Effect of graded concentrations of gossypol on calf performance: toxicological and pathological considerations.

The effects of feeding diets containing 0, 100, 200, 400, or 800 ppm of free gossypol were examined in 60 Holstein bull calves from 1 to 120 d of age. The concentrations of free gossypol were varied by varying amounts of cottonseed meals from three different sources. Cottonseed meal totaled 31% of each treatment ration. Feed consumption, BW, and blood parameters were collected on all calves at 30-d intervals throughout the trial. There were no significant differences between the groups for feed consumption, BW, or average daily gain. Changes in the group means for hematology and chemistry variables examined were modest and insufficient to distinguish diagnostically between safe and unsafe free gossypol concentrations for the different groups. Clinical evidence of disease was limited to the calves fed 400 or 800 ppm of free gossypol after 90 d of age. One calf in the group fed 400 ppm and 4 in the group fed 800 ppm died as a result of circulatory failure associated with gossypol consumption. We conclude from this study that a ration containing up to 200 ppm of free gossypol is safe, 400 ppm of free gossypol is toxic, and 800 ppm of free gossypol results in death losses. These results are compatible with previously reported naturally occurring toxicological outbreaks.