Effects of <i>Flourensia cernua</i> ingestion on nitrogen balance of sheep consuming tobosa

TitleEffects of Flourensia cernua ingestion on nitrogen balance of sheep consuming tobosa
Publication TypeJournal Article
Year of Publication1996
AuthorsKing D., Fredrickson E.L., Estell R.E., Havstad K, Wallace J.D., Murray L.W.
JournalJournal of Range Management
Volume49
Pagination331-335
Date Published1996
Keywordsalfalfa, blood chemistry, body weight, cholesterol, digestible protein, dry matter, feed intake, Flourensia, grasses, Leaves, New Mexico, nitrogen balance, nitrogen retention, Pleuraphis mutica, sheep, urea, weed palatability
Abstract

Flourensia cernua DC. (tarbush) is a deciduous shrub with potential as a high-protein forage source for livestock. Twenty-four Polypay x Rambouillet wethers housed in metabolism crates were used to evaluate tarbush as a N source for sheep fed a low quality grass diet. Treatments were 100% ground tobosa grass (Pleuraphis mutica Buckl.) or tobosa substituted with 10, 20, or 30% whole pre-bloom tarbush leaves (n = 5) or 26% ground alfalfa (n = 4, Medicago sativa L.) on a dry matter basis (dmb). Sheep were fed ad libitum for 11 days, after which feed was restricted to 1 % (dmb) of body weight for 11 days to reduce sorting and maintain uniform intake. Apparent dry matter digestibility was not improved (P = 0.2646) with tarbush or alfalfa. Fecal N was similar (P = 0.1626), but urinary N varied (P = 0.0008) among treatments. Apparent N digestibility differed (P = 0.0042) among treatments (43, 46, 50, 56, and 63% for sheep consuming 0, 10, 20, or 30% tarbush or alfalfa, respectively). All treatments resulted in similar (P = 0.1569) but negative N retentions (-2.4, -2.2, -2.8, -2.0, and -1.5 g day-1 for sheep consuming 0, 10, 20, or 30% tarbush or alfalfa, respectively). Serum clinical profiles (day 22) confirmed all sheep were nutritionally stressed, but did not indicate toxicosis. Although neither tarbush nor alfalfa N compensated for the low quality basal diet, N from 30% tarbush was utilized with similar efficiency to alfalfa N. The major impediment for using tarbush as a N source appeared to be low palatability.

URL/files/bibliography/497.pdf