Glenn E. Shewmaker

Soil ingestion by cattle grazing crested wheatgrass.

Soil ingestion rates were determined using four 350-kg esophageal fistulated heifers. Soil concentrations in feces, as determined indirectly by titanium analysis, averaged 14 and 20% in June and August, respectively. Calculated soil ingestion rates were 0.73 and 0.99 kg/animal-day for the two respective periods.

Silicon in C-3 grasses: Effects on forage quality and sheep preference

Silicon in forage reduces dry matter digestibility and may reduce grazing preference. Two studies were conducted with the following objectives: (1) to evaluate a method of determining grazing preference, and (2) to characterize the distribution and solubility of silicon in 31 accessions of C-3 grasses and relate these traits to grazing preference and estimated forage digestibility. Forage samples were clipped at the beginning of each 7 to 10-day grazing period corresponding to 6 phenological stages of the Agropyron sp. Samples were washed and analyzed for acid detergent fiber (ADF), neutral detergent fiber (NDF), and silicon in ADF and NDF residues. Leaf silicon concentrations increased from the vegetative to seed-ripe stage. Genera were aligned into 3 groups based on the increase in leaf silicon concentration with advancing phenological age. Silicon concentrations in leaves of Agropyron, Pseudoroegneria, and Thinopyrum increased at nearly twice the rate of those in Critesion, Hordeum, Leymus and Psathyrostachys. Elymus leaves contained higher concentrations of silicon at the vegetative stage than the other groups, but the accumulation rate was intermediate. About 32% of total leaf silicon remained in NDF and 76% in ADF residues at the vegetative stage. These insoluble portions of silicon increased with aging. Preference was positively related to estimated dry matter digestibility at boot and anthesis, but was not related to fiber or silicon measurements. Leaf harshness was negatively related to preference at seed-ripe stage. Further progress in characterizing the role of silicon in C-3 forage grasses should be possible by studying a representative species from each group.

Utilization of globemallow (Sphaeralcea) taxa by sheep.

Globemallows (Sphaeralcea spp.) are well adapted to semiarid and arid environments. They are potentially useful as the forb component of seeding mixtures for rangeland improvement in the western states. However, the degree of acceptability of globemallow forage to livestock has not been well established. We tested 13 globemallow accessions representing 4 species and compared their utilization by sheep (Ovis aries) with that of crested wheatgrass [Agropyron cristatum (L.) Gaertn. X A. desertorum (Fisch.) Schult.] and alfalfa (Medicago sativa L.) during fall 1988 and 1989, and spring 1990 and 1991. Alfalfa consistently produced more forage per plant than wheatgrass or globemallows, and a greater portion of the alfalfa was eaten than of the other species. Sheep utilized wheatgrass more than globemallows in the fall, but the converse was true during spring pasturing. Over the 4 years, sheep ate similar proportions of wheatgrass and individual globemallows. The percentage of S. coccinea (Pursh) Rydb. forage consumed equaled that of crested wheatgrass or alfalfa in the fall but did not equal the percentage of alfalfa consumed in spring. However, S. coccinea produced much less total forage than the other species evaluated. Pre-grazing plant dry weight, dry matter content, and the occurrence of rust caused by Puccinea sherardiana Korn were negatively associated with globemallow utilization. Over-winter mortality of grazed globemallow exceeded that of ungrazed plants. Crested wheatgrass and alfalfa stands were not reduced by grazing. Globemallows are acceptable, but not highly preferred, forbs which can be seeded in environments where alfalfa and other more desirable species are not adapted.

Alfalfa Establishment Guide

High yielding, high-quality alfalfa often provides the foundation for profitable feeding programs for dairy and other livestock. Thick, vigorous stands are essential for high yields (Fig. 1). Obtaining such stands is dependent on proper seeding practices and favorable seedbed and environmental conditions. The key factors for obtaining thick, vigorous stands are proper soil pH and fertility, seedbed preparation, crop sequences that avoid herbicide residues from previous crops, selection of high-quality seed, seeding at the right time, good seeding techniques with equipment precisely adjusted for seeding rate and depth, and adequate control of weeds and insects.

Element concentrations in globemallow herbage.

Globemallows (Sphaeralcea spp.) are native, drought-resistant forbs of interest for inclusion in seed mixtures for semiarid rangeland renovation. Little is known of their nutritional value for ungulates. We measured element concentrations in representative globemallow species and evaluated their adequacy for livestock nutrition. We also correlated forage selection by sheep (Ovis aries) with element concentrations. Alfalfa (Medicago sativa L.), crested wheatgrass [Agropyron cristatum (L.) Gaertn. X A. desertorum (Fisch.) Schult.], and 13 accessions of globemallows [S. coccinea (Pursh) Rydb., S. grossulariifolia (H. & A.) Rydb., S. munroana (Dougl) Spach., and S. parvifolia A. Nels.] were transplanted into replicated grazing trials in southern Idaho. Herbage was sampled and the pastures were grazed by sheep in the fall of 2 years and in the spring of the following 2 years. Concentrations of Ca and Mg in crested wheatgrass were lower than in forbs. Differences between seasons were greater than the differences among globemallow species. Forage selection ratios were positively associated with the N concentration of globemallow leaves and with the Ca:P ratio of globemallow stems but were negatively associated with stem Zn concentrations. Herbage from pastures containing crested wheatgrass with globemallows and/or alfalfa would meet the dietary element requirements of beef cattle (Bos taurus) and sheep.