Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1999
Publication Date: N/A
Citation: FREDRICKSON, E.L., ESTELL, R.E., HAVSTAD, K.M., SHUPE, W.L., MURRAY, L.E. EFFECT OF FEEDING EWE LAMBS A 15% TARBUSH (FLOURENSIA CERNUA DC) PELLET PRE- AND POST-WEANING ON SUBSEQUENT DIET SELECTION OF TARBUSH. JOURNAL OF ARID ENVIRONMENTS. 2000. V. 44(1). P. 123-131. Interpretive Summary: An attempt was made to manipulate the dietary preferences of sheep to increase their intake of tarbush, a shrub rapidly increasing in dominance within the desert grasslands of the Chihuahuan Desert region. By increasing utilization of tarbush by sheep we hope to use sheep as a biological control of tarbush populations while improving the nutritional status of sheep. Although tarbush has a nutrient profile similar to alfalfa, sheep rarely use tarbush due to its low relative palatability. By exposing sheep to tarbush early in life, we hoped to enhance the palatability of tarbush to sheep. In this experiment ewe lambs were fed a creep feed containing 15% tarbush from birth until 60 days after weaning. Rather than enhance palatability of tarbush we actually decreased animal preference for tarbush. Ewe lambs fed a creep feed containing 15% alfalfa exhibited a greater preference for tarbush than ewe lambs by previously fed dtarbush. We currently believe this aversion to tarbush was caused by tarbush toxicosis that occurs with chronic intake of tarbush leaves. Further studies attempting to increase the consumption of tarbush by sheep will also need to consider the dose of tarbush toxicants in order to avoid toxicosis and its effect on tarbush palatability.
Technical Abstract: The shrub Flourensia cernua (tarbush) has rapidly increased in dominance within Chihuahuan Desert grasslands, and is comparable to alfalfa in nutrient density. Increasing tarbush in livestock diets may improve diet quality, while decreasing tarbush dominance. We determined dietary preference for tarbush by sheep and the effect of previous exposure on preference. Thirty-eight ewe lambs received either tarbush or alfalfa in sorghum-based pellet 120 days postparturition; after which, dietary preference was assessed. Previous exposure averted lambs from tarbush consumption. Lambs without previous exposure maintained greater intakes initially, but declined with time. This decline corresponds with onset of tarbush toxicosis.