Valorization of rapeseed meal. 4. Effects of iodine, copper and ferrous salt supplementation in growing rats.

Ten groups of 10 growing male rats (65 g) were fed ad libitum either a control diet or rapeseed diets (15 mM glucosinolates/kg DM) supplemented either with l- alone, l- and Cu++ (2 levels), l- + Cu++ and methionine or l- and Fe++ (2 levels) (table 1) for 35 days. When the rapeseed diets were given as powder or as mash, food intake decreased 24 and 32%, respectively; live weight gain was reduced by 36 and 46%, liver weight increased 20 and 33%, thyroïd gland was 3 and 4 times as big, and a 30 and 50% decrease in the T4 plasma level was noted (table 2). l- supplementation did not prevent the deleterious effects of rapeseed meal feeding. l- and Fe++ supplementation had detrimental effects on food intake, live weight gain and kidney weight, but beneficial effects on liver and thyroïd weights and on plasma thyroïd hormone levels. The low level of l- and Cu++ supplementation suppressed the depressive effects of rapeseed meal on food intake and live weight gain and reduced the deleterious effects on kidney, liver and thyroïd weights and on plasma thyroïd hormone levels, whereas the higher level almost suppressed them. The results are discussed considering the likelihood of a bivalent cation effect on glucosinolates.