2004 National Allium Research Conference
Oral Sessions - Pest Management

FEEDING CULL ONIONS TO LAMBS AND EWES

Thomas M. McBride, County Extension Director, Colorado State University Extension in Adams County, 9755 Henderson Road, Brighton, CO 80601-8114. Telehone: 303-637-8110, Fax: 303-637-8125, Email: tmcbride@co.adams.co.us, Website: www.adamscountyextension.org

Cull onions, as by-products of the onion industry, are commonly fed to sheep and cattle in major onion producing areas. This is mutually beneficial to both the onion producers and the livestock industry because cull onions provide an inexpensive source of feed for livestock, and thereby an easy means for disposing of the onions. Leaving the onions in the field to rot increases the prevalence of disease in subsequent onion crops. Sheep rapidly adapt to eating onions in a day or two, and in many instances will prefer eating onions even when other forages are present. Sheep producers can lower feed costs by utilizing cull onions that are unsuitable for human consumption. The objectives of the studies in this project were: 1) to determine the effects of feeding cull onions in finishing lamb diets on growth rate, carcass traits, cost analysis, and meat sensory attributes and 2) to determine the adaptation of pregnant ewes to an exclusive onion diet. In a number of trials lambs were fed a diet containing 0%, 10%, 20%, 25%, 50%, 75%, and 100% of the dry matter as cull onions for approximately the last 60 days of the feeding period. The remainder of the diet included a commercial finishing ration. Lambs in all experiments received their respective diets at a constant daily rate (3.5% of body weight on an as-fed basis.) All lambs were slaughtered commercially and carcasses were evaluated for USDA quality and yield grades. A random selection of loin samples from each treatment group were evaluated for shear force determination and sensory panel evaluation. The results of the slaughter lamb study indicated that cull onions could be used as an alternate feed source for finishing lambs with minimal impact on the overall palatability of the product. Based on commercial feed costs, cull onions can be used as various percentages of the diet to reduce feed costs. In the ewe study, a diet consisting entirely of cull onions was fed to pregnant ewes for the last 102 days of gestation. The control ewes were fed an alfalfa and grain diet. Blood samples were taken in regular intervals throughout the trial and analyzed to determine the packed cell volumes (PCU) and the presence of Heinz body anemia. In this study, the ewes rapidly adapted to eating the cull onions and although they all developed a Heinz body hemolytic anemia, they did not appear to be adversely affected when compared to the controls. Body condition scores, fleece weights and, the reproductive performance of the ewes on the inclusive onion diet was comparable to the controls.

to the 2004 National Allium Research Conference Home Page