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United States Department of Agriculture

Agricultural Research Service


Location: Livestock Behavior Research

2012 Annual Report

1a. Objectives (from AD-416):
The long-term objective of this project is to optimize animal well-being 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. Over the next five years we will focus on the following objectives: Objective 1: Develop scientific measures of, identify husbandry and environmental challenges to, and develop sustainable alternatives that safeguard well-being of swine. Objective 2: Develop scientific measures of, identify husbandry and environmental challenges to, and develop sustainable alternatives that safeguard well-being of dairy cattle. Objective 3: Develop scientific measures of, identify husbandry and environmental challenges to, and develop sustainable alternatives that safeguard well-being of poultry.

1b. Approach (from AD-416):
This project will examine animal agricultural practices, using behavior, physiology, immunology, and neurobiology, in order to maximize both animal well-being and productivity. Our approach will be to conduct multiple research projects on common production practices and evaluate how these practices affect livestock behavior, physiology, and physical condition, and we will work to assess the animals’ mental state. This unit is charged with the difficult task of conducting research for three animal species: dairy cattle, swine, and poultry. To accomplish this goal, unit scientists representing different backgrounds and areas of expertise will work together on multiple and varying projects to cover the main issues characteristic of the production system of each species. The broad view of our ultimate goal is that we wish to 1) discover and further refine objective measures of stress, and 2) evaluate and create appropriate management and housing methods. Each objective in this project is a step forward toward our ultimate goal. Our success will provide stakeholders with assurance that animal well-being is optimized and it will provide producers with technology to remain competitive.

3. Progress Report:
Euthanasia using novel gas. This project went very well this year and was completed on schedule. Two separate experiments were conducted to determine the aversiveness of gases used to euthanize pigs. A third experiment was conducted to determine which gas was more humane. Lameness in sows. This year we concluded in collecting data from all sows on the study. We are currently statistically analyzing blood sample, weight, lameness and production data from these animals. Lab work continues to identify the cell characteristics of the lesions we have found in the cartilage of the leg joints. Housing enrichment for swine. We conducted a study using different housing enrichments to determine if one enrichment proved to be more effective than another. We found that the enrichments had positive effects on physiology and behavior. Data analysis is not yet complete. Sow aggression. We have completed a study in which sows were formed into groups of three after being housed in stalls. Groups were formed using neighbors or non-neighbors. Groups formed using neighbors increased aggression when they were mixed. Further analysis is ongoing. Induced molting. We have completed the experiment on induced molting in laying hens. Data analysis is partially complete. We have identified the different effects of different molting methods on hen welfare. Hens fed a diet mixed with a compound to reduce hunger tended to be better in welfare. Further analysis is ongoing. One manuscript is prepared to be submitted. Heat stress in poultry. Data analysis has been completed from the two experiments on heat stress in poultry. We have identified different responses between the chicken lines selected based on egg production and longevity; and found that oxidative damage can be reduced by antioxidants. Poultry aggression. Data analysis has been completed. We have identified that aggression in chickens can be reduced or inhibited by modifying brain development (the serotonergic system) in both the prenatal and postnatal stages. Heat stress in cattle. Our research on heat stress effects in cattle has been completed. We identified a specific immune system modulator that is low in calves when they are born to a cow who has experienced heat stress. These calves also carried a heavier bacterial load and thus were more susceptible to disease. Group size for veal calves. We conducted a study to determine the optimal group size for raising veal. Calves were raised in groups of 2, 4, or 8 while holding space per calf the same. Video was used to record their behavior and blood samples were taken every third week to assess stress physiology and immune function. Data are currently being analyzed.

4. Accomplishments
1. Humane euthanasia. Swine producers are seeking a non-physical manner in which to humanely euthanize piglets. ARS researchers in West Lafayette, IN have found that a unique combination of gases are able to anesthetize piglets prior to euthanasia with a second more harmful gas to allow for humane euthanasia. Development of this technique for on-farm use will allow pigs to be humanely euthanized. It will also decrease the use of physical techniques of piglet euthanasia which are often criticized by animal rights groups and often found to be objectionable to perform by farm workers.

2. Osteoporosis in laying hens. Currently, most laying hens are housed in conventional cages in the United States, which limits their movement and ability to perform natural behavior, such as roosting, which can cause osteoporosis (a progressive decrease in mineralized structural bone). Osteoporosis causes 20 to 35% of all mortalities in caged White Leghorn hens. Reducing or eliminating osteoporosis associated with conventional cages would considerably improve hen health and well-being. ARS researchers in West Lafayette, IN have examined the effects of exercise, using perches, on bone mineralization in laying hens. Results indicate that mechanical loading achieved through perching have beneficial effects on pullet health by increasing leg and bone strength. Thus producers can increase both welfare and profitability by providing hens with perches.

3. Calf morbidity in summer. Calves born in summer frequently have greater morbidity. To explain this phenomenon, ARS researchers at West Lafayette, IN found total bacterial counts (aerobes) on the hide and udder of dams and in the nose of calves were greater in summer. Potential disease causing bacteria were greater in feces and in the nose of winter born calves showing competitive exclusion by the increased number of total bacteria in these calves. An immune system modulator (tumor necrosis factor-alpha) was low in summer calves suggesting immune suppression in the first two weeks of life. These data suggest that measures to cool cows during the month prior to giving birth and additional attention to calving environments are warranted in summer.

4. Aggression in laying hens. Feather pecking and cannibalism occur in all the current egg production systems including cage and free range, which is an eminent cause of mortality in untrimmed chickens. Beak trimming is a common practice to prevent feather pecking and cannibalism but it causes tissue damage, resulting in inflammation and pain in trimmed chickens. ARS researchers in West Lafayette, IN have identified that aggression in chickens can be reduced or inhibited by modifying brain development (the serotonergic system) in the early embryonic stage. The method could replace beak trimming to eliminate chickens suffering from pain. Currently this technology needs further development.

5. Heat stress in poultry. Heat stress is one of the most important environmental factors adversely affecting overall poultry production and causing death of chickens in the U.S, especially; in the hot regions and/or during summer. ARS researchers in West Lafayette, IN have identified different responses between two different chicken lines and found that damage from heat stress can be reduced by anti-oxidants. The results provide additional evidence that genetic selection can be used to reduce the negative effects of heat stress, thus improving animal welfare. Currently the use of anti-oxidants to reduce heat stress is being further developed.

6. Infrared beak trimming improves hen welfare. Beak trimming, using a hot blade, is a common practice in the poultry industry that is often criticized as inhumane. ARS researchers at West Lafayette, IN investigated an alternative method of beak trimming which uses an infrared laser, similar to those used in biomedical procedures. They used both treatments and studied 1,056 chicks which were either trimmed with a laser or hot-blade. Their data indicates that beak trimming at a young age (1 day of age) causes acute pain but not chronic pain. In addition, infrared trimming performed at 1 day of age was better than hot-blade trimming at 7 days of age with bird exhibiting less pain behaviors and less scar tissue; however infrared trimming at 1 day of age was similar to hot-blade trimming at 1 day of age. This study provides scientific evidence to support the use of infrared beak-trimming by producers and addresses the welfare concern of the current practice when performed early in life.

Review Publications
Rault, J., Lay Jr, D.C., Marchant Forde, J.N. 2011. Castration induced pain in pigs and other livestock. Applied Animal Behaviour Science. 135:214-225.

Dennis, R.L., Cheng, H. 2011. The dopaminergic system and aggression in laying hens. Poultry Science. 90(11): 2440-2448.

Xu, L., Eicher, S.D., Applegate, T. 2011. Effects of increasing dietary concentrations of corn naturally contaminated with deoxynivalenol on broiler and turkey poult performance and response to lipopolysaccharide. Poultry Science. 90(12):2766-2774.

Dennis, R.L., Cheng, H. 2012. Effects on selective serotonin antagonism on central neurotransmission. Poultry Science. 9(4) 817-822.

Mack, L.A., Felver-Gant, J.N., Dennis, R., Cheng, H. 2013. Genetic variations alter production and behavioral responses following heat stress in two strains of laying hens. Poultry Science. 92:285-294.

Last Modified: 07/20/2017
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