The Effects of Protein Supplementation on Bitterweed Toxicosis in Lambs

Abstract

This study determined if a supplemented protein diet high in escape protein or consisting of sulfur-containing amino acids would reduce the likelihood of bitterweed (Hymenoxys odorata DC) toxicosis. Forty recently weaned Rambouillet lambs were used with eight lambs randomly allocated to each treatment. They were placed in individual pens and allowed a seven-day adjustment period. Lambs were fed alfalfa pellets at 2.5% body weight, their respective treatment diet, and bitterweed. Treatments received either a (1) cottonseed meal (CSM), (2) CSM and Distiller’s Dried Grain (DDG), (3) soybean meal (SBM), or (4) SBM and DDG-based supplement. Treatment 5 received only alfalfa pellets. All supplements were isonitrogenous (37%), and lambs were fed enough supplement and alfalfa to achieve 150 g of growth per day. Bitterweed was offered immediately after supplemental diets for one hour daily for 15 days. Intake of supplemental diets, bitterweed, and alfalfa were measured on an individual animal basis. Lambs fed the SBM-based supplement ate more (P < 0.05) bitterweed than lambs fed alfalfa alone. Other supplemental diets did not improve bitterweed intake. None of the lambs from any treatment exhibited signs of toxicosis. Producers should consider feeding a SBM-based supplement to reduce the likelihood of bitterweed toxicosis in sheep.