Dietary supplementation of arachidonic acid is associated with higher whole body weight and bone mineral density in growing pigs

Essential fatty acids are fundamental to normal growth and development, but North American formulas do not contain arachidonic (AA) and docosahexaenoi c acid (DHA). The main objective of the present study was to determine whet her addition of AA and DHA to formula elevates growth and bone mineralizati on in piglets. A secondary objective was to establish whether liver fatty a cid composition is related to that of bone. Twelve 10-d-old male piglets we re randomized to receive either a standard formula with an n-6:n-3 fatty ac id ratio of 4.9:1.0 or the same formula made with an equal amount of fat bu t containing AA (0.5% wt/wt total fat) and DHA (0.1% wt/wt total fat) for 1 4 d. Piglets in the supplemented group had significantly (p < 0.05) higher weight and greater bone mineral density of the whole body, lumbar spine, an d femur. No differences were observed in whole body length, calcium absorpt ion, or biochemical markers of bone metabolism. Feeding AA resulted in lowe r linoleic acid (p < 0.05) and higher (p < 0.05) AA in liver total lipid (% wt/wt) and bone FFA (% wt/wt) but no change to DHA. Liver AA (% wt/wt tota l lipid) was positively related (p < 0.05) to growth, free AA (% wt/wt) in bone, bone mineral content, bone mineral density, and urinary prostaglandin E-2 but negatively related (p < 0.05) to free linoleic acid in bone. Inver se relationships were observed when liver linoleic acid was substituted for liver AA as the independent variable. These data indicate that feeding AA is associated with elevated weight and higher whole body and regional bone mineral density.