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

Animal health problems caused by silicon and other mineral imbalances

Plant growth depends upon C, H, 0, and at least 13 mineral elements. Six of these (N, K, Ca, Mg, P, and S) macro-elements normally occur in plants at concentrations greater than 1,000 mg kg- 1 level. The remaining micro-elements (B, Cl, Cu, Fe, Mn, Mo, and Zn) normally occur in plants at concentrations less than 50 mg kg". Trace amounts of other elements (e.g., Co, Na, Ni, and Si) may be beneficial for plants. Silicon concentrations may range upwards to 50.000 mg kg' in some forage grasses. Mineral elements required by animals include the macro-elements Ca, Cl, K, Mg, N, Na, P, and S; the trace or micro-elements Co, Cu, Fe, I, Mn, Mo, Se, and Zn; and the ultra-trace elements Cr, Li, and Ni. When concentrations of these elements in forages get 'out of whack' their bioavailability to animals may be jeopardized. Interactions of K x Mg x Ca, Ca x P, Se x S, and Cu x Mo x S are briefly mentioned here because more detail will be found in the literature. Limited published information is available on Si, so we have provided more detail. Silicon provides physical support to plants and may reduce susceptibility to pests. However, Si may have negative effects on digestibility and contribute to urinary calculi in animals

Elemental Uptake in Relation to Root Characteristics of Tall Fescue

HiMag, an accession of tall fescue (Festuca arundinacea Schreb.), was selected for high magnesium (Mg) concentration in leaves to reduce grass tetany risk to ruminants. However, the mechanism for enhanced Mg uptake in HiMag leaves has not been determined. The objective was to investigate if increased Mg uptake in HiMag could be explained by differences in elemental distribution among plant parts, root characteristics, or organic acid concentrations compared to its parental cultivars, ‘‘Kentucky 31’’ (KY31) and ‘‘Missouri 96’’ (MO96). The study was conducted on a surface-irrigated calcareous Portneuf silt loam (coarse-silty, mixed, mesic, Durinodic Xeric Haplocalcid). Vegetation and soil cores of 7.6-cm diameter were sampled to a 45-cm soil depth in 15-cm increments. Mass and ash were determined for leaves, crowns, and roots. Leaf area, root length, root area, root length density, elemental concentration, and uptake [potassium (K), calcium (Ca), Mg, sodium (Na), and phosphorus (P)], and malate and citrate concentrations also were determined. Leaf Mg concentration was higher in HiMag than parental cultivars. HiMag generally did not differ in crown and root elemental concentrations from its parents. Risk of causing grass tetany, indicated by leaf K/(Ca+Mg), was lower in HiMag than KY31 and MO96 in both 1994 (P=0.03) and 1995 (P=0.01). Root length, area, and mass were not related to cation concentrations in the three tall fescue accessions, suggesting that HiMag may have an active uptake or transport mechanism for Mg

Volatiles from fresh and air-dried vegetative tissues of tall fescue (Festuca arundinacea Schreb.): Relationship to cattle preference

Volatiles from fresh and air-dried forage of eight tall fescue cultivars were collected on Tenax-TA adsorbent and then examined by gas chromatography/mass spectrometry (GC/MS) and GC/flame ionization detector chromatography (GC/FID). Fifty of 52 compounds emitted from fresh forage and 99 of 103 emitted from hay were identified. The same compounds were common to all cultivars, and quantitative differences, within fresh forage or hay, were not dramatic. Fresh forage yielded 12-32 pg/L of volatiles, while dry forage yielded 0.18-0.47 µg/L. (Z)-3-Hexenyl acetate made up 82% of total emissions from fresh forage but only 0.24% from hay. Green-leaf odor compounds made up 11% in fresh forage and 6% in hay. Previously determined grazing preferences by cattle were related positively to 6-methyl-5-hepten-2-one and negatively to (Z)-3-hexenyl propionate and acetic acid, which together made up <0.2% of volatiles from fresh forage

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

Optical Trapping with High Forces Reveals Unexpected Behaviors of Prion Fibrils

Amyloid fibrils are important in diverse cellular functions, feature in many human diseases and have potential applications in nanotechnology. Here we describe methods that combine optical trapping and fluorescent imaging to characterize the forces that govern the integrity of amyloid fibrils formed by a yeast prion protein. A crucial advance was to use the self-templating properties of amyloidogenic proteins to tether prion fibrils, enabling their manipulation in the optical trap. At normal pulling forces the fibrils were impervious to disruption. At much higher forces (up to 250 pN), discontinuities occurred in force-extension traces before fibril rupture. Experiments with selective amyloid-disrupting agents and mutations demonstrated that such discontinuities were caused by the unfolding of individual subdomains. Thus, our results reveal unusually strong noncovalent intermolecular contacts that maintain fibril integrity even when individual monomers partially unfold and extend fibril length.National Institutes of Health (U.S.) (Grant GM025874)National Science Foundation (U.S.). CAREER (Award 0643745

Determining animal preference for grasses: Methods and error analysis

Grazing preference of 8 tall fescues was evaluated by 1) clipping and weighing forage before and after grazing (CW), 2) a selection ratio (SR), and 3) preference scores (PS). The coefficients of variation were 96, 52, and 20% for SR, CW, and PS methods, respectively. The ranking of preference was similar for CW, SR, and PS methods. The PS method was done in 6% of the time and with less error than CW and SR, used the entire row, and was nondestructive