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Foraging Strategies On Rangeland: Effects On Intake And Animal Performance, Peter O’Reagain

IGC Proceedings (1977-2023)

Rangelands exhibit extreme spatial and temporal variability in forage quality and availability. The animals that utilise these rangelands have consequently evolved a range of foraging strategies in an attempt to cope with this variability and maintain nutrient intake. In general, animals respond to and exploit spatial variability at all scales by selecting those items or units which optimise the intake of digestible nutrients and hence animal production. Animals similarly employ a variety of strategies to cope with temporal variability on rangelands. These strategies may include adjusting foraging behaviour and/or exploiting critical resources or resource areas to buffer temporal variability in …

On The Scale Dependence Of Foraging In Terrestrial Herbivores, John M. Fryxell, C. B. D. Fortin, J. Wilmshurst

IGC Proceedings (1977-2023)

Meaningful modeling of the spatial and trophic dynamics of terrestrial herbivores demands understanding of the constraints and fitness objectives that presumably underlie behavior. This is complex in terrestrial herbivores, because of scale-dependent constraints on nutrient or energy gain. Mechanistic processes of forage cropping, forage mastication, movements between feeding stations, and forage digestion each have unique constraints that apply on different time, size, and spatial scales. Moreover, competing activities are rarely taken into account. Experimental testing of foraging objectives is therefore clouded by uncertainty regarding which time scale is most relevant from the animal’s perspective, leading to confusion and misrepresentation in …

Safflower (Carthamus Tintorius): A Promising Forage Crop For Semi-Arid Regions, Y. Leshem, I. Bruckental, S. Y. Landau, G. Ashbell, Z. Weinberg

IGC Proceedings (1977-2023)

The yield, quality, preservation and intake of safflower hay were determined in two successive years - 1998 and 1999. Field experiments carried out at the Bet Dagan experimental station on the coastal plain of Israel under rain-fed conditions. A spineless variety was tested under three sowing dates. Yield decreased and quality improved as the sowing date receded from November 12 to February 3. Respective yields, IVDMD and CP content were: 22 and 8 ton DM/ha, 48.9% and 65.5% , 10.0% and 14.6%. Safflower at 290, 410 and 770 g/kg DM was ensiled in 1.5-l anaerobic glass jars with or without …

Effects Of Different Levels Of Energy On Growth Of Grazing And Drylot Fed Holstein Heifers, L. P. Novaes, C. E. Polan

IGC Proceedings (1977-2023)

Growth of Holstein heifers were studied to evaluate the combination of a drylot phase followed by feeding energy for pasture supplementation during the grazing season of 1988. Heifers grazed a grass-legume mixture in six paddocks of 1.5 ha each. After drylot, animals were equally allotted to pasture and none or 2.0 kg/d of corn were fed in addition to grazing in a changeover design with repeated measurements. Heifers were fed a high (HE) or low energy (LE) diets in confinement and daily gains were 1190 (HE) and 990 g/day (LE) which were different. On pasture, corn supplementation did not enhance …

Nitrogen Fertilization In Paspalum Dilatatum, Poir: Herbage Production, Nutritive Value And Structural Characteristics, G. Acosta, V. A. Deregibus

IGC Proceedings (1977-2023)

It was studied the effect of nitrogen application on structural changes and quantity and quality characteristics of a Paspalum dilatatum Poir sward, under field conditions during two growing seasons. The nitrogen (N) rates were 0 and 440 kg ha^-1 applied during the first year in split applications. The nitrogen fertilization increased leaf, stem and cumulative total dry matter yield, plant height, tiller density, cover ground and leaf crude protein yield.

Growth Responses Of Acacia Angustissima To Vesicular-Arbuscular Mycorrhizal Inoculation, N. Lucena Costa, Valdinei T. Paulino, T. S. Paulino

IGC Proceedings (1977-2023)

The response of Acacia angustissima to VAM species (Acaulospora laevis, A. muricata, Entrophosphora colombiana, Glomus mosseae, G. fasciculatum, G. macrocarpum, G. etunicatum, Gigaspora margarita, G. gigantea and Scutellospora heterogama) was evaluated under greenhouse conditions, in a P-deficient clayey Oxisol of pH 5.5. The soil was sterilized at 110^oC for one hour each day for three days and reinoculated with a soil microbial suspension free of mycorrhizal fungi spores. The several VAM fungi were effective in increasing DM yield, nodulation, and N and P uptake of A. angustissima plants. The most efficient species were E. colombiana, A. …

Impact Of Overseeding Cool-Season Annual Forages On Spring Regrowth Of Tifton 85 Bermudagrass, Ricardo A. Reis, Lynn E. Sollenberger, D. Urbano

IGC Proceedings (1977-2023)

Field observations have shown stand reduction and slow spring regrowth of Tifton 85 bermudagrass (Cynodon spp.) pastures overseeded with temperate forages for grazing during the cool season. This experiment compared the effect of cool-season management programs, including overseeding and use of different grazing treatments, on productivity of Tifton 85 the following warm season. There were seven treatments: four were bermudagrass overseeded with a cool-season annual forage mixture (two grasses and two legumes) and grazed differentially, and three were bermudagrass controls with differences in amount of residual stubble remaining at beginning of autumn. There was only a slight delay in …

Influence Of Grazing Frequency On Biomass Production Using Several Selected Tropical Grasses, P. Mislevy, F. G. Martin, F. M. Pate, N. F. G. Rethman

IGC Proceedings (1977-2023)

To provide commercial growers with forage grasses that produce well throughout the year, there is a constant need for screening and testing new germplasm. Two rhodesgrasses (Chloris gayana cv. Rhods and Callide), four stargrasses (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. Florona, Zimbabwe, Okeechobee, and Rhodesian No. 2), one bermudagrass (C. dactylon var. dactylon cv. Jiggs), and one creeping signalgrass (Brachiaria humidicola CIAT 6369) were tested under a mob-grazing system. Dry biomass yield increased linearly as grazing frequency (GF) was delayed from 2 to 7 weeks. The cultivars, Florona, Zimbabwe and Okeechobee stargrasses and Jiggs bermudagrass, yielded …

Nutritive Value Of Double Cropped Corn For Ruminant Production, D. Vaz Martins, A. Fassio

IGC Proceedings (1977-2023)

The viability of double cropping corn (Zea mays L.) in Uruguay, germplasm combination, dry matter yield and nutritive value were evaluated. An early (E) maturing hybrid, an early to medium (E-M) one and an E-M variety were planted as spring crops. One E-M hybrid, one medium to late (M-L) hybrid and a late (L) variety were planted as a second crop. PVC laboratory scale silo of the spring crop and the whole plant of the summer crop were chemically analyzed. The nutritive value of the silages were related to plant maturity stage. No differences were detected in nutritive value among …

Novel Pilot Development Of A Closed-Loop Sustainable System Between Biogas Renewable Energy, Distilling, And Aquaculture By Vermiculture Of Stillage Wastes, Samuel C. Kessler

The Cardinal Edge

This study provides a mixed-methods approach in analyzing a potential closed-loop system between renewable biogas production from anaerobic digestion, vermiculture production, aquaculture production, and organic wastes with a particular focus on stillage wastes. Such system may hold significant promise for significantly reducing organic carbon and methane emissions from its components, and should be assessed for such. The 2021 IPCC report essentially identified methane reduction as the single fastest way to slow global warming (IPCC, 2021), making the study and implementation of methane-reducing systems and supportive policy for them critical. Knowledge gaps to implementing this system were qualitatively identified as disconnect …

Stable Isotopes Used To Infer Trophic Position Of Green Turtles (Chelonia Mydas) From Dry Tortugas National Park, Gulf Of Mexico, United States, David C. Roche, Michael S. Cherkiss, Brian J. Smith, Derek A. Burkholder, Kristen M. Hart

Marine & Environmental Sciences Faculty Articles

Evaluating resource use patterns for imperiled species is critical for understanding what supports their populations. Here we established stable isotope (δ¹³C, δ¹⁵N) values for the endangered green sea turtle (Chelonia mydas) population found within the boundaries of Dry Tortugas National Park (DRTO), south Florida, USA. There is little gene flow between turtles sampled at DRTO and in other rookeries in Florida, underscoring the need to study this distinct population. Between 2008 and 2015 we collected multiple sample types (skin [homogenized epidermis/dermis], whole blood, red blood cells, plasma, carapace) from 151 unique green turtles, including …

Adapting Tropical Forages To Low-Fertility Soils, Idupulapati M. Rao

IGC Proceedings (1977-2023)

Tropical forages growing in low-fertility acid soils usually increase the amount of dry matter partitioned to roots at the expense of shoot growth, but substantially different adaptive attributes to such soils have been found, both between and within species. By possessing the C₄ pathway of photosynthesis, grasses are more efficient than legumes in using N, Ca, and P, whereas legume roots are more efficient in extracting nutrients from low-fertility soils. Phosphorus uptake efficiency (mg of P uptake in shoot biomass per unit root length) of the legume Arachis pintoi is several times higher than that of the grass Brachiaria …

Adaptation Of Forage Species To Drought, D. J. Barker, J. R. Caradus

IGC Proceedings (1977-2023)

Variability in rainfall is the single greatest cause of variation in forage production for a given site. Current climate scenarios predict future annual rainfall to decrease at some geographic regions. The intensity of future rainfall is also predicted to increase at other regions, with the expectation of greater variability in soil moisture. The adaptation of forage species to drought is an issue that is likely to remain with us into the future.

Precise definitions are critical to water relations work, and imprecise use of terms has complicated comparisons of some studies on plant response to drought. Drought is a purely …

Grassland Plant Diseases: Management And Control, S. Chakraborty

IGC Proceedings (1977-2023)

Grasslands cover 40% of the earth’s surface and support animal-based industries; maintain soil cover, watersheds and biodiversity; sequester atmospheric carbon for storage in the soil; and provide tourism and leisure income. Diseases continue to decrease herbage and seed yield and reduce nutritive value and palatability of grasslands to impact on animal health and productivity but realistic data on loss are hard to find. Although principles of disease management remain the same, strategies used in crop protection can not be directly applied to grasslands due to differences in heterogeneity, population size, density and spatial distribution and population continuity. Low per hectare …

Micronutrients In Grassland Production, U. C. Gupta, F. A. Monteiro, J. C. Werner

IGC Proceedings (1977-2023)

Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are …

Novel Grasses And Legumes Germplam: Advances And Perspectives For Tropical Zones, E. A. Pizarro

IGC Proceedings (1977-2023)

It has been the aim, in the present article, to bring together as much as possible scientific evidence and experience in new available germplasm for tropical zones.

The economic importance of the Brachiaria, Paspalum and Pennisetum grasses is well established. New germplasm has become available since 1980. This paper reviews evaluations of Brachiaria accessions in humid lowlands and savannas of tropical America. The selection criteria need to be revised. Also, it is necessary to expose the new material as early as possible to farmers in order to select new germplasm with high chances of adoption.

Within the genus Paspalum …

Temperate Forage Grass-Legume Mixtures: Advances And Perspectives, A. S. Laidlaw, N. Teuber

IGC Proceedings (1977-2023)

The paper summarises some of the advances which have been made a) in increasing understanding of the grass-legume association, especially grass-white clover, so that the association can be more predictably exploited and b) in overcoming limitations in the use of such mixtures. The contribution which forage legumes make to the N economy of mixtures is reviewed with estimates approaching 400 kg N ha^-1 for some. Uptake by grass of legume- derived N (N transfer) reduces soil mineral N levels and increases the proportion of fixed N in the total legume N relative to legume monoculture. Although N transfer also …

Computer Science Principles With C++, Seth D. Bergmann

Open Educational Resources

This textbook is intended to be used for a first course in computer science, such as the College Board’s Advanced Placement course known as AP Computer Science Principles (CSP). This book includes all the topics on the CSP exam, plus some additional topics. It takes a breadth-first approach, with an emphasis on the principles which form the foundation for hardware and software. No prior experience with programming should be required to use this book. This version of the book uses the C++ programming language.

Assessing The Effect Of N And P Supply On Dry Matter Yield Of Three Tropical Grasses, O. Topall, C. Jouany, M. Duru, P. Cruz

IGC Proceedings (1977-2023)

The objectives are to study the effects of N and P supply and their interaction, on herbage dry matter yield and nutrient status of three tropical grasses. In order to estimate direct and indirect effects of P supply we express above-ground dry matter production as a function of the herbage nutrient status obtained from plant analysis. Results show that in absence of N, the significant increase in P nutrition status has only moderate consequences on herbage production and suggest that both N and P are limitant for herbage growth. P fertilization results in significant increase in dry matter yield only …

Sources And Rates Of Phosphorus In Improving Degraded Pasture In Brazilian West Amazon, Valdinei T. Paulino, N. L. Costa, C. R. Townsend, J. A. Magalhães, R. G. A. Periera

IGC Proceedings (1977-2023)

The effects of phosphorus sources (triple superphosphate – TSP, single superphosphate – SSP and partially acidulated rock phosphate – PARP) and rates (0, 50 and 100 kg/ha of P₂O₅ on dry matter (DM) yields and chemical composition of a degraded Brachiaria brizantha cv. Marandu pasture were evaluated in a cutting trial. Phosphorus fertilization, irrespective of sources and rates, showed an effective agronomic technique for pasture recuperation. The grass DM yields and potassium contents were significantly improved by phosphorus application, while weed DM yields were depressed. Irrespective of sources and rates, crude protein, phosphorus, and calcium contents were …

Understanding Shoot And Root Development, C. Matthew, E. N. Van Loo, E. R. Thom, L. A. Dawson, D. A. Care

IGC Proceedings (1977-2023)

Shoot and root development of the grass tiller is presented as a series of events on the tiller axis. Leaf, tiller bud, true stem, and root development are successive events in the life cycle of a single phytomer and the tiller is a co-ordinated series of phytomers, successive phytomers being progressively more advanced than the previous phytomer. In reviewing the individual growth processes of leaf, tiller, true stem, and root formation, fundamental determinants of light and nutrient capture are examined and examples presented to illustrate the link between component processes, plant morphogenesis, and plant performance. An example of the application …

Ecophysiology Of Grasslands: Dynamic Aspects Of Forage Plant Populations In Grazed Swards, G. Lemaire

IGC Proceedings (1977-2023)

The aim of this paper is to review knowledge of the ecophysiological mechanisms influencing the dynamics of plant populations in grazed swards. Such an objective requires some definitions. Firstly, it is necessary to define “ecophysiology” as the study of the interactions between biological individuals (plants) with their own environment: how individuals perceive and react to any constraint and change of their environment, and how the functioning of plants as a population can modify their own environment. Such a definition implies a dynamic approach to pant population functioning as resulting from constant plant-plant interactions mediated by micro-environment modifications. In a grazed …

Bite Depth Penetration Patterns Of Dairy Cows Foraging On Complex Swards, W. M. Griffiths, J. Hodgson, G. C. Arnold

IGC Proceedings (1977-2023)

Sward height was the dominant cue used by dairy cattle to determine the depth of penetration on young vegetative swards. On more complex swards, bite depth penetration was controlled by variations in the depth of regrowth. Evidence showed that cattle grazed to the pseudostem:lamina interface, but sward height exerted a stronger effect on bite depth than pseudostem height. Modelling efforts to predict how the herbivore places bites in space in the vertical dimension across sward states are currently being restricted by the absence of detailed canopy structure descriptions. We argue that the contrast between strata is an important determinant of …

Nitrogen Response Efficiencies From Grazed Dairy Pastures Under Dry Conditions, Frank R. Mckenzie, Joseph L. Jacobs

IGC Proceedings (1977-2023)

Experiments were conducted within a long-term nitrogen (N) fertiliser experiment under grazing. The objective was to examine N response efficiencies (kg dry matter (DM)/kg N) and herbage crude protein (CP) content to fertiliser N applied under dry soil conditions (gravimetric soil moisture content of 17% at 10cm; soil field capacity = 38% and wilting point = 11%) during autumn (April 1999) and late spring (November 1999) in southeastern Australia. Visually, N treated plots were greener in colour than control (no N) plots. No differences were recorded in primary or residual DM yields, N response efficiencies, and pasture growth rates between …

Effect Of Defoliation Frequency And Planting Density On Yield And Nutritive Value Of Coursetia Ferruginea (Hbk) Lavin, H. J. Delgado Gómez, R. González Anciani, G. López, D. Urdaneta, L. Ramírez Avilés

IGC Proceedings (1977-2023)

The aim of the present study was to asses the influence of the frequency of defoliation and density of sowing on yield and nutritive value of Coursetia ferruginea. Three defoliation frequencies (6, 8 and 10 weeks) and three densities of planting (1 x 1 m, 1 x 1.5 m and 1 x 2 m) were evaluated. A randomized block design, in a split plot arrangement and four repetitions, was used. Frequency of defoliation has a strong significant (P< 0.01) effect on dry matter (DM) yield (13.6, 18.1 and 27.8 g DM/plant for 6, 8 and 10-week defoliation frequencies), plant height (63.5, 76.6 and 101.2 cm) and plant survival (71, 74 and 86%). Nutritive value was significantly (P< 0.05) affected by the frequency of defoliation. Mineral content was reduced as the defoliation interval increased. Density of planting did not affect (P> 0.05) any of the variables. It is concluded that, C. ferruginea is a forage shrub with potential to improve animal feed …

Interactions Between The Effects Of Nitrogen, And Phosphorus, Potassium And Sulphur On Grass Production, J. D. Morton, L. C. Smith

IGC Proceedings (1977-2023)

The interactions between rates of nitrogen (N) and rates of phosphorus (P), potassium (K) or sulphur (S) on yield of ryegrass dominant swards were measured with no return of mown clippings in Southland, New Zealand. In the second year of the trial, the yield response to 176 kg N ha^-1 compared with no N increased only slightly with increasing soil Olsen P from 8 to 91 µg g^-1 soil. At 352 and 704 kg N ha^-1 there was a large increase in the yield response (from 5 to 9.4 and 11 t DM ha^-1 respectively) up …

Application Of Near Infrared Reflectance Spectroscopy (Nirs) For Macronutrients Analysis In Alfalfa (Medicago Sativa L.), A. Morón, D. Cozzolino

IGC Proceedings (1977-2023)

Near infrared reflectance spectroscopy was used to assess the mineral composition of alfalfa (Medicago sativa L.) as a tool for nutritional diagnosis. One hundred and ninety four (n = 194) samples of alfalfa from different locations representing a wide range of soils were used. Samples were reflectance scanned in a NIRS 6500 (NIRSystems, USA) instrument. The coefficients of determination (R²) of the regression estimate of the concentration of nitrogen, calcium, phosphorus, potassium, magnesium and sulphur and the errors in cross validation (SECV) were 0.93 (SECV: 1.6), 0.95 (SECV: 1.3), 0.93 (SECV: 1.9), 0.88 (SECV: 2.8), 0.82 (SECV: …

Effect Of Liquid Cattle Manure Application On The Botanical Composition Forage Dry Yield And Soil Chemical Characteristics In Mixed Pastures, J. K. Lee, W. H. Kim, D. E. Shin, S. Seo, G. J. Choi, E. S. Chung, G. J. Park

IGC Proceedings (1977-2023)

Many farmers apply liquid cattle manure on grassland, often in excess of crop N requirement, resulting in groundwater contamination. Our experiment was carried out to determine the effect of liquid cattle manure application on the botanical composition, forage dry yield and soil chemical characteristics in mixed pastures at the forage experimental field, National Livestock Research Institute, RDA, Korea. Five treatments consisting of no fertilizer, chemical fertilizer (210kg N/ ha), liquid cattle manure (40, 60 and 80 ton N/ ha) were arranged in a randomized complete block design with three replicates. No fertilizer treatment consistently had lower botanical composition rate of …

Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart

Faculty Publications

Background: Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things and expect the same outcomes in a larger-scale trial that were done in a smaller-scale preliminary study (i.e., pilot/feasibility) is wishful thinking, yet common practice. Starting small makes sense, but small studies come with big decisions that can influence the usefulness of the evidence designed to inform decisions about moving forward with a …

Biological Interactions In Grassland Soils And Productivity, R. Cook, R. D. Bardgett, W. R. Eason, L. Skøt, K. J. Webb

IGC Proceedings (1977-2023)

This paper describes research on interactions between grassland plant species and soil microorganisms. Both parasitic and symbiotic microorganisms modify nutrient transfers between plants and soil. Experiments are described in which nematode infection of clover increased nitrogen transfer to companion ryegrass plants. Infection of clover enhanced activity of soil bacterial and fungal communities. Legume genotypes differing only in responses to symbionts (rhizobium and arbuscular mycorrhizal fungi) and pathogens are being developed for studies of gene expression during establishing and functional symbioses. Such plants can be used in experiments as defined perturbations that will provide information on the interactions and functions of …