Unprocessed Rapeseed Treated With Propionic Acid in Diets of Growing Pigs: Performance, Energy and Protein Digestibility, and Nitrogen Retention, Carcass Measurement, and Fatty Acid Composition of Backfat

Forty-two crossbred weanling pigs, equalized between gilts and barrows, were fed ad libitum in two replicates of seven dietary treatments. Diets contained 0, 5, or 10% unprocessed ground rapeseed of Brassica campestris type with or without propionic acid (PA) at a level of 10% of the rapeseed. Rapeseed was treated with PA prior to grinding. Additional pigs were fed diets containing 1 or 4% PA. Feed intake decreased, but not significantly when the diet contained rapeseed or 4% PA. Pigs fed the diet without rapeseed or PA gained 0.65 kg/day and required 2.79 kg feed/leg gain. Daily gain (0.47 kg) was lowest (P < 0.01) for pigs receiving 10% rapeseed with those receiving 5% rapeseed being intermediate between those fed 0 or 10% rapeseed. The addition of PA to a diet containing 10% rapeseed improved (P < 0.01) gain. Digestible energy (DE) in the diet containing 10% rapsseed was less efficiently (P < 0.01) utilized than DE in the basal diet with 0% rape-seed, even though digestibility studies suggested no depression in DE or metabolizable energy values from rapeseed addition. Nitrogen digestibility (DN) was higher (P < 0.05) at 88.5% for pigs fed 10% rapeseed plus PA than for the control pigs in which DN averaged 83.5% with other treatments being intermediate. Carcass measurements were not significantly influenced by treatment. Addition to the diet of 5 or 10% rapeseed, which provided 2.1 or 4.2% oil and 0.65 or 1.3% C 22:1 (erucic acid), respectively, increased C 18:2, 18:3, and 22:1 and decreased C 16:0, 18:0, and 18:1 fatty acids in the backfat. C 22:1 reached a maximum of 3.7 weight percent of the total fatty acids. PA had no influence on backfat composition.