• Alpaca liveweight variations and fiber production in Mediterranean range of Chile

      Castellaro G., G.; García-Huidobro P de A, J.; Salinas, P. (Society for Range Management, 1998-09-01)
      A study of liveweight changes of alpaca adult males, females, and their progeny, was conducted through 3 seasons under continuous grazing on natural grasslands on the Mediterranean range of the Chilean Central Zone. Liveweight changes were positive and highest in spring (100 to 200 g day-1), moderate during winter (50 to 100 g day-1), and negative only at the end of summer and in fall (-110 to -150 g day-1). Weight gains of new born alpacas were greatest (110 to 150 g day-1) in the first 90 days after birth and then decreased slightly, reaching values of 75 g day-1 at 8.5 months old. Weight gains stabilized at 10 to 20 g day-1 at 3-years of age. The average annual fibre production was 1.57 and 236 kg in females and males, respectively; staple length varied between 8 and 10 cm.
    • Seasonal preferences of steers for prominent northern Great Basin grasses

      Cruz, R.; Ganskopp, D. (Society for Range Management, 1998-09-01)
      The objective of this research was to determine, on a seasonal basis, the relative preferences of cattle for 7 native grasses and d crested wheatgrass (Agropyron desertorum (Fischer ex Link)Schultes), a long-used introduction in the Pacific Northwest. Methods involved observing forage selection processes of 3 steers in paddocks, where plants existed in equal densities and in rangeland pastures with variable forage composition. Design of paddock and pasture studies was a randomized-complete-block with 3 replications, 3 stages of phenology (vegetative, anthesis, and quiescent), and 8-11 forages. Dietary proportions as indexed by bite-counts changed (P < 0.01) with phenology and varied among species. Diets were more similar (P < 0.05) than forage composition between the 2 study areas (paddocks and native pastures), and became less similar (p < 0.05) as phenology of the grasses advanced from vegetative growth through anthesis and quiescence. Steers were selective grazers during vegetative and anthesis stages of phenology, and despite variations in herbage availability, 'Nordan' crested wheatgrass was the most prominent dietary component in paddocks and pastures. Variation in proportions of grasses in the diet was associated (P < 0.05) with measures of available forage in the paddocks (r = 0.46-0.89, average = 0.72) but poorly associated with herbage composition in pastures (r = 0.41-0.02, average = 0.12). Inconsistencies in rankings of relative preference indices and dietary proportions of grasses suggested that measures of herbage availability may confound the predictive utility of relative preference indices. More grasses were acceptable to cattle at quiescence, with crested wheatgrass ranging from 8-26% of the diet. We suggest that with proper management, interseedings of crested wheatgrass on native range may be used to lessen grazing demands previously borne by native perennials early in the grazing season.
    • Spring defoliation effects on bluebunch wheatgrass: I. Winter forage quality

      Clark, P. E.; Krueger, W. C.; Bryant, L. D.; Thomas, D. R. (Society for Range Management, 1998-09-01)
      The winter forage quality of bluebunch wheatgrass (Agropyron spicatum [Pursh] Scribn. &Smith) is generally inadequate for maintenance of wintering Rocky Mountain elk (Cervus elaphus nelsoni Bailey). Previous attempts to improve the winter forage quality of bluebunch wheatgrass by clipping and livestock grazing have achieved mixed results. We report crude protein (CP), (in vitro dry matter digestibility (IVDMD), and dry matter (DM) yield responses of bluebunch wheatgrass to 3 phenological stage/defoliation intensity treatment combinations. The study was conducted in 1993 and 1994 at 2 sites in the Blue Mountains of northeastern Oregon. Bluebunch wheatgrass was hand clipped 1 to a 7.6-cm stubble height in early June under 1 of 3 treatment combinations: 1) mid-boot/whole-plant clipped, 2) mid-boot/one-half of the plant's basal area clipped, and 3) inflorescence emergence/whole-plant clipped. Early November levels of CP and IVDMD were greater under all 3 treatments compared to an unclipped control. Mean forage quality improvement over the control was greatest in the inflorescence emergence treatment with an improvement of 1.3 percentage points for CP and 5.8 percentage points for IVDMD. Dry matter yield of the control exceeded that of all clipping treatments. Increases in forage quality resulting from forage conditioning treatments may be important to the viability of elk populations wintering on rangelands where forage quality, rather than quantity, is limiting.