During the past decades, chicken and pig production in Asia has increased dramatically, following the higher demand for meat products, thus rising the demand for animal feed. Even though the major food and feed crops (rice, maize, and cassava) increased markedly in the continent, they were not able to comply with the local demand and resulted in more importation of grains like maize and soybeans.

The competition of locally produced grains with imported grains depends largely on prices and availability. The recent increase in grain prices worldwide, as well as shortages, has forced feed producers to search for alternative energy and protein sources.

Agro-industrial by-products (AIBP) are derived from agricultural processing industries, such as rice milling and oilseed extraction, can be utilized as straight feeds and/or supplements for upgrading the nutritional value of feedstuffs available. AIBP may present other advantages: lower cost and higher availability, especially in periods of feed shortage, allowing scope for imports substitution.

The local authorities of the region are providing suggestions of suitable alternatives, including grains and processing byproducts to replace corn and soy, and they are highlighting that import substitution also favors the development and expansion of the local market, productive capacity, and resources.

Among the local sources of protein and carbohydrates in Southeast Asia, this article will review three of them: cassava, rice brand and palm kernel cake.

Cassava

Cassava (Manihot esculenta) is famous due to its starchy, edible root or tuber, known as manioc, mandioca or yuca. Cassava has its origin in South America, and was traded by Europeans to Africa, and later Asia, as a food security crop and for the starch extraction.

After the World War II, it became an important industrial crop in Thailand, mainly for starch production for local consumption, and chips and pellets for the export to European and Chinese markets. More recently, there has been an increased use of this plant in Vietnam and Southern China for industrial products (sweeteners and alcohol production), as well as for animal feeding (especially pig). Vietnam is exporting dry chips and starch mainly to China.

In terms of consumption and production, Nigeria is the main worldwide producer of cassava, followed by the Democratic Republic of Congo and Thailand. In Southeast Asia, Thailand and the Philippines are experienced in using cassava as animal feed.

Cassava is cultivated and considered an important resource for human and animal consumption in tropical and subtropical regions due to its high protein and energy content and its relatively low cost. It is relatively drought-hardy and can grow on marginal lands. Cassava roots are an important energy staple in many regions. Peel fraction can also be a primary energy source in feeding programs, while leaves provide protein, minerals, and antioxidant vitamins.

The value of cassava can be limited by some specific nutrient imbalances (deficiencies in specific amino acids, fatty acids, minerals, and vitamins) and antinutritional factors (like cyanide, among others), but despite of it, all parts of cassava can be successfully used in livestock and aquaculture feeds. Cassava-based feeds require specific nutrient balancing, as well as treatments to reduce the toxic and harmful compounds, like drying, but offer viable and local alternatives.

Products relatively free of cyanogenic glucosides can replace corn without any problems, as long as the formulas remain well balanced for all other nutrients, in case of monogastric species, as ruminants are more sensitive to cyanide poisoning. In addition, talking about laying hens and egg pigmentation, it should be noted that corn is relative rich in pigments, while cassava contains none.

Several research reports revealed how cassava can substitute maize at up to 40% in ruminants and poultry, 60% in aquaculture and 100% in swine when paired with appropriate nitrogen sources. The cassava-soybean mixes can now be considerably cheaper than maize-soybean mixes with the same crude protein contents. Cassava starch is also used as pellet binder in aquaculture feeding.

When cassava is grown specifically for leaf production and is well-managed, cassava tops can be cut five times and produce more 3-4 times higher production (t/ha) than soybean crops. Enzyme additives can improve the utilization of cassava peel in monogastrics, and replace other protein sources by 10-25%, and even higher if mixed with other parts of the plant or silage.

Rice Bran

Rice bran is the most important rice by-product, obtained after polishing brown/rough rice to produce white rice, and represents around 10% of the weight of the grain. More than 40-45 million tons of rice bran are produced annually, mainly in Southeast Asia and Far East Asia.

It is the most nutritious part of the grain, comparable with other cereal by-products in amino acid profile and even superior to some grains. Rice bran contains about 14% protein, 7-10% fiber and ~18% oil. Rice bran fiber is similar to wheat bran in composition, as it is rich in pentosans, especially arabinoxylans.

Bran protein and fat are of relatively high biological value, although full nutrient potential is not available due to the presence of antinutritional factors, like endogenous lipase and peroxidase enzymes, which start the oxidation of fats during rice processing; trypsin inhibitors, phytate and hemagglutinin-lectin.

Rice bran oil has over 70% of unsaturated fatty acids and a high content of essential fatty acids. Linoleic acid is proven to improve laying potential and egg weight. On the other hand, this presence of oil may limit its use because of the risk of rancidity during storage if the bran is not de-fatted, that may lead to feed refusal by animals, especially young ones.

Only around 18% of the phosphorus in rice bran is available, being the rest in the form or phytate complexes or phytic acid, which reduces the phosphorus availability and can impair the use of other minerals. The inhibition of digestive enzymes, like trypsin, may also affect feed digestibility and energy use.

Extrusion has been reported to be a viable method to stabilize the oil in rice bran and extend its shelf life, although its economic cost factor should be considered. The use of feed enzymes, like phytases, aimed to improve the nutritive value of rice bran. Supplementation of the rice-bran based diets with phosphates is also common.

Several studies demonstrate that rice bran can be included in livestock, chicken, and aquaculture feed as a useful energy source, combined with a local feedstuff, substituting the imported ingredients, to reduce the feed costs with no adverse effect in the performance, compared to standard commercial diets.

A maximum of 10-20% is recommended in chicken diets. Non-defatted rice bran is also a useful binder in mixed feeds. In the case of aquaculture, the oil content offers an advantage in buoyancy of the feed, reducing feed wastage.

The processing of rice provides a mixture of hulls and bran. Thus, the offal of the processing can erroneously be marketed as rice bran but still contain rice hull. Hulls addition may significantly change its nutrient composition, as they are rich in silica, and may have harmful effects to the animals. Testing rice bran for silica is recommended to avoid this situation.

The stabilization of the oil and the absence of hulls offers to rice bran the category of a high nutritive ingredient, which is sometimes undervalued in feed formulation and commodities market and considered a value-added product to include in small amounts.

The surge in wheat and corn prices during the last months has diminished the price difference between wheat and rice. Some low grades of rice, or broken rice, could be of the interest in animal feeding if the wheat and maize high prices persist.

Palm Kernel Cake

Palm kernel cake (PKC) is a by-product of palm oil extraction obtained through press or solvent extraction. Oil palm by-products are important in Southeast Asia, because of its large crop areas.

Because of this, PKC is an important locally available and inexpensive agricultural product that is being used quite extensively as a protein supplement in feed formulation.

These crops are common in tropical rain countries and the largest producing and exporting countries of palm oil and palm oil by-products are Indonesia and Malaysia, accounting for around 80% of the total production.

PKC is rich in protein and carbohydrates, and it is considered to be a partial replacement of soybean meal and corn in poultry diets. Palm kernel cake contains around 14-18% of protein, 12-20% of fiber and 3-10% fats. Fat content depends on the method of extraction: more fat is present in PKC obtained from the mechanical expeller than from the solvent extraction technique.

PKC is a highly fibrous and medium grade protein feed, commonly included in ruminant’s feed formulation. The inclusion level in poultry diets is limited (6-8%) due to the digestibility of the fiber content, although it is very variable depending on the quality of PKC, source and processing or treatments applied. Enzyme additives to improve fiber digestion in monogastrics will positively impact the available energy and allow to increase the inclusion rate to 10% or more.

PKC is an important feed commodity and 90% of its production is exported. More extensive use in its countries of origin of this by-product would help to fill the gap created in this trade war and reduce the dependance on imported soybean meal, offer a fresh and highly palatable ingredient, and reduce the problems of effluent disposal and pollution.

Conclusions

In order to comply with the local demand of feed commodities in Southeast Asia in the current prices’ situation occurring worldwide, alternative sources of energy and protein to corn and soy, including other grains and processing byproducts are being considered. Locally available alternatives can prevent raw material shortages and reduce feed costs.

There is a vast potential for increased utilization of local sources of carbohydrates, like cassava or rice bran, and protein, like palm kernel cake, for animal feed in Southeast Asia. Understanding these ingredients and their limitations will help nutritionists use it in feed formulation with confidence.

Sources:

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• David J. Farrell (1994) Utilization of rice bran in diets for domestic fowl and ducklings, World’s Poultry Science Journal, 50:2, 115-131, DOI: 10.1079/WPS19940012
• Howeler, R. (2018). Trends in Production and Utilization of Cassava in Asia and its Potential as a biofuel. Conference paper
• Lukuyu, B; Okike, I.; Duncan, A.; Beveridge, M.; Blümmel, M. (2014). Use of cassava in livestock and aquaculture feeding programs. CGIAR. ISBN: 92–9146–348–5.
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