Enriquecimento nutricional da palma forrageira (Opuntia ficus-indica Mill): estudo experimental de ampliação de escala.

Abstract

Conditions in the semi-arid region of northeastern Brazil has made farmers use cactus pear (Opuntia ficus-indica Mill) as a basic feed for their herds, since its use is possible all year round, mainly during long periods of drought. However, this cactus has a low protein and dry matter content when compared to other fodders used, and this brings unfavorable consequences to the herds, when used exclusively. Through research, in laboratory scale, performed at LEB/UAEQ/CCT/UFCG, the solid state fermentation process showed itself technically viable for the protein enrichment of the cactus. From the results obtained from these researches, it was verified that there is the possibility of performing its expansion to an experimental scale up, using simple methodologies that are of easy usage in the field. The objective of this research was to study the enlargement of the experimental scale up of the nutritional (protein, mineral, and energy) enrichment process of the fodder cactus pear with yeast Saccharomyces cerevisiae, through solid state fermentation, aiming at producing a nutritional supplement for animal feed. The influence of adding urea associated to the addition of the yeast over the crude protein (PC) content and the protein increase (PI) were also studied, as well as the use of tray bioreactors and rotating drums. The results of the preliminary tests suggest that the temperature of fermentation was a variable that didn’t present statistical influences over the answers studied, and that the greatest PI was found after 24 h of fermentation. With the analysis of the experimental data of posterior studies, it was verified that both with the usage of trays and with rotating drums, the conditions in which greater percentages of PC and PI were reached were the same, being: yeast concentration 3% and urea concentration 5%. In these conditions the fermentations performed in the two bioreactors reached an average of 45% of PC, which represents a PI around 6 times, having as base the content of crude protein of the natural cactus. In relation to time, in the fermentations performed in trays, the best time was 8 h and in the rotating drums this time was reduced to 4 h. The enriched cactus may be used as a nutritional supplement for animal feed, for it obeys the norms established by the NRC (1989) and can partially substitute conventional feed, becoming an alternative for decreasing the farmers’ costs. To store enriched cactus it is necessary that the ideal range of water activity be between 0.25–0.35, which corresponds to a moisture content (d.b.) less than 0.03, thus eliminating, any growth of microorganisms.