SESSION 3a (contd.)

THE POTENTIAL OF TREE LEGUME LEAVES AS SUPPLEMENTS IN DIETS FOR RUMINANTS IN ZIMBABWE

L. Hove, C Chakoma and P Nyathi
Department of Research and Specialist Services, P O Box CY594, Causeway, Harare, Zimbabwe

Introduction

Ruminant livestock production in the tropics is based on natural pasture as the major feed resource. Both the quantity and quality of this pasture are low during the seven-month long dry season and this is a major constraint to ruminant livestock production. The most limiting nutrients are energy and protein. Provision of protein supplements to animals subsisting on the natural pasture is one of the strategies farmers use to alleviate the problem of poor forage quality. When provided with the protein supplements, animals are able to increase intake of the low quality forages (natural pasture and crop residues) and therefore enchance productivity. However, the commercially available protein supplements are not used by most producers due to non-availability and high costs. Affordable, readily available supplements are required to cost-effectively prevent reductions in animal productivity that are associated with the dry season.

The on-farm production of high quality forages is one option available to the farmers. Herbaceous legumes have not been successfully integrated into the farming systems in Zimbabwe due to poor establishment and persistence. Tree legumes are potential sources of good quality fodder during the dry season as they are less susceptible to climatic fluctuations than herbaceous plants. Their deep roots enable them to use moisture and nutrients that are beyond the reach of most herbaceous plants. Besides the provision of fodder, the tree legumes reduce soil erosion and provide timber and fuelwood.

The International Centre for Research in Agroforestry, in collaboration with the Department of Research and Specialist Services, has been assessing the potential of exotic tree legumes as dietary supplements for ruminant livestock in Zimbabwe since 1991. The research is focusing on the development of agronomic and feeding management strategies for trees for optimal fodder production and utilization. This paper provides highlights of the findings on agronomic performance and the effects of feeding leaves from the trees on animal nutrient intake and utilisation.

Tree survival and leaf yields

The initial plantings of the tree legumes were at Domboshawa Training Centre and Makoholi Research Station, areas representing high and low rainfall areas, respectively. The biophysical data of the two sites are given in Table 1. The tree legumes are of tropical origin and included seven species from six genera. The objective was to assess the adaptability of these species to local edaphic and climatic conditions. An ideal tree forage legume should have the following characteristics: high survival rates, frost and drought tolerance; high leaf yields, be seed producing, desirable profiles of nutrients and anti-nutrients and be palatable.

Table 1. Climate and soil data for Domboshawa and Makoholi Research Station

The leaf biomass yields from these species are presented in Table 2. After four years of establishment, the species Acacia angustissima, Oxford Forestry Institute (OFI) accession number 34/88, Leucaena leucocephala, Gliricidia sepium and Calliandra calothyrsus (OFI9/89) were the most productive in both study areas, producing more than three tonnes per ha per year of leaf biomass when cut once at the end of the wet season. G. sepium was highly productive although it was highly sensitive to frost. Although the initial provenance of C. calothyrsus was highly productive in terms of leaf biomass, it did not produce seed under local conditions, raising questions about its sustainable integration on-farm.

Table 2. Leaf yields (m/t per ha) for forage tree legumes established at Domboshawa and Makoholi Research Station, Zimbabwe during the 1990/91 season

Source: Dzowela et al., (1997)

Based on the performance of the initial plantings, more provenance of A. angustissima and C. calothyrsus and species and provenances of Leucaena were later introduced. This broadening of the genetic base was undertaken to guard against incidences of pests and diseases, and to identify species that perform well under a wide ecological amplitude. Among the A. angustissima provenances, the provenance OFI 34/88 was outperformed by provenances OFI 70/93 and OFI 68/92 (Table 3). All the provenances had high survival rates and produced seed. The yields of C. calothyrsus provenances ranged from 2.5 m/t per ha per year (OFI 12/91) to 5.6 m/t per ha per year (OFI 23/91). The original provenance (OFI 9/89) was one of the most productive in terms of leaf biomass yields (Table 4). However, two provenances (OFI 10/91 and 12/91) have consistently produced large quantities of seed, a desirable characteristic for on-farm growing of forage trees.

Table 3. Performance of Acacia angustissima provenances during the 1998/99 season, four years after establishment

Sed - Standard error of differences between means;
Level of significance: ns-not significant P > 0.05; *P < 0.05; **P < 0.01

Table 4. Leaf dry matter yields during the 1998/99 season (four years after establishment) and the soluble proanthocyanidin content (SPA) and gelatine precipitation capacity (GPC) of extracts from the leaves of Calliandra calothyrsus provenances

Survival rates of 10 of the 20 species/provenances of Leucaena were very low and these may not be suitable for conditions similar to those found in the study areas (Table 5). The psyllid tolerant species such as L. pallida, L. esculenta and L. diversifolia were among the most productive with yields of over five m/t per ha per year four years after establishment.

Table 5. Performance of Leucaena species/provenances during the 1998/99 season, four years after establishment

Assessment of nutritive value

Chemical composition

The chemical composition of browse is closely related to its nutritive value and this varies according to species/provenance, stage of growth at harvest, height of cutting and season of harvest. The leaves from the tree legumes had high N (18 to 35 g per kg DM), low NDF (less than 550 g per kg DM) making them potential protein supplements (Table 6). The browse contains tannins and the tannins in some of the species (A. angustisima, C. calothyrsus, L. pallida and L. diversifolia) affect the efficiency of nutrient use by the animal (Dzowela et al., 1997; Hove, 1999).

Table 6. Chemical composition of promising forage tree legumes grown at Domboshawa, Zimbabwe

¹ Constituent-g per kg dry matter except for dry matter (g/kg),
² PAs-proanthocyanidins, Quebracho equivalent; nd-not determined
Source: Adapted from Dzowela et al., (1997)

Voluntary intake and digestibility

The major determinant of livestock productivity is dry matter intake, which in turn is influenced by the palatability, chemical composition and physical attributes of the diet (Ndlovu, 1992). Intake of the forage tree legumes varied with plant species provenances, the status of leaves (fresh or dry) and the animal species (Table 7). Goats readily consumed fresh Cajanus cajan leaves but refused dried leaves of the same species. On the other hand, sheep refused C. cajan leaves in both the dry and the fresh states. Other studies have shown differences in intake as influenced by status of browse at offer (Palmer and Schlink, 1992; Dzowela et al., 1997). Plant secondary compounds that were not identified could be responsible for the responses observed. However, status of browse did not influence the intake and digestion of leaves from the most promising shrubs (Hove, 1999). In Zimbabwe, the tree legumes drop their leaves at the onset of winter, making it necessary to cut the leaves and conserve them either as hay or as silage.

Table 7. Dry matter intake (g per head per day) of various browse species by goats and sheep

Source: Dzowela et al., 1997

The species/provenances show large variation in terms of rumen degradation and post-rumen digestibility. While L. leucocephala and G. sepium were highly degradable, A. angustissima, F. macrophylla, C. calothyrsus, L. pallida and L. diversifolia had low degradabilities of N and dry matter (Dzowela et al., 1995., Hove, 1999). Tannins may be responsible for the low degradabilities observed in these species as tannins have been shown to depress degradability by inhibiting bacterial enzymes and/or forming indigestible complexes with protein and structural carbohydrates (McLeod, 1974; Barry and Manley, 1984). Crude tannin extracts of A. angustissima and C. calothyrsus were shown to inhabit the growth of the rumen bacteria Prevotebacteria Prevotella ruminicola and Butyrivibrio fribisolvens and the activity of the xylanase from the rumen fungus Neocallimastix frontalis (Hove, 1999).

The protection of protein from rumen degradation would be desirable for animals with requirements for dietary rumen undegraded protein (lactating and growing animals) if the protein becomes digestible in the small intestines. While the tannins in A. angustissima have a protective role, the tannins in C. calothyrsus render the protein indigestible post-rumen (Table 8).

Table 8. Water solubility, rumen degradability and post-rumen disappearance (g per kg initial weight) of nitrogen in leaves from the shrub legumes Acacia angustissima, Calliandra calothyrsus and Leucocephala estimated by the mobile bag technique

Level of significance; ns-not significant (P<0.05);
^* P<0.05;
^** P<0.01;
^*** P<0.001
Source: Hove (1999)

Animals supplemented with leaves (fresh or dry) from all the species/provenances had consistently better nutrient intake and digestion than their counterparts subsisting on the basal diet alone. In a study undertaken to compare A. aungustissima, C. calothyrsus and L.leucocephala, animals fed C. calothyrsus leaves had the lowest digestible DM intake and N retenation. This is largely due to tannins in this species forming stable complexes with microbial and dietary protein (Table 9).

Table 9. Nitrogen utilisation by goats fed graded levels of cottonseed meal (CM) or leaves from shrub legumes A. angustissima (AA), C. calothyrsus (CC) and L. leucocephala (LL) as supplements to native pasture hay (NPH)

¹ NPH alone - not included in statistical analysis;
² sup.- type of supplement;
³ level - level of offer (g/day); sed - standard error of differences between means; Significance levels - ns, not significant (P>0.05);
^* P<0.05;
^** P<0.01;
^*** P< 0.001
Source: Hove (1999)

Increasing levels of C. calothyrsus in the diet resulted in more N being excreted through faeces than through urine. This increases the potential of the N being recycled into the soil for uptake by both fodder and food crops as animal excreta is used as fertilizer in mixed crop-livestock systems. However, most of the N is bound to the detergent fibre fractions and may not be readily available for uptake by plants (Hove, 1999).

Animal production

Growth and milk production studies were undertaken using goats and cattle to determine the potential of promising forage trees as protein supplements. While animals fed native pasture hay alone lost weight during the feeding period, animals supplemented with leaves from the tree legumes showed weight gains ranging from nine g per head per day (F. macrophylla) to 24 g per head per day (L. leucocephala and C. calothyrsus) (Table 10). The good response to feeding C. calothyrsus observed with goats was not observed with dairy cows.

Table 10. Dry matter intake and growth rates (g per head per day) of goats fed browses from forage tree legumes as supplements to native pasture hay (NPH)

AA - A. angustissima;
LL - L. leucocephala;
CC - C. calothyrsus;
FM - F. macrophylla
Source: Adapted from Dzowela et al., (1994)

Holstein cows fed C. calothyrsus had the lowest milk yield. Cows fed L. leucocephala gave the highest milk yield among the browse types and this was similar to yields from animals fed the commercial dairy supplement (Table 11). While C. calothyrsus and other browse of similar quality may not be suitable supplements in diets for high producing animals, these forages may play an important role as supplements for dry season feeding to maintain body condition, and as supplements for dry dairy cows. Research is being undertaken to develop harvesting and feeding strategies that alleviate the deleterious effects of the tannis in some of the species. Some of the strategies are based on the use of synthetic polymers that preferentially bind tannis (e.g. polyethylene glycol); mixing the leaves with commercial supplements, or mixing the leaves with highly degradable leaves.

Table 11. Nitrogen (g per day) and ME (MJ per day) intake, and lactation performance of Holstein cows offered dried leaves of tree legumes or cottonseed meal as the major source of nitrogen

Integration of forage tree legumes into farming systems

The economic importance of forage tree legumes can only be realised if they are widely produced on-farm. Farmers could grow the trees in pure stands, or intercrop them with other fodder crops. The trees may also be used to reinforce the natural veld. Contour bunds in arable lands are a possible niche for planting of fodder trees. A study carried out at Domboshawa showed that four- row (50 × 50 cm) hedges of A. angustissima, C. calothyrsus and L. leucocephala planted on contour bunds produced more than 700 kg DM per 100 m of hedge. with minimum effects on the yields of the adjacent maize crop (Table 12). In addition to providing fodder, the trees will help stabilise the contour bunds with spillover benefits (increased moisture retention and soil fertility.

Multi-sectorial research involving animal nutritionists, social scientists, economists and farmers is required to develop tree based fodder production systems in Zimbabwe. Modeling techniques to show or predict variations in production when different tree crop arrangements are used are long overdue for Zimbabwean conditions.

Table 12. Leaf yields (kg dry matter/per running metre of hedge) for promising tree legumes established during the 1992/93 season

Source: Dzowela et al., (1997).

Conclusions

There are many exotic tree legumes that are highly productive under Zimbabwe conditions. Although inputs are minimal once the trees are established, protection of the young plants is essential for establishment. Leaves from all species have high levels of N and low levels of NDF making them potential protein supplements. A. angustissima, C. calothyrsus and Leucaena have the greatest potential. Tannins in A. angustissima, C. calothyrsus, L. pallida and L. diversifolia adversely affect the efficiency of nutrient use. Management strategies have to be developed to maximise the beneficial effects and minimise the deleterious effects of tannins in these species. In addition, multi-sectorial research is required to facilitate wide-scale integration of the tree legumes into the farming systems.

References

Barry, T.N. and Manley, T.R. 1984. The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. Quantitative digestion of carbohydrates and protein. British Journal of Nutrition. 51: 493–504.

Dzowela, B.H., Hove, L., Mafongoya, P.L. and Maasdorp B.V. 1997. Recent work on the establishment, production and utilisation of multipurpose trees as a feed resource in Zimbabwe. Animal Feed Science and Technology. 69: 1–15

Dzowela, B. H., Hove, L., Topps, J. H. and Mafongoya, P.L. 1995. Nutritional and anti-nutritional characters and rumen degradability of dry matter and nitrogen for some multipurpose trees with potential for agroforestry in Zimbabwe. Animal Feed Science and Technology. 55: 207–214

Dzowela, B.H., Mafongoya, P. L. and Hove, L. 1994. SADC-ICRAF agroforestry project, Zimbabwe. 1994 progress report.

Hove, L. 1999. Proanthocyanidins and their influence on the nutritive value of leaves from the shrub legumes Acacia angustissima (Miller) Kuntze, Calliandra calothyrus Meissn and Leucaena leucocephala (Lam.) de Wit fed as supplements in diets for ruminants. DPhil Thesis, University of Zimbabwe, Harare, Zimbabwe.

McLeod, M.N. 1974. Plant tannins-their role in forage quality. Nutrition Abstracts and Reviews. 44: 803–815.

Ndlovu, L. R. 1992. Complementarity of forages in ruminant digestion: theoretical considerations. In: The complementarity of feed resources for animal production. Proceedings of the joint feed resources networks workshop held in Gaborone, Botswana, 4–8 March 1991. Eds: J. E. Stares, A. N. Said and J.A. Kategire African Feed Resources Network. ILCA, Addis Ababa, Ethiopia. 430pp

Palmer, B. and Schlink, A.C., 1992. The effect of drying on the intake and rate of digestion of the shrub legume Calliandra calothyrsus. Tropical Grasslands. 26: 89–93.

THE ROLE OF COMMERCIAL STOCKFEEDS

G.W. Smith
Agrifoods (Pvt) Ltd, P O Box 290, Kopje, Harare, Zimbabwe

Introduction

The diversity of the countries comprising the Southern African region is large, especially when considering aspects such as climate, topography, government policies and status of the economy. These aforementioned factors are interdependent and largely determine the agricultural policies and systems employed in the countries.

When looking at climate alone, the Southern African region has temperatures that drop as low as - 20°C in winter and soar to highs of 56°C in summer. The rainfall of the region is seasonal and varies from five mm per annum in certain areas in the west to 3 000mm in the mountainous regions in the east. The region is also highly susceptible to droughts.

Most, if not all, of the Southern African countries have an economy based on agriculture. In order to ensure a healthy economic growth in Southern Africa it is vital to have strategies in place to cope with these climatic extremes. Optimizing the resources that are available to produce high yielding, high quality agricultural commodities will ensure this economic growth.

The stockfeed manufacturer

Worldwide, stock feed manufacturers produce a range of stockfeeds aimed at the commercial livestock producer. These stockfeeds are formulated to what could be termed a “Best cost” formulation, which will result in the production of a kilogramme of protein at least cost under good commercial management practices.

The role of the stockfeed manufacturer

In order for a stockfeed manufacturer, or any business for that matter, to survive, it has to be able to add value. This is done by having certain core competencies that are unique to that company or business. With the stockfeed manufacturer these core competencies are:-

Sourcing and procuring raw materials at least cost

Raw materials make up 80 percent of the cost of a stock feed manufacturer. Due to this fact it is vitally important that the raw materials are sourced so at least cost.

The stockfeed manufacturer is able to do this by having a considerably larger buying power than the individual livestock producer. Monitoring the availability and pricing of raw materials both on the local and international market also allows seasonal shortages and price variations that may occur on the local market to be kept to a minimum.

In Southern Africa the main raw materials that are used in the manufacture of stock feeds can be classified into six groups, namely:-

Group 1
Animal proteins

Meat and bone meal
Blood meal
Bone meal
Fish meal
Poultry by-product meal
Feather meal

Group 2
Oils seeds and cakes

Whole cotton seed
Cottonseed cake
Soyabeans
Soyabean meal
Full fat soya
Sunflower seed
Sunflower cake

Group 3
Grains and cereals

Maize
Wheat
Sorghum
Millet
Oats
Barley
Cassava

Group 4
By products

Hominy chop
De-fatted maize residue
Maize bran
Wheat feed
Wheat bran
Pollard
Brewers grain
Paprika waste
Molasses

Group 5
Roughages

Hays and straws
Cotton hulls
Maize crop residues

Group 6
Additives

Vitamins and minerals
Synthetic amino acids
Urea
Medicinals
Growth promotants
Enzymes
Buffers

Nutritional expertise

Qualified nutritionists are employed to formulate rations at “Best cost” and to keep at the forefront of nutritional research.

When solving for the ‘Best cost’ solution for a particular diet, certain considerations are taken into account, which include:-

• Nutritional requirements of livestock
• Genetic potential of livestock
• Stage of production
• Raw material specifications
• Raw material availability
• Maximum inclusion levels of raw materials
• Palatability of raw materials
• Cost of raw materials
• Distance of customer from mill
• On farm management systems
• Producer price for the product

Rations formulated in such a manner will satisfy the needs of livestock producers with similar management and production systems. This type of formulation will also provide an assurance that the livestock producer is receiving a balanced ration that will tap the genetic potential of his livestock at minimum cost.

Technical advice and service

In the majority of African countries the governmental organisations, that in the past, offered valuable advice on management practices, production systems, and agricultural and economic trends to farmers has deteriorated substantially. This service is now being offered to farmers by fertilizer companies, seed companies, agricultural equipment companies and stock feed manufactures. Qualified personnel are employed by these companies to fill the void left by the deterioration of the government departments. The advise that the farmer receives is vital for making decisions that affect the day to day running of his operation.

Low cost production

The large stock feed manufactures of today are able to produce high volumes of a high quality feed at low cost. This is facilitated by cost effective formulations. modern production system and the ability to source large quantities of raw materials at low cost.

The stockfeed manufacturer in Southern Africa

4339000 m/t of stockfeed is produced annually by South Africa and Zimbabwe. This is estimated to equate to 80 to 85 percent of the total stockfeed produced in Southern Africa.

Of this 4.3 million m/t, 2.77 million m/t (64%) is consumed by poultry, 0.2 million m/t (5%) by pigs, 0.7 million m/t (16%) by dairy, 0.5 million m/t (12%) by beef and 0.2 million m/t (5%) by other species.

Table 1. Stockfeed production statistics for South Africa and Zimbabwe during 1998

Poultry production consumes the majority of the stock feed that is produced, this not only holds true for Southern Africa, but is a general trend worldwide. Poultry production systems tend to be more intensive that of the beef and dairy industry. As a result the consumption of poultry feed tends to be fairly constant throughout the year and is mainly affected by the demand for poultry products and the price of substitutes.

In Southern Africa due to the relative abundance of land and the prevailing climatic conditions, ranching of beef, and to some extent dairy, is fairly widespread. This type of system relies heavily on the availability and quality of veld and homegrown feeds.

During the dry season when the quality, and in some instances the quantity, of the veld drops off, the first limiting nutrient becomes protein. The demand for high protein licks and roughage containing feeds increase dramatically. In Zimbabwe 70 percent of beef feed sales occur between May and November.

In a drought situation, the demand for dairy and beef stock feed increases significantly. The strategy of the livestock producer changes from a maximum production/maximum profit strategy to a survival strategy. In this survival strategy the livestock producer reduces his herd numbers to a level that his financial resources can provide sufficient nutrients to keep the animals alive until the next rainy season. As a result the type of feed purchased changes from high protein licks to high roughage containing feeds.

During the 1991–1992 drought, the total tonnage sold in Zimbabwe increased by 20.6 percent over the previous year. Beef feed sales increased by 18.2 percent while dairy feed sales increased by 24.4 percent. To put this into perspective the average annual growth in the tonnage sold over the past four years, that had a normal or above average rainy season, was 6.2 percent.

The total effect of a drought, on the livestock industry, is realised in the following three to five years. The year after a drought the total tonnage sold decreased by 27.5 percent. Dairy feed sales decreased by 13.3 percent while beef sales decreased by 50.3 percent. This illustrates how the cattle numbers and financial resources had been depleted during the drought.

Stockfeed availability

Stockfeed manufacturers in Southern Africa provide a wide variety of products to fill the needs of farmers with different production systems and for different times of the year. The products produced fall into four broad categories.

Complete feeds

These are total mixed rations that are fed directly out of the bag and do not require any further mixing.

Semi-complete feeds

These are rations that are designed to be fed in conjunction with pastures or other home grown feeds.

Concentrate feeds

These are feeds that require further mixing with maize, snapcorn, or roughage in order to make a complete feed. The concentrate supplies the protein and micro nutrient portion of the ration while the farmer supplies the energy and/or fibre portion of the ration.

Supplementary feeds

These feeds can be divided into winter supplementary feeds and summer supplementary feeds.

• Summer supplementary feeds

These feeds supply nutrients that may be limiting in grazing cattle during the summer period. An example would be phosphorus, which has been shown to restrict production in the sour veld areas of Zimbabwe.

• Winter supplementary feeds

These are high protein feeds designed for normal dry season feeding of cattle. During a normal dry season the limiting nutrient is protein. A range of blocks, licks and cubes are produced by stock feed manufacturers to supplement commercial beef herds in order to obtain good calving percentages and birth weights.

Availability of stockfeed is a function of raw material supply, manufacturing capacity and demand. In normal rainy seasons the Southern African region is generally self-sufficient in the major raw materials used by the stock feed industry. However due to the variable climatic conditions that can be experienced from year to year, raw material shortages are experienced in above average rainfall seasons as well as in drought years.

The raw material shortages can be alleviated by importing from further a field, but this tends to cause dramatic stock feed price increases as the currencies of the majority of Southern African countries tend to be unstable. This instability tends to be exaggerated in times of drought as currency outflows tend to exceed currency inflows and as a result the currency devalues.

Conclusion

The role of the stockfeed manufacture is to supply a quality cost effective feed to livestock producers. This partnership allows the stock feed manufacturer to focus on the production of feeds, which is their speciality. In doing so the livestock producer can concentrate on the production of quality animal products. This partnership results in better efficiencies within the value chain and improves the quality of the end product significantly.

Whether the production system is extensive or intensive, be it the rainy or dry season the stockfeed manufacturer can offer a products to complement the production system being used by the livestock producer.

References

Agricultural Feed Manufacturers Association South Africa. 1998. Animal Feed Manufacturers Market Statistics

Central Statiscal Office Zimbabwe. 1991–1998. Livestock on Large Scale Commercial Farms

Central Statistical Office Zimbabwe. 1991–1998. Agricultural Production on Small Scale Commercial Farms

Central Statistical Office Zimbabwe. 1991–1998. Census of Registered Poultry Producers

Cowan, Manchadi & Co. 1991–1998. Stock feed Manufacturers Association Market Statistics.

FAO INFORMATION RESOURCES ON DRY SEASON FEEDING OF ANIMALS¹

A. Speedy
Senior Officer (Feed and Animal Nutrition), FAO Animal Production and Health Division, Viale delle Terme di Caracalla, 00100 Rome, Italy.

The problem of dry season feeding occurs every year in the arid areas of southern Africa but there is considerable between and within year variation in the extent of the drought and the availability of feeds.

Papers already presented at this workshop have highlighted the range of options for dry season feeding of animals, including stovers and straws, forages and tree leaves, hays and silages, energy supplements, protein supplements and urea. Given the range of possibilities in different circumstances, there is a need to consider many options which can be selected by the farmer or producer, depending on economic and environmental circumstances. One of the functions of FAO, as set out in its constitution, is “To collect, analyse, interpret and disseminate information relating to nutrition, food and agriculture (including fisheries and forestry)”. In this context, the Animal Production Service of FAO has a large collection of technical and scientific information of value to decision makers, scientists, extensionists and farmers. It is suggested that there is no single solution to effective dry season feeding and the principle here is to provide choices, backed by detailed information on feeds and feeding systems.

Much of the information referred to here is available on the World-Wide-Web (WWW) and also on a CD-ROM published jointly with the International Livestock Research Institute (ILRI), called “Farmers, their Animals and the Environment”1 which contains hundreds of relevant documents.

Figure 1. The FAO/ILRI CD-ROM “Farmers, their animals and the environment”

¹ The FAO/ILRI CD-ROM “Farmers, their Animals and the Environment” (May 1999) can be obtained from the author at the address above or by email request to [email protected].

There are many data on the chemical analysis and calculated nutritive value of animal feeds but the emphasis has been on grains and supplements used in developed country systems. Far fewer data exist on the less conventional feeds and forages, especially those found in developing countries. To satisfy the need for information on locally available feed resources, FAO has developed the FAO Tropical Feeds database and electronic library which provides information on over 700 plant and other materials, based on the original book by Göhl (1981).

A number of important principles of animal nutrition are recognized. Heterogenous materials like forages and fodders are subject to enormous variation. Plant age, component, location and season are among the many factors which may influence the composition. Even if the actual material were analysed, if the animal is given choice, it may select a part of the material which differs from the remainder which it refuses. Secondly, nutrients are not additive, especially in ruminant diets. Thus straw may have a very low feeding value on its own but when combined with a protein or simple nitrogen source such as urea, can give markedly improved animal performance. Urea treatment of straw can actually improve the availability of energy, which is not reflected in the chemical analysis. Thirdly, many plant materials contain compounds other than nutrients which influence digestion and metabolism of the feed. Non-nutritional factors, such as phenolic compounds, are of principal concern in the case of many plant materials.

In short, the whole ration must be considered, as there are optimal and sub-optimal mixtures of available plant materials, in terms of digestion, metabolism and animal performance. These basic yet fundamental concepts are not yet widely accepted among nutrition chemists who continue to rely on ‘feed analysis’.

In summary, the problems of applying conventional feeding standards and analysis to developing country problems are:

• Sampling difficulty
• Selection by the animal
• Non-additivity of nutrients
• Energy-protein interaction
• Time-course of digestion and metabolism
• Disease-nutrition interaction

The FAO Feed Resources Database however relies on:

• Feed description
• Animal performance data
• Special observations (species)
• Farming system
• Links to information sources
• Chemical analysis, digestibility, degradability - but only as an adjunct to description and animal experiments.

The database is now produced in HTML format with search facilities and can be viewed using a web browser such as Netscape or Microsoft Internet Explorer (Figure 2). Selecting the feed displays a text describing the agronomy, feeding and limitations of the material for different species of livestock. Figure 3 shows information on the important legume tree, Leucaena leucocephala. Chemical analysis from published information in a number of tropical countries, including proximate analysis, digestibility and rumen degradability data are given (Figure 4), although these are seen only as guides given the variation, especially of forages and fodders. Most importantly, each page contains the references from which the information and data were obtained and links to abstracts from the scientific literature which are included in the system (Figure 5).

Figure 2. Feed categories listed in FAO Tropical Feeds

Figure 3. Descriptive information on Leucaena leucocephala

Figure 4. Chemical analysis data for Leucaena leucocephala

Figure 5. Links to references and scientific abstracts

The FAO Animal Production Service has been involved for many years in Field Projects, Missions and Research Programmes. Successful innovations have been developed and include:

• Use of by-products
• Molasses/urea blocks
• Urea treatment of straw
• By-pass protein
• Legume trees
• High quality forages

Information and data on these subjects is included in the database and linked to abstracts and articles included in the system.

In addition, there is further agronomic data in the Grass and Legumes Index produced by the author for the FAO Crops and Grassland Service (AGPC) which is also included on the WWW and CD-ROM (Figure 6).

Figure 6. The FAO Grass and Legumes Index

AGPC also maintains a system known as the Global Plant Protection Information System which, despite the name, contains further extensive resources on plants and feed resources. An example of the page on Leucaena leucocephala, showing the hybrid variety KX2 is shown in Figure 7.

Figure 7. FAO GPPIS showing Leucaena Hybrid KX2

In addition to the databases, references and abstracts, there are a number of FAO publications which relate to suitable feeds for the dry season. One of these is the Proceedings of the FAO Expert Consultation on Legume Trees and Other Fodder Trees as Protein Sources for Livestock, edited by Speedy and Pugliese (1996) (Figure 8).

Figure 8. Electronic publication of FAO Legume Trees and Other Fodder Trees as Protein Sources for Livestock

Publications are available in printed form FAO but they are now included in electronic form on the WWW and CD-ROM. These contain full text articles, like the one shown in Figure 9 on trees forages in Tanzania by Komwaihangilo et al., (1995).

Figure 9. Full text article on Local Trees and Shrubs in Tanzania

Extensive reviews on animal production and health subjects are also available in the FAO journal World Animal Review which is also now in electronic form (Figure 10). Of relevance to the subject of this workshop is the paper by Sansoucy (1995) on Multinutrient Blocks.

Figure 10. World Animal Review in electronic format

This issue also contains important articles on urea treatment of roughages, fish silage and other byproducts.

The policy of providing electronic documents on CD-ROM is now established in FAO. A large number of such documents are available. One of the latest, currently being prepared for conventional and electronic publication is on Hay and Straw Conservation by JM Suttie (in press). This gives extensive and knowledgeable information on hay crops and hay making worldwide, with the benefit of conveying ideas from different countries. (Figure 11).

Figure 11. New publication on Hay and Straw Conservation (1999)

The electronic medium allows information to be disseminated more widely at much reduced cost, making it available to more people in developing countries. In the same way, electronic conferences can provide a wider forum for exchange of information than was possible with conventional meetings. A conference is currently in progress (September-November 1999) on Tropical Silage, jointly run by FAO Animal Production and Grasslands groups. This operates by electronic mail with the papers and “poster papers” (country reports and short presentations) available on the WWW (Figure 12).

Figure 12. The home page of the FAO Electronic Conference on Tropical Silage

This is one of a series of electronic conferences run on Tropical Feeds and other subjects by FAO. The proceedings are subsequently published on the WWW and CD-ROM and contain a large amount of useful and relevant information. In this context, there is also the important conference on Coping with Drought (1998), jointly run with the Overseas Development Institute, UK (Figure 13).

Figure 13. Home page of the FAO/ODI Electronic Conference: Coping with Drought (1998)

Many more electronic versions of FAO publications are included on the WWW and 2CD-ROM. Of additional relevance are Tropical Animal Feeding: a Manual for Research Workers (Preston, 1995) and Roughage Utilization in Warm Climates (Chenost and Kayouli, 1996). Also on the WWW are the journals Tropical Animal Production (1976–85) and Livestock Research for Rural Development (1989–99) with 20 years of scientific papers from developing country scientists.

However, it is recognized that much of the information provided here is aimed at scientists and technicians rather than extensionists and farmers. There is undoubtedly a need to translate such information into a form that may be used in the field. This is the objective of a new proposal known as the Village Information Project being developed by FAO in conjunction with IFAD. This builds on the successful training programme developed by TR Preston and coworkers in Vietnam and Cambodia (Figure 14).

Figure 14. The home page of the Tropical Ecological Farm training centre

The principle lies in training the trainers, young technicians in developing countries, given access to the electronic library and network. Working in farm and village projects, including Farmer Field Schools, these persons will go on to operate the village information centres.

The Minister of Agriculture of Zimbabwe in his opening address to this workshop observed that “Feeding strategies have not been adopted because of complexity and inappropriateness”. There are many technical options for dry season feeding of animals. The major needs in the future, if this problem is to be addressed, are for appropriate information, training and extension.

References

Chenost M. and Kayouli, C. 1997. Roughage utilization in warm climates. Animal Production and Health Paper. 135. FAO Rome.

Göhl, B. 1981. Tropical feeds. Feed information summaries and nutritive values. Animal Production and Health Series. 12. FAO Rome.

Komwihangilo D, M. Goromela E H. and Bwire, J M N. 1995. Indigenous Knowledge in Utilization of Local Trees and Shrubs for Sustainable Livestock Production in Central Tanzania. In: First FAO Electronic Conference: Tropical Feeds and Feeding Systems.
http://www.fao.org/waicent/faoinfo/agricult/aga/agap/frg/econf95/econf95.htm

Preston, T. R. 1995. Tropical animal feeding. A manual for research workers. Animal Production and Health Paper. 126. FAO Rome.

Sansoucy, R. 1995. New developments in the manufacture and utilization of multinutrient blocks. World Animal Review. 82: 1995/1, 78–83. FAO Rome.

Speedy, AW and Pugliese, P-L. 1992. Legume trees and other fodder trees as protein sources for livestock. Animal Production and Health Paper. 102. FAO Rome.

INTENSIVE PRODUCTION SYSTEMS - FEEDING AND MANAGING THE HIGH PRODUCING DAIRY COW.

M.H. Neitz
Meadow Feeds S.A. Menlopark 0081, South Africa

Introduction

An indication of the milk yield potential of modern dairy cows is shown by the current South African Holstein/Friesland production record:

Patrysvlug Frost Erika

Feeding dairy cows will always be a combination of science and art. Although the ration is important it probably represents less that 15 to 20 percent of the total nutrition programme. In 1944, Keeney describes dairy herd management in his book “Cowphilosophy” as follows;

• We have to eat what you provide
• Drink what you give us
• Live where you put us
• We may be good cows or we may not
• We may be healthy, or we may not
• We may be comfortable, or we may not
• We may be profitable or we may not
• So much depends on you, the dairyman

Bailey (1998) 54 years later, describes a successful herd manager as follows:

• They constantly strive to become better every day
• They don't take no for an answer
• They surround themselves with ‘can do’ people that get the job done
• They want to get their daily herd average to more than 50kg
• Whatever, they are obsessed with getting ahead and are detail oriented
• These people mow their lawns, paint their barns and make lots of milk from each cow
• They love the challenge of doing things better

Dairy farmers should be focusing on feed conversion and how to improve their gross margin, not just on how many cheques they wrote for feed. The gross margin is simply the milk price less feed costs, both on a hundred weight basis.

The real problem is that in order for farmers to improve their margins, they must be willing to take responsibility for their cow management. Nutritionists can help with the diet, but overall management must also be up to par.

• An important profit variable is volume.
• The best way to improve that margin is to increase milk output per cow (Bailey, 1998).

Transition period

This is the period from three weeks before calving to three weeks after calving. It is the most critical phase in the lactation cycle.

The signs of an inadequate transition programme are:-

• Cows are slow to come onto feed after calving
• An excessive incidence of metabolic disorders
• Cyclic feed intakes
• Excessive loss of body condition after calving
• A lack of nutrient dense diets

The reasons for inadequate transition programmes are:-

• A relative lack of research in this area
• The need to compensate for lower dry matter intakes (the dry matter intake) of cows declines 10 to 30 percent during the last seven to 14 days before calving). Separate transition diets therefore need to be developed that contain increased nutrient densities.

Some guidelines for transition diets are shown in Table 1.

Table 1. Nutrient level guidelines for dairy cattle

In addition, it is important to try and increase dry matter intakes during the calving period, and the following management practices will help:-

• Correct body condition (BCS=3.5)
• Correct feed management
• Excellent quality roughage
• Correct neutral detergent fibre (NDF) and non-fibre carbohydrate (NFC) balance
• The right anion-cation ratio in the diet during the dry period
• Maximizing cow comfort

Targets for dry matter intakes after calving are shown in Table 2.

Table 2. Expected DMI of Holstein cows and first calf heifers during the first five weeks post partum

Source: Drackley (1998)

Ration formulation

Ration formulation models for the feeding of dairy cows e.g. Cornell Net Carbohydrate and Protein Systems (CNCPS); CPM dairy and Shur-Gain's model are dynamic and will be continuously updated. New programmes will also be developed.

The aim is to accurately predict requirements and feed utilization in each unique production setting in order to improve ration formulation accuracy. The final test is when predicted and observed performance (daily gain, milk yield and composition, and body condition score changes) agree, and observed responses to change in management and feeds can be explained by predicted effects on ruminal fermentation, intestinal digestion, metabolizability of energy and amino acids, and product amount and composition.

The factors that must be described as accurately and completely as possible are:-

• Animal type
• Animal's requirements
• Environment
• Climate
• Management
• Cow comfort and behavior
• Feed analysis
• DMI

An example of animal description would be:-

• Animal age
• Sex
• Frame size
• Body weight
• Flesh condition (BCS)
• Days pregnant
• Days since calving
• Lactation number
• Milk production
• Butterfat
• Milk true protein
• Breed type
• Breeding system
• Dam breed

The detail required in feed analysis figures is shown in Table 3.

Table 3. Forages-Legumes (feed analysis)

The following aspects will become more important in future when evaluating feed programmes and recommendations.

• Predicted rumen pH
• Microbial protein synthesis
• Amino acid requirements
• Milk urea nitrogen values (MUN)

The key components that form the basis of a total nutrition programme (Chase, 1996):

• Feed selection
• Feed and forage analysis
• Ration formulation
• Feed quality (chemical, physical)
• Feed mixing
• Feed delivery
• Feedbunk management
• Feed utilization (digestion)
• Cow behaviour
• Animal monitoring

“To eat feed, forms an important part of a cow's job description”.

There are four rations on the farm for each cow each day, and variation can occur at each stage.

1. The ration formulated
2. The ration mixed
3. The ration delivered
4. The ration actually consumed

If a balanced ration has been formulated-why isn't it working

Key points (Chase, 1996):

• Cows don't lie!
• If you can't measure it, you can't monitor it. If you can't monitor it, you can't manage it.
• What has changed
• Cows like consistency

Cow comfort and behaviour

Cows should not be standing - cows should be either milking, eating, or lying down resting!

Why is cow comfort important

• Leads to better feed management
• Maximises intake and production, and
• Eliminates stress

What can be considered as stress condition:-

• Two weeks before calving to two weeks after calving
• First eight weeks after calving when DM consumption lags milk yield
• Cows losing over 1 kg of bodyweight a day
• Heifers milking over 30 kg FCM
• Heat and himidity
• Mud, snow or rain exposure
• Dirty conditions
• Disease and metabolic disorders
• Flushing cows

The feeding of high nutritionally dense total mixed rations and establishment of intensive housing systems seem to be the only solution to the mentioned stress problems.

Feed additives

Two examples:-

The inclusion of enscapsulated enymes for ruminants will increase in future e.g. Fibrozyme (Alltech)

Advantages of Fibrozyme:

Improves fibre digestibility
Stimulates production of rumen VFA's
Stimulates feed intake
Improves productivity

Flavomycin

Advantages:

-   Increase in milk yield of up to 12 percent
-   Equal or increased concentration of milk components and thus rise in production of milk fat, protein and lactose
-   Positive influence on microflora in rumen and therefore:

• Raised digestibility of cell wall cellulose and cell contents
• Increased formation of propionic and acetic acids
• Decrease in methane-caused energy loss
• Reduction of ammonia burden
• Improvement of microbial protein synthesis

-   Improved energy and protein conversion from feed
-   Increased feed intake
-   Reduction or adjustment of the negative energy/protein balance of high performance dairy cows during lactation
-   Tendency to positive influence on fertility
-   Stabilisation of health of udder
-   Absolutely no substance residues in milk or animal tissue

Increased number of milkings per day

High producing cows prefer to be milked four to five times per day. In trials cows produced 15 to 20 percent more milk when milked four to five times per day compared with the conventional 2 or 3 times milking per day.

Conclusion

Without enthusiasm all the technique in the world won't help.

SESSION III (a)
DISCUSSION

1.   De Waal

Q.   The ability that you show of the grazing animal to select for plants of higher protein content will surely have deleterious effects on the veld in the long term?

A.   This is quite correct. It is calls for a balanced approach to grazing management.

Q.   You talk of the need for long-term strategies and objectives, but presumably there must be flexibility?

A.   Clearly there must be flexibility. Our paper recommends not constantly changing and not changing at every whim.

2.   Duncan

Q.   As we have a very sensitive environment in this part of the world, is it sensible to modify a sensitive environment?

A.   Studies have shown that digestive modifiers do not increase the amount of browsing across the board, they rather tend to facilitate better utilisation of the browse.

Q.   You mention cattle not being totally adapted to their environment. Surely indigenous cattle are adapted?

A.   Certainly more than exotic cattle, but they are still in the process of adapting to certain aspects of their environment. Wildlife species tend to be fully adapted.

Q.   Tell us about Browse plus.

A.   Browse plus is a commercial product which acts as a digestive modifier and neutralises the effects of tannin in browse. It is supplied to the animal via a feed supplement or the water. Positive results have been reported from its use in Zimbabwe and Australia.

3.   Manyuchi

Q.   How effective is urea treatment of roughage in the small scale sector?

A.   It is a relatively cheap and effective technology, but lack of money in the smallholder sector is the main brake on its use. However, there is a credit scheme available to small scale farmers in Zimbabwe. There is also an important requirement for accurate weighing/calibration on the farm.

Q.   What about post-treatment storage?

A.   The important thing is to avoid water getting into the stored product.

Q.   How effective is the dissemination of research information to the farmer?

A.   There is a constant drive to try and improve this. If researcher technology is made farmer friendly, then it leads to farmers requesting demonstrations.

4.   Dube

Q.   What are the differences in nutritive value between new leaves and dropped leaves?

A.   Nutrient content will tend to be higher in new leaves. However, the situation is complicated in terms of value to the animal by variations in palatability and the presence of tannins. Tannin levels will often vary considerably during the growing period.

5.   Titterton

Q.   What type of bags are you using for the small-scale silage making? Can you use them more than once

A.   Any plastic bag which can be made air-tight. We normally put about 8kg of material in one bag. Bags can be reused if they are not damaged. Fertilizer bags are strong enough to be used more than once.

Q.   How digestible is Pennisetun silage?

A.   If made at the right stage, it is very similar to the other silages.

Q.   Have you done a gross margin analysis on the value of making silage?

A.   No, not yet.

6.   Hove

Q.   Do you see a future for Glyricidia in the small scale sector?

A.   Yes, but there is relatively little information available and the potential has still to be explored.

Q.   What sort of yields do you expect from Leucaena?

A.   In the right conditions, a lot of dry matter is produced. The stems of Leucaena are also consumed by livestock.

7.   Smith

Q.   How viable is home mixing on the farm?

A.   It is viable in many circumstances, but costings are often not done accurately before decisions are made. We like to look at the relationship between the producer and his stockfeed company as a partnership. The stockfeed company provides that part of the ration which the farmer cannot access.

Q.   Do you consider the genetics of the animal when formulating feeds?

A.   Definitely. A good example is poultry which are the most advanced species genetically and we provide very high quality rations to provide for high levels of performance.

Q.   How do you cope in drought years?

A.   It becomes very difficult to source raw materials and sometimes we fail to meet demand.

Q.   Of your total sales of stockfeeds, what proportion goes to smallholder farmers?

A.   Approximately one per cent.

Q.   Do you provide packaging for small units, or just 50kg bags.

A.   Small packages are available.

8.   Speedy

Q.   It is presumably important to provide a choice of technologies to small-scale farmers.

A.   We try and provide a range in order to allow farmers to make informed choices.

Q.   Has FAO got a formula to apply to small-scale on-farm experimentation.

A.   There is no easy solution as one must use standard statistical techniques. The aim must be to try and increase the number of farms and animals used in trials in order to get valid results.

8.   Neitz

Q.   Cottonseed meal has been shown to be very effective in improving milk yield in low yielding cows in smallholder systems. What is the situation in high yielding cows?

A.   With higher yields, one has to consider protein degradability and quality-hence we use a variety of protein sources if possible.

Q.   How much time should be given to changing diets?

A.   Changes should always be gradual, so at least one week for the complete change.

Q.   How quickly will milk yield respond to a change in diet?

A.   Five to seven days.

Q.   What variety of sorghum did you use?

A.   Sweet sorghum. We would always aim to use a mixture of cereal grains in the diet.