Lameness in breeding-age gilts and sows is a major cause of culling, resulting in increased economic losses and welfare concerns. This study determined if exercise during gestation would affect the musculo-skeletal system, production variables, and behavior. Gilts were blocked by BW and assigned to 1 of 3 treatment groups: control (n = 10; no exercise), low exercise (n = 14; 122 m/d for 5 d/wk), and high exercise (n = 14; 122 m/d for 2 d/wk and 427 m/d for 3 d/
wk). All gilts were stall-housed during gestation, and gilts were exercised between d 35 and 110 of gestation.
Lameness score, BCS, BW, and blood were taken at multiple points before gestation, and during gestation
and lactation. Blood serum was analyzed for carboxyterminal telopeptide of type I collagen. Sow lying behavior
was recorded for 3 d after farrowing. Farrowing data included litter weight and size at birth and weaning,
and preweaning mortality. After weaning, 38 sows were slaughtered and muscles and the bones of the
left fore- and hind-limbs were harvested. Bone density and quality were determined by computed tomography
(CT) scans, dual energy x-ray scans, and bone-breaking force tests. The control group took longer to lie down
than both exercise groups, and the low exercise group took longer to lie down than the high exercise group
(P < 0.05). The number of pigs weaned was greater in the high exercise group than the control group (P <
0.05). Piglet preweaning mortality was greatest in the control group compared with both exercise groups (P <
0.05). The low exercise treatments exhibited a greater bone density (CT) in the humerus, radius, and tibia
compared with that of the control group (P < 0.05). The bone density (CT) of the humerus in the low exercise
group was greater than that of the high exercise group (P = 0.03). Breaking force in the humerus and femur
was greater (P < 0.05) in the low exercise group than the control group. Breaking force in the tibia of the
high exercise group was greater than the control group (P = 0.01). The tibia of both the low and high exercise
groups had a greater breaking force (P < 0.05) than the control group. Although there was no benefit of exercise
on lameness, differences in bone density and quality, lying behavior, and piglet survivability may provide
useful insight into alternative housing for sows.

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