Submitted to: Swine Day Report
Publication Type: Experiment Station
Publication Acceptance Date: 8/28/1997
Publication Date: N/A
Citation: Interpretive Summary: Livestock producers want to maximize production and minimize unnecessary stress in their animals. In order to fully understand the status of well-being in an animal, we must first identify some indicators of well-being in that animal. Eleven boars were trained to mount an artificial sow for semen collection. Blood samples were collected from each boar before, during, and after semen collection (Control treatment, CONT). Day later, each boar was put into the pen with the artificial sow and allowed to go through courtship behaviors, but semen was not collected. (Frustration treatment, FRUS). Overhead video cameras recorded the behavior of the boars. Blood samples were collected and three hormones were measured. These hormones, cortisol, beta-endorphin, and testosterone have been linked to stress and/or well-being in humans and some other animals. Neither the CONT nor the FRUS treatments affected levels of testosterone in nthe blood, whereas cortisol increased following both treatments. The amount of beta-endorphin increased in the blood during the FRUS but not during the CONT treatments. Analysis of the behavior found that the frustrated boars spent less time lying down and more time moving around the pen than control boars. In summary, these results indicate that increased beta-endorphin levels and decreased time spent lying down may serve as indicators of frustration in the boar. Researchers and livestock producers may be able to utilize these two biological indicators of stress to help eliminate stressors from the production environment; thus, improving animal well-being.
Technical Abstract: The goal of this experiment was to gain a greater understanding of how boars respond to different, and presumably stressful situations. Specifically, we wanted to identify physiological indicators of different types of stressors in boars. Eleven mature boars were trained to mount an artificial sow as if they were to be used for semen collection purposes. Each boar was fitted with a jugular catheter to facilitate frequent blood sampling. Two treatments were imposed upon the animals: 1) a control (CTRL) stressor which allowed the animal to proceed with normal copulatory behaviors culminating in ejaculation, and 2) a frustration (FRUS) stressor which allowed the animal to mount and display courtship behaviors toward the dummy but ejaculation was prevented. Frequent blood samples were collected for 30 min before, during, and for 30 min after exposure to the artificial sow. These samples were analyzed for three stress-related hormones: cortisol (C), beta-endorphin (BE), and testosterone (T). Behaviors were recorded with overhead video cameras. T levels did not change during or following either treatment. BE concentrations increased (P<.05) during FRUS treatment but not during CTRL treatment. Following return to the housing pen, cortisol levels were elevated over pre-exposure concentrations for both treatments (CTRL, P<.04; FRUS, P<.06). Analysis of the behavior found that following FRUS, the boars spent less time lying down and more time moving around the pen (P<.05) than following CTRL. In summary, these results indicate that increased BE levels and decreased time spent lying down may serve as indicators of frustration in the boar. Furthermore, cortisol and testosterone changes were not useful for differentiating between CTRL and FRUS stressors.