Plant Biology Commons^™

Renovation Of Tropical Legume-Grass Pastures In Northern Australia, H G. Bishop, B Walker

IGC Proceedings (1977-2023)

Live-weight gain of cattle on tropical legume-grass pastures is highly correlated with legume content. Legume-yield decline is a major problem in 200,000 ha of siratro (Macroptilium atropurpureum [DC] Urb.)-based pastures in northern Australia. This decline is largely associated with overgrazing. Resting for at least one year has been required to improve siratro yield substan­tially. A more rapid method of restoring the yield of siratro was required. The effect of various forms of mechanical soil disturbance on siratro population and yields was compared with resting pasture (control) in 4 replicated experiments and on 3 commercial pastures near Mackay in coastal northeastern …

Effectiveness And Safety Of Translocated Herbicides Applied To Pasture Weeds With A Rope-Wick Applicator, E J. Peters

IGC Proceedings (1977-2023)

Applying herbicides with a rope-wick applicator is a new technique that permits treatment of tall weeds without treatment of low-growing forage species. The objective of this study was to determine the effectiveness of several herbicides and to evaluate their safety to forage species. The effectiveness of 2,4-D [(2,4-dichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), and glyphosate [N-(phosphonomethyl) glycine] in water-herbicide con· centrations of 2: 1, 4: 1, and 8: 1 were evaluated on gray goldenrod (Solidago nemoralis Ait) when applied with a rope-wick ap· plicator in one and two directions on 15 June and 17 July 1979. The goldenrod …

Production Of Big Trefoil On Acid, Low-Fertility Soils In New Zealand, R S. Scott

IGC Proceedings (1977-2023)

On undeveloped, acid (pH< 5.0) soils in New Zealand, growth of the conventional legumes white clover (Trifolium repens L.), red clover (T. pratense L.), and alsike clover (T. hybridum L.) is limited by acidity. The objective of this research was to identify an alternative legume species better adapted to both acidity and low inputs of phosphorus (P) and to examine grazing management. Big trefoil (Lotus pedunculatus Cav.) cv. Grasslands Maku and birdsfoot trefoil (L. rorniculatus L.) cv. Maitland were examined. Seed was inoculated with appropriate strains of rhizobia and sown into undisturbed tussock grasslands on acid soils of low P status at altitudes of 550-880 m. Lime and phosphorus …

Influence Of Pesticide, Fertilizers, Row Spacings, And Seeding Rates On No-Tillage Establishment Of Alfalfa, L R. Vough, A M. Decker, R F. Dudley

IGC Proceedings (1977-2023)

Two experiments were conducted to investigate seeding techniques associated with no-tillage establishment of alfalfa (Medicago sativa L.) in barley (Hordeum vulgare L.) stubble. The objective of experiment 1 was to evaluate the influence of car­bofuran (CF) insecticide/nematocide and of P and N fertilizers on seedling weight, plant population, and forage yield. All materials were applied in the row with the seed. The largest seedlings at 10 weeks after seeding occurred with CF + P + N. The smallest seedlings were associated with the check and P treatments. The highest plant populations at 6 and 30 weeks after seeding …

Reduced-Tillage Pasture Renovation In The Semi-Humid Temperate Region Of The U.S.A, S K. Barnhart, W F. Wedin

IGC Proceedings (1977-2023)

Studies conducted in Iowa have shown that precision seed placement, good seed-to-soil contact, and reduced competition from other species are just as important when introducing legumes into an existing grass sward as when seeding into a conven­tional seedbed. Tillage of strips 5.1 cm wide or wider was necessary for adequate sward suppression prior to and during legume establish­ment. Paraquat (1,1' dimethyl-4,4' bipyridinium ion) at 2.8 or 5.6 kg/ha could substitute for strip tillage in sward suppression. Paraquat banded over the seeded row provided satisfactory sward suppression, but legume establishment was improved when paraquat was applied broadcast or glyphosate [N-(phosphonomethyl) glycine) …

Techniques Of Overdrilling For The Introduction Of Improved Pasture Species In Temperate Grasslands, C J. Baker

IGC Proceedings (1977-2023)

Experiments over several years are summarized. Collectively, these experiments sought to improve the reliability of overdrill­ing techniques during growth periods of temperate swards. The studies sought first to identify the important physical re­quirements of seeds and seedlings in untilled soils, especially in unpredictably dry situations, and then to develop drilling machinery and techniques to fulfill these requirements more nearly than had hitherto been achieved in New Zealand. The studies first involved closely controlling and monitoring the drilling and seed-groove-covering procedures, the soil moisture status and mechanical properties, and postdrilling climates, using a tillage-bin technique. Cereal seeds were drilled into large …

The Potential Of Forage Legumes And Their Role In Scotland, J Frame, R D. Harkess, A G. Boyd

IGC Proceedings (1977-2023)

Intensive forage production requires fertilizer nitrogen (N), the manufacture of which depends upon fossil-fuel energy. In­creasing energy costs and possible scarcity raise doubts about the future. Thus, there has been renewed interest in forage legume production. In ongoing research at The West of Scotland Agricultural College, the effects of applied N levels and closeness of cutting on white dover varieties of differing morphological types are being assessed under a simulated grazing regimen. Also, the influence on production of white clover, diploid and tetraploid red clover, and lucerne swards, sown alone or with each of five companion grasses, is being evaluated …

Animal Production With Controlled And Fixed Stocking And Managed Stocking Rates, R E. Blaser, J T. Johnson, F Mcclaughterty, J P. Fontenot, R C. Hammes Jr, H T. Bryant, D D. Wolf, D A. Mays

IGC Proceedings (1977-2023)

Grazing experiments were conducted to implement and improve animal-grazing-management systems. The primary objec­tives were (experiment 1) to investigate animal production with fixed and controlled stocking and (experiment 2) to study animal production and canopy characteristics with three managed stocking rates. Live-weight gains/head for the grazing season were similar for fixed and controlled stocking; during a summer period, gains/head were higher for controlled stocking. Gains/head were not associated with available herbage. The canopies with fixed stocking had 28% to 82% more forage than those with controlled stocking, the former being high in dead tissues and stems. Controlled stocking gave 61 % …

Proposed Hay-Grading Standards Based On Laboratory Analyses For Evaluation Quality, D A. Rohweder, N Jorgensen, R F. Barnes

IGC Proceedings (1977-2023)

-The progress report of the Forage Analysis Subcommittee of the Hay Marketing Task Force organized by the American Forage and Grassland Council (Rohweder et al. 1978) proposed new hay standards that would express feed value more ade­quately and communicate this value more fully. The subcommittee studied the potential for expanding the standards to include legume-grass mixtures; however, individual legume and grass equations gave more consistent predictions of quality. Digesti­bility and dry-matter intake by cattle and sheep fed the same forages were compared. Digestibility was nearly identical in the two livestock species; however, cattle were somewhat more efficient than sheep in …

Prediction Of Forage Quality With Nir Reflectance Spectroscopy, F E. Barton Ii, D Burdick

IGC Proceedings (1977-2023)

Near-infrafred (NIR) reflectance spectroscopy can be used to predict the quality of forages and their chemical composition. Studies were conducted on warm-season grasses with a filter-type NIR reflectance spectrometer to evaluate the NIR technique and the tilting filter spectrometer. Hay and drum-dehydrated samples of bermudagrass were used. A monochromator NIR reflectance spectrometer was used to narrow the possibilities of wavelengths to be investigated. The following compositional and quality parameters were determined: crude fiber (CF), fat, acid detergent fiber (ADF), neutral detergent fiber (NDF), crude pro­tein (CP), acid-insoluble lignin (AIL), and in-vivo digestibility of dry matter (DDM). The results of bermudagrass …

Forage Analysis With Near-Infrared Reflectance Spectroscopy: Status And Outline Of National Research Project, W C. Templeton Jr, J S. Shenk, K H. Norris, K H. Norris, G W. Fissel, G C. Marten, J H. Elgin Jr, M O. Westerhaus

IGC Proceedings (1977-2023)

Objectives of this paper are to review the status of near-infrared reflectance spectroscopy (NIRS) in forage-quality evaluation and to indicate the approach being used in a national research effort to further test, validate, and develop the technology for use in forage breeding, production, and utilization programs. Use of NIRS assay of forage quality was first reported 5 years ago. Research has now been initiated at many locations.

A national research project, involving personnel at six widely dispersed locations in the U.S., was established in 1978. Com­puterized, high-precision near-infrared reflectance spectrophotometers are employed. A set of 30 forage samples provided ex­perimental …

Influence Of Sward Structure Upon Herbage Intake Of Cattle Grazing A Perennial Ryegrass Sward, M H. Wade, Y.L P. Le Du

IGC Proceedings (1977-2023)

To examine the influence of structural distribution of herbage within a sward on intake by grazing animals, two swards of contrasting structure were established at two periods in the grazing season by either infrequent mowing (C) or hard sheep graz­ing (G) of a perennial ryegrass (Lolium perenne) pasture. The plots were then allowed to grow undisturbed for about 5 weeks before being grazed by young cattle for periods of 2 weeks at two levels of herbage allowance, 30 and 60 g dry matter/kg live weight/day, in July (1) and in September (2). Detailed measurements of sward structure were …

A Mathematically And Conceptually Unified Approach To Grazing-Management Terminology, D L. Scarnecchia, M M. Kothmann

IGC Proceedings (1977-2023)

Expressions such as "stocking density," "stocking rate," "grazing pressure," "herbage allowance," "grazing intensity," "stock­ing intensity," and "stocking pressure" have long been used to describe animal-pasture systems. In general, these expressions describe relationships among the basic variables of animal demand, forage quantity, pasture area, and grazing duration. Our objective was to develop a conceptually dynamic mathematical framework of expressions summarizing all of the meaningful relationships among these variables. Elementary differential and integral calculus were used to develop this dynamic approach. The resulting expressions are dimensionally valid and are capable of accurately describing dynamic animal-pasture systems. Adoption of this system would standardize …

Regeneration Of Windmill Grass Pastures Following Severe Grazing In Semiarid Southeastern Australia, D L. Michalk, G E. Robards

IGC Proceedings (1977-2023)

Stability of windmill grass pastures in west central New South Wales was examined by measuring regeneration of two impor­tant grasses (Enteropogon acicularis and Chloris truncata) on two range sites grazed at three stocking rates (2.5, 3.7, and 4.9 sheep/ha) following 5 months of abusive grazing at 25 sheep/ha. Severe grazing reduced density and size of mature E. acicularis plants on both sites, particularly when heavy grazing (4.9 sheep/ha) was reintroduced during the period of pasture recovery. However, during the study E. acicularis density remained relatively stable because seedling cohorts compensated for plant losses in all treatments. Moderately grazed plots were …

Screening Perennial Forages By Mob-Grazing Technique, P Mislevy, G O. Mott, F G. Martin

IGC Proceedings (1977-2023)

Mob-grazing allows the study of forage response to severe defoliation by grazing animals on a limited land area. This tech­nique was used to evaluate two Digi,taria spp., one Paspalum sp., and 13 Cynodon spp. at grazing frequencies of 2, 3, 4, 5, and 7 weeks. Average dry-matter (DM) yield generally increased as grazing frequency decreased from 2 to 7 weeks. Decreasing the grazing frequency from 4 to 7 weeks resulted in a DM yield increase of 50% to 75% for most entries. Grazing at 4-and 5-week intervals resulted in the highest (42%) and lowest (22%) weed contamination, respectively, when compared …

Grazing Techniques For Evaluating Quality Of Forage Cultivars In Small Pastures, A G. Matches, F A. Martz, D A. Sleeper, R L. Belyea

IGC Proceedings (1977-2023)

Because plant beeders have few laboratory analyses of forage quality that are good predictors of animal performance when grazing pasture, • we studied the feasibility of grazing small pastures with cattle in order to detect possible forage-quality dif­ferences among cultivars of tall fescue (Festuca anmdinacea Schreb). Kentucky 31, Kenmont, Fawn, and Missouri 96 tall fescue cultivars and Kenhy, a Lolium-Festuca derivative, were grown in 0.47-ha pastures and grazed in separate periods ranging from 35 to 68 days during the spring, summer, and autumn of 1974-1976. Between grazing periods, cattle grazed a reserve pasture of the same cultivar. All test pastures …

Structural Characteristics Limiting Digestion Of Forage Fiber, D E. Akin

IGC Proceedings (1977-2023)

Cell walls of forage were studied for structural and chemical factors that limit digestion by rumen microorganisms. Tech­niques used to investigate digestion were histochemistry, electron microscopy, and anaerobic culturing of rumen populations on specific substrates. Certain tissues, such as the xylem cells, totally resisted degradation by rumen microorganisms; these tissues stained positive for lignin with acid phloroglucinol (Weisner test). Other supportive tissues, such as the sclerenchyma in blades, stained positive for lignin with chlorine-sulfite (and also the Maule test) and were also generally resistant to microbial digestion. Microscopic studies revealed that certain living tissues (i.e., those having cytoplasm and organelles …

Relationship Of Forage-Evaluation Techniques To The Intake And Digestibility Of Tropical Grasses, S M. Abrams, H Hartadi, C M. Chaves, J E. Moore, W R. Ocumpaugh

IGC Proceedings (1977-2023)

Seventy-six grass hays, harvested at 2, 4, 6, and 8 weeks of regrowth, were fed ad libitum to wethers in a digestibility and in­take trial. Range of organic-matter digestibility (OMD) was 54.l % to 72.3% and that of organic-matter intake (OMI) 17.3 to 27.4 g/kg. Lignin was the chemical component most highly related to OMD (r = - 0.72). Neutral detergent fiber (NDF) was bet­ter than acid detergent fiber (ADF) as a predictor of OMD (r = - 0.66 vs. - 0.45). In-vitro NDF digestibility (IVNDFD) was superior to in-vitro organic-matter digestibility (IVOMD) and all other analyses as a predictor …

Using A Dynamic Model Of Fiber Digestion And Passage To Evaluate Forage Quality, D R. Mertens, L O. Ely

IGC Proceedings (1977-2023)

Assessing forage quality depends not only upon the characteristics of the plant and animal, but also upon the dynamic interac­tion of the forage, rumen microorganisms, and animal. Although static variables, such as composition or 48-hour in-vitro fermentation, are important for characterizing feeds and predicting in-vivo responses under standard conditions, they provide little information that can be used to assess forage quality in dynamic situations. Dynamic properties, such as rates of digestion and passage, can be used to predict digestion under varied circumstances but require an appropriate mathematical model. Our objectives were to describe a dynamic model of fiber digestion and …

Bulk Volume: A Parameter For Measuring Forage Quality And Its Influence On Voluntary Intake, P J. Van Der Aar, H Boer, G Hof

IGC Proceedings (1977-2023)

The experiment evaluated bulk volume (ml/g meal) as a method of estimating forage quality. Samples of Lolium perenne (Lp) and Festuca arundinaea, and hay samples of Lp were collected at different stages of growth. Voluntary intakes of these forages by dairy cattle had been measured previously. Volumes of samples and volumes of cell-wall residues after 0, 6, 12, 24, and 48 hours in vitro digestion were determined.