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Embrapa – National Center for Beef Cattle Research Caixa Postal 154 Campo Grande, MS 79002-970, Brazil
cacilda{at}cnpgc.embrapa.br
Pastures in the tropics represent the single most valuable resource for transforming photosynthetic energy into high quality protein for human consumption. Besides covering 20 to 30% of the earth's surface, tropical pastures are the basis for meat and dairy production systems in the region. Their importance and impact on the environment, thus, are unquestioned. As clearly stated in the preface, the intention of this multiauthored book is to offer a global overview to complement the body of information already available from other tropical environments, particularly Australia. Regrettably, by gathering mostly North American authors lesser attention was given to expertise published in Portuguese or Spanish; therefore, the Latin American perspective was fairly overlooked. The comprehensiveness of topics included however—covering a broad range of subjects on the most relevant aspects of forage conservation and utilization, complemented by the breadth of opinions, and illustrated by factual examples—makes for interesting and worthy reading for agronomists and pasture specialists.
The book is divided into four sections. Despite the variety of styles, the subject follows a logical sequence and takes the reader through the complexity of working with a natural resource still largely underexploited and decisively deserving of research investment, both in teamwork and funding, to fully secure its potential.
Beinroth and Pitman concisely introduce the tropical environment in the first two chapters. Their presentation of the singularities of soil types and their limitations to plant growth, as well as the environmental constraints for sustainable production in the tropics, makes for a sound and elucidative prologue to the topics to follow. Concepts are well presented and emphasis on choice of adapted germplasm reflects the priorities of major forage research teams throughout the tropics.
The second section deals with the subject of germplasm resources, breeding, use of biotechnology, and overcoming constraints in their development. The first two chapters dwell on tropical germplasm of grasses and legumes, and here the Latin American input is notably lacking. Some of the genera included as important germplasm resources are, in truth, restricted to a few sites or are no longer relevant, while other genera and species of unequivocal significance are superficially reported. However, the grass and legume breeding chapters provide a thorough coverage of a complex subject and appropriately refer the reader to more comprehensive reviews. Both these chapters are, in fact, sufficiently specific and elucidative as to be useful in graduate studies. Breeding is a crucial activity that needs to be stimulated if tropical forages are to continue sustaining animal production in the tropics. With the genetic resources of several of the relevant genera available and characterized, major efforts should be directed to overcoming problems related to broader utilization through breeding, as considered by the authors. In Chapter 8, R. Smith argues that since forages have lower visibility and profit, they have received lower research priority. However, research in the use of biotechnology has profited by advances in closely related model systems. The subjects of transformation, tissue culture, genetics, and DNA markers are concisely summarized in this chapter and current methods, principles and applications in tropical forages are presented.
Section 3 encompasses the use of tropical forages. Authors in this section (i) offer basic concepts and guidelines on how to produce good quality seed, as well as hay, silage and haylage; (ii) refer to intensive management of pastures for the humid tropics with very specific reference to work done in Puerto Rico, thereby raising the question of applicability elsewhere; (iii) promote the use of host-plant resistance as the most promising means of counteracting the effects of myriad pests and diseases, these presented in informative and comprehensive contexts; (iv) contribute a short and general report on the use of elephant grass and sorghums in integrated feeding systems; (v) stress the advantages of animal production on grass-legume pastures, emphasizing the need for on-farm trials, but by pointing to legume limitations implying the need for breeding more competitive, palatable but pest resistant legumes; (vi) discuss concepts and processes in nitrogen fixation and present lists of suppliers of Rhizobium inoculants; and (vii) in the last chapter, analyze the contribution of grazing land systems to animal production and compare sustainability among the tropical regions, stressing the challenge of using land capability effectively all year long in order to realize forage potential.
The last section of the book focuses on current developments from research on forages from all tropical regions. Jones highlights decades of efforts and accomplishments in Australian research, presents comprehensive lists of genera, species, and cultivars, accentuating major strengths and weaknesses of each. The chapter on Africa brings an interesting overview, different from the traditional approach in that it considers that production bottlenecks probably can best be dealt with if pastures are looked upon as an integral part of animal husbandry. The chapter on the Americas contrasts two widely apart perspectives on forage production and utilization, Asian and American, written in an interesting and captivating style.
Tropical forage plants represent a enormous potential for use in developing sustainable, integrated agricultural production systems in the tropics everywhere. This book contributes through synthesis of information to a global overview of tropical plants, their potential and constraints, their use and importance, and current research activities. It was not intended to explore subjects in depth so much as to contribute to advanced studies. However, it condenses important information and critical views on tropical forages and their context of utilization in pastoral systems.
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