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

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

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

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

Cattle grazing preference among eight endophyte-free tall fescue cultivars

`HiMag' tall fescue (Festuca arundinacea Schreb.) was selected for high Mg concentration to reduce grass tetany risk to ruminants, but neither animal preference nor consumption of HiMag were known. The objectives were to evaluate methods of quantifying preference and to determine intake and preference by cattle (Bos taurus L.) of HiMag relative to seven other tall fescues. All entries were free of a fungal endophyte [Neotyphodium coenophialum (Morgan-Jones & Gams) Glen, Bacon & Hanna] that reduces cattle performance. The experimental design was a randomized complete block with three replications of eight cultivars nested within each of three test pastures. Six heifers grazed the vegetative to boot-stage pastures for 48 h in May, June, August, and September of 1993 and 1994. The pastures, located at 1200 m elevation, were furrow irrigated. Pre- and post-grazed forage were clipped and weighed to determine yield and utilization (48-h utilization < 50%). Preference scoring of 0 to 10 (0 to 100% of forage eaten) was done by four trained observers at 24, 30, and 48 h. The heifers quickly learned to distinguish between cultivars, and their order of preference was Kenhy > KY 31 > HiMag = Barcel = Cl = Stargrazer > M096 = Mozark. The cultivar x trial(year) interaction for preference indicated that cultivars responded differently to weather conditions, which in turn affected animal preference. Preference scoring had high repeatability and ranked cultivars similarly to the clip-and-weigh method of measuring utilization. Preference scoring was accomplished with 27% of the experimental error and only 6% of the time required for clip-and-weigh. Only 44% of the variation in preference score (PS) was explained by the model: PS = 8.8 - 1.1(Mg DM yield ha-1). Estimated dry matter (DM) intake of HiMag was 6.4 kg (animal unit day)-1. Consumption and preference of HiMag by cattle are satisfactory relative to other tall fescue cultivars

Malate, citrate, and amino acids in tall fescue cultivars: Relationship to animal preference

Grazing animals depend on little-understood chemical and physical cues when selecting forage diets. This study determined malate, citrate, and amino acid concentrations in endophyte-free tall fescue (Festuca arundinacea Schreb.) and related those concentrations to cultivar, harvest time, and grazing-animal preference. Barcel', 'Kenhy', 'Kentucky-31', 'Missouri-96', `Mozark', `Stargrazer, and the two accessions Cl and HiMag were established in three replicates within each of three pastures. Organic acids were determined on regrowth within each plot during four seasons and two years; amino adds were determined on regrowth of four cultivars across three replicates during both spring and fall seasons in one year. Malate and citrate were extracted with boiling water and quantified by high-performance liquid chromatography (HPLC) with an organic add column. Amino adds were hydrolyzed, separated by ion-exchange HPLC, and quantified as their ninhydrin derivatives. Both malate and citrate concentrations differed between years. During one year only, malate concentrations were higher in Kenhy (68 g kg-' dry matter [DM], most preferred) than in Mozark (54 g kg-, DM, least preferred). Citrate concentrations (13 g kg-' DM) were not different among cultivars. Eighteen amino acids (including tryptophan) accounted for 75% of total N. Thus, tissue N data were used as covariates to amino add data in the ANOVA. Kenhy contained higher concentrations of eight amino acids than did other cultivars. These differences may reflect presence of Lolium genes in Kenhy. Cattle (Bos taurus L.) grazing preference (0 = not eaten; 10 = completely eaten) was not related to malate, citrate, or amino add concentrations among cultivars