Pathological lesions in lambs fed raw or processed cottonseed meal.

Abstract

Thirty male lambs of 3-4 months of age, were assigned equally to five dietary 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 either 1%, calcium hydroxide or iron (1:3, free gossypol: Fe). The mixtures containing raw or variously processed CSM replaced about 50% of the nitrogen of the reference concentrate mixture. These concentrate mixtures were fed to 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 the 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 microm thickness, and duplicate sections were stained with either haematoxylin and eosin or Perl's Prussian blue. The lambs fed diets incorporating raw, cooked, Ca(OH)2- or iron-treated cottonseed meal consumed respectively 302, 215, 250 and 222 mg free gossypol/day. No morbidity. mortality or gross lesions were observed in any organs and the histopathological lesions due to cottonseed meal were limited to the testes and epididymis. Spermatogonial cells were absent in the majority 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 cells. The epithelium of the epididymal ductules was degenerated, desquamated to a variable degree with hyperplastic changes, and they were devoid of spermatozoa. Most lambs fed any of the processed cottonseed meals did not show any of these lesions, and such lesions as occurred in affected lambs in these groups were relatively mild. Iron pigments were deposited around the portal areas of the liver, the tip of intestinal villi and the spleen of lambs fed the iron-treated cottonseed meal diet. Cooking or treatment with 1%, Ca(OH)2 effectively minimized the toxic effects of free gossypol.