QTL Analysis of Mineral Content and Grass Tetany Potential in \u3cem\u3eLeymus\u3c/em\u3e Wildryes

Grass tetany is a metabolic ailment in ruminants, occurring when animals graze rapidly growing C3 grasses with a K/(Mg+Ca) ratio (KRAT) greater than 2.2. High KRAT values have been documented in several forage grasses including diploid Russian wildrye (Jefferson et al., 2001). The objective of this experiment was to identify quantitative trait loci (QTLs) controlling KRAT in allotetraploid wildryes

Seasonal Changes in Forage Quality of C3 Grasses on Sagebrush Grassland

Annual and perennial grasses growing in the semiarid, west-central North American continent mature by early to midsummer. Forage mineral concentrations in these C-3 grasses decrease curvilinearly as the season advances from day of year (DOY) 75 to 300. Total digestible dry matter (TDDM) and digestible cell wall (DCW) decrease linearly with DOY while neutral detergent fiber (NDF) increases curvilinearly. By midsummer; energy, N, P, and Zn usually become deficient for ruminant nutrition

Border Effects on Cattle Grazing Preference

The objective was to examine the effect of row position on cattle grazing preference. Grazing preference of eight tall fescues [Festuca arundinacea (Schreb.)] was evaluated by ocular preference scores at 30 hr (PS30) and 48 hr (PS48). Six rows of a cultivar—numbered consecutively within each plot from left to right—formed one plot. Rows 1&6 were on the outside edges of the plot and rows 3&4 were in the middle. Within a replication, rows 1 and 6 were adjacent to rows 6 and 1 of adjacent plots, respectively. During the first year, row position was not a significant effect. However, in the second year, preference for middle rows was significantly higher than the outer pairs of rows—rows 2&5 and 1&6. This could have been a result of the animals’ ability to distinguish preferred cultivars in the middle of the plot because of more distinct olfactory and visual cues. Row position was important in experimental design because of an interaction with animal behaviour

Near Infra-Red Measurement of Nonstructural Carbohydrates in Alfalfa Hay

Recently documented benefits from afternoon versus morning cut forage have encouraged laboratory reporting of total nonstructural carbohydrate (TNC) values as part of forage quality testing. Our objective was to determine if infra-red spectroscopy (NIRS), which is being used in many forage testing labs, could be reliably used to quantify forage sugars in hay samples. We used two alfalfa (Medicago sativa L.) sample populations that were analyzed by wet chemistry for sugars and scanned by NIRS. The first set consisted of field-dried hay samples that were oven dried at 70oC and the second consisted of fresh, freeze-dried samples. TNC values were determined more precisely with NIRS than by wet chemistry

Effects of a Fall Wildfire on Herbaceous Vegetation on Xeric Sites in the Selway-Bitterroot Wilderness, Idaho

Trends in productivity and mineral content of herbaceous vegetation in Ponderosa pine and montane grassland over a 4-year period are reported. Dry matter production on burned areas was 1.4, 1.3, 2.2 and 1.6 times that on unburned sites in the four successive years following the fire. Annual forbs and annual grasses contributed 56% of total dry matter the first year following fire. Perennial forbs contributed 40, 75, 75, and 77% of dry matter on the burned sites in successive years following the fire, compared with 66% on the unburned site. Herbage mineral concentrations did not change appreciably following fire, although low values for nitrogen and potassium were apparent in the first year

Herbivore Preference for Afternoon- and Morning-Cut Forages and Adoption of Cutting Management Strategies

Photosynthesizing forage plants accumulate total nonstructural carbohydrates (TNC) during daylight, but then TNC concentrations are reduced during the night. Afternoon-cut forage (PM) has greater TNC value and thus economic value, than morning-cut (AM). Livestock prefer PM-cut hay and this can be readily demonstrated by offering animals a choice of hays cut in PM and AM. Alfalfa growers in the western United States are readily adopting PM-cutting technology to increase profits

Soil Ingestion by Cattle on Semiarid Range as Reflected by Titanium Analysis of Feces

Soil ingestion was determined for cattle grazing a Bromus tectorum range in southern Idaho by measuring titanium concentrations in animal feces collected at 2-week intervals during the droughty 1973 grazing season. The experiment was based on the premise that titanium, which is abundant in soils, is contained only in small quantities (less than 1 ppm) in plants not contaminated with soil. Fecal-soil values averaged 14%, with values ranging from 3 to 30% of fecal dry matter, increasing as forage availability decreased. Soil ingestion levels were estimated to range from 0.1 to 1.5 kg with a median of 0.5 kg soil/animal-day. This soil was ingested primarily with the roots of Bromus tectorum, which were often pulled up and consumed with the aboveground plant parts. Dust on leaves and stems accounted for only a small portion of the ingested soil. Measurements of acid-insoluble residue concentration in feces overestimated soil ingestion because of the probable presence of SiO? of plant origin. Large changes in forage SiO? concentrations of the diet reduce the effectiveness of this method compared to the Ti method. Ingested soil may be a possible source of trace minerals, pesticides, heavy metals, and radionucleides that may be sorbed to surface soil particles

Parent-progeny relationships and genotype X environment effects for factors associated with grass tetany and forage quality in Russian Wildrye

Grass tetany (hypomagnesemia) has caused severe economic losses in ruminant animals grazing cool-season grasses, including Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski]. The malady has been associated with deficiencies in Mg, Ca, and carbohydrates, and high levels of K. The K/(Ca + Mg) ratio (KRAT), expressed as moles of charge, is often used to express the grass tetany potential of forage. Development and use of new cultivars with an improved balance of the associated minerals would be an economical approach to reduce the incidence of grass tetany. Objectives of this study were to characterize the genetic variability, genotype by environment interactions, and intercharacter relationships for P, K, Ca, Mg, KRAT, crude protein (CP), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD), among 21 clonal lines of Russian wildrye and their polycross progenies. Evaluations were made for 2 yr at three diverse locations in the USA and Canada. The clonal lines were derived from cultivars and plant introductions. Although the clone x location interaction was usually significant, differences among the clonal lines were significant for K, Ca, Mg, and KRAT, and three forage quality estimates of CP, NDF, and true IVDMD. Although the magnitude of the genetic variability among the progenies was substantially less than that found among the clonal lines, we conclude that the grass tetany potential, CP, NDF, IVDMD, and P concentration of this breeding population can be altered through breeding. Opportunities for genetic improvement in forage quality were particularly favorable for CP. Genetic correlations among the clonal lines suggested that selection for higher levels of CP would be accompanied by increased K, Ca, Mg, and IVDMD and reduced KR AT and NDF

Biotransfer possibilities of selenium from plants used in phytoremediation

We are investigating the biotransfer of accumulated Se by the plant in several phytoremediation systems. In study I, we evaluated the biotransfer of Se from Indian mustard, a Brassica species, to the insect-cabbage looper (Trichoplusia ni); mortality, deterrence, and biomagnification of Se were examined. We determined that feeding behavior of food chain consumers was affected not only by the plant concentration of Se, but also by the mobility of the insects and choice of feed available. In study II, we examined the survival and development of beet armyworm (Spodoptera exigua) fed Se-enriched plant tissues from different lines of saltbush (Atriplex spp.) After feeding on lines of saltbush that produced high biomass and accumulated high concentrations of Se, insect growth and survival was reduced. In studies III, IV, and V, lambs, dairy cows, and rabbits were fed Se-enriched Brassica and Medicago (alfalfa) plants as part of their feed ration. None of the tested animals exhibited any Se toxicity symptoms, but they had increased levels of Se in most tissues sampled (e.g., organs, blood, urine, feces), excluding milk. In study VI, we evaluated biotransfer of Se from broccoli to rats to determine efficacy of Se for reducing colon cancer. We found that Se-enriched plant material was more effective than inorganic sources of Se for preventing precancerous colon lesions. Results from all studies clearly show that Se absorbed by plants can be transferred biologically in an intentional or unintentional manner to insects and animals