Utilization of trees and shrubs by growing goats

Theng Kouch

Royal University of Agriculture

Chamcar Daung, Phnom Penh, Cambodia

kouch@mekong.org

 

 

1.0 Introduction

Cambodia is an agrarian country where farming systems are traditionally based on rice cultivation (Yang Saing Koma 1997; Khieu Borin 1996; Maclean 1998). In this context, it has been recognized that livestock play an important role in human society, especially the large ruminants, such as local breeds of cattle and buffaloes, which have occupied an important position as the livestock component of the systems (Maclean 1998). Nevertheless, small ruminants such as goats have been used for meat production in certain areas of the country (Tilchit 1981; Yang Saing Koma 1997; Maclean 1998), as occurs in other neighboring regions (Devendra 1993).

In integrated farming systems, the livestock are able to utilize feed sources that are rejected by humans, such as kitchen wastes, grass from unused land or wastelands, crop residues (Schier and Kater 2001) and foliage from tree plant species, to convert into valuable production. In this case goats have a role to play as they have the potential to use crop residues and foliage from tree plant species, that are not consumed by other animals (Goatcher and Church 1970). They are sources of multiple products, such as meat, milk, fibre, social status and income, while dung and urine are valuable for fertilizing gardens and fields (Schier and Kater 2001) and serving as a substrate for earthworms (Nguyen Quang Suc et al 2000). However, the practice of goat husbandry has not been extensively used in Cambodia as yet (Maclean 1998), although goat production would appear to be more feasible for poor farmers, from the point of view of financial inputs.

Trees and shrubs play an important role in the farming system, because they are sources of edible biomass, especially in the dry season. They also provide shade for the soil and for animals. The idea of introducing trees and shrubs into cropping and grazing systems is to provide green fodder high in protein to supplement the available low protein grasses and cop residues (Leng 1997). In Cambodia it has been observed that in the dry season, or when the land is flooded, period, the farmers traditionally use the leaves and foliages from trees and shrubs to feed their animals, due to shortage of grass. 

2.0 Objectives

• To report several observations made on the feeding behaviour, intake and digestibility of tree foliages in growing goats. 

• To identify constraints related to goat feeding, production and reproduction that are met by farmers

 3.0 General discussion

3.1 Benefits from raising goats

Goats are often accused of causing soil degradation and erosion. However, in reality the feeding behaviour of goats is not  damaging, if they are confined or allowed  to graze in land that has been already been deforested for cropping and timber.

Goats play an important role in the economic life of the smallholder farmer in converting low-cost inputs to high value products (meat, milk and skins). Goats in mixed farming systems are multipurpose animals. They produce meat, milk, offspring, skin and hair; they also serve as a savings account and provide available money when needed. Goat meat is highly appreciated in countries where pig and/or cattle meat is taboo (Devendra and McLeroy 1982). In Africa, according to the report of Ogwang et al (1994), goats play an important role in tribal customs and culture. Panin (1996) reported that, in Botswana, small ruminant production was both profitable and economically viable.

Goats can be a means to reduce poverty by increasing the household income. Women and children can easily take care of goats, so the selling of goats could improve the welfare of farmers, because women distribute the income more equitably (Ikwuegbu et al 1994). Dinh Van Binh et al (2000) also reported that the introduction of dairy goats to smallholder farmers in North Vietnam led to increases in profitability.

The livestock production system is like other business; it will be profitable only when expenses are minimized, income is maximized and existing resources are utilized efficiently. The efficient use of existing resources requires knowledge about the farming system and the way to manipulate it to make it profitable.  In this connection, the goat is more suitable than other ruminants (sheep and cattle) in using natural resources, such as shrubs and tree leaves, which are normally rejected by other ruminants, because the goat has greater tolerance to bitterness (Goatcher and Church 1970). Hoppe et al (1977), Huston (1978) and Devendra and Burns (1983) considered that goats in the tropics offered greater potential than sheep because of their capacity to eat selectively and thus consume feed fractions of higher nutritional quality. However, these observations are largely based on grazing animals, most of them on natural rangelands (Lu 1987).

It is easier to increase the population of small ruminants such as goats, as compared with large ruminants, because  less capital investment is needed, smaller land areas can be used, and the reproductive rate is high (Devendra and McLeroy 1982); thus goats are highly appropriate for poor farm families (Schier and Kater 2001). According to recent observations on goat production in village conditions, in Cambodia (Theng Kouch 2003a), the pregnancy period ranges from 138 to 150 days and kidding rate from 1.53 to 1.7, or three kiddings in 2 years. Similar data were reported by Sutama (1992) and Saithanoo et al (2001). With respect to litter size, it was found that twin births are the most common (54%), followed  by singles (42%) the balance (4%) being triplets.

Some grazing areas are badly degraded or are in the process of becoming unproductive due to the encroachment of dense bush and spiny shrubs; according to Aucamp (1976) the production potential of these areas will be increased if goats are integrated into the cattle farming system). Mixed species grazing has received little research attention in Africa, despite the fact that most communal and small-scale commercial farmers in Zimbabwe graze cattle and goats together. Schier and Kater (2001) reported that mixing goats with sheep and cattle is a means of making better use of the varied forage resources found on and around the farm. The goat has the ability to browse effectively because of the presence of mobile upper-lips. The selective grazing behaviour of goats encourages them to go long distances in search of food (Devendra and Coop 1982). The hard mouth parts allows the goat to macerate the toughest spines without injury (Cheeke and Palo 1995).

Goats are reported to browse on tannin-rich foliage from oak trees, with no apparent ill effects (Nastis and Malachek 1981). This is because of the praline-rich salivary proteins which bind tannins, after which the tannin complexes are stable through the gut, thus preventing the toxic effects of free tannins (McArthur et al 1993).

 

Goats seem to survive droughts better than cattle. This has led to the belief that goats degrade rangelands more than cattle (Sikosana1 and Gambiza 1994).  In contrast, it has been reported that in some temperate regions, goats be can used to control or help eradicate certain weeds (Steele 1996).

 

When goats are managed in full or semi-confinement, the manure can be  collected from the goat houses and used as fertilizer (Ikwuegbu et al 1994). Goat manure has been shown to be a better substrate for earth worm production as compared with manure from cattle or buffaloes (Nguyen Quang Suc et al 2000).

In the survey of goat management practices in Cambodia (Theng Kouch et al 2003), it was found that the farmers grazed their goats together with cattle, as well as in areas rejected by cattle. In this way they made better use of the available resources. It was also noted that many of the farmers practiced the use of the manure as fertilizer and to improve soil properties in the cropping area or home garden.

3.2 Factors affecting feed intake:

3.2.1 Definition 

Feed intake is a behavioral activity representing the amount of food eaten by an animal in a given period of time. Baile and Forbes (1974), Forbes (1980), Van Soest (1982) and Grovum (1986) defined voluntary intake as the amount consumed by the animal when its access to forage is unrestricted. Voluntary intake is an important aspect of animal production systems because of its close relationship with rate of animal performance and profitability of the livestock system (Gill et all 1986; Illius 1998). The more food a goat eats, the better is likely to be the performance.  But eating is a special voluntary activity; it is difficult to force a goat to eat something that it does not want to eat. So it is important to understand the factors that affect the amount of food a goat eats, and how these influences can be manipulated so that the goat can be encouraged  to maximize it’s voluntary feed intake  (Peacock 1996).

In experimental conditions,  voluntary intake is determined by offering animals a known quantity of feed and recording the amount refused at the end of the feeding period (Osuji et al 1993). Ruminants usually consume the optimum level of forage to meet their nutrient requirements if they have no physical or metabolic restrictions (Weston and Poppi 1987). Under grazing conditions, forage intake is a modified expression of voluntary intake and is influenced by the quality, availability and harvestability of the forage as well as by environmental stress and management (Arnold and Dudzinski 1978; Finch 1984; Allison 1985; Young 1986, 1987). Environmental factors are linked with nutrient intake, because the nutrient demand, physical movement and the diurnal and seasonal thermal fluctuations, occur more often under free-grazing than in controlled feeding conditions. According to Grovum (1986), the feed intake of grazing ruminants is controlled by distension of the reticulum and cranial sac of the rumen; this is decreased when digesta passes to the lower tract and/or ingesta volume and mass is reduced by mastication and fermentation. The mastication, both primary and secondary, is the major means to reduce the particle size resulting in more dense, less bulky digesta and more rapid fermentation and passage (McLeod and Minson 1988). 

3.2.1 Influence of Animal Factors on Feed Intake

Eating is an activity to meet nutrient requirements. However, the level of eating differs among livestock, because of anatomical and physiological adaptation. In general, all ruminants prefer living to dead materials, young to older materials, and leaves to stems. Among the ruminant species, goats are the most selective and cattle are the least selective animals. The goats often select buds, leaves, fruits, and flowers, which contain less fiber and more protein, and in this way consume the parts of the plant of highest nutritional value (Lu 1987).

In ruminants, voluntary feed intake is  determined by the nutritional demands due to maintenance requirements and the potential level of production (Fox 1986). Growing animals tend to eat more as a percentage of body weight and this will tend to decrease as mature weight is reached (Hicks et al 1986). Intake also tends to increase in mid-gestation, decrease towards the end of pregnancy (NRC 1987) and show a drastic decrease at parturition (Stelwage et al 1992). After parturition, intake again increases (Weston 1982; Warrington et al 1988). The decreasing intake during late gestation is caused by the decrease of reticulo-rumen capacity due to the rapid fetal growth and/or the increase of abdominal fat and hormonal mechanisms (Forbes 197l; Baile and Della-Fera 1981). Voluntary intake increases after giving the birth because of the increase in the volume of the rumen (Weston 1982).

ARC (1980), Johnson (1984) and Minson (1990) reported that lactating females consumed more feed than non-lactating ones, at the same weight and on the same diet. The relationship between intake and body condition appears to be variable (Holloway and Butts 1983; Adams et al 1987). According to Freer (1981) and Weston (1982) there is no clearly defined relationship between body condition (fatness) and nutrient intake in cattle and sheep. However, there is general consensus that abdominal fat restricts voluntary intake (Cowan et al 1980; Freer 1981; Fox 1986).  

3.2.3 Influence of Environmental Factors on Feed Intake

Thermal conditions affect intake more than any other environmental factor. Ruminants tolerate a range of temperature and humidity, the equilibrium of which is referred to as the thermo-neutral zone. Thermo-neutral zone was defined by NRC (1981) as the range of effective ambient temperature within which the heat from normal maintenance and productive functions of the animal in non-stressful situations offsets the heat loss to the environment without requiring an increase in rate of metabolic heat production. According to NRC (1981) and Finch (1984), beef cattle have a thermo-neutral zone for feed intake of 10 to 25 ^ºC. In experimental situations, feed intake has been observed to increase when the temperature falls below the thermo-neutral zone and to decrease when it is above that zone (NRC 1996). Below the thermo-neutral zone, the animal suffers cold stress, and intake increases in response to heat loss if fill limitations are not encountered. Above the thermo-neutral zone, under conditions of heat stress, intake decreases in response to heat loading. However, the general response to temperature can vary with thermal susceptibility of the animal, acclimatization, and diet (Young 1986). Other adverse environmental conditions (eg: wind, precipitation, muddy conditions) can accentuate the effects of ambient temperature (NRC 1996).

Peacock (1996) reported that during the hottest part of the day goats may stop eating, not because they are full, but because they have great difficulty in keeping their body temperature down to a tolerable level, if they are actively digesting feed and producing heat. In contrast, goats will feed more actively at a cooler time of day.

During the experiment reported in Paper I (Theng Kouch et al 2003b), it was observed that the feed intake of the goats decreased on days when it was very hot or there was heavy rain and wind.  In contrast, human activity in the goat house appeared to stimulate intake, especially during 24 hour periods of continuous observation when measurements were being made of eating behavior.

3.2.4 Influence of Forage or Feed and Nutrient Requirement on feed intake

3.2.4.1 Forage quantity and quality

According to Preston and Leng (1987), the nutritional features of a feed that influence feed intake by ruminants are the digestibility and the capacity of the feed to supply the correct balance of nutrients required by animals in different productive states. They suggested that the two major variables to be considered are:

• The amounts and balance of nutrients required.
• The quantitative availability of nutrients from the diet.

The amount of feed consumed by animal is often determined by the rate of absorption of the soluble components and rate of passage through the rumen of both soluble and insoluble digesta. The composition of a diet determines an animal’s voluntary feed intake (Preston and Leng 1987). Feed intake is reduced by nutrient imbalance. The first limiting nutrient may be ammonia in the rumen or essential amino acids in the animal. Forbes (1995) reported that the intake is reduced by diets of low or very high protein concentration. Kempton and Leng (1979) also reported that suboptimal protein supply to the microbial population in the rumen results in a lowered fermentation rate, decreased digestibility of food consumed and decreased voluntary intake. Supplementing the diet with bypass protein often increases the intake of feeds that are deficient in protein (Leng et al 1977). This is supported by the study of Lindsay and Loxton (1981) in which supplementation with urea, sulphur and bypass protein to a basal diet of imbalanced grass hay increased voluntary feed intake.

The amount level of the feed also affects feed intake. Zemmelink (1980) found that the roughage intake increased with increasing amount of feed offered, because the animal has an opportunity to select between or within botanical fractions. Feeds that are dusty tend to cause irritation of the nose and eyes of animal and decrease feed intake (Preston and Leng 1987).

3.2.4.2 Foraging or feeding strategies

It is known that goats are selective feeders preferring to browse the leaves of trees and shrubs when given the opportunity. In this respect, some recent observations appear to be relevant. According to the observations of Preston (1998, unpublished) in Viet Nam and Leng (2001, unpublished) in Bangladesh, the intakes of leaves of the Jackfruit tree (Artocarpus heterophyllus) were much higher when they were offered attached to the stem compared with offering the leaves separately. This implies that the feeding behavior of goats fed tree foliages could be an important area of study in terms of developing strategies to improve feed intake.

The results of the experiment described in Paper 1 (Theng Kouch et al 2003b) confirmed the above observations. Foliages from mulberry, jackfruit and cassava were consumed in greater quantities when they were suspended from the top of the cage than when they were offered in the feed trough. The lowest intakes were recorded when only the leaves were offered in the trough. It was observed that when the foliages were hanging, the goats pulled off the whole leaf and chewed it a little before swallowing it. When the foliage was in the trough more time was needed to eat the leaves because the goat found it difficult to bite them. When only the leaves were offered in the trough, the goats picked up each leaflet one by one and took a longer time to swallow it.  The advantages of hanging the foliages were well appreciated by the farmers in the village study (Theng Kouch et al 2003a), as in all cases this was the chosen procedure.

3.3 The Role of Tree plants Species in Feeding Goats

Farmers in the rural area, unlike the urban backyard farmers, do not have the opportunity to purchase balanced feed concentrates or the ingredients used in such feeds. Thus, they have to rely on crop residues, collected from their own farms, or foliage of multi-purpose trees, shrubs and grasses, which they harvest from their farms or roadsides (Tuah et al 1994).

The use of multipurpose trees has been advocated in the tropics for several reasons. These include: the supply of fodder for livestock; use as wind breaks; providing protection and supplying nutrients to the soil and therefore to plants; fuel for cooking and heating; acting as live fences; and providing shade to both humans and livestock (Mtenga et al 1994). Drought feeding strategies have included the intensive use of browse because trees are less susceptible to climatic fluctuations than herbaceous plants. Tree foliage also produces considerably higher amounts of protein biomass than grasses (Dube and Ncube 1993). Leng (1997) advocated the use of tree foliages as supplements to low-nitrogen crop residues and by-products. However, the presence of secondary compounds may limit the feeding value of tree and shrub foliage through depression of intake and digestibility (McLeod 1974).

According to the observations on goat production in the village situation in Cambodia (Theng Kouch et al 2003a), the selected tree foliages fed to the goats were from the kapok (Ceiba pentandra) and manila tamarind (Pithecellobium dulce)trees. This was especially the case in the flooding season when there is a shortage of feed due to the limited grazing area.

3.3.1 Mulberry 

Mulberry (Morus spp) is the traditional feed for the silk worm, and has been selected and improved for leaf yield and quality in many environments. It’s potential as a protein supplement for ruminants is also now being appreciated (Sánchez 2002). It can be grown with high yields of according to Ly and Preston (2001). Protein content in leaf dry matter ranges from 16 to 26% according to literature reports (Table 1).

Jegou et al (1994, cited by Sánchez 2002) reported that the DM digestibility of leaves was in the range of 78.4 to 80.8%. Even higher values for leaves (80 to 93%) were claimed by Benavides (1995, cited by Trujillo 2002), while digestibility of stems reached 50%. Yao et al (2000) found that in vitro organic matter digestibility in goats varied from 66 to 72% and from 56 to 61% for spring and autumn mulberry leaves, respectively. The latter value is similar to that reported by Singh et al (1984) for digestibility of the organic matter fraction (58%).

According to Alez and Milera (web page, no date), dietary DM intake by goats increased with the level of mulberry leaves up to 1.5% of live weight (DM basis), with a slight decrease at the highest level (2.5% of live weight). However, growth rates and feed conversion were best with the highest level of the leaves.  Similar results were reported by Malamsha et al (2000) who found that the daily voluntary DM intake, expressed as proportion of metabolic body weight, increased with increasing level of mulberry leaves in the diet (from 56.2 77.2 g/kgW^0.75.

3.3.2 Jackfruit

In general, farmers plant the jackfruit tree for harvesting the fruit, but its price in the market is often low, and sometimes it is difficult to find a market, especially in rural and mountainous areas. In this case, it may be more economical to use the leaves as feed for goats, because the fresh leaves of jackfruit trees were found to have a high nutritive value for growing goats when combined with a multi-nutrient block supplying urea and minerals (Keir et al 1997b and Nguyen Thi Mui 2001).

The leaves are high in DM (27 to 41%) but rather low in protein (15 to 18% in DM), according to various authors [Table 1]).  DM digestibility values of 52.6%  and 66%, were reported by  Nguyen Thi Mui (2001) and Keir et al (1997a), respectively.  In my research (Theng Kouch et al 2003b), the DM content of the leaves was found to be 36.3% with 13% protein in the DM. DM digestibility values, measured with foliage or leaves as the sole diet of growing goats, were 48.5 and 52.5 for leaves and foliages offered in the feed trough and reached 63.3% when the foliage was hanging from the roof of the cage., are within the range.

Jackfruit leaves have been used in a diet combined with sugarcane tops, molasses-urea blocks and small amounts of rice bran for lactating goats and growing kids, especially during the dry winter season when grasses are in short supply (Dinh Van Binh et al 2001). These authors reported that milk yield from the goats fed leaves from jackfruit was 756ml/day, and higher compared with other forages. The does gained weight on the diet containing Jackfruit leaves. The weight gain of kids fed only jackfruit leaves and a molasses-urea block was 70 g/day according to Keir et al (1997b). 

3.3.3  Cassava

Cassava is harvested mostly for the root and the leaves are a by-product. However, dual-purpose production systems are also possible whereby one or two harvests of the leaves are taken before the plant is allowed to continue the normal development of the roots (Wanapat et al 1997). Cassava can also be managed as a semi-perennial forage, taking successive harvests regularly at 2-3 months intervals, cutting the stems at about 50-70 cm above soil level (Seng Sokerya and Rodriguez 2001; Preston 2001). The planting of cassava at 60 cm between rows and inter-cropping with cowpea or leucaena enriches soil fertility and the legumes can be used as food and feed for humans and livestock, respectively (Wanapat 2001). Seng Sokerya and Rodriguez (2001) also reported that the feeding of cassava foliage rather than grass can reduce nematode infestation and give  a good growth rate in goats.  

Literature values for the crude protein in cassava leaves are in the range of 17 to 28% in DM (Table 1). In the report of Him Aun (2002), DM digestibility was 83.5% for cassava foliage hung in the cage and offered as the sole diet to growing goats. When cassava hay (sun-dried foliage) was fed as the sole diet to cattle, DM digestibility was 71% (Wanapat et al 1997). In my research (Theng Kouch et al 2003b), the crude protein in the DM of cassava leaves and foliage was 21.8 and 20.2%, respectively. DM digestibility was 68.8 and 73.1 for goats fed leaves and foliages in the feed trough, and 80.1% when the foliage was suspended from the roof of the cage.  

3.3.4 Manila Tamarind (Pithecellobium dulce)

Manila tamarind is a spiny leguminous tree, which grows to a height of up to 15 to 20 m. The tree has a spreading habit with irregular branches, and greyish bark becoming rough, then furrowed. Leaves are pari-pinnate with one single pair of pinnae and one single pair of leaflets per pinna. The leaflets are 2.0 to 3.5 cm long and  1.0 to 1.5 cm wide. There are small thorns (2.0 to 5.0 mm long) in auxiliary pairs inserted on each side of the leaves' pedicels. The leaves are deciduous but the foliage is persistent, as new leaves appear while the old ones are being shed; so that the tree looks like an evergreen. Flowers are disposed in small spherical glomerules approximately 1 cm in diameter, forming short auxiliary panicles of 5 to 30 cm in length. The legume pods are greenish-brown to red or pinkish in colour, rather thin, 10 to 15 cm long and 1 to 2 cm wide. There are about 10 seeds per pod (NAS 1980).

Manila tamarind is often planted as a living fence or thorny hedge, eventually becoming nearly impenetrable. The tree furnishes food, forage and firewood, while fixing a little nitrogen. This plant is drought resistant, and grows well in low rainfall areas developing an extensive root system. It has great adaptability and grows on most soil types, including clay, oolitic limestone, and rather barren sands. It can also be found in wet sands that have brackish water (NAS 1980). The flowers are attractive to bees as a source of pollen. The resulting honey is of good quality. Manila tamarind normally competes successfully with other vegetation. It can be established in grass ecosystems without the need for weed and grass control. Thus it can be planted in pastures for providing shade or as a shelterbelt with a great tolerance of arid and harsh sites (Brewbaker 1992).

The pods are traditionally harvested for sale. They are eaten by livestock of all kinds. The leaves are browsed by horses, cattle, goats, and sheep; and hedge clippings are often gathered for animal feed. The plants withstand heavy browsing (Duke 1983). Perry (1980) reported that in the Philippines the tree is known as "Kamachil". The wood is used for boxes, crates, fuel, and wagon wheels. The gum exuding from the trunk can be used for mucilage, and the tannin for tanning.

There appear to be no data on the intake and digestibility by goats of the foliage from Manila tamarind; however, it was observed in Cambodia (Theng Kouch et al 2003a) that it was used frequently by farmers in feeding their goats. The procedure was to cut large branches which were offered to the goats. The uneaten stems and branches were kept for firewood. They were also put it in the river to attract the fish.

Values of 17 and 23% protein in foliage DM have been reported (Table 1). Samples from our study (Theng Kouch et al (2003a) had a protein content of 23%.

3.3.5 Kapok Tree (Ceiba pentandra)

The Kapok tree is one of the giant trees of the area; the trunk is very straight and cylindrical, having gray bark with dark, vertical fissures. In general, it has one set of horizontal branches at the top. The crown is large, and it is perhaps one of the widest-crowned trees in the world (some may reach 40 m in crown width), but has rather thin foliage. It has compound leaves with 5 narrow, pointed leaflets arranged radially, placed in alternating form.

According to Witsberger (1982), the flowers of the kapok are pollinated by bats, colibríes and bees. Flowering and formation of the fruit occur in the months of January and February and the fruits mature some 4 to 6 weeks later. Baker (1991) reported that the kapok tree does not bloom every year and 5 to 10 years may pass  between two episodes of flowering. The fruits have oblong capsules of elliptical form. When maturing they are of brown color and they are opened in five parts. The seeds are black, and due to their size and form are easily dispersed by the wind. The tree can be planted by stem cuttings to form a living fence or as a source of feed for animals.

In the study reported by Nguyen Thi Hong Nhan (1998), the protein content in the foliage DM was 14.3% (Table 1); DM digestibility in growing goats fed the foliage as the sole diet was 76% and growth rates (74 g/day) were similar to what was obtained with foliage of Leucaena. In our study (Theng Kouch et al 2003a), the kapok foliage contained 17% DM with 18% crude protein. It was observed that the farmers usually plant the tree by stem cuttings so as to form a living fence. The leaves were often dried to make incense sticks while the fresh foliage was fed to the goats.

Conclusion

The review of the literature indicated that:

• Goats are more suitable than large ruminants for poor farmers, due to their small size and high reproductive turnover, which facilitates income generation.
• Goats consume many kind of feed that are rejected by other animals, such as by-products and tree leaves. Including goats in mixed farming systems is a means of increasing the efficiency of land use.
• Farmers have wide experience in using tree foliages to feed the goats, especially from the kapok (Ceiba pentandra) and manila tamarind (Pethicelobium dulces) trees.
• Tree foliages are a valuable source of nutritious feed, especially during the dry season and when grazing areas are limited by flooding.
   

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