Qualidade da parte aérea da mandioca in natura e fenada das cultivares boi-tatá e paraguaia produzidas no inverno na região Sul do Brasil

Abstract

The aerial part of cassava (Manihot esculenta) has stood out as a promising alternative forage for ruminants, especially during periods of forage scarcity, due to its good nutritional composition and wide availability. However, the method of preservation, whether fresh or as hay, can significantly alter the chemical quality, digestibility, and microbiological profile of the material. Furthermore, during storage, the presence of filamentous fungi can compromise the stability and safety of the feed through the production of mycotoxins. Therefore, this study aimed to evaluate the proximate composition, in vitro digestibility, protein and non-fibrous carbohydrate fractionation, as well as the microbiological characteristics of the aerial part of cassava from the Boi-tatá and Paraguaian cultivars, preserved in fresh and hay forms during the winter. The plants were harvested between June and July, 30 cm above the ground, shredded, and sun-dried for 20 days. Sixteen samples were collected for proximate analysis, in vitro digestibility, protein fractionation, and microbiological evaluation. Haymaking promoted an increase in dry matter, neutral detergent fiber, acid detergent fiber, and lignin contents, and a reduction in the soluble protein fraction (fraction A) and in vitro dry matter digestibility. On the other hand, an increase in crude protein and fiber digestibility was observed, as well as a reduction in the indigestible protein fraction (fraction C), indicating greater utilization of the less degradable fractions. The two cultivars showed similar nutritional behavior. In the microbiological analysis, the hay from the Paraguaian cultivar showed a higher fungal count, while the Boi-tatá cultivar showed a predominance of yeasts. The identified genera Fusarium, Penicillium, Aspergillus, and Cladosporium are considered spoilage and potentially toxic fungi, as they can produce mycotoxins, that are harmful to animal production. It is concluded that the aerial part of cassava has high potential as an alternative forage, maintaining relevant nutritional quality even after the haymaking process under winter conditions, provided that good drying and storage practices are adopted to minimize the growth of undesirable fungi.