Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001
Performing Department
ANIMAL HEALTH RESEARCH CENTER
Non Technical Summary
Cannibalism is a serious welfare problem in domestic fowl of layer strains. Although relationships between cannibalism and genetic, environmental, and nutritional factors are known, little research has been conducted on the role of steroids in cannibalistic behaviors. Our goals are to understand the physiological mechanisms involved in the expression of cannibalism in poultry and provide viable alternatives to beak amputation in the prevention of cannibalism. We will test a Gonadal Steroid Hypothesis of cannibalistic behavior. We hypothesize that high levels of circulating estradiol and/or progesterone during development and at the onset of lay promote cannibalistic behavior. Further, we hypothesize that testosterone, dihydrotestosterone, or androstenedione exposure during development or after the onset of lay is protective against cannibalistic behavior.Three projects will determine whether: cannibalistic attacks are correlated with levels of circulating gonadal
steroids, direct manipulation of gonadal steroids using exogenous treatments can prevent or alter ongoing cannibalism and modify the activational effects of steroids produced by hens that are in lay and showing cannibalistic behavior, if post-hatching exposure to gonadal steroids will act as a preventative for or predisposing agent to cannibalism associated with the onset of lay. Completion of these projects will improve the understanding of the mechanisms controlling expression of cannibalism in the domestic fowl, thereby facilitating development of effective and humane strategies for controlling this behavior.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
The impetus for our proposed projects is concern regarding the impact of cannibalistic behavior on the well-being of the domestic fowl. We are also concerned about the use of beak trimming to control cannibalism in light of evidence that the procedure causes acute and chronic pain. Our long-term goal is to understand the underlying mechanisms controlling expression of cannibalism in poultry, thereby facilitating the development of effective preventative and control strategies for this behavior without resorting to beak trimming. Previous research and preliminary data from our laboratory suggest a link between gonadal steroid levels in developing and adult laying hens and the incidence of cannibalism. We hypothesize that high levels of circulating estradiol (E2) and progesterone (P4) both during development and associated with the onset of lay stimulate cannibalism. Furthermore, we hypothesize that testosterone (T), dihydrotestosterone (DHT) and androstenedione (A4)
inhibit cannibalism. From this Gonadal Steroid Hypothesis we intend to test the following predictions: 1) that high levels of E2 and P4 will be positively correlated with cannibalistic behavior at all ages; 2) that plasma levels of T, DHT, and A4 will be negatively correlated with cannibalistic behavior at all ages; and, 3) that chicks exposed to relatively high levels of maternal androgens deposited in the yolk, primarily A4, will be less cannibalistic. Thus, our specific objectives are to determine whether: a.cannibalistic attacks, arecorrelated with levels of circulating gonadal steroid hormones; b.direct manipulation of circulating gonadal steroid levels can prevent or promote cannnnibalistic and feather pecking behaviors; c.levels of gonadal steroid hormones in the yolk, and therefore plasma of the newly hatched chick, are associated with subsequent cannibalistic, feather pecking or aggressive behavior; and, d.changes in developmental exposure to gonadal steroids can prevent or
promote adult expression of cannibalistic behavior and feather pecking behaviors.
Project Methods
Project 1: The purpose of this project is to determine the normal ontogeny of gonadal steroids in laying hens using a cannibalistic strain as a model. Chicks will be brooded and raised. Blood samples will be taken from the birds within 24 hours of hatch, and regularly over the developmental period Project 2: The purpose of this project is to determine whether manipulation of gonadal steroid levels can alter ongoing cannibalistic behavior. After the rise in cannibalistic behavior associated with the onset of lay hens will be randomly assigned to different steroid treatment groups (control, E2, P4, A4 and DHTBirds will be observed for an additional four weeks. Blood samples will be taken before capsule implant and four weeks after implant when the project will be considered completed. Project 3: The purpose of this project is to determine if direct manipulation of gonadal steroids in the nearly sexually mature pullet can either prevent or accelerate activation of
cannibalistic behavior. We shall rear groups of female chicks. At 14 weeks, prior to the expression of cloacal cannibalism, they will be regrouped at random to form different steroid treatment groups. Blood samples will be taken before capsule implant, at the expression of the first cloacal cannibalism, and at the end of the project. Project 4: The purpose of this experiment is to determine if early developmental exposure to gonadal steroids can alter the natural expression of cannibalistic behavior. Chicks will be randomly assigned to steroid treatment groups and treated immediately after hatch. Chicks will be raised as described in using standard husbandry methods. Blood samples will be taken at throughout the experiment and analyses for circulating gonadal steroid levels.