Chemical changes and influences of rapeseed antinutritional factors on lamb physiology and performance. 3. Antinutritional factors in plasma and organs

The impact of a high level of rapeseed meal in the diet on the concentration of antinutritional factors in plasma and organs was studied in 66 Texel, Suffolk or crossbred lambs. From 1 month of age till slaughter (132+/-21 days), they were fed ad libitum with concentrates containing 0% or 25% of rapeseed meal obtained either Samourai or Honk rapeseed varieties. Lambs were weaned at 88+/-8 days of age and 24+/-5 kg live weight. Blood and organ samples were taken fortnightly for the determination of antinutritional factors. In plasma and organs, the thiocyanate concentrations were systematically higher in the Samourai and Honk lots than in the control. After weaning, the SCN- concentration in plasma increased up to 490 mu mol l(-1) in the Samourai lot. The goitrogen 5-vinyl-1,3-oxazolidine-2-thione (5-VOT) was determined in muscle, organs (thyroid, liver, kidney and lung) and biological fluid (plasma). The 5-VOT was present only after the ingestion of rapeseed meal but not to the same extent for the two varieties. The Honk rapeseed meal induced a 5-VOT level significantly (p<0.05) higher in the target organs such as lung and thyroid than Samourai. Very low levels were found in muscle, liver, kidney, plasma and lung. (C) 2000 Elsevier Science B.V. All rights reserved.