What was previously discarded in cassava crops can become an alternative to feed livestock during the drought in Mato Grosso. In partnership with the Mato Grosso Research, Assistance and Rural Extension Company (Empaer), researchers from the Federal University of Mato Grosso (UFMT) are developing a study that uses the aerial part of cassava — the upper third of the plant usually discarded — as a nutritious, sustainable and low-cost supplement for animal feed, especially during the dry period in the state.
The study is developed by the Study and Extension Group on Forage Culture and Forage Conservation (GEFOR), linked to the Faculty of Agronomy and Zootechnics at UFMT, under the guidance of professor Dr. Joadil Gonçalves de Abreu. According to him, the proposal is to offer a nutritious and low-cost alternative to reduce the impacts of pasture scarcity during the drought, one of the main challenges faced by livestock farmers in the region.
Empaer has been carrying out research with cassava since 2012, seeking to identify cultivars best adapted to the different regions of Mato Grosso and increase productivity. In addition to research, the institution works to bring results to farmers through cassava top branches, field days, technical meetings and guidance for producers.
At UFMT, the research is still in its initial phase. To date, some cassava varieties intended for industry have been analyzed. The varieties of table cassava still need to be evaluated. After completing the analyses, the results can be published and presented to producers, including during field days promoted by the university.
Table cassava is that produced mainly for human consumption, such as cassava cooked or used in recipes.
Industrial cassava is cultivated mainly for the production of flour, starch, starch and other derivatives.
The nutritional power hidden in cassava
Traditionally, cassava is cultivated with a view to selling its roots and using the thick stem for new plantings. The top leaves and branches, however, are often left in the field. GEFOR's research, carried out in partnership with Empaer — through researcher and agronomist Dr. Dolorice Moreti — identified that this discarded material is a true "superfood" for cattle.
During the dry season, conventional pastures suffer a drastic drop in quality, recording around 5% to 6% of crude protein. In order not to lose weight, an ox needs at least 7%.
"The aerial part of cassava, in our data, exceeded 15% of crude protein, reaching more than 20% in some specific cultivars, it is a food that, in addition to maintaining the animal, guarantees weight gain in the middle of a drought" highlighted Professor Joadil.
In addition to the high quality, the productivity is impressive. In field tests, the crop reached the mark of 28 tons of green mass per hectare. For comparison purposes, corn hybrids used for silage produce around 35 tons. The proximity of the numbers surprises researchers, given that cassava is not even a genetically improved crop for producing leaves, but rather roots.
"When we compare the production of green mass, we realize that cassava is close to the productivity of corn for silage, but with a great advantage: it withstands dry periods much better", highlights Joadil.
Genetic validation in the field
The work at Empaer consists of validating the behavior of these genetic materials (from Embrapa, IAC and other bodies) in different regions of the state. At the Tangará da Serra Experimental Field, the institution today maintains an impressive living bank:
70 genetic materials from table cassava (white, yellow and pink pulp);
25 cassava genetic materials aimed at industry.
In addition to the development of more productive cultivars, research also monitors the evolution of technologies adopted by farmers. According to the researcher, in recent years producers have started to invest more and more in soil analysis, fertility correction, fertilization and irrigation, practices that enhance the performance of improved varieties.
"We don't just evaluate productivity. We observe disease resistance, culinary quality, starch content, plant architecture and adaptation to different regions of the state. The objective is to recommend materials to the producer that really bring economic returns", stated Dolorice.
Before being offered to animals, the part of the cassava that is above the ground needs to go through a drying period. According to Professor Joadil, this process reduces the presence of a natural substance in the plant that can release toxic compounds and cause health problems in animals when the material is still wet.
"The only precaution that we always emphasize is drying. The producer cannot chop and provide the wet material to the animal, because there is a risk of death from asphyxiation due to the presence of hydrocyanic acid. After the material dries, this compound volatilizes and the food can be used safely", explains the professor.
The solution found by the group is simple, cheap and efficient: hay production.
Chopping: The material is crushed into pieces of approximately 2 centimeters.
Drying: The contents are laid out on plastic sheets in the sun and turned over every hour. As hydrocyanic acid is volatile, it evaporates completely during the process.
Salt Test: To check if it is done, students mix the material with table salt; If the salt does not stick to the plant, the hay is ready and completely safe to eat.
The average proportion is that one ton of green mass results in 200 to 300 kg of hay. This amount is enough to feed up to 25 adult animals for one day, considering the average consumption of 10 kg per head per day.
In addition to being used for personal consumption, bagged hay appears as a new source of income for farmers who do not have a herd, allowing the by-product to be sold to cattle, goat and sheep breeders in the region.
Training of new professionals
In addition to the laboratories, the project fulfills a fundamental social and pedagogical role. The students and technological initiation scholarship holders (PIBITI), João Henrique (7th period of Agronomy) and Camila Neves (9th period of Animal Science), face the heavy routine of the field on the UFMT experimental farm to make the research happen.
"During the drought it is very complicated. There were times when we needed to go on the weekend to be able to irrigate the experimental field due to the routine full of classes" [...] "Many producers throw this away due to lack of information. Passing on this knowledge and seeing that practice resolves bottlenecks that theory alone does not show is gratifying," reports João Henrique.
Camila also reinforced the economic impact of the sustainable alternative.
"Many want to use only corn, which is expensive. Cassava is rustic, cheap and requires little fertilization. This experience opens our minds to helping small producers grow," adds Camila.
Research continues to expand
Even with the promising results, Dolorice said that the work has just begun and that the research needs to be permanent to keep up with the demands of the sector.
"Research needs to be continuous and dynamic, because new problems and new technologies always arise and need to be evaluated. Today in Tangará, we have around 70 table cassava genetic materials and another 25 intended for industry. Many have already been evaluated and others are still in the multiplication phase. We need to guarantee conditions to continue this work", he highlighted.
Next steps
The partnership between UFMT and Empaer plans to hold, at the beginning of the next agricultural year, a Field Day aimed at rural producers in Santo Antônio de Leverger and the region. During the event, the students involved in the research, together with Professor Joadil, will present the techniques for using the aerial part of cassava, the production of hay and the new cultivars evaluated. The activity will also present ways of using the plant and the results obtained in the study.
