Location: Livestock Behavior Research2012 Annual Report
1a. Objectives (from AD-416):
1) To determine if perch availability during all or part of the life cycle of White Leghorns affects skeletal mineralization and gene expression of parathyroid hormone (PTH), PTH related protein (PTHrP), PTH/PTHrP receptors as well as sox9 and col2a1 during bone development; 2) To determine the economic impact of adding perches to conventional cages; and 3) To determine when the majority of bone fractures occur in the life cycle of the bird so as to provide an assessment of the length of time chickens may experience pain from fractures.
1b. Approach (from AD-416):
A total of 1,064 White Leghorn females of the Hy-Line W36 strain will be used in the study. Chickens will be raised at the Purdue University Poultry Research Farm using standard management practices. Beak trimming will be done prior to 10 days of age to prevent cannibalism. At 17 wk of age, 324 pullets will be transferred to 36 laying cages housed in one room of Management House II. Half of the cages will be retrofitted with a perch, while the other 18 cages will be without a perch. Samples (spinal cord, brain, and blood), legs, and behaviors will be collected at 3, 6 12 and 72 weeks of age (one bird/cage, n=12/time point calculated based on alpha = 0.05 and 1-beta = 0.80). Brain and blood samples will be analyzed for changes in pain-associated neuropeptides (substance P and calcitonin gene-related peptide), corticosterone, and immune function (T- and B-lymphocytes) using HPLC, RIA, or qt-PCR. Perch-associated changes in behaviors will also be analyzed. In addition, mortality data, body weight, feather score, feed intake, egg production, and feed efficiency will be collected. Data will be compared statistically between the treatments.
3. Progress Report:
We have examined the effects of exercise, using perches, on bone mineralization in laying hens. All samples have been collected and data analysis is partially complete. We identified mechanical loading achieved through perching, its beneficial effects on pullet health by stimulating leg muscle deposition, and increasing the mineral content of certain bones without causing a concomitant decrease in bone mineral density. The project relates to parent project sub-objective 3 “Developing scientific measures of, identifying husbandry and environmental challenges to, and developing sustainable alternatives that safeguard well-being of poultry”. The benefits to the research project include conducting specific research related to improving well-being of laying hens and developing pain indicators which is a specific component and direct extension of the milestones within the sub-objective 3.A.