**1. Introduction**

Cultivated forage legumes and range legumes are contributing in sustainable agriculture production apart from nutritional security to the livestock population of India. Cultivated forage legumes and range legumes are also crucial for the nutritional security for mankind as they are integral component for increased availability of animal protein and product which has higher biological value than the plant proteins. The major fodder legumes crops cultivated in India are *Medicago sativa*, *Trifolium alexandrinum*, *Vigna unguiculata*, *Mucuna pruriens*, *Vigna umbellate* and range legumes are *Stylosanthes* spp., *Desmanthus virgatus*, *Clitoria ternatea* and others. Among these, *Medicago sativa*, *Trifolium alexandrinum* and *Vigna unguiculata* are more popular among cultivated legumes and *Stylosanthes* in range legumes because of easy availability of seeds of improved varieties and well developed technology to increase the forage yield and quality. To understand the current status and scope of tropical forage legumes of India for sustaining income through livestock sector, their importance in livestock production, soil health and ecosystem services and diversity among germplasms, evaluation and breeding for improved varieties are discussed in this chapter.

production in cows is attributed to the feeding of animals when both concentrates and green fodders are fed as mixed ration. When the milk production is primarily depend upon concentrate based feeding, the cost of feeding towards milk production reaches to 80%, however, in case of forage (legumes) based feeding, it is reduced to only 40% of the total expenditure [4]. Hence, any attempt towards enhancing availability of quality green fodder, and economizing

Tropical Forage Legumes in India: Status and Scope for Sustaining Livestock Production

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From an animal perspective, one of the largest benefits provided by legume forages is that they provide a better level of nutrition than cereal forages/grasses at a similar stage of growth, leading to greater forage intake by livestock and increased animal performance. The symbiosis between legumes and Rhizobia provides the plant with an ample supply of N and it is one of the reasons why crude protein (CP) concentrations of legumes are higher than cereals/grasses. In addition to higher concentrations of CP, forage legumes also provide a higher quality protein which may be of equal or greater importance in case of non-ruminant livestock species like equines. Legumes also contain more concentrations of digestible energy than grass/cereal forages due to the structure and development of the legume cell wall. Indeed, the cell wall of legume plants contains fewer hemicelluloses and more pectin compared to that of cereals, thus increasing their digestibility by livestock. However as the cell matures, a secondary cell wall consisting of cellulose and lignin is deposited on the interior of the primary cell wall and reduces the overall availability of the structural carbohydrates in the digestive system. In cereal forages, this phenomenon occurs in all tissues types (i.e. leaves, stems, etc.) while being primarily restricted to the vascular tissues of legume stems. The lignin of non-legumes is also more esterified to hemicelluloses and is more recalcitrant in composition (e.g. higher proportion of syringyl subunits) indicating a more suppressed degradability than in legume species.

Forage legumes is essential for providing a source of biological nitrogen fixation (BNF) for enriching soil fertility (15–40 kg fixed N/ha), reduction in land degradation, disease breaks and

precisely is challenging because statistics on the areas and productivity of these legumes are

reliable and also estimates of %Ndfa (nitrogen derived from atmosphere) of fodder legumes in those lands. There are very few reports available on forage legumes—BNF in India. But, all works mainly focused on application of *Rhizobium* inoculants to fodder legumes and testing their potential for enhancing fodder production (fresh and dry weight, crude protein content, forage quality aspects, nodulation properties, etc.). Appreciable amount of atmospheric N (~60–100%)

of land is under fodder and forage legumes and green manure crops, with assumed average

 fixation rates of 200 kg N/ha/year for alfalfa, 150 kg N/ha/year for clovers (*Trifolium* spp.), 100 kg N/ha/year for other forages and 50 kg N/ha/year for legume-grass pastures [7]. From this

fixation of the forage and fodder legumes

[5]. Quantity of forage residues

and rice cultivated following

[6]. About 100–120 Mha

fixation values of forage and fodder legumes will be less

the feed cost would result in better remuneration to livestock farmers/producers.

**3. Forage legumes in soil health and ecosystem services**

for mitigating climate change. Estimating biological N2

is fixed by forage legumes annually, fixing up to 380 kg N ha−<sup>1</sup>

available for soil incorporation range from 80 to 143 kg N ha−<sup>1</sup>

forage legumes yields the same as rice with 24–50 kg fertilizer N ha−<sup>1</sup>

highly difficult to obtain. Therefore, N<sup>2</sup>

N2
