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Factsheet: Managing Pasture Resources by Elide Valencia, Research Assistant Professor of Agronomy, UVI; L.E. Sollenberger, Professor, University of Florida; and Gerard D'Souza, Professor of Agriculture and Resources Economics, WVU A publication of the University of the Virgin Islands Agricultural Experiment Station January, 2002 INTRODUCTION Pastures typically account for the largest proportion of land use in the tropics (e.g., 80% of land use in the U.S. Virgin Islands; USVI). Proper management of pasture lands, then, is critical to sustainable land use and overall success of animal production enterprises. For animal production, assuming the right animal type, adequate water source, and good infrastructure (i.¢c., fencing and shade), the main focus of pasture management is usually on pasture productivity, nutritive value, and longevity. Pasture productivity is depen- dent on seasonal rainfall, soil and pasture type, weed competition and composition, and number of live- stock carried. Fertilizer manage- ment, weed control, selection and introduction of new plant species (i., higher yielding or more desirable growth characteristics) and re-seeding are some agronomic techniques that have been used to increase pasture productivity. Pasture quality is also dependent on seasonal rainfall, soil and pasture type, amount of forage present and maturity of the plant, and the number and type of livestock grazed. Fertilizer N applications and addi- tion of forage legumes to pastures have been used to enhance nutritive value. Pasture composition also plays Pasture management makes economic and environmental sense. an important role in productivity and quality. Sustained productivity and pasture longevity, however, are strongly dependent on the intensity and frequency of grazing. The objective of this factsheet is to provide a guide to grazing managers for maintaining long-term sustainability of their pasture re- sources. GRAZING MANAGEMENT CONCEPTS The Forage and Grazing Termi- nology Committee (1992) defined several terms in grazing manage- ment. The manipulation of livestock grazing to accomplish desired re- sults (i.e., high levels of production and long-term persistence) best describes grazing management. Main variables in grazing manage- ment are stocking rate, stocking density, and grazing method. Stock- ing rate is the number of animals per unit area (related to the total area that the animals will graze). Stocking density is the number of animals per unit area at a given point in time. If 20 cows graze a 10-acre area, either continuously or rotationally, the stocking rate is two animals per acre ing forages (1.¢., hay production). In addition, the manager sees his livestock and pasture more often and can manage both more effectively. Continuous stocking may be preferred over rotational because it requires less initial expense in terms of fencing and water lines and there are fewer decisions to be made. Also, there is less variation in the nutritional value of the animal's diet from day to day than under a rotational system, because animals are more selective when continu- ously stocked. There is, however, a give and take between how often and how close to graze forages. If a forage is grazed very closely, then it will generally require a longer rest period than if a taller stubble was left. Likewise, leaving a taller stubble may allow more frequent grazing than if plants were grazed closely. It is critical that we can predict how a plant will respond to the manage- ment imposed, so that we do not destroy pasture stands. ECONOMICS OF GRAZING METHODS Additional costs for rotational stocking include fencing (usually movable electric fencing) and a battery (usually a solar panel). These costs amount to around $750 for one acre, assuming the pasture is divided into three paddocks. Since equip- ment lasts for several years, these costs should be “annualized” (a simple way to annualize costs is to divide the equipment cost by the number of years of useful life). Assuming a 10-year equipment life, the annualized equipment costs amount to 575. Another cost associated with rotational grazing is labor for moving fences. This could amount to $150 (4 hrs./acre/ month) for a 6-month production season, resulting in total additional costs of $225 for the rotational system. However, rotational graz- ing can preclude the need for supplemental forage which is generally needed in a continuous grazing system. If rotational graz- ing is used, this could result in cost savings of $275 per acre (mostly in the form of additional labor to harvest forage). Since the cost savings are greater than the additional costs, rotational grazing can result in additional income of $50 per acre per year. If additional animal weight gains result from the rotational grazing system, as is likely, then the monetary gains could be even greater. CONCLUSIONS Taking care of your pastures makes economic and environmental sense. Good pasture management 1s key to higher profits and healthier natural resources. It is a powerful tool to influence plant and animal performance in forage-based live- stock systems. For this tool to be used effectively, however, the graz- ing manager must understand what the plant provides nutritionally and what the animal needs nutritionally, and then choose a management that balances the two. The most impor- tant choices to be made in any pasture management system are how close and how often the pastures are going to be grazed. These choices affect pasture performance, which, subsequently determines how well the animals will perform. The key to maintaining productive pastures and minimizing animal impacts is recog- nizing that forage plants have specific requirements for persis- tence, and then prescribing a level of grazing management that best ad- dresses those needs. Choice of pasture management will affect pasture productivity, forage nutritive value, and longev- ity. Profitability of enterprises that are based on grazed pastures will be greatly influenced by the way in which pastures are managed. t keeps the seed moving. REFERENCES Sollenberger, LE, and CG. Chambliss. 1989. Grazing management of improved pastures. p. 42-44. In Beef Cattle Short Course Proc., Gainesville, FL, 3-5 May 1989. Inst. Food Agric. Sci. Univ. of Fla., Gainesville, FL The Forage and Grazing Terminol- ogy Committee. 1992. Terminology for grazing lands and grazing animals. J. Prod. Agric. 5:191-20. Prepared by E. Valencia, Assistant Professor, University of the Virgin Islands; L.E. Sollenberger, Professor, University of Florida; and Gerard_D'Souza, Professor, West Virginia University. Issued by the University of the Virgir Director. Funding for this Factsheet was provis and Education (SARE) LS 99-107. icufural Experiment Station, James Rakocy,