Location: Livestock Behavior Research
2019 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. Data is currently being prepared for publication in a peer-reviewed journal. Two 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. At the present time, three of the four animal testing repetitions have been completed. The fourth repetition is scheduled to be completed in the Fall of 2019. Data from the first three repetitions are currently being entered and prepared for final analysis.
Sub-objective 1.B. To improve our ability to identify and evaluate pain experienced by animals as a result of routine husbandry practices (castration, dehorning) in conjunction with behavioral indicators of pain and plasma stress parameters, HRV (linear and nonlinear). The swine data analysis is complete, and a manuscript has been submitted. The calf data collection is also complete, and a manuscript has been submitted.
2.B. Simultaneously enhance the thermal environment of sows and piglets to increase sow comfort and piglet survivability. A study was carried out that investigated an optimal management of light and mat surface temperature that may promote greater piglet use of the creep, which has been associated with reduced piglet crushing. The results suggest that piglet use of the creep increased with warm mat temperatures and brightness, which should be further investigated as potential strategies to promote piglet safety and reduce crushing in pen farrowing systems.
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 and data are currently undergoing analysis.
Sub-objective 3.B. Probiotics to support development of dairy calf respiratory immunity. Calves were assigned to control or symbiotic (mixture of pre- and probiotics) in their milk replacer until weaned, then received the synbiotic in their dry feed. Weekly weights were recorded. Nasal and tonsil swabs were collected on day 7, 21, 42 as well as jugular blood samples. Calves were completely weaned on day 49 and a bronchial alveolar lavage performed on day 52. Blood was analyzed for immune system activity. This work is complete, analyzed, and a paper written. Nasal and tonsil swabs were sent to ARS collaborators in Clay Center Nebraska for microbiome analysis.
Sub-Objective 3.C. Determine if probiotics prevent osteoporosis in laying hens. Behavioral and physiological collection for the probiotic effect on skeletal health was completed. Data is undergoing analysis and interpretation.
Sub-Objective 3.D. Reduce heat stress in broiler chickens by activating the microbiota-gut-brain axis using synbiotics. Behavioral, physiological, and production data of phase 1 have been finished and phase 2 has been initiated. The data collected from phase 1 have been reported through peer-reviewed journal publications and attending scientific annual meetings.
Sub-Objective 3.E. Reduce social stress in laying hens by prenatal modification of the serotonergic system with tryptophan. Behavioral and physiological data collection was completed. Data is currently undergoing analysis and interpretation and will be prepared for submission next year.
Sub-Objective 3.F. Demonstrate that providing beneficial enrichment materials to swine will decrease problem behaviors and improve welfare and productivity. One longitudinal study is in progress which will examine the effects of enrichment delivered to slaughter pigs over three phases of life, namely during lactation, nursery and grow-finish. The first replicate has been weaned and the second replicate is still in the farrowing house. Behavior, production and physiological data are being collected.
Accomplishments
1. Synbiotic (probiotics and nutrients necessary for them to flourish) reduces heat stress (HS) in broiler chickens. Ambient temperature that is elevated beyond the temperature tolerance 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, birds furthest away from the air inlets are not cooled 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. The results indicate that the synbiotic supplement may prove to be an important management tool for the broiler industry to diminish the negative effects of HS, potentially safeguarding the welfare and production of broiler chickens, particularly in areas that experience hot climates.
2. Determined the thermal preferences of sows. Currently, there are no ambient temperature recommendations for gestating sows. Furthermore, swine temperature threshold recommendations provided by the Guide for the Care and Use of Agricultural Animals in Research and Teaching (AgGuide) are based on data that are over 30 years old and likely do not represent the thermal preferences of modern commercial swine. ARS scientist in West Lafayette, Indiana, performed a study to determine what temperatures sows at three reproductive stages (open, mid-gestation, late-gestation) preferred. In order to determine thermal preference, we designed and constructed two thermoclines that provided a temperature gradient in which sows could choose the temperature at which they wanted to spend the most time. Through this experiment, it was determined that sows preferred temperatures ranging from 13 to 16°C, with late-gestation sows preferring temperatures at the lower end of the range compared to open and mid-gestation sows. These data indicate that current recommendations by the AgGuide should be updated to reflect the genetic and metabolic improvements of modern swine.
3. Synbiotics had some beneficial effect on the immune system of calves. Synbiotics (probiotics and the nutrients necessary for them to flourish) are used to enhance enteric immunity and gut health. ARS researchers in West Lafayette, Indiana, hypothesized that these synbiotics may also be having a beneficial effect for neonatal calf respiratory immunity when delivered daily from birth through weaning. Blood work showed changes in immune cell populations, cell markers, but not cell functions on day 21. These data suggest that the synbiotics were preventing stimulation of the immune cells by the pathogens. However, the DNA analysis showed no treatment differences of the blood cells nor the lung cells. The results suggest that the synbiotic may be preventing inflammation for calves during their most vulnerable period around 21 days of age when maternal antibodies are waning, and the calf immunity is just beginning to develop. Thus producers can target feeding these synbiotics to improve welfare and productivity.
4. Evaluated the postnatal stress response and performance of in utero heat-stressed piglets following weaning and transport. In utero heat stress negatively impacts swine welfare and productivity and is a growing concern for the U.S. swine industry. Numerous studies have determined that in utero heat stress reduces swine productivity, alters metabolism, impacts nutrient partitioning, and can cause birth defects. However, the effects on swine welfare have yet to be elucidated. To address this, ARS researchers in West Lafayette, Indiana, performed two studies to evaluate the post-weaning and transport behavioral and physiological stress response of piglets previously exposed to in utero heat stress. It was determined that in utero heat stressed piglets had a greater stress response, reduced growth rate, and altered post-absorptive metabolism relative to their in utero temperature tolerance zone counterparts following weaning and transport. These data suggest that piglets gestated during Summer months may be more susceptible to post-weaning and transport welfare issues compared to those gestated during the Fall, Winter, or Spring seasons. Thus, management strategies to decrease these stressors need to be employed.
5. Discovered that the use of non-linear measures of heart rate variability may be a useful measure to assess pain in swine. The measurement of pain is essential to assess the welfare of animals subjected to different managerial procedures. If pain can be accurately assessed, then those procedures which minimize pain can be employed. Yet, pain is difficult to assess in livestock. ARS researchers in West Lafayette, Indiana, investigated several novel methods of heart rate variability analysis when pigs were subjected to castration. Two measures were specifically enlightening to distinguish pain from the mere stress of handling. These results are expected to provide researchers with a more advanced procedure to determine which procedures are less painful.
6. Analysis of microbial populations following dietary L-glutamine inclusion (an essential amino acid) revealed impacts on microbial populations and links to behavior. There is growing widespread concern about antimicrobial resistance and the use of antibiotics in livestock production, which is driving research into alternatives that will safeguard the health and welfare of animals during times of stress. For pigs, one of the most stressful events is weaning, during which the piglet has sudden change in diet from milk to solid food, is separated from the sow and mixed with unfamiliar piglets and may be transported to a different farm. To combat this stress, ARS researchers in West Lafayette, Indiana, examined an experimental diet containing the amino-acid L-glutamine, comparing it with a diet containing antibiotics and a control diet containing neither. Piglets fed the glutamine diet showed similar responses to stressors as the piglets fed the antibiotic diet. Piglets showed less aggression, had smaller tear stain areas (a stress indicator) and were more interactive with novel objects placed in the pen, than piglets on the control diet. The gut microbiota (mixed populations of bacteria that reside in the gut) of glutamine-fed pigs was more diverse and correlations between aggression, stress and anxiety indicators and bacterial populations were medium to high. Overall, glutamine appeared to confer similar benefits to antibiotics and could be a viable alternative for piglets at weaning. Thus, the use of L-glutamine may prove to be a viable alternative to antibiotics.
7. Demonstrated improved creep area use by piglets by adjusting creep brightness and temperature. There is growing public support for sows to give birth in open pens rather than be confined in crates, which is currently the most common system, due to concerns about the welfare of the sow. However, open pens have generally resulted in an increase in piglet mortality before weaning, and most of this mortality can be attributed to being crushed by the sow. Most pens have separate areas for the piglets to rest in - the creep area - and ideally, the temperature and light levels within the creep area will attract the piglets to spend more time in this safe area of the pen. ARS researchers in West Lafayette, Indiana, compared two different light levels (dark and bright) within the piglet creep areas, and measured creep temperature to see whether these affected the amount of use by the piglets. Piglets spent more time in the bright creeps than the dark creeps, with a resulting decrease in time spent in areas that might place them at greater risk of crushing by the sow. Also, as mat temperature increased, use of the creep area increased. These results indicate that these environmental factors should be further investigated as potential strategies to promote piglet safety and reduced crushing in pen farrowing systems.
Review Publications
Chapel, N.M., Radcliffe, J.S., Stewart, K.R., Lucas, J.R., Lay Jr, D.C. 2018. The impact of farrowing room noise on sows’ reactivity to piglets. Translational Animal Science. 3(1):175-184. https://doi.org/10.1093/tas/txy134.
Byrd, C., Chapel, N., Lugar, D., Safranski, T., Lucy, M., Johnson, J.S. 2019. Evaluating the effects of in utero heat stress on piglet physiology and behavior following weaning and transport. Animals. 9(4):191. https://doi.org/10.3390/ani9040191.
Johnson, J.S., Baumgard, L.H. 2019. Postnatal consequences of in utero heat stress in pigs. Journal of Animal Science. 97(2):962-971. https://doi.org/10.1093/jas/sky472.
Kpodo, K.R., Duttlinger, A., Johnson, J.S. 2019. Effects of pen location on thermoregulation and growth performance in grow-finish pigs during late summer. Translational Animal Science. https://doi.org/10.1093/tas/txz033.
Johnson, J.S., Zhang, S., Morello, G.M., Maskal, J.M., Trottier, N.L. 2019. Technical note: Development of an indirect calorimetry system to determine heat production in individual lactating sows. Journal of Animal Science. 97(4):1609-1618. https://doi.org/10.1093/jas/skz049.
Duttlinger, A.W., Kpodo, K.R., Lay Jr, D.C., Richert, B., Johnson, J.S. 2019. Replacing dietary antibiotics with 0.20% L-glutamine in swine nursery diets: impact on health and productivity of pigs following weaning and transport. Journal of Animal Science. 97(5):2035-2052. https://doi.org/10.1093/jas/skz098.
