“Legumix” Stylosanthes pellets: A healthier and more sustainable animal feed

Abstract

The development of a range of animal feeds based on leaf meal of the tropical forage legume Stylosanthes guianensis var. guianensis (“tropical alfalfa”) in Costa Rica, their potential for improving health of animals and consumers of animal products, the local and national economy, and ecological implications are described. A subproduct of the oil palm industry (palm oil fatty acid distillate) is used to supplement the Stylosanthes leaf meal with sufficient energy to produce a complete pelleted feed. Customer case studies showed that Stylosanthes-based feeds are highly palatable and improve health and performance of farm animals (horses, rabbits, calves, sheep, and goats) over that observed when using grain-based feeds. The improved quality of Stylosanthes-based over grain-based feed for ruminants could play an important role in the reduction of methane emissions and their negative consequences for climate change. A sustainable system whereby Stylosanthes is planted in association with plantation trees is proposed, providing a supplementary income for tree farmers and other benefits, such as weed control and soil amelioration. Stylosanthes can be rotated with sugarcane and pineapple, and cash flow projections show that Stylosanthes leaf meal production would be a favorable alternative activity for local farmers, yielding a greater and more constant income than sugarcane. Achieving economy of scale in the industrial process would permit production at lower cost to compete with the price of imported grain-based feed. Lack of finance is currently the major obstacle to scaling up the process, implementing the technology in different countries, and obtaining the concomitant benefits of food security, import substitution, improved ecological sustainability, and healthiness of animal products.

Keywords

feed pellets tropical alfalfa grain-based feed horse feed import substitution food security methane emissions early weaning tropical forage legumes

Introduction

The definition of policies to increase the pace of development and implementation of new technologies that can help to intensify food production for the growing world population, under conditions of climate change, is a complex challenge (Thornton et al., 2018). A decrease in demand for animal products may be achievable in industrialized countries in the next decade by a change to more flexitarian diets, as recommended by Springmann et al. (2018). However, it is still likely there will be an increase in overall world demand for animal products of up to 50% in the next 30 years, according to the Global Agenda for Sustainable Livestock (GASL, 2019), because the current consumption level of animal products is relatively low in developing countries. In addition, the rate of population growth is much greater, so even if the increase in demand per capita is small, it will create a much greater total increase. The expected annual consumption of meat in developing countries by 2030 is 37 kg per capita, whereas in developed countries, it is expected to reach 100 kg per capita (FAO, 2003). Animal production is relatively more important in developing countries, where the proportion of small farmers using livestock as an integral part of their production systems is much higher than in developed countries (Mlambo and Muisi, 2019). These authors recommend strategies for overcoming some of the unintended negative consequences of livestock production. In Latin America, animal production represents a high proportion of farm income but presents many environmental challenges, such as increased deforestation, and the increasing use of intensification of production by fattening with grain-based feeds or other industrial subproducts by larger meat-producing companies, causing contamination of rivers and air (Milesi, 2016). ILRI (2019) describes approaches to improving livestock management in developing countries. For example, they have shown that waste cassava peel can be converted into high-quality feed in Nigeria, which could replace the use of grain-based feed in industrial animal production units.

In Latin America, new cultivars of forage grasses and legumes have been identified (Holmann and Lascano, 2001). However, intensification of animal production through the use of grass–legume pastures by cattle farmers in South and Central America has been limited, possibly because growing and maintaining grass–legume associations require improved management practices, which may be too difficult to apply in many cases, as compared to using grass monocultures and supplementing with grain-based feed. As a small seed company in Costa Rica during the period 1990–2000, our experience was that farmers were simply not interested in buying seeds of forage legumes, whereas they were prepared to buy grass seeds and grain-based feeds to fatten their animals.

On the other hand, forage legumes grown as crops are relatively easy to manage. They are also more productive than when subjected to grazing, where trampling and competition from grasses can significantly reduce yield. Crop farmers are accustomed to the management practices required. For example, the techniques required for tobacco farming, which has practically disappeared in Costa Rica, are similar to those needed for producing leaf meal of forage legumes. There are many well adapted and highly productive legumes, which are native to the region. These legumes are more likely to adapt well to local conditions than plants introduced from elsewhere. They are currently just seen as weeds, but could contribute very significantly both economically and ecologically to the food production system, and generate a stable income for small farmers. Crop rotations incorporating legumes could be very important in breaking the increasing tendency for monoculture in modern agricultural systems. Legumes sown between rows of plantation trees can also play an important role in weed control and income supplementation. This was therefore the main driving force behind our decision to develop a legume-based feed for animals.

Why produce feed from Stylosanthes?

Stylosanthes (known as “tropical alfalfa”) is of similar quality to alfalfa or lucerne. It is a perennial crop, which yields three or four times more protein/ha/year than a soybean crop. Yields of over 18 metric t (MT) per hectare of dry leaf meal per year with 16% protein content are attainable. Even if biological nitrogen fixation represented only 50% of the total N yield of the plants, this is equivalent to 1440 kg N fixed biologically per hectare per year, and in several cases up to 70% of biologically fixed N has been measured in Stylosanthes guianensis (Cadisch et al., 1989; Zemek et al., 2018). Meat and milk from animals fed with high-quality grass–legume forage contain significantly more conjugated linoleic acid (CLA), a substance known to help prevent heart attacks (Smit et al., 2010) than from grain-fed animals. Animals fed on higher quality diets, such as those containing legumes, produce less methane (Trupa et al., 2015), and grinding and pelleting forage can reduce methane production (Iqbal and Hashim, 2014).

Stylosanthes is a tropical legume native to Latin America. Its distribution extends from southern Mexico to northern Argentina (CSIRO, 2004). The importance of the Stylosanthes genus as a forage plant has been recognized for more than a century. In 1914, Stylosanthes humilis (Townsville Stylo) was released as a variety for use in improved pastures in Australia. Other cultivars of Stylosanthes spp. were released subsequently and are widely used in China, Thailand, Vietnam and India (http://tropicalforages.info/key/forages/Media/Html/entities/stylosanthes_guianensis_var._guianensis.htm).

For the production of feed pellets, Stylosanthes guianensis was selected over other legumes, including S. capitata and several varieties of Vigna radiata and V. unguiculata, because it was more productive, easier to mechanize sowing and harvest, and better adapted to the grinding and pelleting process, as well as being more palatable to horses, cattle, and sheep. The technology is based on growing, drying, grinding, combining with other ingredients, and making feed pellets from a Stylosanthes guianensis var. guianensis cultivar (Figure 1), which contains five lines of anthracnose resistant ecotypes. Solar drying is used when feasible, and a rotary drier using firewood when further drying is needed. Stylosanthes does not tolerate poorly drained soils but is tolerant of soil acidity and drought. Regrowth after cutting is vigorous if the right cutting intervals are used. As a crop, the most important factor is to achieve good control of broad-leaved weeds.

Figure 1.

Technology for producing Stylosanthes feed pellets.

Comparing Stylosanthes with grain-based feed

The practice of using grain as opposed to forage as an energy source is known to be detrimental to the environment for several reasons (McLaughlin and Walsh, 1998). Even if only taken from an economic point of view, the vast amount of grain imported by poor countries to feed animals is an unnecessary expense, if the feed can be produced locally at a lower cost for a more healthy product. The total amount of balanced feed produced in Costa Rica annually is more than 1 million MT, of which about 20% is for ruminants (CIAB, 2018). Soybean imports to Costa Rica have increased 26-fold since 1985 to 300,000 MT, at a cost of US$116 million in 2018.

Central America produced 3.598 million MT corn in the period 2018–2019 (www.agrochart.com), whereas the total imported in the same period was 4.350 million MT (Figure 2). It is clear from these data that Costa Rica produces very little corn; nearly all is imported. The international price of corn is currently US$355/MT, which would convert to a cost of US$320 million per year for corn imports to Costa Rica.

Figure 2.

Maize and soybean importation and production in Central America for use as ingredients in animal feed.

The cost of imported soybeans and corn is equivalent to 83% of Costa Rica’s positive trade balance in 2018 (US$525 million according to https://atlas.media.mit.edu/en/).

It is important to take into account that to reduce costs, no soybean meal at all is added to many grain-based concentrates for ruminants. They are almost entirely based on corn, and the source of N is urea, which is metabolized into protein in the rumen. However, for young calves and horses, urea is toxic. More than 40% of starch in the diet is considered to be detrimental for milk quality and energy use (Wattiaux and Armentano, 2004). An excess of starch (nonfiber carbohydrates (NFC)) in the diet of horses is also considered to be detrimental and can cause colic and even death. The NFC content of a horse’s total feed should be below 12%. From this perspective alone, it is thus reasonable to look for methods to substitute most of the NFCs in animal diets with an ingredient containing high-quality fiber as the main source of energy.

Stylosanthes contains 2.4 MCal/kg metabolizable energy, 15–21% protein, 26–32% crude fiber, 1% calcium (Ca), and 0.2% phosphorus (P). Feed for dairy cows requires 3.4 MCal/kg metabolizable energy, 16% protein, 1% Ca, and 0.2% P. Stylosanthes supplemented with a relatively small amount of energy can therefore provide a complete diet for a dairy cow.

Fudesemillas currently markets four Stylosanthes-based feeds, known as “Legumix,” under the registered trademark Alimentos Santa Juana. They contain different levels (0–15%) of added energy from palm oil fatty acid distillates (PFAD), which is a subproduct of the oil palm industry and is principally used for milk production as a rumen bypass energy supplement but has also been shown to be a suitable energy source for horses (Ganagras in Colombia).

Soto-Morales and Rojas-Bourrillon (2016) evaluated the effect on digestibility of nutritional components of the total feed when grain-based feed was substituted with increasing amounts of pure Stylosanthes-based feed pellets in four thoroughbred geldings. They found that up to the maximum level of substitution tested (45%), there was no statistical difference in digestibility of nutritional components (dry matter, crude protein, acid detergent fiber) between treatments, and the cost of the feed was reduced by 10.3% at the highest substitution level.

To compare Stylosanthes-based feeds with grain-based feeds, it is necessary to take into account that grain-based feeds for dairy cattle often contain a large number of other additives, including the antibiotic sodium monensin, which increases milk production and CLA content of milk (De Marchi et al., 2015). Dos Pinos and Sigma, two of the largest dairy companies in Costa Rica, carried out some preliminary comparisons of their grain-based feeds with Stylosanthes-based feed. The results showed increased milk solids, but not volume, when using Stylosanthes-based feed (e.g. Alfaro Blanco, 2015). However, because of the presence of additives such as sodium monensin in the grain-based feed, the results are not directly comparable, and further testing is needed to separate their effects.

Cost-benefit evaluations

Our observations show that Stylosanthes-based feed benefits the health and productivity of different types of animal, namely horses, goats, sheep, cattle, chickens, rabbits, and pigs, in some cases, as a complete feed, and in others as a supplement. Our current price for Stylosanthes leaf meal is US$450/MT, but we expect to be able to reduce the price significantly to about US$300/MT when we obtain economy of scale. The PFAD we add to the leaf meal as an energy source currently costs US$1125/MT, which when 15% weight is added to the leaf meal (the energy needed by dairy cattle) increases the cost of the final product by US$177/MT to US$530/MT. The price of grain-based feed for dairy cattle ranges from about US$380/MT to US$480/MT. For horses, the prices are higher: approximately US$550/MT. If we can obtain the economy of scale that we expect by increasing our leaf meal production levels and finding a cheaper source of PFAD, we could reduce the price of the final Stylosanthes-based feed product to at least US$440/MT by 2022 and thus compete successfully with grain-based feeds for cattle (Figure 3).

Figure 3.

Projected price reduction of Stylosanthes-based feed and ingredients obtained with economy of scale.

Thus, especially if the quantity and quality of the animal products increase on using Stylosanthes-based feed, in addition to the increased health of the animals, farmers could easily be convinced to make the change. Also, if the environmental costs of producing and transporting the imported grain were included, and distortions of the market price for soybeans and other commodities due to subsidies and tariffs (https://gro-intelligence.com/insights/articles/what-new-us-subsidies-mean-for-soybean-farmers) were to be eliminated or reduced, the cost of imported grain would be likely to increase, thus making Stylosanthes-based feed more competitive.

Case studies of some customers using Stylosanthes-based feeds

1. Finca de los Pura Sangre, Platanillo de Barú, Pérez Zeledón.

This farm brought two 11-year-old offtrack thoroughbred ex-racehorses from Arizona, United States, to Costa Rica in December 2018. Over 4 years in Arizona, the two horses had been fed a well-balanced diet based on pelleted feed brands available in the United States but not in Costa Rica. The two horses, Proud and Decar, had been very stressed by the journey and lost a lot of weight. They were noticeably thin, depressed, and off their food. During this transition period, they were being fed hay, a locally available corn-based pelleted feed (Corcel), and a vitamin and mineral supplement.

After arriving at the farm in Platanillo in February 2019, they were fed with 2 kg per day of the Santa Juana Premium Plus Legumix formula, which contains 52% Stylosanthes leaf meal, 15% PFAD, and approximately 11% each of soybean meal, ground maize, and DDGS (dried distillers grains with solubles). The owners had previously observed that when they had changed feed, the horses were initially reticent to eat it, but in this case, they really liked it and would even enjoy a handful of pellets as a treat. They added flax seed, a vitamin and mineral supplement, and salt. Weight gain was still only slight, so the quantity was increased to 3.5 kg/day with an additional feed time at mid-day and three-fourth cup of liquid fat for horses. By mid-March, there was a very noticeable difference in their appearance, they were much less stressed and seemed much happier. By mid-April, it was estimated that both horses had regained all the weight they had lost due to the journey (about 70 kg each), and their appearance and the health of their feet and coats had improved significantly (Figure 4). The owners consider it is extremely important that thoroughbred horses should like their feed and enjoy eating it, because a good psychological state is fundamental to maintaining their weight and good condition, and this is what they find so impressive and surprising about the Santa Juana feed, because it is unusual to find a feed that is so palatable, as well as providing excellent feed value.

Figure 4.

Recuperation after stress of ex-racehorses.

2. Complete feed for high-performance horses.

One of the most successful formulas of Alimentos Santa Juana is a combination of both grass and legume leaf meal, mineral salts, and other additives and is fed at a rate of 10 kg per day per animal. Use of this feed eliminates the need for hay bales, which are of dubious quality in many Latin American countries. For horse owners, this offers savings in labor and waste management, as hay bales are costly in transport, handling and wastage. At the San José Polo Club, six high-performance horses have been fed exclusively with this diet for over a year, which has been beneficial to their health and activity levels. In addition, the droppings are a better consistency and the waste is much less voluminous.

3. Caprinos M&M del Valle, Arizona, Pérez Zeledón, Costa Rica.

This farm, property of Manuel Mora, produces about 50 l of milk per day, using Saanen goats (Figure 5). The goats are kept indoors 100% of the time and milked twice a day by hand. They were being fed with 2 kg/day of a grain-based feed recommended for dairy cows produced by Dos Pinos cooperative and about 8 kg chopped legume and other grass fodder. The 2 kg of Dos Pinos feed were substituted with a cheaper grain-based feed at 1.2 kg/day supplemented with 0.8 kg Stylosanthes-based feed. The quantity of green fodder was also reduced, which resulted in more solid excrement, and therefore more cleanliness in the dairy. Overall, the cost was reduced by 17%, and milk production increased by 20% (increase from 5 to 6 l/day/goat). In addition, marked increases in corporal health and the success rate of artificial insemination were observed.

Figure 5.

Goat milk production by M&M del Valle with Stylosanthes supplement.

4. Early weaning of calves.

We have formed an alliance with the veterinary company Vetco to develop strategic Stylosanthes-based feed formulae for dairy cattle. Initially, we are developing a high protein supplement for calves, pelleted or in powdered form, which contains 21% protein, 17% fiber, and 300 µg/kg selenium, from the first day after birth, during the first 2 months, and continuing after weaning, in order to detect benefits during the stressful weaning period. According to Heinrichs (2005), the feeding of calves with forage in place of grain-based concentrate delays the development of the ruminal adsorptive surface area (papillae). However, if the fiber-containing supplement is introduced gradually, the rate of adaptation of the calf to this type of feed could be increased. In addition, the supplementation with selenomethionine strengthens the immunological system, and promotes muscle development and absorption of vitamin E. In initial trials, 0- to 3-month-old Jersey calves were fed either with or without the Stylosanthes-selenium supplement. The supplement showed a high degree of palatability (Figure 6). The amount consumed and the effect on the calves’ development during weaning are being measured. In a second phase, the effect of the supplement on the cows’ performance during and after weaning will be evaluated.

Figure 6.

Early weaning of dairy calves with Stylosanthes supplement.

Scaling up Stylosanthes production

Fudesemillas has planted areas of Stylosanthes to produce approximately 800 MT of feed per year (35 ha). Cash flow projections show that to obtain economy of scale and evaluate the ecological sustainability of the system, we need to increase production at least 10-fold, to produce about 8000 MT feed per year. Instead of producing the green Stylosanthes ourselves, we will include local farmers in the process, so that Stylosanthes production becomes an alternative source of income for them. Our calculations show that a farmer would obtain about US$1200/ha/year from this activity, which is more than the amount they currently earn from sugar cane production.

Initial trials in collaboration with two local companies (Coopeagri, R.L. and Pindeco Del Monte) have shown that Stylosanthes can be rotated with industrial crops such as sugar cane and pineapples. It can also be grown between rows of plantation trees. By installing processing plants which can each handle the material from approximately 350 ha (8000 MT per year, that is, 30 MT of dry leafmeal per day), Stylosanthes leafmeal could replace at least part of the imported ingredients currently used in animal feed. For example, if we could establish five processing plants in Costa Rica, each of which produced 8000 MT/year of feed, this would produce a total of 40,000 MT/year, which would represent 20% of the total feed for ruminants currently used in Costa Rica.

As an additional part of the technology, Fudesemillas proposes a sustainable system (Figure 7) whereby Stylosanthes is grown in oil palm plantations and harvested with specialized equipment. During the first 3 years of an oil palm plantation, there is sufficient light, and the new smaller varieties of oil palm allow more light to penetrate to the understory over longer periods. Harvesting the Stylosanthes and selling it to an animal feed industry could supplement the income of the oil palm farmers and help to reduce the cost of weed control. A similar strategy could be used with other plantation crops where the distance between trees is sufficient to allow for harvesting the Stylosanthes. Preliminary calculations indicate that each hectare of oil palm plantation with Stylosanthes, using the subproduct PFAD as an energy source, could sustain 11 animals consuming 5 kg feed per day each, as well as the production of other outputs (fruit, fiber, oil, timber, organic fertilizer).

Figure 7.

Proposal for a sustainable system associating Stylosanthes with plantation crops.

Scaling up the process of producing Stylosanthes-based feed would benefit the crop farmers producing it, animal farmers using it, food security and balance of payments of the countries implementing the technology, as well as environmental and health advantages. Once we have built up our own production level, further production plants could be established in other regions and countries through a franchising scheme. Potential investors have expressed interest in applying the technology in Nicaragua, Panamá, and Colombia, as well as in other regions of Costa Rica. To scale up the technology, we need to implement technical assistance for farmers, increase the efficiency of the processes in the industrial plant, install solar panels in order to reduce energy costs, develop further technology improvements, and carry out more animal testing.

The difficulty of obtaining finance for scaling up the technology, due to extremely slow bureaucracy and lack of a functional system for financing innovative agricultural technology in Costa Rica, is currently the main obstacle to implementing it over a wider region and showing whether it can be used to substitute grain-based feeds on a significant level.

Conclusions

Stylosanthes-based feeds were shown to be highly palatable and improve health and performance of farm animals (horses, rabbits, calves, sheep, and goats) over that observed when using grain-based feeds. The improved quality of Stylosanthes-based ruminant feed could play an important role in the reduction of methane emissions and their negative consequences for climate change. Achieving economy of scale in the industrial process would permit production at lower cost, to compete with the price of grain-based feed. Production of Stylosanthes leaf meal would be a favorable alternative activity for local farmers. Lack of finance is currently the major obstacle to scaling up the process, implementing the technology in different countries, and obtaining the concomitant benefits of food security, import substitution, improved ecological sustainability, and healthiness of animal products.

Footnotes

Declaration of conflicting interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Fudesemillas is a not-for-profit organization.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Rosemary Sylvester-Bradley

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