Slow doesn't win the race: Reduced energy diets did not improve sow articular cartilage

Abstract Text: Sow lameness accounts for approximately 15% of culling, resulting in a decrease in productivity and welfare.  Previous research in our laboratory has shown a high incidence of osteochondritic lesions in young sows.  We hypothesized that decreasing the growth rate of sows would allow for proper formation of articular cartilage.  The objectives of this study were to 1) quantify behavioral changes associated with the diet and 2) prevent the development of osteochondritic lesions.  Therefore, 70-d old gilts were placed on either a control diet (CON; n = 23) or a low energy diet (LOW; n = 24).  The CON diet contained 3,427 Kcal/kg ME.  The LOW diet utilized wheat middling and soy hulls and contained 2,643 Kcal/kg ME, targeting 65-70% of growth.  Both diets were available ad libitum from d 70 to 182.  Gilts were fed LOW or CON diets in four 28 d phases and were weighed at diet changes to calculate ADG and ADFI, which were 0.80 and 0.92 kg, respectively for CON gilts and 0.61 and 1.06 kg, respectively, for LOW gilts.  A G:F of 1.15 resulted for CON and 1.73 for LOW gilts.  Behavioral observations were recorded monthly and included posture, activity, agonistic behavior and vices. Joint samples were taken (CON = 9; LOW = 10) between d 182 to 361 and analyzed for damage.  Joints were evaluated for number of lesions, lesion size and received an articular cartilage score from 0 to 4, with 0 representing healthy cartilage and 4 representing severely lesioned cartilage.  The LOW gilts spent more time standing (P < 0.01), sitting (P < 0.01), and feeding (P < 0.01). Overall, diet did not alter sham chewing (P = 0.76), nosing (P = 0.11), or tail biting (P = 0.36).  Both LOW and CON gilts did not differ in the number of fights (P = 0.67), however CON gilts spent less time fighting than LOW gilts (P < 0.01).  Energy restricted feed did not decrease the lesion size or prevalence of lesions (P > 0.10).  Older gilts had larger lesions on the proximal humerus (P < 0.01) and femur (P < 0.01) and the distal humerus (P < 0.03) and femur (P < 0.04) than younger gilts.  An energy restricted diet is not a suitable solution to decrease fighting or to improve joint health in young sows.

Keywords: articular cartilage, energy restriction, sow longevity