title: Adaptation of pregnant ewes to an exclusive onion diet.
abstract: A diet consisting entirely of cull onions fed to pregnant ewes produced Heinz body hemolytic anemia in all sheep after 21 d. After 28 d of daily consumption of 20 kg of onions/ewe, the anemia stabilized, and for the remaining 74 d the packed cell volume increased in the majority of sheep, although it did not return to normal. Compared to control ewes fed an alfalfa and grain diet, the onion-fed ewes had comparable body condition scores and fleece weights. There was no significant difference (alpha = 0.05) in pregnancy or lambing rate, number of lambs born/ewe exposed, or number of lambs born/ewe lambing. Greater numbers of sulfate-reducing bacteria (Desulfovibrio spp) and more ruminal hydrogen sulfide were present in onion-fed sheep compared to controls. Although an average 27% reduction in packed cell volume and Heinz body anemia developed in the onion-fed ewes, on the basis of this study it appears that pregnant ewes may be fed a pure onion diet with minimal detrimental effects. This adaptation to a pure onion diet is in part likely due to the apparent ability of the sheep's rumen to quickly develop a population of sulfate-reducing bacteria that decrease the toxicity of onion disulfides.
authors.affiliation: Department of Clinical Sciences, Colorado State University, Fort Collins 80523, USA.
authors.forename: A P
authors.initials: AP
authors.lastname: Knight
authors.forename: D
authors.initials: D
authors.lastname: Lassen
authors.forename: T
authors.initials: T
authors.lastname: McBride
authors.forename: D
authors.initials: D
authors.lastname: Marsh
authors.forename: C
authors.initials: C
authors.lastname: Kimberling
authors.forename: M G
authors.initials: MG
authors.lastname: Delgado
authors.forename: D
authors.initials: D
authors.lastname: Gould
mesh_terms: D000222:Adaptation, Physiological; D000743:Anemia, Hemolytic / Q000139:chemically induced; D000821:Animal Feed; D000818:Animals; D004032:Diet; D005260:Female; D006366:Heinz Bodies / Q000187:drug effects; D050885:Hydrogensulfite Reductase; D019697:Onions / Q000009:adverse effects; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000032:analysis; D011247:Pregnancy; D012417:Rumen / Q000382:microbiology; D012756:Sheep / Q000502:physiology*
chemical_list: D050862:Oxidoreductases Acting on Sulfur Group Donors; D050885:Hydrogensulfite Reductase