In the first of two experiments, four wether lambs (BW = 26.8 kg) and four wether Angora goats (BW = 31.7 kg) were used in two simultaneous 4 x 4 Latin squares to study the influence of condensed tannins (CT) on nutrient usage and concentrations of serum urea N, somatotropin (GH), and insulin (INS) when the animals were fed low-quality diets containing mountain mahogany (MM; Cercocarpus montanus) leaves. Diets were 8% CP and contained 25% or 50% MM (with hay or straw, respectively), either untreated or treated with polyethylene glycol (PEG; molecular weight 3,350) to reduce total reactive CT. Diets treated with PEG and 25% MM diets had less (P less than .05) CT than diets without PEG or those with 50% MM. Diets containing 50% MM resulted in greater N balance and lower serum urea N (P less than .01) than 25% MM diets. Concentrations of GH and INS were similar in animals fed the 25% and 50% MM diets. Reducing CT by adding PEG did not affect N balance or improve nutrient digestion by lambs or goats fed low-quality diets. In Exp. 2, four wether lambs (BW = 28.4 kg) were used in a 4 x 4 Latin square and fed the same diets as animals in Exp. 1 to study the influence of CT on ruminal fermentation and digesta kinetics. Dietary PEG treatment did not affect digesta kinetics except for a 30% increase in ruminal volume; 50% MM diets had faster particulate passage rates (P less than .05) than 25% MM diets. Ruminal ammonia N was greater (P less than .01) in lambs fed PEG-containing or 25% MM diets; however, rate of in situ NDF disappearance was not reduced by the lower ammonia N in the latter diets.

In viva digdbiiity trials were conducted to evaiuate the infhtence of shrubs contafning low and high ieveis of soluble pbenoiic/tannins on dig-and nitrogen retention by Angora goats. Each of 6 shrubs and alfaG hay (M&ugo sutiva L.) were fed to goats at 30% (dry matter b&s) of the diet in 8 bariey straw-pr&ie bay mixture. Tbe mixture was reguiated so that ali diets contained about 8% crude protein. High soluble pl~enotic shrubs used included big sagebrush (Artemi.du-Nutt. ssp. &i&&da), gray oak (Querc~~ grireu Liebm.), true mountain mahogany (Cercocaqur montanus Raf.), and one-seed juniper (Juniperus ntonoqwma LEqdm.] Sug). Low-soluble pbenoiic species included common wfnterfat (CeruU&ftu lrurrrtr [pursh.], J.T. Howell), fourwfng saitbwh (A rr@fex cunescuw [purse.), Nutt.), and aifaifa. Nftrogen w of wfnterfat, gray oak, mount& mahogany and one-seed juniper dfets were iess QY.05) than the rifaifa controls, but big sagebrush did not differ (IP.05) compared with the rlfaifa control. Retafned nitrogen (g/d) differed (PC.05) only among aifaif8, juniper, 8nd mount8in mahogany die&t. Goats fed juniper had greater (IYO.05) retain4 nitrogen than the alfti control. Shrubs high in soluble phenolics, with the exception of bfg sagebrush, had elevated fecai nitrogen losses, but reduced urfnary nitrogen losses compared witb tbe aifalfa control. Forage organic matter intake (96 body weight) and nitrogen intake (g/d) were correlated more hfghiy with nitrogen retention thnn dietary crude protein (96) or dfgestibie protein (%). Present data indicate that protein found in paiatabie natfve shrubs is a&niiated with simiiar efficiency to that in aifalfa hay ff these shrubs are consumed at moderate ieveb.

No abstract

Establishment, yield, and nutr&ional quality of 'Nordau'crested wheatgrass (&rqyrorr &uertonuu Fischer ex Link] Scbadtesb 'Fairwa~crested wheatgrass (Agropyron cr&&tum tL.1 Ca-tner), 'Arriba' western wheatgrass (.Pusc~yrum rudUrti [Rydb.] A. L&e), 'Luua' pubescent wheatgrass (Thinopyrum intermdum subsp. bmb&&ur[Schur.] Rarkw. and D.R. Dewey), and 'Large' tag wheatgrass(T.por&ruufRarkw.and D.R.Dewey)were evaluated on big sagebrush range (Artanhib tn&ntata Nutt. tridentata) in nortbcentral New Mexico during a S-year study. AU tbc above wheatgrasses showed nigh initial densities and long-term persistence. Wheatgrass yields acrow years and seasons during the last 2 years ofstudy averaged 760 kg/ha compared to forage yields of 355 kg/ha on surrounding ungrazed native rangeland. There were no differences (J9.05) among wheatgrasses in standing crop of current year's growth during spring, summer, or fag. Crude protein concentrations did not differ (J5.05) among wheatgrasses with seasonal advance. However, all the wheatgrasses showed a consistent decline in nutritional quality from spring to summer to fall. All the wheatgrasses we studied will provide highquality, spring (mid-April to mid-June) forage for livestock. During summer, use of native range is advantageous because it contains a high component of warm season grasses and forbs. Interseeding shrubs in wheatgrass seedings could reduce protein supplementation costs in winter.

In vivo digestibility trfnls were conducted in metrbolism stalls at New Mexico State University to evaluate the influence of leaves of true mountain mahogany (Cercocurpus montanus Raf.) and fourwing saltbush (A tr@w cunescens [Pursh.] Nutt.) on nitrogen retention and digestibility hy Angora goats. Each of the 2 shrubs were fed at 3% and 6% (air dry basis) of the diet along with prairie hay that was comprised mostly of blue grama (Bouteloua grucilis [H.B.K.] Lag. Ex. Griffhhs). High and low shrub diets contained about 12% and 8% crude protein, respectively. Nitrogen retention did not differ (IQO.05) among mountain mahogany and fourwing saltbush diets; however, goats fed the 60% shrub level had greater (P