Sward Structure Effects on Light Interception in Rotationally-Grazed Orchardgrass (\u3cem\u3eDactylis glomerata\u3c/em\u3e L.)

Grazing managers need to know the relationship of sward height and mass to photosynthetic capacity. The aim of this study was to measure the interception of photosynthetically active radiation (PAR) and relate it to sward structure throughout the grazing season on rotationally-grazed orchardgrass/cocksfoot (Dactylis glomerata L.) pastures

Livestock grazing effects on phosphorus cycling in watersheds

Elevated phosphorus (P) loading of wetlands, streams, lakes, and reservoirs can occur from nonpoint sources such as grazing of uplands, wet meadows, and palustrine wetlands. Erosion caused by livestock grazing or any activity will increase the total P load in streams; however, herbivores can also harvest P from forage and export a significant amount of P from the watershed. Some land managers fail to recognize that the P taken up by plants will continue to cycle through soil and water. Dissolved P or P attached to soil particles suspended in water are the primary vectors of P movement in a watershed. Herbivores add another vector with more opportunities to export P from the watershed. Using best management practices such as rotational grazing, buffer strips next to wetlands, and proper irrigation management should reduce overland flow and streambank erosion. Livestock grazing should harvest and remove a significant amount of P from the ecosystem by incorporation into bone and tissue mass of growing animals and beef export from the basin. The Phosphorus Uptake and Removal from Grazed Ecosystem (PURGE) model uses three separate methods to estimate P retention in cattle, and using limits of the input variables, predicted a range from 4 to 50 Mg P could be removed annually from 17,700 ha of pasture in the Cascade Reservoir watershed in west-central Idaho. With proper grazing management, cattle should be part of a long-term solution to P loading and improvement of water quality in Cascade Reservoir

Late-afternoon-cut hay makes more milk

Pouring a glass of milk is only a few steps away from pouring a glass of sunshine. Solar energy drives photosynthesis in green plants to produce simple sugars. When these plants are eaten by the cow, those sugars provide energy to rumen microorganisms which, in turn, provide energy to the cow for milk production. On warm sunshiny days, soluble sugars accumulate in plants faster than the plants can use them. At night, photosynthesis does not operate, and there is a loss of soluble sugars. This whole process results in a daily cycling of soluble sugars in the forage. Figure 1 clearly shows the gradual accumulation of plant sugar which builds as the day progresses. The drop in plant sugars occurs sometime after sunset

Nonstructural carbohydrates: Challenges and progress in forage testing

Forage testing has evolved by adapting new technology but acceptance of different tests for forage quality is slow and some tests are impractical. Reliance on technology has replaced intuition and experienced knowledge in some cases. For example, alfalfa grown at high elevations was preferred as dairy hay in the 1960's and 1970's. The use of forage testing in the 1980's and 1990's appears to favor alfalfa hay grown at lower elevations. Moreover, the forage tests of acid detergent fiber (ADF) and neutral detergent fiber (NDF) do not consistently predict animal intake or performance across cuttings. For example, hot season cuttings usually have finer stems, are greener in color, and conventional tests show similar values of ADF and NDF to first (cool season) cuttings, yet animal intake is less for the hot-season cuttings. Using current forage testing to compare high versus low elevation grown hay, or to compare hays from different cuttings, is not dependable. There are some promising developments which should improve our ability to predict animal performance. The testing for nonfibrous carbohydrates (NFC) or total nonstructural carbohydrates (TNC) are additional tools you may want to use. Nonfibrous carbohydrates are defined by the National Research Council (2001) as NFC = 100 - (%NDF + % CP + %Fat + %Ash), where CP is crude protein. Total nonstructural carbohydrates are determined by a fractionation of the sample and are calculated as the sum of monosaccarhides, disaccharides, short chain polysaccharides, and starch. This paper reviews the underlying principles of forage quality and the development of testing; environmental, genetic, and harvest management effects on forage quality; and reviews diurnal cycling of total nonstructural carbohydrates and related animal preference studies

The Benefits of Tannin-Containing Forages

This fact sheet describes tannins, a group of chemical compounds produced by a number of broadleaf forage plants, that can bind proteins

Daily changes in alfalfa forage quality

Several studies are reviewed which relate the daily variation in total nonstructural carbohydrates (TNC) to hay quality, implications for animal preference studies and hay tests, forage intake by animals, and resulting animal production. From these results we conclude that TNC concentrations in alfalfa can increase linearly during the day. Alfalfa forage samples taken for animal preference or TNC analyses should be taken within lh to control daily variation within 5%. We estimate 136 (first cutting) and 81 lbs TNC/ac (fourth cutting) increase by PM- versus AM-cutting. Increasing windrow width in heavy hay from 48 to 60 in windrow allows for faster dry-down, however in light hay increased windrow width is not necessary. The "super conditioner" may provide faster dry-down of alfalfa hay in some conditions

Harvest management effects on alfalfa quality

To produce dairy quality hay, alfalfa should be cut at an early maturity (pre-bud stage). Harvest management such as the time of day the forage is cut and the rate of hay dry-down can also affect forage quality. Alfalfa accumulates total nonstructural carbohydrates (TNC) during daylight because photosynthesis produces TNC more rapidly than they are exported and utilized for new growth and maintenance. Total nonstructural carbohydrates are composed of starch, fructans, sucrose, glucose, and fructose. Continued plant respiration during darkness depletes 'INC concentration. After hay is cut, plant and microbial respiration will continue to consume TNC until the hay reaches less than about 16% moisture. Therefore it is important to dry the hay as quickly as possible to retain as much INC' as possible, as well as avoiding rain showers and allowing the next crop to grow. New developments in conditioners and forming a wider windrow were evaluated for the effects on hay quality. Our objectives in Study 1 were to: 1) determine daily variation of carbohydrate concentrations and accumulation rates in Alfalfa (Medicago sativa L.), 2) predict a time interval to maximize for TNC levels in hay, and 3) estimate the impact of PM cutting on TNC yield. Study 2 objectives were to evaluate the effects of windrow width and conditioner type on alfalfa hay moisture and forage quality

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

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