Department of Animal Science
First Advisor
Dr. Benny E. Mote
Date of this Version
8-2023
Abstract
Lameness is a financial concern for producers and a welfare concern for the animals. Utilizing both the GAITFour and NUtrack systems, gilts’ natural tendencies and gait were analyzed to better understand the onset of lameness and what indicators can be identified in a commercial setting. Beginning at 20 weeks of age, video on replacement gilts was collected for 9 consecutive days and processed using the NUtrack System to identify individual gilts’ distance travelled (m), avg speed (m/s), angle rotated (degrees), and time standing (s), sitting (s), eating (s), and laying (s). NUtrack is a deep learning-based multi-object tracking system that has been shown to achieve greater than 92.5% precision and recall when tracking the long-term location and identity of individual pigs in group-housed settings. At the start of evaluation under the NUtrack system, gilts were walked across a pressure sensing mat (GAITFour system) to evaluate the gait metrics of Step Length (cm), Stride Length (cm), Swing Percent of Cycle, Swing Time (sec), Stance Percent of Cycle, Stance Time (sec), Total Scaled Pressure (TSP), GAITFOURDog Lameness Score (GLS), Total Pressure Index (TPI), and Step/Stride ratio. A total of 3,150 replacement gilts were analyzed utilizing the data derived from NUtrack with 1,379 gilts culled based on structural unsoundness as determined by an experienced herdsman. A subset totaling 2,634 gilts were analyzed utilizing the data derived from GAITFour with 1,199 being culled primarily based on structural unsoundness as determined by an experienced herdsman. Heritability estimates were done on novel objective measurements that can be utilized for gilt selection for increased sow longevity. For the NUtrack system, heritabilities are 0.14±0.0069, 0.14±0.0074, 0.31±0.0418, 0.35±0.0425, 0.32±0.0420, 0.30±0.0409, 0.21±0.0359, 0.22±0.0370, and 0.23±0.0372 for angle, average speed, distance, eat, lie lateral, lie sternal, lie total, sit, and stand respectively. Average speed (p<0.001) and time standing (p<0.01) were significantly associated with gilt retention. For the GAITFour system, heritability estimates ranged from 0.03 to 0.36. Step length of both the left and right front legs (p<0.001), stride length of both the left and right front legs (p<0.01), stance time of the right front leg (p<0.05), total scaled pressure of the right hind leg (p<0.05), step/stride ratio of both the left and right front legs (p<0.001), and step/stride ratio of the left hind leg (p<0.05) were all found to be significantly associated with gilt retention. As a result of this project, we aim to increase the selection of sound replacement females in order to decrease the progression of lameness.
Advisor: Benny E. Mote
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professor Benny E. Mote. Lincoln, Nebraska: August 2023
Copyright © 2023 Lexi M. Ostrand