@article {51356, title = {Effects of Flourensia cernua ingestion on nitrogen balance of sheep consuming tobosa}, journal = {Journal of Range Management}, volume = {49}, year = {1996}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1996}, pages = {331-335}, 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.

}, keywords = {alfalfa, 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}, url = {/files/bibliography/497.pdf}, author = {D. King and E.L. Fredrickson and Richard E. Estell and Kris Havstad and Wallace, J.D. and L. W. Murray} } @conference {51408, title = {Effects of tarbush ingestion on intake, digesta kinetics, in situ digestion, ruminal fermentation, and nitrogen balance of sheep consuming low quality tobosa grass diets}, booktitle = {Journal of Animal Science}, volume = {74 (Suppl. 1)}, year = {1995}, month = {1995}, pages = {Abstract 205}, abstract = {Tarbush (Flourensiacernua) represents a substantial biomass in the Chihuahuan Desert. Two studies were conducted to assess intake, in situ digestion, passage rate, ruminal fermentation, and nitrogen balance of sheep fed a low quality tobosa (Hilariamutica) diet containing up to 30\% tarbush leaves. Tarbush was harvested and air dried, and leaves were separated from stems. In Exp. 1, 16 ruminally cannulated Polypay x Rambouillet lambs (avg BW = 46 kg) were individually fed (twice daily) ground (2.54 cm) tobosa (5.9\% CP, 80\% NDF; DM basis) substitued with 0, 10, 20, or 30\% (DM basis) tarbush (18.9\% CP, 33\% NDF) leaves ad libitum for 28d. In Exp. 2, 24 Polypay x Rambouillet wethers (avg BW = 47 kg) in metabolism crates were allotted to one of the four treatments described above (n = 5) or 26\% ground alfalfa (n = 4). Sheep were fed ad libitum for 11 d and then restricted to 1\% of BW for 11 d to equalize intake. In Exp. 1, DMI for 20 and 30\% tarbush treatments was greater (P = .0049) during week 3 than 0 and 10\% treatments. Molar butyrate proportions (P = .0032) and total VFA concentrations (P = .0064) were greater for the 30\% tarbush treatment than other treatments. Sheep fed 30\% tarbush had greater (P < .0046) ruminal ammonia concentrations than sheep fed other diets at 6, 8, and 12 h postfeeding. In Exp. 2, all treatments resulted in similar but negative N retentions (-2.4, -2.2, -2.8, -2.0, and -1.5 g/d for sheep consuming 0, 10, 20, or 30\% tarbush or alfalfa, respectively). Because only 30\% tarbush elicited measurable responses in Exp. 1 (based on ruminal ammonia dn total VFA concentrations), nutrients contained by tarbush (especially CP) did not appear to be completely available to sheep. Low DMI observed in Exp. 2 was likely due to secondary compounds in tarbush and may partly explain why no differences in N balance were observed in Exp. 2.}, keywords = {intake, nitrogen balance, rumen ammonia, sheep, tarbush ingestion, tobosa grass}, author = {D. King and Richard E. Estell and E.L. Fredrickson and Kris Havstad and Wallace, J.D. and L. W. Murray} }