Date of Graduation

5-2012

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Kuenzel, Wayne J.

Committee Member

Stripling, Jeffrey S.

Second Committee Member

Erf, Gisela F.

Keywords

Biological sciences; Corticosterone; Gait score; Lameness; Lateral motor column; Spinal cord

Abstract

Since the second half of the twentieth century lameness in broiler chickens has been known to be caused by different types of disorders, however the etiology of several type of lameness remain unknown. Because of the intense selection of broilers for rapid growth, some birds are more prone to physiological insults resulting in lameness. This study focuses on possible neural problems in the lower spinal cord associated with lameness in broilers. Broilers were raised in pens with wire floors and provided with food and water ad libitum. Three groups of birds 1) birds displaying a normal gait (Controls), 2) lame birds with normal leg bones (Neural Associated Lameness), and 3) lame birds with femoral head separation/necrosis (Bone Associated Lameness) were selected based upon behavioral observations of gait. Motor neurons in the lateral motor column of the lumbosacral region of birds in the neural associated lame group were observed to have changes in the perikarya of motor neurons. The lumbosacral segment 4 (LS 4) of the spinal cord was selected for analysis, based upon its central location in the lumbosacral region and the highest number of motor neurons when compared to other segments. In the neural associated lame group the motor neurons were more globular in appearance with a 25% to 40% reduction in protrusions from the perikarya when compared to controls. The corticosterone level, an indicator of stress, was increased 3-4 fold in the lame birds when compared to the controls. Additionally, an association between decreased percentage body weight gain and increased corticosterone level in lame birds was observed. Results of this study indicate an association between the reductions of neurites in the motor neurons of the lumbosacral spinal cord and a leg weakness in broilers with normal leg bones.

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