Summary Twenty‐four cottonseed meals fed to chicks in practical feeding rations for eight weeks led to good growth performance and favorable feed efficiency in many cases, despite the unusually high free gossypol content of the rations. The results from replicated, protein‐quality evaluations in chicks fed for eight weeks at the 15% protein level were closely parallel to those from similar experiments in rats fed at the 9% protein level and showed that the percent nitrogen solubility in 0.02N sodium hydroxide of cottonseed meals is a poor indicator of protein quality. Constant gossypol levels of 0.1%, supplied by additions of different amounts of cottonseed pigment glands, caused greater body‐weight depressions than did the same gossypol level supplied by pure gossypol. The toxicity of cottonseed pigment glands and of cottonseed meals cannot be accounted for solely on the basis of analyzed gossypol content.

SummarySix samples of cottonseed pigment glands and two samples of pure gossypol stored for more than four to nine years were re‐evaluated for their acute oral toxicity in the rat and re‐analyzed for gossypol content. There was no appreciable effect on the acute oral toxicity or gossypol content after these long storage periods.

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Summary Toxicological evaluation of 68 cottonseed meals in rats failed to show a direct correlation between their toxicity and their free, total or combined gossypol content. The common practice of considering the free gossypol content of cottonseed meal as a yardstick for its toxicity is questioned. There was poor correlation between biologically evaluated protein quality of cottonseed meals and their nitrogen solubility in 0.02N sodium hydroxide. Application of this chemical test for indicating the protein quality of cottonseed meals is likewise questioned on the basis of existing evidence.

Summary In a series of four tests in which three deliberately chosen toxic cottonseed meals were treated with aqueous solutions of salts and alkalies, it was found that the best detoxifying effect was obtained with sodium hydroxide, followed very closely by potassium and ammonium hydroxides. Dry heat treatment alone did not detoxify, and mortality was high. Treatment with moisture plus heat gave partial detoxification. Of the 22 chemically‐treated cottonseed meal samples tested, those treated with alkalies showed the best weight gains, the order of decreasing effectiveness being NaOH>KOH>NH4OH>italicCafalse(italicOHfalse)2. The residual toxicity of treated cottonseed meals cannot be explained on the basis of their free gossypol content as analyzed for meals with high values gave better growth performance than some with lower levels of free gossypol. There were also very marked differences in final body weight after 8 weeks of feeding six different treated cottonseed meal samples having practically the same free gossypol content.