Growth, heart weight, cardiac lipid, and pathology of chickens fed soybean oil or oil extracted from different rapeseed cultivars.

A total of 384 male Single Comb White Leghorn chicks of the Hyline strain were randomized in 24 Petersime battery units of 16 birds per unit. Four replicate pens were fed either a basal (control) diet containing no added oil or a diet supplemented with 20% by weight of either soybean oil or rapeseed oil (RSO) from cultivars Tower, Candle, Regular, or R-500. Levels of crucic acid (22:1) in the RSO's ranged from .1 to 51.6%. Four birds from each unit were killed at 4, 8, 12, and 16 weeks for cardiac lipid analysis and pathology. Feeding RSO had no consistent effect on body weights, heart weights, or the heart-to-body weight ratio. Only the diet containing R-500 (51.6% 22:1) consistently increased cardiac lipid levels as measured gravimetrically. Maximum deposition of the long-chain monoenes (22:1) and eicosenoic acids (20:1) occurred in the cardiac lipids by 8 weeks, and the levels remained high throughout the 16-week trial. The relative concentration of these long-chain monoenes in the cardiac lipids was positively correlated to the dietary levels of these acids. The incidence of lesions found in heart, liver, and skeletal muscle was significantly higher in chickens fed RSO's high in 22:1 than in chickens fed control or soybean oil, and the incidence significantly correlated to the level of 22:1 in the diet. The incidence of heart and muscle lesions and sinusoidal distention in chickens fed RSO's low in 22:1 was not significantly different from that of chickens fed the control diet or soybean oil, but the incidence of hepatic necrosis was significantly higher for chickens fed RSO's low in 22:1 compared to those fed the control diet or soybean oil.