The potential of mulberry as feed for ruminants in central Tanzania

C.M. Shayo
Zonal Research and Development Centre
Livestock Production Research Institute
Mpwapwa, United Republic of Tanzania

INTRODUCTION

Ruminant livestock in most areas of the United Republic of Tanzania are managed under semipastoral and agro-pastoral systems, feeding mostly on natural pasture and crop residues.

The amount of high-quality pasture is usually sufficient during the rainy season but, as maturity advances, the nutritive value decreases (Shayo and Msangi, 1989). Therefore, available feed resources during the dry season are usually unable to provide sufficient nutrients for reasonable livestock productivity, and livestock generally lose weight, become susceptible to diseases and have reduced breeding performance.

Although supplementation using commercial feeds or by-products such as maize bran and oilseed cakes is widely used to improve growth rates and milk yields, these supplements are expensive and not easily available in remote villages. Similarly, improvement of low-quality roughage by physical and chemical treatment is expensive, difficult to apply in rural areas and may result in environmental pollution.

In recent years there has been a growing interest in many tropical regions to identify potentially important feed sources among shrubs and trees for inclusion in ruminant diets. The increased importance of trees and shrubs as a non-conventional feed resource has been recognized as one of the most effective means of improving forage supply in smallholder livestock production (Blair, 1989). Emphasis on the use of trees in farming systems is based on their high-quality leaves and pods and the overall role they play in the natural ecosystems and human and animal welfare improvement (Shayo, 1998).

There are a number of introduced and native trees that are important sources of nutrients for livestock in Tanzania. However, some of the introduced trees have had difficulties adapting to the local environment (e.g. Leucaena leucocephala). More over, most native deciduous browse species shed their leaves during the dry season, and during this period most evergreen species are known to contain some physical structures or chemical compounds that defend them against herbivores (Coley, Bryant and Chapin, 1985).

Efforts to explore the potential use of mulberry (M. alba) trees as livestock feeds in the semi-arid areas of central Tanzania were initiated by Shayo (1997). There are positive indications that the tree could be an alternative for improving farm animal diets and reducing feed costs in many production systems. This has prompted more studies on the effect of mulberry leaves on growth and milk production in farm animals (e.g. goats), currently being carried out at the Livestock Production Research Institute in central Tanzania and at the Sokoine University of Agriculture.

This paper presents the initial findings of the potential of mulberry for livestock production in the semi-arid areas of central Tanzania.

DISTRIBUTION AND USE OF MULBERRY

According to FAO (1988), mulberry is both a temperate and a subtropical plant grown in many regions of the world, predominantly in eastern, southern and southeastern Asia, southern Europe, southern North America, northwestern South America and parts of Africa. In Africa, it has been reported to occur in humid, subhumid and semi-arid areas at an altitude up to more than 1 000 m above sea level (Le Houerou, 1980). It is not well known when mulberry was introduced in Tanzania but it appears to have been in the country for many decades. In the humid areas of the northern highlands mulberry trees are incorporated into the intensive farming systems and are widely used to feed sheep and goats in a cut-and-carry system. In some situations mulberry is used as live fence. However, there have been reports (unpublished) that some missionaries have established mulberry trees for wine making, using the fruit.

Apart from the highlands of the north, mulberry is also present in the semi-arid areas of central Tanzania, in the coastal belt and in the southern highlands. So far, there have been no formal studies on the distribution and use of mulberry in the country. However, survey studies (Shayo, 1997; Omar, 1998) in some villages in two districts of the semi-arid areas of central Tanzania (Mpwapwa and Kondoa districts) showed that mulberry trees were found in 5 percent of homesteads. The trees were grown close to the dwellings and the number of trees per household did not exceed five (the average was 2). Some trees were found away from the homesteads, where they were left by farmers who previously occupied the land. The trees were used for a range of purposes: for fruit, shade, vegetables (to a lesser extent), medicinal purposes and as fuel wood. The leaves were rarely used for livestock feeding, since most farmers were not aware of this use.

PRODUCTIVITY

There are several natural and management factors affecting the productivity of mulberry, such as soil and climatic conditions, mode of propagation and harvesting techniques. In general, longer intervals between defoliation have increased total yield; however, the proportion of inedible wood may also increase, leading to a decline in forage quality (Ivory, 1990; Shelton and Brewbaker, 1994). On the other hand, as plant spacing is reduced, yield per plant decreases owing to competition, but total forage yield per unit area increases, as does the leaf:wood ratio (Ella et al., 1989). This was confirmed by Shayo (1997) in a trial to study biomass production at different spacing and harvesting intervals in the semi-arid areas of central Tanzania (Table 1).

Although yield per season increased with harvesting interval, the amounts and nutritive value of edible components decreased considerably due to senescence and drop of leaves. Tikader et al. (1993) found that maximum mulberry leaf yields could be obtained by harvesting three times per year. The results in Table 1 show that mulberry harvested twice, at the end of rainy season and in the middle of the dry season, gave considerably higher amounts of fodder.

It is interesting to note that mulberry harvested during the peak of the dry season developed considerable numbers of shoots. As reported by Walker (1980), regeneration of new shoots after pruning is independent of rainfall. The advantage with the new shoots is that they are more tender and nutritious than ordinary branches and grow more rapidly. This is also reflected by higher proportion of leaf:stem in younger plants and regrowths than older plants (Table 2).

NUTRITIVE VALUE

Mulberry leaves are highly digestible and contain high concentrations of crude protein (CP) and minerals, and low cell wall contents (Table 3). This suggests that mulberry could be used to minimize nutrient deficiencies faced by grazing animals in the semi-arid areas of central Tanzania. Furthermore, the bark is reasonably digestible, with CP concentrations higher than in dry season pastures and crop residues. Older leaves contain lower concentrations of CP than young leaves (Table 3). Young leaves and bark are more degradable than old leaves and bark (Shayo, 1997).

TABLE 1

Mean yield of mulberry, by fractions, under different spacings at various periods of the year

Harvest (years)	Spacing1	Yield/plant (kg DM)				Yield/ha (tonnes/DM)
		Leaf	Stem	Bark	Total	Leaf	Stem	Bark	Total
1 st-23	S1	0.59ab2	0.97a	0.18a	1.74a	16.9a	28.2a	5.3a	50.4ab
	S2	0.65a	1.37c	0.28b	2.30b	3.4b	7.1b	1.4b	11.8c
	S3	0.63a	1.12ab	0.22ab	1.97ab	8.5c	15.1c	3.0c	26.6d
1st-2	S1	0.08c	1.65bd	0.46c	2.19ab	2.3b	47.8d	13.2d	63.3b
+ 190 days4	S2	0.31bc	2.14d	0.54c	2.98b	1.6b	11.0bc	2.8bc	15.4cd
	S3	0.14c	2.00cd	0.49c	2.64ab	2.0b	27.1a	6.6a	35.7ad
2nd-120 days5	S1	0.14a	0.12	0.05a	0.31	4.0a	3.5a	1.4a	9.00a
	S2	0.13a	0.14	0.06a	0.33	0.7bc	0.7b	0.3bc	1.7b
	S3	0.11a	0.14	0.06a	0.30	1.5b	1.9bc	0.8d	4.1c
2nd-190 days6	S1	0.05b	0.16	0.02b	0.22	1.3b	4.5d	0.6cd	6.4d
	S2	0.06b	0.17	0.02b	0.25	0.3c	0.9b	0.1b	1.3b
	S3	0.05b	0.17	0.02b	0.23	0.6c	2.3c	0.3b	3.1bc

¹Plant spacing: S1 = 0.5 x 0.7 m; S2 = 1 x 2 m; S3 = Double row (1 x 1 x 0.5 m).
²Means within harvest type in same column with different letters are significantly different (P < 0.05)
³Harvested two years after establishment (first cutting, end of the rainy season)
⁴Harvested for the first time at the peak of the dry season (190 days after the first cutting)
⁵Regrowth harvested 120 days after the first cutting (mid-dry season).
⁶Regrowth harvested 190 days after the first cutting (peak of the dry season)

TABLE 2

Proportion of mulberry fractions as affected by spacings and harvest time

Type	Treatment1	Part of the plant (%)
		Leaf	Stem	Bark
First harvest at 2 y	S1	33.6	55.9	10.5
	S2	28.3	59.6	12.2
	S3	31.8	56.8	11.4
	Mean	31.2a2	57.4a	11.4a
First harvest at 2 y + 190 days	S1	3.6	75.5	20.9
	S2	10.2	71.7	18.1
	S3	5.5	75.9	18.6
	Mean	6.4b	74.4b	19.2b
Regrowth at 120 days	S1	44.7	39.4	15.9
	S2	39.3	42.5	18.2
	S3	36.1	45.4	18.4
	Mean	40.0	42.4c	17.5b
Regrowth at 190 days	S1	20.5	70.1	9.3
	S2	23.7	66.8	9.5
	S3	20.3	71.9	8.0
	Mean	21.5d	69.6b	8.9a

¹Plant spacing: S1 = 0.5 x 0.7 m; S2 = 1 x 2 m; S3 = Double row (1 x 1 x 0.5 m).
²Means in the same column with different letters are significantly different (P <0.05).
Source: Shayo, 1997.

The results have shown that mulberry can survive in the semi-arid areas of central Tanzania and possibly in other areas of the world with a similar climate. Mulberry produces large quantities of highly digestible forage, high in protein. It is encouraging to note that biomass production of edible forage from mulberry is comparable to that of other introduced browse species. The multi-purpose nature of the mulberry makes it suitable for incorporating in the agro-forestry systems of central Tanzania. However, since mulberry is not a nitrogen fixing plant and since the leaves will be harvested for livestock feeding, recycling of the nitrogen and other nutrients removed from the soil will be necessary. Studies to determine distribution and use of mulberry in the whole country are encouraged. Also, studies to determine production and reproduction performance of different types and classes of livestock fed mulberry fodder are necessary.

TABLE 3

Chemical composition and digestibility of mulberry leaves and bark in central Tanzania

Parameter (% DM)	Part of the plant
	Leaf	Bark	Leaf	Bark
Ash	14.3	6.1	13.3	6.3
Crude protein	18.6	7.8	14	8.7
Neutral detergent fibre	24.6	46.8	27.6	44.5
Acid detergent fibre	20.8	36.9	25.1	38.3
Hemicellulose	3.8	9.9	2.5	6.2
Acid detergent lignin	8.1	7.1	-	-
Cellulose	12.6	29.7	-	-
Acid detergent insoluble ash	2.5	1.1	-	-
In vitro DM digestibility	82	60	-	-
In vitro organic matter digestibility	-	-	89	85
Reference	Shayo (1997)		Omar, Shayo and Udén (1998)

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