Effects of diet composition on vanadium toxicity in laying hens.

Vanadium added to laying rations as NH4 VO3, VOCl2 or VOSO4 at levels of 20 to 80 ppm resulted in a rapid and substantial reduction in albumen quality as measured by Haugh units. Dietary vanadium also resulted in reduced egg production, egg weight, body weight, feed consumption, and poorer shell quality as measured by specific gravity. Ascorbic acid at .4 to .5% effectively protected the hen from the reduction in albumen quality, egg production, and body weight for up to 40 ppm vanadium, but not the reduction of egg weight. Replacement of soybean meal by 20% dietary cottonseed meal also protected the hen from the reduction in albumen quality, egg production, and body weight for up to 40 ppm vanadium. Added at levels of 4 to 8 times the molecular concentration of vanadium, EDTA had no consistent effect on vanadium toxicity. Dehydrated grass, at levels of 6 to 12%, maintained egg production but had no effects on the reduction in albumen quality caused by 40 ppm vanadium. Replacement of soybean meal with herring fish meal and part of the grain with sucrose intensified the depression of albumen quality, egg production, and loss of body weight caused by added vanadium. Neither varying dietary protein levels from 12 to 25% using soybean meal nor the addition of 20 ppm chromium had any effect on the toxicity of added vanadium. It appears that vanadium expresses its toxicity in laying hens by several routes since the protective effects of different dietary changes and additives differentially affected the loss of albumen quality, egg production, body weight, and egg weight.