ABSTRACT
A 431-d experiment was conducted to determine the effects of whole cottonseed containing gossypol (7400 mg/kg) on growth and development from weaning until pregnancy in Holstein heifers. Treatment diets (n = 5) contained 0, 15, or 30% whole cottonseed. The basal diet included alfalfa hay, corn grain, soybean meal, molasses, and dicalcium phosphate. Gossypol content of the treatment diets was 0, 1300, and 2000 mg/kg, and gossypol content in feces was 0, 290, and 1170 mg/kg, respectively, for treatments containing 0, 15, and 30% whole cottonseed. Estimated ingestion of gossypol (accumulated) was 0, 8, and 12 g/kg of BW, respectively, for treatments containing 0, 15, and 30% whole cottonseed during the 431-d experiment. Erythrocyte fragility was similar among treatment groups on d -3; on d 228, erythrocyte fragility was similar for heifers fed treatments containing 0 and 15% whole cottonseed, but was lower than that for heifers fed the 30% whole cottonseed diet. However, on d 430, fragility of erythrocytes increased linearly as the percentage of whole cottonseed increased. Clinical profiles of serum suggest possible impairment of liver and kidney function on d 144 and 430. Age and BW at onset of puberty and pregnancy rates were similar among treatments. One heifer fed the 30% whole cottonseed died on d 396, possibly from gossypol toxicosis. Long-term dietary supplementation at 15 to 30% whole cottonseed for long periods should be examined further for gossypol content and toxicity response of heifers and for effects on growth and development.
