The potential of mulberry foliage as a feed supplement in India

B. Singh
Indian Veterinary Research Institute
Regional Station
Palampur, Himachal Pradesh
India
and
Harinder P. S. Makkar
Animal Production and Health Section
Joint FAO/IAEA Division
Vienna, Austria

INTRODUCTION

A major constraint to animal production in developing countries is the scarcity and fluctuating quantity and quality of the year-round feed supply. These countries experience serious shortages in animal feeds of the conventional type. Grains are required almost exclusively for human consumption. By the year 2020, world population is expected to reach eight billion and most of the population growth will occur in developing countries. With increasing demand for livestock products as a result of rapid growth in the world economies and shrinking land area, future hopes of feeding the millions and safeguarding their food security will depend on better utilization of unconventional feed resources that do not compete with food for human beings. In addition, over-exploitation of soil resources has resulted in wide scale land degradation. This calls not only for better utilization of already known unconventional feed resources but also for the identification and introduction of new and lesser known plants capable of growing in marginal soils. The propagation of such plants can play a vital role in the control of soil erosion, bring economic benefits to farmers, create jobs and bridge the wide gap between supply and demand for animal feeds. These factors would also lead to diversification in traditional agriculture and conservation of biodiversity through sustainable utilization of natural resources.

The rearing of livestock is an integral part of the economy of most of the developing countries. The economy of the Indian farmer is based to a large extent on animal production. However, production is quite low as the animal is undernourished for a significant part of the year. The low productivity is exacerbated by long calving intervals and a late age of puberty. Crop residues and low quality forages are the major feed resources. The primary constraint to ruminant production on such feeds is the low efficiency of feed utilization. Livestock development over the past three decades has been mainly directed towards satisfying the rapidly increasing demand for milk and meat in the urban centres. The resource-poor small farmers produce a major part of this milk and meat. Appropriate technologies to improve the performance of locally available animal and feed resources within the rural system are lacking. Animal productivity can be increased by the introduction of low cost technologies that improve the current systems of husbandry. Acceptable and successful feeding systems are those that are simple, practical, consistently reproducible and within the limits of the farmer’s capacity and available resources.

Fodder, the mainstay for livestock rearing, is cultivated on only four percent of the total cultivable land in India and this figure has remained more or less static for the last three decades. Because of the increase in human population, demand for food grains and other cash crops is increasing, resulting in a smaller area for fodder cultivation. The denuded grasslands, pastures, forest openings and the forests are the major source of herbage for livestock. The 1993 draft report of the Policy Advisory Group on Integrated Grazing Policy, Ministry of Environment and Forests, Government of India indicated the deficit was 584 and 745 million tonnes of dry and green fodder respectively. The present level of availability of animal feeds indicates a deficiency of about 19 percent DM, 55 percent DCP and 28 percent TDN for feeding the existing livestock population. The increasing human population, limited land holdings and the growing requirements of food grains for the human population have a direct impact on livestock production.

Recent nutritional research has demonstrated the possibility of a large increase in animal production that can be achieved by alterations to the feed base (FAO, 1997). Production can be increased by up to fivefold by providing the critical catalytic nutrients that are deficient in the diet and by balancing the availability of nutrients closer to requirements. In the rangelands, particularly in the semi-arid areas, tree forages, seeds and pods represent by far the greatest potential source of protein meals.

In more recent times, trees and shrubs have been introduced into cropping and grazing systems to provide green fodder that is high in protein to supplement the available low protein forage. These are grown in banks or hedges, between crops (alley farming) or as a component of pastures and as shade trees. Multipurpose trees can make a significant contribution to agricultural systems by improving soil fertility and providing a variety of useful products, including valuable forage and wood. The feeding value of low-quality roughages and grasses can be greatly improved by the foliage from trees, which can be integrated directly with pastures and in fences. In some cases, pure stands of forage shrubs and trees can be the best option to intensify animal production replacing traditional low performing grass-based systems. The potential roles of tree foliage in ruminant nutrition are a) a high quality and high digestibility biomass resource, available in and around the farm; b) a supplement to provide nutrients deficient in the diet resulting in enhancement of microbial growth and digestion of cellulosic biomass in the rumen; c) a source of undegradable protein; d) a source of vitamins and minerals to complement deficiencies in the basal fed resource, and e) a reduction in the requirements for purchased concentrates and as a result the decrease in a cost of feeding.

Tree forages form an integral part of ruminant feeds in the high altitudes of the Himachal Pradesh, Jammu and Kashmir and Uttar Pradesh states of India. The use of tree forages as components of diets is a widespread practice in many tropical countries. Considerable diversity exists in the type of forage supplements of value, particularly to ruminants. Recognition of the potential of tree foliage to produce considerable amounts of high protein biomass has led to the development of animal farming systems that integrate the use of tree foliages with local bulky feed resources. In order to determine the suitability of trees/shrubs as components of ruminant fibrous diets, knowledge is required in many areas, including:

• the capacity and ability of the tree to regenerate foliage when grazed or harvested;
  
• the feeding behaviour of animals when confronted with tree forages;
  
• the voluntary intake of tree foliage under different environmental conditions;
  
• the adaptation of trees to the local conditions and their potential to become weeds;
  
• the growth pattern of trees/shrubs in relation to crops or pasture;
  
• the required soil pH characteristics and nutrient status;
  
• the nutritive value of the foliage and its change with harvesting, grazing or cultivation.

The mulberry plant in the tropical belt is grown as a low bush while it is grown as a high bush in temperate regions. In tropical conditions, individual leaf and branch harvest yields 10 to 30 tonnes/ha/year, while shoot harvesting in temperate regions has a leaf yield of 25 to 30 tonnes/ha/year. The percentage of moisture, protein and carbohydrates is higher in temperate regions when compared to the tropics. Mulberry is a monoecious, occasionally dioecious shrub or moderate-sized tree with a fairly cylindrical straight bole, up to 3.0 m high and 1.8 m in girth. Leaves are very variable, ovate or broadly ovate, serrate or crenate-serrate, and often deeply lobed. The plant is frost hardy but liable to wind damage. It regenerates itself naturally from seeds that are dispersed by birds and to a limited extent by jackals and human beings. It can be propagated artificially by seeds or cuttings. It grows rapidly in the early stages and reaches maturity at an early age; the growth rate falls off rapidly after approximately ten years. Mulberry coppices vigorously and pollards well. When grown close in plantations, the tree develops a long clean bole.

At present in many other parts of the world, mulberry leaves are predominantly used for silk production, and therefore it will be pertinent to mention the status of silk production from mulberry in India. This might encourage workers to develop strategies to integrate silk and livestock production at the village level, resulting in higher incomes for farmers.

SILK PRODUCTION

Numerous types of mulberry are under cultivation in various silk-producing countries of the world; the types differ in their adaptability to various soils and climates, resistance to diseases, food value of the leaf crop for the silkworm and suitability for use as stock or scion in grafting. In Japan, the world's major silk-producing country, approximately 700 types of mulberry are known to exist, of which 21 have been selected for extensive cultivation. Some of these types are adaptable to a wide range of climatic conditions.

The most important type of mulberry grown in India for rearing silkworms is Morus alba var. multicaulis Loud, which is a native of China or the Philippines. It is fast-growing and adapted for cultivation as a field crop producing large, tender and thick leaves. M alba var. atropurpurea (Shahtut), also a native of China, is cultivated widely as a tree crop for its large, cylindrical, dark purple, succulent fruits. It is also fast-growing and yields large thick leaves, which are at the same time smooth, tender and succulent fruit. Atropurpurea is recommended for cultivation along the borders of bush plantations in Bengal.

Mulberry is grown on an extensive scale in various parts of India, particularly in Mysore, West Bengal and Jammu and Kashmir for its leaf, which constitutes food for the silkworm. Its cultivation is an integral part of the sericultural industry. In some areas, it has run wild and spread. It is also grown as a roadside and avenue tree. In the Himalayas, it reaches a height of about 1 200 m. In the hills, it is mostly confined to stream beds or places where sufficient moisture is available. It does not grow on dry slopes or shallow soils where moisture is a limiting factor. The old leaves are shed in November to December and the trees are leafless during the winter season. The new leaves appear in March to April depending upon the climate of the locality. Mulberry tolerates shade and it can with advantage be grown as an understory with other light-demanding species.

In Mysore and West Bengal, mulberry is grown as a field crop and the leaves are harvested several times a year to feed the multivoltine races of silkworm. In Jammu and Kashmir, it is grown as a tree and the leaves are lopped only in one season for rearing the univoltine races of the worm. A system of growing dwarf grafted trees or "high bushes" has recently been tried in West Bengal. Mulberry is also grown to a small extent in the Punjab, Himachal Pradesh, Uttar Pradesh, Madhya Pradesh, Bihar, Orissa, Assam, Manipur and Andhra Pradesh states of India, where small quantities of silk are produced. The largest area is in Mysore, which accounts for more than 75 percent of the total mulberry raw silk production in the country.

Young leaves that have attained full size are best suited for feeding silkworm larvae. The composition of the leaves varies according to the type, degree of maturity and the soil in which the plants are grown. The content of protein and soluble sugars in leaves decreases with the maturity of leaves whereas fibre, fat and ash constituents increase. Young leaves are more acidic than older ones. An analysis of leaves collected from different silk-producing localities in India gave the following ranges of values (percentage in DM): CP 16-39, soluble sugars 7.6-26 and ash 8-17.

India has the advantage of producing of all the four known commercial silk varieties in the world, i.e. mulberry, tusser, eri and muga. Mulberry silk is domesticated while the rest are wild. India produces currently about 14 050 tonnes of silk of which mulberry alone accounts for more than 90 percent of the total silk production, practised in over 60 000 villages in the country. Mulberry sericulture is well suited for marginal, small and landless farmers since it has several advantages over other crops in the rural sector. It is estimated that one hectare of irrigated mulberry will generate employment for about 13 people starting from mulberry cultivation to trading throughout the year and that, in value addition, 48.3 percent goes to the farmer; 21.6 percent to traders and the rest to weavers, reelers, twisters and dyers (Lakshmanan and Devi Geetha, 2000).

Year	Area under mulberry (Million ha)
1950-51	0.05673
1960-61	0.08295
1970-71	0.09424
1980-81	0.17000
1990-91	0.31310
1995-96	0.35000

In Himachal Pradesh, mulberry is grown as a shade tree on wastelands, roadsides, borders of fields and around farmers’ houses. Himachal Pradesh is predominantly a univoltine/bivoltine silk-producing state. Mulberry leaves for silkworm rearing are collected from trees grown on the border of the fields, around the houses and on the wastelands under rainfed conditions. Family labour is employed in sericulture; women play a major role. Sericulture is adopted mainly by small and marginal farmers and landless labourers as a subsidiary occupation.

The preferential food value of mulberry leaf for silkworm larvae is attributed to the presence of three stimulant factors in it, i.e. an attractant, a biting factor and a swallowing factor. The substances that attract the larvae to the leaves have been identified as citral, linalyl acetate, linalol, terpinyl acetate and hexenol. Sitosterol (approximately 0.2 percent in leaves), together with some sterols and a water-soluble substance, is the main factor that stimulates the biting action.

ANIMAL FEEDING

The leaf fodder of mulberry is reported to be of good quality and can be profitably utilized as a supplement to poor quality roughages. Leaf yield varies according to the fertility of the soil, irrigation and frequency of plucking of the leaves. In West Bengal, one hectare of well manured and irrigated plantation can yield about 19 to 28 tonnes of leaves in five pluckings. On a DM basis, the leaves contained 15.0-27.6 percent CP, 2.3-8.0 percent ether extract (EE), 9.1-15.3 percent crude fibre (CF), 48.0-49.7 percent nitrogen free extract (NFE), 63.3 percent total carbohydrates, 14.3-22.9 percent ash, 2.42-4.71 percent Ca, 0.23-0.97 percent P, 0.196 percent S, 1.66-3.25 percent K, 350-840 ppm Fe (Jayal and Kehar, 1962; Singh, Goel and Negi, 1984; Singh, Makkar and Negi, 1989; Makkar, Singh and Negi, 1989). The cell wall constituents were: NDF 33-46 percent, ADF 28-35 percent, hemicellulose 5-10 percent, cellulose 19-25 percent, and lignin approximately 11 percent (Lohan et al., 1979; Makka, Singh and Negi, 1989). The content of total phenols was very low (1.8 percent as tannic acid equivalent), and tannins by the protein precipitation capacity method were not detectable (Makkar, Singh and Negi, 1989; Makkar and Becker, 1998).

A prolamine has been separated from the alcoholic (alkaline) extracts of mulberry leaves and it forms the principal protein of the leaves. The nitrogen (N) distribution in a preparation containing 12.6 percent N was as follows: HCl-insoluble N 0.50; humin N 0.45; amide N 0.96; diamino acid N (arginine N 0.89, histidine N 0.49, lysine N 0.35, cystine N 0.01) 1.74; and monoamino acid N 7.89 percent. Protein preparations from young mulberry leaves form an excellent supplement to protein-deficient diets.

Non-protein nitrogen accounts for approximately 22 percent of the total N in young leaves and approximately 14 percent in mature leaves. The amino acids identified in the free form are: phenylalanine, leucine, valine, tyearosine, proline, alanine, glutamic acid, glycine, serine, arginine, aspartic acid, cystine, threonine, pipecolic acid and 5-hydroxy pipecolic acid.

The mulberry leaves are thus rich in CP, EE, calcium and ascorbic acid (200-300 mg/100 g; 90 percent of which are present in the reduced form) and low in CF. They also contain carotene, vitamin B1, folic acid, folinic acid and vitamin D. The presence of glutathione in leaves has been reported. Copper, zinc, boron and manganese occur in traces. Phytate phosphorus accounts for 18 percent of the total. Sulphur is required together with nitrogen for microbial protein synthesis in the rumen. Concentrations of sulphur greater than 1.5 g/kg DM or nitrogen: sulphur ratios less than 15:1 are considered adequate. Both these requirements are met in mulberry leaves. Similarly the levels of potassium and iron in mulberry leaves are also higher than their recommended levels (Fe 30-50 ppm, K 0.5-1.0 percent) in diets (McDowell, 1997). Higher Ca content in mulberry leaves (2.4 -4.7 percent) than the required level in diet (0.19-0.82 percent; McDowell, 1997) could be useful for high yielding ruminants during the early stages of lactation. Ca is closely associated with phosphorus metabolism. A high ratio of Ca:P in mulberry leaves could create some problem with calcium, phosphorus and vitamin D metabolism at a high level of supplementation of leaves in diets. It has been suggested that high Ca:P is associated with infertility in cattle. It should be noted that mulberry leaves would usually be used only as a part of livestock diets.

Feeding experiments with sheep showed that the leaves are highly palatable. The digestibility coefficients for CP, EE, CF, NFE and total carbohydrates were found to be 71, 4, 54, 84 and 76 percent respectively (Jayal and Kehar, 1962). The digestible nutrients per 100 kg of leaves on a DM basis were 10.7 kg CP, 0.27 kg EE, 8.3 kg CF, 40.2 kg NFE and 59.6 kg total nutrients.

Mulberry leaves are also useful as cattle fodder - they are nutritious and palatable, and are stated to improve milk yield when fed to dairy animals. The feeding value of mulberry leaves is rated high by livestock owners. Feeding experiments have shown that up to 6 kg of leaves per day can be fed to milch cows without adversely affecting the health of animals or the yield and butter content of milk.

Mulberry leaf stalks, left after feeding silkworms, can also be used for feeding cattle without any adverse effect on their health and performance. The chemical composition of leaf stalks (percent in DM basis) was: 11.5 CP, 7.0 true protein, 2.7 EE, 34.0 CF, 42.5 NFE, 76.5 total carbohydrates, 9.3 total ash, 1.56 Ca, 0.20 P (Subba Rao, Amrith Kumar, 1971). Digestibility coefficients of organic matter (OM), CP, EE, CF, NFE and total carbohydrate were 58, 69, 73, 49, 60 and 56 percent respectively. The balances of N, Ca and P were positive and the adult bullocks gained body weight during the experimental period.

Mulberry leaves can also be used in poultry rations. Incorporation of shade-dried mulberry leaves in layers’ mash to the extent of 6 percent showed an increase in egg production with desirable yolk colour without any adverse effect on body weight and egg quality (Narayana and Setty, 1977). Mulberry leaves, owing to their high carotene content, can form a valuable source of vitamin A for the health of poultry birds and increased egg production.

The effect of supplementing mulberry leaves ad libitum to concentrate diets of Angora rabbits on wool production has been studied by Singh, Goel and Negi (1984). The average intake of mulberry leaves was 10.4 g/day/kg W 0.75 while the total DM intake was 29.5 g/day/kg W 0.75. The digestibility coefficients for DM, CP, CF and NFE were 69, 66, 72 and 78 percent respectively. The nutritive value of mulberry leaves (percent in DM) calculated by difference was digestible CP 9.8 and total digestible nutrients 64. The results indicated that mulberry leaves can be advantageously incorporated in the diets of Angora rabbits for wool production. Mulberry leaves may be supplemented up to a level of 40 percent of the DM with impunity.

Studies have recently conducted at the Regional Station of the Indian Veterinary Research Institute on the characterization of mulberry leaves for digestion kinetics parameters and comparison of these values with other tree foliages (Devarajan, 1999). Degradation kinetic parameters as studied by the in vitro gas production technique (Menke et al., 1979) showed that the potential gas production in young leaves was 60.6 ml/200 mg while the rate of degradation was 0.0703. The corresponding values for the mature leaves were 35.4 ml and 0.0624 respectively, indicating the fall in fermentability with maturity. The potential gas production for the young leaves was highest among the forages studied and the rate of gas production lower compared with only Moringa oleifera (Table 1), suggesting high nutritive value of the young leaves. The fermentability of the mature leaves was also high and comparable with Leucaena leaves. The high rate of gas production for mulberry indicates high intake potential of this forage.

The rate, potential extent and effective degradability (at passage rate of 0.05/hours) of DM using the in sacco method of Orskov and McDonald (1979) were 0.0672, 85 percent and 52 percent respectively. These values for CP were 0.0467, 95 percent and 57 percent and for NDF 0.0368, 82 percent and 43 percent respectively. The effective DM degradability of various Leucaena species has been reported to be 46-51 percent (Tolera, Seygoum and Sundstol, 1998) and the value obtained in India was 51 percent (Table 3). For mulberry leaves, the kinetic parameters for CP were also comparable to those for other good quality tree fodders (Table 4).

In sacco 48-hour degradability (percentage) values for DM, CP, NDF and NDF-linked N were 76, 87, 70 and 79 respectively. It is clear from these values that nitrogen linked to NDF is degraded in the rumen to a considerable extent but depending on the rate of passage could well serve as source of undegradable nitrogen. The leaves of Artocarpus and Ficus are regarded as the most valuable fodder by farmers in the hilly areas of Nepal and India. The degradability values for mulberry are similar to those for Leucaena leucocephala, Artocarpus lakoocha and Ficus roxburghii (Table 5). The contents of NDIN and ADIN in mulberry leaves were 56.5 and 20.4 percent of the total nitrogen respectively. The solubility of nitrogen (as percent of total nitrogen) in borate phosphate buffer was 17.3 percent and in phosphate buffer 15.7 percent. These values are of order similar to those for Leucaena, Artocarpus, Dendrocalamus and Ficus (Table 6). It was interesting that all the soluble N in mulberry was in the NPN form.

TABLE 2

Potential and rate of gas production from some tree forages

Forage	Gas production
	Potential (ml/200 mg)	Rate
Acacia catechu	24.4	0.0456
Albizzia stipulata	17.4	0.0586
Artocarpus lakoocha	51.1	0.0379
Bauhinia variegata	23.1	0.0308
Dendrocalamus hamiltonii	33.8	0.0256
Ficus roxburghii	42.6	0.0462
Leucaena leucocephala	37.2	0.0578
Morus alba (young)	60.6	0.0703
Morus alba (mature)	35.4	0.0624
Moringa oleifera1	49.5	0.0852

Source: Makkar and Becker, 1996.

Rate and potential extent of dry matter degradation (PD) and effective degradability (ED) of dry matter (passage rate of 0.05/hours)

Forage	Rate	PD	ED
Acacia catechu	0.0390	55	33
Albizzia stipulata	0.0348	32	24
Artocarpus lakoocha	0.0953	85	57
Bauhinia variegata	0.0489	42	27
Dendrocalamus hamiltonii	0.0347	56	26
Ficus roxburghii	0.0647	93	56
Leucaena leucocephala	0.0693	75	51
Morus alba (mature)	0.0467	85	52

TABLE 4

Rate and potential extent of crude protein degradation (PD) and effective degradability (ED) of crude protein (passage rate 0.05/hours)

Forage	Rate	PD	ED
Acacia catechu	0.0295	42	14
Albizzia stipulata	1.0907	22	21
Artocarpus lakoocha	0.0693	93	64
Bauhinia variegata	1.2233	53	51
Dendrocalamus hamiltonii	0.0283	75	35
Ficus roxburghii	0.0540	95	60
Leucaena leucocephala	0.0426	78	43
Morus alba (mature)	0.0672	95	57

TABLE 5

In sacco degradability (48 hours) of dry matter (DM), crude protein (CP), neutral detergent fibre (NDF) and neutral detergent fibre bound nitrogen (NDF-N)

Forage	DM	CP	NDF	NDF-N
Acacia catechu	47	34	28	11
Albizzia stipulata	30	25	2	0
Artocarpus lakoocha	85	92	75	90
Bauhinia variegata	42	64	20	27
Dendrocalamus hamiltonii	45	57	39	51
Ficus roxburghii	88	86	84	87
Leucaena leucocephala	72	71	58	56
Morus alba (mature)	76	87	70	79

TABLE 6

Solubility of nitrogen (N) for some tree leaves

Forage	(% of total N)
	Borate phosphate buffer (pH 8.1)	Phosphate buffer (pH 6.8)
Acacia catechu	21.5	13.0
Albizzia stipulata	21.6	12.2
Artocarpus lakoocha	16.9	14.6
Bauhinia variegata	42.0	23.5
Dendrocalamus hamiltonii	14.5	12.3
Ficus roxburghii	14.4	14.8
Leucaena leucocephala	19.1	13.3
Morus alba (mature)	17.3	15.7

From the in sacco data, the values for rumen degradable nitrogen (RDN), rumen undegradable nitrogen (UDN) and rumen undegradable but available post ruminally (DUN) calculated are shown in Table 7, and the values for digestible organic matter, metabolizable energy and intake potential calculated from the gas production data in Table 8.

It is evident from the data presented in these tables that the nutritive value of mulberry is as high as some well-known good quality fodders. In addition, tannins at high levels are present in the leaves of most trees (Makkar and Becker, 1998), whereas mulberry leaves are free of tannins. Mulberry leaves have the potential to be used as a supplementary feed for increasing livestock productivity in crop residue-based livestock systems.

It has been a popular misconception that the low productivity of ruminants in developing countries is mainly the result of the low energy density (low digestibility) of available forages.

TABLE 7

Rumen degradable nitrogen (RDN), rumen undegradable nitrogen (UDN) and rumen undegradable but available post ruminally (DUN) of some tree forages calculated at a passage rate of 0.05/hours (values are g/kg DM)

Forage	RDN	UDN	DUN
Acacia catechu	4.8	28.7	16.0
Albizzia stipulata	7.3	28.4	11.6
Artocarpus lakoocha	19.7	11.4	4.6
Bauhinia variegata	16.9	16.1	9.45
Dendrocalamus hamiltonii	11.1	20.6	11.2
Ficus roxburghii	13.2	8.9	2.6
Leucaena leucocephala	14.6	19.1	5.8
Morus alba (mature)	16.3	12.2	5.8

TABLE 8

Digestible organic matter (DOM), metabolisable energy (ME) and intake potential calculated from the gas data production data

Forage	DOM (%)	ME (MJ/kg)	Intake potential (g/kg W0.75)
Acacia catechu	45	10.5	58.2
Albizzia stipulata	44	6.8	65.8
Artocarpus lakoocha	63	9.1	58.8
Bauhinia variegata	42	7.6	47.7
Dendrocalamus hamiltonii	40	6.7	46.5
Ficus roxburghii	54.9	9.2	62.0
Leucaena leucocephala	59.1	13.1	69.6
Morus alba (mature)	64	11.3	61-72
Moringa oleifera1	74	9.5	-

¹Source: Makkar and Becker (1996).

The use of high protein mulberry tree fodder should be encouraged to provide supplementation of crop residues and natural pastures, thereby increasing productivity and the overall use of available on-farm biomass. Mulberry tree forage is well accepted by ruminants, pigs, poultry and rabbits. There is a need for systematic research on the optimization of the use of this tree forage and for developing strategies for its optimum supplementation under different feeding situations. The promotion of mulberry should be viewed in context of a holistic farming systems approach with the aim to increasing farmers’ incomes, generating employment and conserving the environment. An attractive option to achieve an integration of silk production and livestock rearing. Acceptance of these strategies could reduce the need for land clearing and pasture establishment in the fragile areas of the world that are prone to erosion following clearing.

According to one estimate, a total of approximately 1.2 billion hectares of land in the world is degraded, barren or marginal and this proportion is increasing every year. Mulberry is an ideal tree species for economic management of unutilized wasteland (under rainfed conditions) for the following reasons:

• it is tap rooted with minimum superficial roots;

• it has good coppicing power and is tolerant to lopping and pruning;

• pruning and training of mulberry enhances the size and quality of its leaves;

• it has easy generation capacity through seeds and vegetative means;

• it is a multipurpose tree that yields fodder, fibre, fruit, wood, etc. The leaves are highly palatable and nutritious for livestock, yet they are used extensively for silk production;

• many varieties of mulberry are available that can grow in varied agroclimatic conditions in both temperate and tropical areas.

Mulberry has the potential to play a valuable role in world agriculture. It is an extremely versatile plant that can fulfil a number of roles in smallholder agricultural production. Its value is multifaceted and the potential for increasing and diversifying its use is enormous. However, its value and benefits as a high-quality supplement to low-quality roughages in ruminant feeding systems have not been widely known nor fully exploited. There is a wide genetic diversity in this species which has wide-ranging soil and climatic adaptation - a large number of provenances are available that grow under different soil and climatic conditions. Systematic studies are warranted to evaluate these provenances in order to know the superior genotypes, collect and maintain germplasm, and conduct agronomy and management studies. Such studies include: environmental adaptation; establishment and propagation; defoliation management of trees; planting density, cutting intervals and cutting heights in intensive forage production systems; seed production in different agroforestry systems (e.g. agrosilviculture, agrosilvi-horticulture, silvipasture, energy plantation, boundary plantation, alley cropping and perennial cropping). This will improve biomass production with high nutrients for livestock feeding and extend the ecological range of the plant. The future role and value of mulberry will depend on the outcome of these programmes.

BIBLIOGRAPHY

Devarajan, S. 1999. Effect of tannins on the ruminal degradation kinetics of locally available tree forages. Izatnagar, India I. RI Deemed University,.

FAO. 1997. Tree foliage in animal nutrition. FAO Animal Health and Production Paper No. 139, FAO, Rome.

Jayal, M.M. & Kehar, N.D. 1962. A study on the nutritive value of mulberry (Morus alba) tree leaves. Indian J. of Dairy Science, 15: 21-27.

Lakshmanan, S. & Devi Geetha, R.G. 2000 Mulberry sericulture: an emerging industry. Yojna 44: 42-44.

Lohan, O.P., Lall, D., Pal, R.N. & Negi, S.S. 1979. Studies on tannins in fodder trees. Fifteenth Dairy Industry Conference, Hyderabad, India.

Makkar, H.P.S. & Becker, K. 1996. Nutritional value and antinutritional components of whole and ethanol extracted Moringa oleifera leaves. Animal Feed Science and Technology, 63: 211-228.

Makkar, H.P.S. & Becker, K. 1998. Do tannins in leaves of trees and shrubs from African and Himalayan regions differ in level and activity? Agroforestry Systems, 40: 59-68.

Makkar, H.P.S., Singh, B. & Negi, S.S. 1989. Relationship of rumen degradability with microbial colonization, cell wall constituents and tannin levels in some tree leaves. Animal Production 49: 299-303.

Menke, K. H., Raab, L., Salewski, A., Steingass, H., Fritz, D. & Schneider, W. 1979. The estimation of the digestibility and metabolizable energy content of ruminant feedstuffs from the gas production when they are incubated with rumen liquor in vitro. J. Agric. Sci. (Camb.), 92: 217-222.

McDowell, L.R. 1997. Minerals for grazing ruminants in tropical regions. University of Florida, Institute for Food and Agricultural Science, USA.

Narayana, H. & Setty, S.V.S. 1977. Studies on the incorporation of mulberry (Morus indica) leaves in layers mash on health, production and egg quality. Indian J. of Animal Sci. 47: 212-215.

Orskov, E.R. & McDonald, I. 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. of Agric. Sci. (Camb.), 92: 499-503.

Singh, B., Goel, G.C. & Negi, S.S. 1984 Effect of supplementing mulberry (Morus alba) leaves ad libitum to concentrate diets of Angora rabbits on wool production. J. Applied Rabbit Research, 7: 156-160.

Singh, B., Makkar, H.P.S. & Negi, S.S. 1989. Rate and extent of digestion and potentially digestible DM and cell walls of various tree leaves. J. Dairy Sci. 72: 3233-3239.

Tolera, A., Seyoum, M. & Sundstol, F. 1998. Nutritive evaluation of Leucaena leucocephala, L. diversifolia and L. pallida in Awassa, Southern Ethiopia. In: H.M. Shelton, R.C. Gutteridge, B.F. Mullen and R.A. Bray, eds. Leucaena - adaptation, quality and farming systems (eds. Shelton, H.M., Gutteridge, R.C., Mullen, B.F. and Bray, R.A.) ACIAR Proceedings No. 86.

Subba Rao, A., Amrith Kumar, M.N. & Sampath, S.R., 1971. Studies on mulberry (Morus indica) leaf stalk palatability, chemical composition and nutritive value. Indian Vet. J., 48: 853-857.