Effects of dry sow housing conditions on muscle weight and bone strength


Confinement has been shown to affect bone strenth in poultry but this weakness has not been documented in other species housed in confinement. The objectives of this experiment were to compare muscle weight and bone strength in non-pregnant sows, of similar age and parity, housed throughout eight or nine pregnancies in two different dry sow systems: (1) individually in stalls and (2) communally in a large group. Following slaughter, the left thoracic and pelvic limbs were dissected and 14 locomotor muscles removed and weighed. A proportional muscle weight was then calculated by dividing individual muscle weight (g) by total body weight (kg). Where there were significant differences, stall-housed sows had lower absolute and proportional muscle weights than group-housed sows. The left humerus and femur were also removed. The bones were broken by a three-point bend test using an Instron Universal Tester. Both bones from stall-housed sows had breaking strengths that were about two-thirds those of group-housed sows. The results indicate that confinement of sows, with a consequent lack of exercise, results in reduction of muscle weight and considerable reduction of bone strength.