Lameness is an important problem in swine industry and joint lesions are the main reasons for culling sows. The pain associated with lameness may adversely affect reproductive performance. Dietary long-chain protected fish oil (PFO) including arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) can regulate the production and bioactivity of inflammatory mediators. The first objective of this study was to characterize the effects of dietary PFO on cartilage, synovial fluid, and bone density and morphology from multiparous sows and market weight gilts of similar genetics. The second objective was to examine the effects of dietary PFO on the response of cartilage explants to IL-1 stimulation in vitro.
Sows were fed either control corn/soybean meal based diets (CON; n=7) or the control diet supplemented with 1.0% of PFO (n=7). Sows were fed their diets for 24.5 mo and slaughtered at 43 mo. Gilts were fed either control diet (CON; n=8) or the control diet supplemented with PFO (n=8) from weaning until slaughter at 111 kg. The PFO diet was formulated to a 10:1 n-6:n-3 fatty acid ratio, which contained 1.5 to 2.3% PFO and increased as the growth phases progressed. Cartilage was harvested from both humeroulnar joints of all animals at slaughter for fatty acid analysis and explant cultures. Synovial fluid was collected from the carpal joints. Bone and cartilage junctions were collected for computed tomography (CT) analysis.
The CT scans of the radius/ulna from gilts revealed no differences for cortical width and bone density. Sows fed PFO had greater cortical width of the proximal ulna (P < 0.05) and decreased cortical width of the distal radius (P< 0.05). Sows fed PFO had increased DHA (P < 0.01) and a decrease in the omega-6 to omega-3 ratio (P < 0.05) in cartilage. Gilts fed PFO had increased DHA (P< 0.01), C22:1 (P < 0.01), and docosapentaenoic acid (P < 0.01) and a tendency for increased EPA (P = 0.093) concentrations in cartilage. Changes in dietary fatty acids had no effect in vitro.
Although the PFO diet increased omega-3 incorporation into chondrocytes, the biological significance is unclear since concentrations of ARA were at least 9-fold higher than EPA or DHA. Therefore, if omega-3 fatty acids can mitigate inflammation in joints, the benefit would likely either be the result of systemic changes in inflammatory mediators or higher concentrations in the diet.
O'Connor-Robison, C.I., Spencer, J.D. and Orth, M.W. 2014. The impact of dietary long-chain polyunsaturated fatty acids on bone and cartilage in gilts and sows. Journal of animal Science, 92: 4607-4615. DOI: 10.2527/jas2013-7028