Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2008
Publication Date: 6/20/2008
Citation: Schenck, E.L., McMunn, K.A., Nielsen, B.D., Richert, B.T., Marchant Forde, J.N., Lay Jr, D.C. 2008. Exercise in stall-housed gestating gilts: Effects on lameness, the musculo-skeletal system, production and behavior. Journal of Animal Science. 86:3166-3180.
Interpretive Summary: Lameness is one of the top three reasons for culling with a culling rate of 16%. In breeding age females, the culling rate for lameness was reported to be 2.8 ± 0.3% in 2000. In 2000, it was estimated that 64.2% of sows and gilts were housed in total confinement for gestation, which greatly restricts the type and amount of movement a sow can perform. Studies have shown that the muscular strength of a sow is less in confined sows compared to group-housed sows. Muscular strength can affect the ability of an animal to move with ease, including basic movements such as sitting up and lying down. The number of sows kept in confinement during gestation has increased over the past 15 years and during that same time period there has been a 10% increase in the number of piglet deaths due to crushing. If exercise can improve the agility of the sows, the sow may be able to control the decent of her body better and crush fewer piglets. This study was designed to determine if exercise contributes to the decrease in occurrence and severity of lameness, improves the ease of lying down, and if exercise has an effect on factors such as litter size and number of piglets weaned. We hypothesized that sows that are exercised would have a decrease in severity and occurrence of lameness, lie down slower than non-exercised sows, have a higher muscle weight to body weight ratio, and that there will be no effect on production parameters or interbirth intervals. Our data showed that exercise had no effect on the occurrence or severity of lameness, interbirth intervals, or muscle mass. However, the High exercise group had an increase in the number of piglets weaned and both exercise groups had a lower percent of piglets lost during lactation than the Control group. The Control group also took the longest amount of time to lie down compared to the exercised sows. The difference in lying times may have caused the differences in the number of piglets weaned and percent of piglets lost in that in taking too much time to lie down allows for piglets to have more time to get underneath the sow, increasing the risk of crushing. By increasing the amount of movement allowed during gestation, producers may be able to increase the number of piglets weaned and thus increase profits even when confinement housing sows during parturition and lactation.
Technical Abstract: The aims of this study were to determine if exercise would decrease the severity of lameness and have an affect on production, inter-birth intervals and lying behaviors during lactation. Fifty-one crossbred gilts were blocked by body weight and assigned to treatment at d 35 of gestation. The study was composed of 3 treatment groups; Control (n = 15, no exercise), High exercise (n = 19, 122 m for 2 d/wk and 427 m for 3 d/wk) and Low exercise (n = 17, 122 m for 5 d/wk). All gilts were stall-housed for the duration of gestation and High and Low gilts were encouraged to exercise from d 35 to 110 of gestation. Exercise consisted of allowing the gilts to individually walk or run laps around the room in which they were housed. Body condition score and lameness score were taken at d -14, 35, 54, 85, 110 and at weaning. Body weight was taken at d 0, 35, 54, 84, 110 and at weaning. Gilts were moved into farrowing crates on d 110 of gestation for approximately 28 d. Video recorders were used to record inter-birth intervals and lying behavior. After farrowing, lying behavior was recorded for 3 d consecutively. Farrowing data, including litter weight at birth and weaning, litter size, percent of piglets lost, and length of gestation were also recorded. After weaning, sows were sacrificed, and specific muscles associated with locomotion were removed from the left fore- and hind-limbs and weighed. There were no differences in body weight, body condition score, lameness score, or muscle weight/body weight (P > 0.10) among treatments. The number of piglets weaned in the High exercise group was greater than both the Control and Low exercise groups (P = 0.007 and 0.01 respectively). The percent loss was greater in the Control group compared to that of the High and Low exercise groups (P = 0.013 and 0.016 respectively). The average piglet weight tended to be greater in the High exercise group (P = 0.09) than the Control group, but not different than the Low exercise group. The total time taken to lie down was greatest for the Control group compared to both the Low and High groups (P = 0.02 and < 0.01 respectively), and the Low group had a tendency to lie down slower than the High group (P = 0.08). Although there was no benefit of exercise on lameness, the differences in piglet survivability and lying behavior may provide useful insight into alternative housing for sows.