Hematologic effects and feeding performance in cattle fed cull domestic onions (Allium cepa)

For 119 days, 36 cattle, allotted to 6 treatment groups, were fed a balanced growth diet containing 0, 5, 10, 15, 20, or 25% cull onions on a dry-matter basis. Cattle performance was comparable to that associated with barley-base non-onion diet; statistical differences were not observed among treatments. During the first 28 days of the study, reduction in numbers of RBC, hemoglobin concentration, and PCV was observed in all cattle fed onions, but clinical anemia was not seen in any individual animal. After onion feeding was discontinued at 119 days, RBC numbers, hemoglobin concentration, and PCV returned to baseline values within 30 days. Heinz bodies were detected in erythrocytes of all cattle fed onions, and the percentage was proportional to the amount of onions consumed. Addictive onion consumption was prevented by mixing chopped or crushed onions in a total balanced ration.