Top international researchers will meet with decision makers, business people, and other stakeholders working in the Nigerian cassava sector in the International Institute of Tropical Agriculture (IITA) in Ibadan, 28 to 30 October. The meeting aims to draw a roadmap for a cassava-based animal feed system that will highlight action plans for adding value to the cassava business in Nigeria. The roadmap will have a potential to serve as a model for all cassava-producing countries in Africa.
"We need to seize this opportunity and harness the benefits of every part of the cassava crop for national development, income generation, nutrition enhancement, and poverty alleviation," says Dr Kenton Dashiell, IITA Deputy Director General, Partnerships and Capacity Development.
Nigeria, the world's top cassava producer, is transforming its cassava sector and strengthening the value chain of the root crop to make it more competitive. Reforms in cassava-growing countries in Africa, backed by supportive government policies and improved varieties developed by agricultural research centers have significantly raised the productivity of cassava. In Nigeria, annual production of cassava climbed to 52.4 million tons in 2011.
The increase in production of cassava roots is also generating 5 – 7.5 million tons of wet peels (10 – 15% of whole tuber), as farmers and industry rev up processing of cassava. Dr Iheanacho Okike, a researcher with the International Livestock Research Institute (ILRI) based in IITA, says the peels could contribute largely to the income of farmers, and provide additional economic options for livestock and fish producers if converted to animal feed. Additional benefits accrue to consumers due to increased production of milk, meat and fish, and the additional availability of maize and other grains that could otherwise have gone into the feed system.
The IITA-hosted meeting involves representatives from many international research institutes and is organized by the Global Cassava Partnership for the 21st Century, the CGIAR Research Program on Roots, Tubers and Bananas (RTB) and co-hosted by the Federal Ministry of Agriculture and Rural Development (FMARD).
As the second most important food crop in the least developed countries and the fourth most important source of food energy in the world after wheat, maize, and rice, cassava is generally grown by small holder farmers, who appreciate its tolerance of drought and poor soils, one of the reasons why the root crop has been dubbed "the crop of the 21st century."
Cassava also holds great posth arvest potential as food for the household, feed for livestock, and raw material for a wide array of value-added products – from coarse flour to high-tech starch gels. Both the roots and leaves can be directly fed to livestock, or used in producing commercial feed.
According to the Food and Agriculture Organization, "animals raised on cassava have generally good health, good disease resistance, and a low mortality, and require few, if any, antibiotics in their feed."
Dr Claude Fauquet, GCP21 Director notes that "When the cassava transformation agenda of Nigeria is completed, the production of cassava by-products (peels) is expected to reach 2 million tons dry matter per year, this is the perfect time to set up a feed manufacturing system on an industrial scale."
Cassava peels as a feed ingredient
Cassava peels can represent 5 to 15% of the root. They are obtained after the tubers have been water-cleansed and peeled mechanically. They may contain high amounts of cyanogenic glycosides and have a higher protein content than other tuber parts.
Fresh cassava peels have 3 main deficiencies: they spoil very quickly, they contain phytates and large amounts of cyanogenic glycosides. They should thus be processed in order to reduce cyanogenic potential and phytate content and to preserve their nutritive quality. Different processes are effective in reducing cyanogenic glycoside including sun-drying, ensiling, and soaking + sun-drying. All these methods have yielded satisfactory results.
Good quality silage can be obtained after chopping the peels to equal lengths of about 2 cm for easy compaction, and wilting for 2 days to reduce moisture content from 70-75% to about 40%. Under these conditions, cassava peel silage after 21 days was light brown in colour, firm in texture and had a pleasant odor. The pH was 4.4, and no fungal growth was observed.
Studies have shown that solid fermentation of a mixture of cassava peels and waste water from fermented cassava pulp with Saccharomyces cerevisiae and Lactobacillus spp. resulted in a product with a higher protein content, lower cyanogenic glycosides and lower phytate content.
Well-processed cassava peels have generally acceptable levels of hydrogen cyanide (HCN), below 50 mg/kg. However, mass HCN poisoning has been reported before in a intensively managed Nigerian pig farm, where more than half of the herd died within a few hours after consuming boiled and overly ripe cassava peels from a bitter variety.
Cassava peels have a high phytate content (up to 1% DM), resulting in low P availability in non-ruminants. Fermentation can slightly reduce phytate content (down to 0.7%).
Cassava peels have a low protein content (< 6% DM) and a high and variable fibre content (crude fibre in the 10-30% DM range).