Intake and Nutritional Quality of Different Types of Onions by Lambs

Abstract

Onions (Allium cepa) may reduce some nutritional deficiencies in ruminants. In addition, onions reportedly contain L-cysteine which may bind with the toxic compound in bitterweed (Hymenoxys odorata) to create a less toxic compound. We compared intake, nutritional quality, and L-cysteine levels among the types of onions. Red, yellow, or white onions were fed to Rambouillet lambs in individual pens in April, July, and November. A fourth treatment only received the basal diet of alfalfa (control). Intake was monitored daily. Weights were taken at the beginning and at the end of the trial. Packed cell volume was measured in each feeding trial to assess anemia. During the April trial, serum metabolite levels, that are indicative of toxicosis, were also measured. Intake of onions and alfalfa were similar (P > 0.05) among treatments. Packed cell volume was lower (P < 0.05) for lambs fed alfalfa alone in April, but was similar among all treatments in July and November. L-cysteine levels were undetected when measured in April. Serum metabolite levels remained within normal levels. Nutritional quality was also similar among types of onions. Lambs readily consumed onions and avoided toxicosis even when onions made up 100% of the diet.