The effect of breed and of dried seaweed meal in the diet on the levels of copper in liver, kidney and plasma of sheep fed on a high copper diet

Abstract

Twenty-one mature ewes of each of two breeds, the Scottish Black-face and the Welsh Mountain, were allocated in equal numbers to three diets based on a complete cobbed feed with a 0, 5 and 15% inclusion of dried seaweed meal (Ascophyllum nodosum). All diets were made up to a Cu content of approximately 30 mg/kg by adding CuSO₄ to the mix. Sheep were housed and fed individually for 15 weeks.There was a significant breed difference in the Cu level of the liver dry matter; the Welsh increased by 316 mg/kg compared with 240 mg/kg in the Blackface and the amount of Cu accumulated in the liver per kg feed consumed was 0·66 mg in the Welsh and 0·46 in the Blackface. Diets also had a significant effect; the Cu levels in liver dry matter rose by 323, 293 and 220 mg/kg for the 0, 5 and 15% seaweed diets respectively and the Cu stored per kg feed consumed was 0·66, 0·61 and 0·41 mg respectively. There was no corresponding effect of diet on plasma Cu level, but there was a breed difference with Welsh higher than Blackface. Cu level in kidney dry matter showed a breed-by-diet interaction. Total food consumption did not differ among the treatments, and live-weight and carcass-weight data suggested no adverse effects from the inclusion of seaweed meal in the diet.