The objective of the study was to determine if exposure of young lambs to leafy spurge (Euphorbia esula L.) would increase the consumption of this plant. Orphan lambs were exposed to leafy spurge from birth to 11 weeks of age as a water soluble extract mixed with milk replacer and as freshly harvested plants. Ewe-reared lambs were exposed to leafy spurge by grazing them on a leafy spurge-infested pasture. Study 1 investigated the consumption of vegetative and flowering leafy spurge paired with arrowleaf balsam root (Balsamorhiza sagittata (Pursh) Nutt.) by orphan lambs during a 30-min feeding period. Experienced lambs consumed a higher percentage leafy spurge than naive lambs (P<0.03). The interaction of leafy spurge phenophase and previous experience (P<0.02) showed that experienced lambs preferred leafy spurge regardless of phenophase (70% of intake) and naive lambs only preferred leafy spurge when it was vegetative. Study 2 investigated the preference for leafy spurge on pastures with high or low leafy spurge biomass. Experienced compared to naive lambs had a higher percentage of bites (P<0.001) and preferred leafy spurge in the high spurge biomass pasture, but not in low biomass pastures. Naive lambs avoided leafy spurge in both pastures. Study 3 was a pasture trial that investigated spurge consumption by orphan and ewe-reared lambs. Percent bites and time spent grazing leafy spurge were not affected (P>0.23) by previous exposure, but daily herbage removal was greater (P<0.09) in pastures grazed by experienced compared to naive lambs (876 vs. 685 g/lamb, respectively). Experienced ewe-reared lambs had a higher rate of biting on leafy spurge (P<0.06) than naive or orphan Lambs. These studies indicate that previous experience will be an important factor affecting the use of sheep as a biological control agent for leafy spurge.

An automated system to weigh and sort free-ranging cattle was adapted to administer cottonseed pellets (41% crude protein) to free-ranging cattle. The frequency with which animals drank water determined the interval between supplemental feedings. The automatic spacing of individual animals was the weakest link in the chain of events leading to the sorting of cattle into groups to administer treatments. Periodically during the study, free-standing water was available due to above-average precipitation. This resulted in an inconsistent supplementation schedule because animals did not have to return through the maze to drink water. Single herd management eliminated potential pasture-treatment confounding but accentuated individual animal behavior, which resulted in a range of supplement intakes and drinking water patterns.

Tallgrass prairies are an important forage resource in the eastern Central Great Plains. The effect of spring burning, fertilization, and atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] on standing crop of selected herbaceous species and categories of vegetation was determined in 6 tallgrass prairie environments located near Lincoln and Virginia, Neb., from 1987 through 1989 and 1 site near Bloomfield, Neb., in 1987. The grasslands were in good to excellent condition at the time these studies were conducted. Portions of each site were burned in mid-to late spring, atrazine was applied at a rate of 2.2 kg a.iha-1 in late April to early May, and fertilizer was applied in mid-May. Despite below-normal precipitation at 6 of the 7 sites, burning combined with fertilization improved warm-season grass standing crop by 50 to 127% in 5 of the 7 grassland environments studied. This reflected the positive response of the dominant warm-season grasses, big bluestem (Andropogon gerardii Vitman var. gerardii Vitman) and indiangrass [Sorghastrum nutans (L.) Nash], to burning or fertilization. Atrazine increased warm-season grass standing crop at only the site near Bloomfield. Kentucky bluegrass (Poa pratensis L.) and annual bromes (Bromus spp.) were more susceptible to atrazine than smooth brome (Bromus inermis Leyss.). Forb standing crop was significantly reduced by atrazine alone or by burning followed by atrazine application in 4 of the 7 prairie environments. Burning combined with fertilizer application improved warm-season grass standing crop in good to excellent condition grasslands and obviated the need to use atrazine.

A 3-year study evaluated weight gain, blood urea nitrogen (BUN), and fecal nitrogen (FN) of beef steers fed 0.00, 0.34, or 0.68 kg/hd/day of cottonseed meal (41% CP) while grazing mesquite (Prosopis glandulosa var. glandulosa Torr.)/tobosagrass (Hilaria mutica [Buckl.] Benth.) range between April and July. Mixed breed beef steers (avg wt 230 kg) were allocated to three 6-pasture grazing cells and group-fed prorated amounts of supplement 3 days a week. Individual weights were recorded every 21 days. Crude protein in clipped forage samples remained above 7.0% except in July, 1985 (6.5%). Gain response varied among periods within year but the primary effects occurred in the first 40 to 60 days of grazing. In 1985, daily gains over 92 days were 0.38, 0.44, and 0.67 kg/hd/day for the 0.00, 0.34, and 0.68 kg supplement groups, respectively. In 1986 and 1987, daily gains during 85-day trials were 0.65, 0.66, and 0.71 kg/hd/day and 0.98, 1.08, and 1.07 kg/hd/day, respectively. Blood and feces were collected from 10 steers in each treatment group on each weigh date during the first 2 years. The 0.68 kg/hd/day supplement maintained higher (P<0.05) BUN and FN than the control group but response to 0.34 kg supplement was inconsistent. Performance and BUN data suggested that protein concentrate was not the appropriate supplement for steers grazing tobosagrass in the spring and summer.

Laboratory tests are often conducted to determine seed germination responses to temperatures for seedbed ecology interpretations and revegetation seeding rate calculations. To determine the utility of laboratory germination tests for indicating seedbank germinability of lovegrasses we measured seedbed temperatures and soil water on 2 semidesert grassland sites in the Southwest. We also tested germination of Lehmann lovegrass (Eragrostis lehmanniana Nees), 'Cochise' lovegrass (E. lehmanniana Nees X E. trichophora Coss & Dur.), and plains lovegrass (E. intermedia Hitch.) seed collections associated with natural or artificial revegetation studies on these 2 sites in relation to an array of constant and alternating temperatures. Germination responses to different temperatures varied with the year and source of collection and seed age and differed compared to those reported in the literature. Lehmann and Cochise lovegrass had high germination at temperature alternations similar to wet seedbed temperature extremes in December (0,2/15 degrees C) and these species and plains lovegrass were germinable at moderate temperature alternations representative of wet seedbeds in April (10/30 degrees C). Ability to germinate in laboratory tests at these temperatures is not necessarily indicative of germinability in the field for Lehmann lovegrass, which has been observed to germinate in April, not December, in wet seedbeds. All species had maximum or near maximum germination at a temperature alternation of 20/40 degrees C, which is similar to wet seedbed temperature extremes during the summer rainy period when these species usually emerge. Because of the variability in germinability of different seed collections of lovegrass over time, specific collections should be tested at specific ages relevant to seedbed ecology and revegetation studies or projects. Laboratory germination tests which mimic actual wet seedbed temperature curves might be more predictive of seedbed germinability than the usual tests which expose the seeds to abrupt temperature alternations.

Eastern redcedar (Juniperus virginiana L.) trees from a location in western, central, and eastern Oklahoma were aged by tree ring analysis to assess the relationship of tree age to tree height and crown area. The relationship of tree age to crown size differed with location. Trees in the oldest age class, 28 to 29 years, ranged in height from 6.2 m on the western Oklahoma location to 8.3 m on the eastern Oklahoma location. The oldest trees at all locations were still actively growing. Height growth rate of the oldest class of trees averaged 0.5 to 0.6 m yr-1 on the western and eastern study locations, respectively. Eastern redcedar reached 2.0 m in height at about 8 years of age on the eastern Oklahoma location. Trees reached 2.0 m in height in 10 to 14 years at the other locations. This suggests that burning intervals should be more frequent on the eastern Oklahoma location than on the central and western Oklahoma locations. Crown area as a function of tree age was not as similar as tree height among the 3 locations. Not only did the relationship differ among locations, but it differed also between 2 central Oklahoma range sites. Crown area of 28-year-old trees ranged from only 15 m2 on the central Oklahoma Loamy Prairie to 40 m2 at the eastern Oklahoma location. These data suggest that the smaller crown area of trees at the central Oklahoma location may be a result of an influence other than environment, such as an introduction of plants of a different race with an inherent columnar growth habit. The reduction in forage production associated with eastern redcedar and the efficacy of prescribed burning for controlling eastern redcedar would change more rapidly as trees age on the eastern Oklahoma location than on the other locations.

A total of 341 Utah rural land sales occurring between 1980 and 1987 were analyzed to identify and quantify the determinants of Utah rangeland and ranch prices. Two factors statistically influenced average sale price (/hectare and/or /AUM): number of hectares sold and whether buildings were included in the sale. Regression analysis incorporated statistically significant (P < 0.05) explanatory variables into a predictive equation that expressed total ranch sale price as a function of number of deeded AUMs, building value, year and month of sale, number of leased AUMs, distance to nearest town, recreation influence, and size of parcel sold. The regression model produced an adjusted R2 = 0.91. Value of buildings and number of deeded AUMs explained most of the variability in total ranch sale price.

Efficient use of roughages is important for calf management in the Boran pastoral system. Using local legumes as protein supplements may improve fiber utilization and thus be an appropriate intervention. Fruits (pods and seeds) of Acacia tortilis (Forsk.) Hayne subsp. spirocarpa (Hochst. ex A. Rich) Brenan, leaves of A. brevispica (Harms), and cowpea [Vigna unguiculata (L.) Walp] hay were compared with alfalfa (Medicago sativa L.) hay as protein supplements for calves using 2 approaches. Sheep fed native grass hay under confinement were used for a controlled evaluation in growth and metabolism trials. Calves grazing dry-season forage under simulated pastoral management provided in evaluation under field conditions. All supplements increased (P<0.05) nitrogen (N) intake, growth rate, and conversion of dry-matter intake into liveweight for sheep compared to unsupplemented animais. Calf growth and water intake were increased (P<0.05) relative to the control by ail supplements except cowpea hay. When statistically adjusted to a common level of N intake, N retention was similar (P>0.05) among all groups of supplemented sheep. Compared to alfalfa and cowpea diets, tanuinfferous Acacia diets had a negative effect (P<0.05) on true-N digestibility, but this was offset by their positive effect (P<0.05) on reducing loss of urinary N. The A. tortilis diet had a lower (P<0.05) true-N digestibflity than the A. brevispica diet, which was probably influenced by soluble phenolics in pods and seeds. On a nutritional basis these Acacia and cowpea materials art suitable for inclusion in improved feeding systems for Boran calves