Introduction

Animal husbandry is an integral component of Indian agriculture supporting livelihood of more than two-thirds of the rural population. Animals provide nutrient-rich food products, draught power, dung as organic manure and domestic fuel, hides and skin, and are a regular source of cash income for rural households. India’s livestock sector is one of the largest in the world. It has 57.8% of world’s buffaloes, 15.06% cattle, 25.07% small ruminants, 2.18% camel, 1.3% equine, 1.2% pigs and 34.72% chicken and contributes 4.1% of the national GDP and 27.25% of the agricultural GDP (Islam et al., 2016).

Animal husbandry in India is driven by the structural changes in agriculture and food consumption patterns; the utility of livestock has been undergoing a steady transformation. Importance of livestock as source of ‘draught power’ has declined considerably due to mechanization of agricultural operations and declining farm size. Sustained income and economic growth, a fast-growing urban population, changing lifestyles, improvements in transportation and storage practices and rise of supermarkets especially in cities and towns are fuelling rapid increases in consumption of animal food products (Birthal, 2012).

Demand for animal food products is responsive to income changes, and is expected to increase in future. Between 1991-92 and 2008-09, India’s per capita income grew at an annual rate of 4.8% and urban population at a rate of 2.5%. By the end of 2017, demand for milk is expected to increase to 155 million tons and for meat, eggs and fish together to15.8 million tons (Birthal, 2012).

Livestock derive major part of their energy requirement from agricultural byproducts and residues. Hardly 5% of the cropped area is utilized to grow fodder. India is deficit in dry fodder by 11%, green fodder by 35% and concentrate feed by 57%. The common grazing lands too have been deteriorating quantitatively and qualitatively which are important sources of fodder for the livestock (Surapa, 2011).

Economical Impact of Some of the Legume Fodders in Livestock Production Agasse(Sesbania grandiflora)

Sesbania grandiflora is a small, loosely branching tree that grows up to 8- 15 m tall and 25-30 cm in diameter and well adapted to hot, humid environments. It has an outstanding ability to tolerate water logging and is ideally suited to seasonally flooded environments. It is a fast-growing tree and do not require complex management and leaves and pods are valued for fodder. The leaves contain 36% crude protein and 9600 IU vitamin A in every 100 g and Sesbania is known to possess anthelmintic, antibiotic, anticancerous, tonic, diuretic and laxative properties and also cure night blindness in cattle. The most effective method of feeding the fodder to ruminants is to supplement with it, up to 15-30% of the total diet. Because of its high protein content, S. grandiflora should not be solely fed to animals but should be combined with roughage that is low in protein and high in energy, such as rice or maize straw. Forage production of 4.5-9.1 ton/ha per year could be expected (Orwa et al., 2009). The chief economic value of the Sesbania is likely to be as a green manure and livestock forage (Gillett, 1963). Sesbania grandiflora can meet production shortages in times of extreme climatic conditions such as droughts. This are easy to grow, require little land, labour or capital, have numerous by-products (Steven et al., 2014).

Impact of Sesbania Supplementation on Milk Yield and Body Weight

Increased growth rate of 7 g/day was observed with goats fed with dried Sesbania grandiflora as 30% supplement to straw over a period of 4 weeks (Robertson, 1988). Goats fed on a diet of S. grandiflora forage ad lib for a period of 8 weeks body weight gain of 17.1 g/head/day was observed by Singh et al. (1980). Gutteridge (1987) reported that when S. grandiflora  fed as supplements to teff straw (30%) to both sheep and goats, the growth rates of sheep was increased by 35 g/head/day while those for goats was 4 g/head/day. Ash and Petaia (1992) conducted an experiment to evaluate the nutritive value of Sesbania grandiflora. The goats (Group 1) were fed on sesbania ad libitum with a basal diet of low quality grass. In group 2 goats were fed with grass alone. The body weight gain of 78.6 g/day in group 1 and 54.7 g/day in group 2 were observed. Pramila et al. (2015) conducted on – farm demonstrations to demonstrate the effect of supplementation of sesbania forage on milk yield in crossbred lactating cows. The average daily milk yields (lit/day) without feeding sesbania was 7.36±0.08 and with feeding sesbania 9.24±0.08. Total increase in milk yield was 1.88 lit/day. Lemma et al. (1988) reported that milk yield was higher in crossbred cows supplemented with sesbania (30%) by 0.85 kg/day. The supplementation of Sesbania grandiflora in bovines at 5 kg/head daily for 45 days, milk yield was increased by 8 per cent (Vijayakumar et al., 2000).

Lucerne (Medicago sativa)

Native of south- western Asia well adapted to warm temperature and cool sub – tropical regions. It is hardy and drought resistant, can withstand high temperature (40 ^oC to 45 ^oC) and an annual rainfall of 45-50cm is optimum but can also survive in low rainfall of 35cm. Lucerne is perennial herb, grow up to 0.6-1.6m tall. First cutting can be taken 45-90 days after sowing and cutting interval 30-40 days. Yield about 40 tones of green fodder per hectare (New South Wales Agriculture Facts., 2003).

Impact of Lucerne supplementation on Milk yield and Body Weight

The diets containing lucerne elicited the greatest DMI and milk yield (West et al., 1997). Kanthraju (2015) conducted on-farm demonstrations and reported that milk yield in crossbred lactating cows was increased (32.5%) on supplementation (5kg/day/cow) of wilted lucerne forage. Steinshamn (2010) compared the effect of White clover (Trifolium repens), Red clover (Trofolium pratense) and Lucerne (Medicago sativa) based diets on feed intake, milk production and milk quality. The results indicated that there was a tendency that lucerne fed cows had higher DMI (0.8 kg/day) and milk yield (2.2 kg/day) compared to other diets. Lucerne hay supplemented (25% of DM requirement) along with maize silage or groundnut haulms resulted in optimum weight gain and reduced feed cost in Nellore ram lambs (Venkateswarlu et al., 2013). The inclusion of lucerne in dairy cows total mixed ration (TMR) can reduce the proportion of supplements in the form of cereals like maize, resulting in reduced feed costs (Dewhurst et al., 2003).

Moringa (Moringa oleifera)

Moringa is native to the Indian subcontinent and has become naturalized in tropical and subtropical areas around the world. It is a multipurpose tropical tree, mainly used for food and has numerous industrial, medicinal and agricultural uses, including animal feeding as fodder. The tree is evergreen and fast growing with high capability to re-grow after pruning. The tree has the capacity to produce high quantities of fresh biomass per unit area even at high planting densities and give dry matter yield from 4.2 to 8.3 ton per hectare with a cutting frequency of 40 days interval (Wasif et al., 2014). The leaves are very nutritious and rich in crude protein (22 – 25%), vitamins A, B and C, and minerals (Moyo et al., 2011).

Impact of Moringa Supplementation on Milk Yield and Body Weight

The inclusions of Moringa as a protein supplement to low quality diets improves DM intake and digestibility, increases milk production and affect milk composition in terms of milk fat and total solids (Nadir et al., 2005). An increase of 43% in milk yield was seen when cows were fed 15-17 kg (fresh matter) of Moringa leaves daily, mixed with their regular feed (Amaglo, 2010). DM intake and growth rate of goats fed on different ratio of dried moringa foliage and concentrate diets was higher than the sole conventional concentrate diet. Replacing moringa foliage supplementation at 75% with conventional concentrate could be used as a cheap protein supplement for goats (Nasrin et al., 2015). Inclusion of Moringa oleifera meal as proteinsupplement in broiler diets at 25% inclusion level produces broilers of similar weight and growth rate compared to those fed under conventional commercial feeds (Gadzirayi et al., 2012). Supplementation of M. oleifera leaves to diet significantly reduced the adverse effects of aflatoxinin broilers (Umaya and Parvatham, 2012).

Berseem (Trifolium alexandrinum)

Indigenous to Egypt and introduced to India in 1904 and by 1916 it was recognized as a widely adaptable and valuable addition to the forage crops of India. First cutting can be taken 50-60 days after sowing and cutting interval of 35-40 days. Berseem is best fed mixed with some dry fodder, like jowar and it is very palatable and nutritious feed for all livestock and stimulates milk production in dairy cows and buffaloes.

Impact of Berseem Supplementation on Milk Yield and Body Weight

Increase in milk yield (0.7lt/day) and VFA levels were observed when berseem (25%) was fed along with wheat straw in HF cross bred cows (Sawal and kurar, 1998). Dry matter intake and milk yield were higher in buffaloes fed with Berseem fodder diet than those fed with Lucerne fodder diet (Sarwar et al., 2005). Berseem forage to concentrate ratio of 75:25 was most appropriate for economical mutton production in Lohi lambs (Jabbar and Anjum, 2008).

Impact of Some Other Legume Supplementations on Milk Yield and Body Weight

Forage legumes, such as red clover offered fresh or ensiled can increase growth rates in ruminants due to higher nitrogen utilization efficiency and dry matter intakes (Speijers et al., 2004). In Tabasco sheep in Mexico, both DM intake and DM digestibility increased when gliricidia was used as a supplement, up to 30% of the diet, with grass hay (Nochebuena and Donovan, 1986). Gliricidia at 25, 50 and 75 percentage supplementation with grass has higher level of improving growth and survival of lambs. Lambs growth rate was almost double by feeding gliricidia (Chadhokar, 1980). The inclusion of forage cowpea in the diet of the cows increases the average milk production per cow from about 0.25liter/day to 1.25litres/day (Grings, 2000). Increased growth rate of 5 g/kgBW/day with ram fed with dried cowpea as a 30% supplement over a period of 4 weeks was observed (Singh et al., 2000). Mupenzi (2009) reported that supplementation of Stylosanthes scabra (3kg/day) to the Ankole cow’s increases the milk yield by 54.4%. A shrub legumes such as Acacia boliviana, Calliandra calothyrsus and Leucaena leucocephalasupplementation improves the milk yield (Maasdorp et al., 1999)

Environmental Impact of Some of the Legume Fodders on Livestock Production

Livestock contributes both directly and indirectly to climate change through the emissions of greenhouse gases such as carbon dioxide (9%) and methane (35%). Globally, livestock sector contributes 18% of greenhouse gas emission accounting for 9.3 Teragram/year (IPCC, 2013). Increases in methane emission from livestock leads to environmental pollution and global warming. If methane emissions continue to rise in direct proportion to livestock number a 60% increase in global methane production is predicted by 2030 (FAO, 2003). Methane production by enteric fermentation in the rumen accounts for the 2-12% loss of gross energy (Johnson, 1997). Changes in feeding regime could remodel the present scenario of methane emission from livestock and thus mitigate some of this increase (US-EPA, 2006).

Contribution of Livestock to Methane Emission in India

India produces 12.45% of the total enteric methane emissions of world (20.56 million tons). Average methane emission from lactating animals in India is about 53.6g CH4/kg milk (IPCC, 2013). India has approximately 512 million livestock and in the total livestock population, about 60% are cattle and buffaloes, which comparatively emit more enteric CH₄ than any other livestock species (Singhal, 2005).

Fig: Species wise contribution of Methane production in India (Veerasamy et al., 2016)

Enteric Methane Production Mechanism

Methane production in the rumen occurs as a consequence of the presence of a group of microorganisms called methanogens. These organisms play an important role in converting organic matter to methane. Proteins, starch and plant cell-wall polymers consumed by the animal are hydrolyzed to amino acids and simple sugars by the bacteria, protozoa and fungi. Primary and secondary digestive microorganisms further ferment the amino acids and sugars into volatile fatty acids, hydrogen, carbon dioxide and other end products. Methanogens then converts carbon dioxide to methane.

Methane Mitigation by the Use of Legumes Fodder

Inclusion of legume-based forages in the diet was associated with higher digestibility and faster rate of passage resulting in a shift toward high propionate in the rumen and reduced methane production. Legumes that contain secondary compounds such as condensed tannins (CT) it was possible to reduce methanogenesis. Some legumes with tannins contribute to the reduction in in-vitro CH₄ production. Sesbania contain saponins, which increases partitioning factor (mg of truly degraded substrate/ml gas produced) and alter the microbial community towards proliferation of fibre-degrading bacteria and inhibition of methanogenic organisms, there by decreases methane production (Jayanegara et al., 2009). Tropical tree leaves containing saponins and tanins such as Autocarpus integrifolia, Jatropha curcus and Sesbania grandiflora have the potential to suppress methanogenesis (Patra, 2010). Tannins and saponins reduce methane due to their inhibitory effect upon methanogens, protozoa and other hydrogen-producing microbes (McCaughey et al., 1997). Enteric methane reduction of 32% was observed due to the addition of 30% Lucerne fodder (Malik and Singhal, 2008). Alfalfa varieties were rich in secondary metabolites such as malate and saponins that can reduce methane production (Klita et al., 1996). Cows grazing the alfalfa-grass pastures had greater dry matter intake and lower methane production was observed compared to their counterparts grazing grass-only pastures (McCaughey et al., 1997). Acaciafodder tree supplementation (25%) reduces methane release by 13% on an average (Carulla et al., 2005). Gliricidia sepium and Acacia mearnsii fodder trees improve livestock productivity and helps to reduce methane emissions per unit of output (Steven et al., 2014). Shrub legumes such as Calliandra calothyrsus and Leucaena leucocephala contain tannins which can reduce methanogenesis (3 – 21% methane reduction) (Elizabeth, 2010).

Conclusion

With the increase in per capita income and urbanization, the consumption of livestock products will continue to rise in the foreseeable future. India has a large livestock population – a resource that provides livelihood opportunity and employment to over 70% of rural people. The shrinking land base and natural resource degradation restricts grazing and forage availability. Consequently, the demand for feed and fodder for fulfilling the requirement of livestock population will also increase. Increase in livestock population also contributes for more enteric methane emission. The percentage increase in enteric methane emission by Indian livestock was greater than world livestock (70.6% vs 54.3%) over the years 1961 to 2010. In this situation legume fodders work handy to supplement as a cheap and quality protein source as well as to reduce enteric methane emission by replacing the concentrates. In this regard educating the farmers on cultivation of legume fodder which is economically and environmentally friendly for feeding their livestock is need of the hour.

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