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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

2021 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
Sub-Objective 1.A. 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 and the University of Illinois. Data collection and analysis for the thermal preference testing of sows has been completed and data has been written up and published as a peer-reviewed journal article in the Journal of Animal Science. 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 and analysis from this experiment has been completed and the peer-reviewed manuscript was published in the Journal of Animal Science. In addition, four abstracts have been submitted and presented at scientific conferences and a third manuscript is in preparation for submission to the Journal of Animal Science based on the data from Sub-objective 1.A. All milestones for Sub-Objective 1.A have been completed. Sub-Objective 1.D. A study was carried out examining tear staining in piglets reared in two farrowing systems (crates and open pens) and subjected to two different handling treatments (routine and additional positive handling). Contrary to the expected findings, pigs from open pens had a higher severity of tear staining compared to pigs from farrowing crates, possibly due to the fact that the particular design of this system meant that piglets were raised in a much more isolated environment, with less visual, auditory and olfactory contact with stock people and other pigs, resulting in increased fear responses to novelty and humans in these pigs and greater stress responses. All data collection and analysis from this experiment has been completed. One abstract has been submitted for presentation at the Australasian Pig Science Association meeting and a manuscript is in preparation. 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 has been accepted for publication. 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. Increasing the warm area in farrowing crates with heated mats over the length of the piglet area increased survivability until day 3, when they were removed. However, this effect was not seen in the weaning mortality. Piglets may benefit further if given enhanced heating until weaning. Behavior, physiology and productivity data were collected and analyzed, and a manuscript is in preparation. Sub-Objective 2.C. 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 two peer-reviewed articles were published in the Journal of Animal Science and one article was published in the journal Animals from this research trial. A fourth manuscript is in preparation for submission to the journal Scientific Reports and a fifth manuscript is in preparation for submission to Frontiers in Genetics from this sub-objective. All milestones for Sub-Objective 2.C have been completed. Sub-Objective 3.A. This project was performed in collaboration with researchers at Purdue University and the company Biomatrix International. 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 up published as a peer-reviewed journal article in the Journal of Animal Science. All milestones for Sub-Objective 3.A. have been completed. Sub-Objective 3.C. Behavioral and physiological analysis for the probiotic effect on skeletal health and related welfare was completed. Some of the data has been published by peer-reviewed journal publications and has been presented during scientific annual meetings. The remaining data is undergoing analysis and interpretation and will be prepared for submission next year. Sub-Objective 3.D. Some of the data has been published by peer-reviewed journal publications and been 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. The effects of tryptophan administration on embryonic brain development and its long-lasting outcomes were examined through biological and behavioral analyses. The results indicate that prenatal injection of tryptophan modified the brain development and reduced aggression in laying hens. Some data have been submitted to peer-review journals and the remaining behavioral and physiological data are undergoing analysis and interpretation for submission. Sub-Objective 3.F. More analysis was carried out on the data from the longitudinal study to examine the effects of enrichment delivered to slaughter pigs over three phases of life, namely during lactation, nursery and grow-finish. During lactation, enrichment consisting of a tethered rubber toy resulted in lower cortisol concentrations, lower lesion scores and less huddling behavior, indicating improved welfare. All data collection from this experiment has been completed and analysis is ongoing. The first manuscript is in preparation.

1. L-glutamine supplementation improves pre-weaning dairy calf growth performance and reduces intestinal permeability. Dairy calves are generally removed from the mother shortly after birth, and then housed individually to reduce disease incidence and improve individualized care. However, the stress imposed by removing newborn calves from the dam can negatively impact intestinal development and the primary cause of pre-weaning mortality in dairy calves is enteric disease. Therefore, preventing enteric disease during the pre-weaning period is a primary concern for dairy producers both in the United States and globally. To address this concern, ARS researchers in West Lafayette, Indiana, determined whether supplementing newborn dairy calves with the conditionally essential amino acid L-glutamine would improve measures of intestinal health and subsequent growth performance and disease resistance. It was determined that L-glutamine supplementation improved pre-weaning feed efficiency and post-weaning body weight gain and reduced pre-weaning mortality. In addition, measures of intestinal permeability were improved for L-glutamine supplemented dairy calves when compared to controls, which has positive implications for improved intestinal function and overall health. These data suggest that supplementing pre-weaning dairy calves with L-glutamine could be used as a management and nutritional strategy to reduce enteric disease and improve overall health and welfare in dairy calves.

2. Electronically-controlled cooling pads improve measures of lactating sow thermoregulation, milk output, and litter performance independent of improved feed intake. Climate change-induced heat stress events can reduce swine growth performance, efficiency, meat production, and producer profitability. The effects of heat stress are of particular concern for lactating sows due to greater heat stress sensitivity, which can have negative downstream impacts on their offspring due to reduced milk production. In previous research, collaborative efforts between ARS researchers in West Lafayette, Indiana, and Purdue University led to the development of electronically-controlled sow cooling pads designed to reduce the effects of heat stress on lactating sows and their litters. However, effects on milk output and litter growth performance under heat stress conditions were unknown. To address this, ARS researchers in West Lafayette, Indiana, performed a study to evaluate the impact of cooling pads to improve measures of sow thermoregulation, milk production, and litter growth under heat stress conditions. Cooling pads were effective in allowing the sows to maintain a normal body temperature under heat stress conditions, leading to improved measures of milk output and increased litter growth performance. These improvements occurred independent of differences in feed intake, suggesting that heat stress reduces milk production independent from depressed feed intake. These data suggest that cooling pads are an effective method to improve sow thermoregulation and litter growth performance under heat stress conditions.

3. Heating a larger area of flooring at 39 degrees C decreased piglet mortality at 3 days of age. Piglets need supplemental heat when they are born to survive. Traditionally a relatively small area is heated to which the piglets can access at will; however, mortality is high. ARS researchers in West Lafayette, Indiana, compared using a traditional heat lamp, with a solid floor heated internally with lights for the entire piglet area. It was found that piglet mortality at three days of age was lower for the pigs with the greater area of heated floors. Heating a greater area of floor space producers may decrease piglet mortality.

4. Synbiotic supplements (probiotics plus nutrients necessary for them to flourish) reduce heat stress in broiler chickens. Heat stress 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 to examine the effects of a dietary synbiotic supplement on the behavioral patterns and growth performance of broiler chickens exposed to heat stress (HS). The effects of synbiotic effects on production, skeletal health, and immune response in broilers subjected to heat stress were examined by measuring body weight, the levels of bone density, inflammatory factors, and antibodies. The results showed that the synbiotic supplement reduced the negative effect of heat stress in broilers by improving their body weight, foot health, leg strength, and immunity.

5. Probiotic, Bacillus subtilis, prevents osteoporosis in laying hens. In laying hens, there is a progressive decrease in the amount of mineralized structural bone resulting in osteoporosis, causing 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 with 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 effects of Bacillus subtilis-based probiotic on egg production and skeletal health of laying hens were examined by analyses of bone mineral density and related hormones. The results showed that the probiotic increases egg production, eggshell quality, and skeletal health through reducing inflammatory effects on calcium metabolism and bone resorption.

6. Conducted a literature review and pig producer survey to identify risk factors for facial lesions in piglets and teat injuries in sows. Piglet facial and sow udder lesions are a welfare concern most commonly addressed by clipping or grinding piglets’ teeth in the belief that the presence of needle teeth is the major contributing factor. However, teeth resection is also a painful procedure and itself a welfare concern. Together with collaborators, ARS researchers in West Lafayette, Indiana, carried out a literature review and a producer survey to identify other factors contributing to lesions and interventions that could be carried out to reduce their incidence. We identified 6 major risk factors, though in some cases the science was scarce: 1) Presence or absence of needle teeth - most studies found that teeth resection reduced piglet facial lesions but the effect on sow teat lesions was less evident, 2) litter size - large litters appear to increase the risk of piglet injuries and sow teat wounds, 3) housing – farrowing in crates appeared to increase the risk of facial and teat lesions, which were lower in pen systems, 4) presence of environmental enrichment – some evidence that enrichment reduces piglet and sow lesions, 5) nutrition and health - milk supplementation for piglets can reduce facial lesions, and several pathogens can exacerbate these lesions, and 6) other management practices - cross-fostered piglets typically have more facial lesions than non-cross fostered and there more udder wounds in nurse sows compared to non-nurse sows. The survey showed that many producers manage poor milk production of the sow, manage large litters and provide enrichment rather than teeth resection to prevent lesions. Overall, there is a lack of research into piglet facial and sow udder lesions and more science-based advice is needed to help producers further understand the cause of, and to apply the different solutions to sow teat and piglet facial lesions.

7. Comprehensive review of genomic regions associated with animal behavior in farmed mammals (beef and dairy cattle, pigs, and sheep). The review conducted by collaborators and ARS researchers in West Lafayette, Indiana identified a total of 687 (cattle), 1391 (pigs), and 148 (sheep) genomic regions associated with 37 (cattle), 55 (pigs), and 22 (sheep) behavioral traits. The majority of the genes identified are likely controlling stimuli reception (e.g., olfactory), internal recognition of stimuli (e.g., neuroactive ligand–receptor interaction), and body response to a stimulus (e.g., blood pressure, fatty acidy metabolism, hormone signaling, and inflammatory pathways). About half of the genes for behavior identified in farmed mammals were also identified in humans for behavioral, mental, and neuronal disorders. The majority of the genes identified are likely controlling animal behavioral outcomes because their biological functions, as well as potentially differing allele frequencies between two breed groups, clustered based on their temperament characteristics. Those candidate genes and polymorphisms can be used as prior biological information to optimize subsequent genomic analyses e.g., genome-wide association studies and genomic predictions as well as describe polymorphisms to be added to existing genotyping platforms for future studies.

Review Publications
Wang, M., Youssef, A., Larson, M., Berckmans, D., Marchant Forde, J.N., Hartung, J., Bleich, A., Lu, M., Norton, T., Rault, J. 2021. Contactless Video-Based Heart Rate Monitoring of a Resting and an Anesthetized Pig. Animals. 11(2).
Robbins, L., Green-Miller, A.R., Johnson, J.S., Gaskill, B.N. 2020. Early life thermal stress: Impacts on future temperature preference in weaned pigs (3 to 15 kg). Journal of Animal Science. 98(12).
Ma, D., Guedes, J.M., Zuelly, S.M., Duttlinger, A.W., Johnson, J.S., Lay Jr, D.C., Kim, Y.H. 2020. Impact of L-Glutamine as Replacement of Dietary Antibiotics during Post Weaning and Transport Recovery on Carcass and Meat Quality Attributes in Pigs. Livestock Science. 244.
Ma, D., Suh, D., Zhang, J., Chao, Y., Duttlinger, A.W., Johnson, J.S., Lee, C., Kim, Y. 2021. Elucidating the involvement of apoptosis in postmortem proteolysis in porcine muscles from two production cycles using metabolomics approach. Scientific Reports. 11(1).
Johnson, J.S., Maskal, J.M., Duttlinger, A.W., Kpodo, K.R., Mcconn, B.R., Byrd, C.J., Richert, B.T., Marchant Forde, J.N., Lay Jr, D.C., Perry, S.D., Lucy, M.C., Safranski, T.J. 2020. In utero heat stress alters the postnatal innate immune response of pigs. Journal of Animal Science. 98(12).
Kpodo, K.R., Duttlinger, A.W., Maskal, J.M., Mcconn, B.R., Johnson, J.S. 2021. Effects of feed removal during acute heat stress on the cytokine. Animals. 11(1).
Duttlinger, A.W., Centeno Martinez, R.E., Mcconn, B.R., Kpodo, K.R., Lay Jr, D.C., Richert, B.T., Johnson, T.A., Johnson, J.S. 2021. Replacing dietary antibiotics with 0.20% L-glutamine in swine nursery diets: impact on intestinal physiology and the microbiome following weaning and transport. Journal of Animal Science. 99(6).
Tuell, J.R., Nondorf, M.J., Maskal, J.M., Johnson, J.S., Kim, Y.H. 2021. Impacts of in utero heat stress on carcass and meat quality traits of market weight gilts. Animals. 11(3).
Hu, J., Cheng, H. 2021. Warm perches: A novel approach for reducing cold stress effect on production, plasma hormones, and immunity in laying hens. Journal of Animal Science and Biotechnology. 100(8).
Jiang, S., Yan, F., Hu, J., Mohammed, A.A., Cheng, H. 2021. Bacillus subtilis-based probiotic improves skeletal health and immunity in broiler chickens exposed to heat stress: An updated review. Animals. 11(6).
Robbins, L., Green-Miller, A.R., Johnson, J.S., Gaskill, B.N. 2021. One is the Coldest Number: Determining How Group Size and Body Weight Affects Thermal Preference in Weaned Pigs (3 to 15 kg). Animals. 11(5).
Mcconn, B.R., Gaskill, B.N., Schinckel, A.P., Green-Miller, A.R., Lay Jr, D.C., Johnson, J.S. 2021. Thermoregulatory and physiological responses of nonpregnant, mid-gestation, and late-gestation sows exposed to incrementally increasing dry bulb temperature. Journal of Animal Science. 99(7).