Pathological lesions in lambs fed raw or processed cottonseed meal

Thirty male lambs of 3-4 months of age, were assigned equally to five dieta ry treatments in a completely randomized design and fed isonitrogenous and isocaloric concentrate mixtures containing 30% de-oiled peanut meal (DPNM) or 40% cottonseed meal, which was raw, cooked for 45 min or treated with ei ther 1% calcium hydroxide or iron (1:3, free gossypol: Fe). The mixtures co ntaining raw or variously processed CSM replaced about 50% of the nitrogen of the reference concentrate mixture. These concentrate mixtures were fed t o meet 80% of the animals' crude protein requirements along with ad libitum feeding of maize (Zea mays) hay for 180 days. The free gossypol content of the raw cottonseed meal (0.27%) was reduced to 0.16%, 0.20% and 0.21% by t he cooking, Ca(OH)(2) and iron treatments, respectively. At the end of the experiment, the tissues of various organs were fixed in 10% formol saline, embedded in paraffin and sectioned at 4-5 mu m thickness, and duplicate sec tions were stained with either haematoxylin and eosin or Perl's Prussian bl ue. The lambs fed diets incorporating raw, cooked, Ca(OH)(2)- or iron-treat ed cottonseed meal consumed respectively 302, 215, 250 and 222 mg free goss ypol/day. No morbidity, mortality or gross lesions were observed in any org ans and the histopathological lesions due to cottonseed meal were limited t o the testes and epididymis. Spermatogonial cells were absent in the majori ty of the seminiferous tubules of testes from lambs fed raw cottonseed meal . Most seminiferous tubules were collapsed, with a reduced wall thickness, owing to there being fewer germ cell layers and vacuolation of the basal ce lls. The epithelium of the epididymal ductules was degenerated, desquamated to a variable degree with hyperplastic changes, and they were devoid of sp ermatozoa. Most lambs fed any of the processed cottonseed meals did not sho w any of these lesions, and such lesions as occurred in affected lambs in t hese groups were relatively mild. Iron pigments were deposited around the p ortal areas of the liver, the tip of intestinal villi and the spleen of lam bs fed the iron-treated cottonseed meal diet. Cooking or treatment with 1% Ca(OH)(2) effectively minimized the toxic effects of free gossypol.