ABSTRACT

Background and Aim: Cassava pulp is an abundant agro-industrial by-product in tropical regions but has limited feeding value because of its low crude protein (CP) content and high structural fiber concentration. Microbial fermentation may improve its nutritional value and increase its use in ruminant diets. This study aimed to optimize cassava pulp fermentation using Saccharomyces cerevisiae, Rhizopus oligosporus, and pectinase and to evaluate the effects of optimized fermented cassava pulp (FCP) inclusion on in vitro nutrient digestibility and ruminal fermentation.

Materials and Methods: The first phase used a factorial arrangement under a completely randomized design to evaluate two pectinase treatments, four microbial treatments, and fermentation periods of 5, 10, and 15 days. Nutritional responses included dry matter (DM), CP, neutral detergent fiber (NDF), and acid detergent fiber (ADF). Based on nutrient enhancement, process efficiency, and practical feasibility, cassava pulp fermented with R. oligosporus without pectinase for 10 days was selected for the second phase. The optimized FCP was incorporated into total mixed ration (TMR) diets at 0%, 30%, 45%, and 55% of DM. In vitro DM digestibility (IVDMD), NDF digestibility (IVNDFD), ADF digestibility (IVADFD), ammonia nitrogen, total volatile fatty acids (TVFA), and individual volatile fatty acid (VFA) profiles were evaluated.

Results: The three-way interaction among enzyme treatment, microbial inoculation, and fermentation duration did not significantly affect the major chemical composition variables. However, enzyme treatment significantly influenced CP, NDF, and ADF. Fermentation with R. oligosporus without pectinase for 10 days provided the most favorable nutritional profile and was selected for subsequent evaluation. Increasing FCP inclusion increased IVDMD, while 45% inclusion significantly improved IVNDFD and IVADFD compared with lower inclusion levels. Ammonia nitrogen concentrations varied during incubation but remained within physiologically appropriate ranges. TVFA concentrations and individual VFA profiles were not adversely affected by increasing FCP inclusion.

Conclusion: Fermentation of cassava pulp with R. oligosporus for 10 days without pectinase improved its nutritional quality and supported enhanced fiber digestibility when incorporated into TMR diets. Inclusion levels of approximately 45%–55% warrant further evaluation in in vivo feeding trials to confirm effects on nutrient utilization and animal performance.

Keywords: cassava pulp, fermented feed, fiber digestibility, in vitro digestibility, Rhizopus oligosporus, ruminal fermentation, solid-state fermentation, total mixed ration.