens. Poultry Science. https://doi.org/10.3382/ps/pez271.
Mohammed, A.A., Jiang, S., Jacobs, J.A., Cheng, H. 2019. Effects of a synbiotic supplement on cecal microbial ecology, antioxidant status, and immune response of broiler chickens reared under heat stress. Poultry Science. https://doi.org/10.3382/ps/pez246.
Chapel, N.M., Thomovsky, S.A., Lucas, J.R., Kushiro-Banker, T., Radcliffe, J.S., Stewart, K.R., Lay Jr, D.C. 2019. Auditory brainstem responses in weaning pigs and three ages of sows. Translational Animal Science. 3(4):1416–1422. doi:https://doi.org/10.1093/tas/txz123.
Hu, J., Hester, P.Y., Xiong, Y., Gates, R.S., Makagon, M.M., Cheng, H. 2019. Effect of cooled perches on the efficacy of an induced molt in White Leghorn laying hens exposed to cyclic heat. Poultry Science. https://doi.org/10.3382/ps/pez317.
Suarez-Trujillo, A., Sun, H., Huff, K., Cummings, S., Franco, J., Steckler, T., Boerman, J., Wernet, G., Townsend, J., Grott, M., Johnson, J.S., Plaut, K., Casey, T. 2020. Exposure to chronic light-dark phase shifts during the prepartum dry period attenuates circadian rhythms, decreases blood glucose and increases milk yield in the subsequent lactation. Journal of Dairy Science. https://doi.org/10.3168/jds.2019-16980.
Zhang, S., Johnson, J.S., Qiao, M., Trottier, N.L. 2020. Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigates heat production associated with milk for lactating sows. Journal of Animal Science and Biotechnology. https://doi.org/10.1186/s40104-019-0414-x.
Kpodo, K.R., Duttlinger, A.W., Radcliffe, J.S., Johnson, J.S. 2019. Time course determination of the effects of rapid and gradual cooling after acute hyperthermia on body temperature and intestinal integrity in pigs. Journal of Thermal Biology. https://doi.org/10.1016/j.jtherbio.2019.102481.
Kpodo, K.R., Duttlinger, A.W., Maskal, J.M., Johnson, J.S. 2020. Effects of feed removal on thermoregulation and intestinal morphology in pigs recovering from acute hyperthermia. Journal of Animal Science. https://doi.org/10.1093/jas/skaa041.
Çavusoglu, E., Rault, J., Gates, R., Lay Jr, D.C. 2020. Behavioral response of weaned pigs during gas euthanasia with CO2, CO2 with butorphanol, or nitrous oxide. Animals. https://doi.org/10.3390/ani10050787.
Byrd, C.J., Johnson, J.S., Radcliffe, J.S., Craig, B.A., Eicher, S.D., Lay Jr, D.C. 2019. Nonlinear analysis of heart rate variability for evaluating the growing pig stress response to an acute heat episode. Journal of Animal Science. https://doi.org/10.1017/S1751731119001630.
Parois, S.P., Duttlinger, A.W., Richert, B.T., Lindemann, S.R., Johnson, J.S., Marchant Forde, J.N. 2020. Effects of three distinct two-week long diet strategies after transport on weaned pigs’ short and long-term welfare markers, behaviors and microbiota.. Journal of Animal Science. https://doi.org/10.3389/fvets.2020.00140.
