Solid-state fermentation with Saccharomyces cerevisiae and Lactiplantibacillus plantarum improves the chemical composition, in vitro digestibility, and sensory characteristics of Sporobolus pyramidalis as a potential goat feed
Abstract
Sporobolus pyramidalis is an invasive grass that has dominated vast areas of rangelands globally; however, its utilization as animal feed is severely limited by poor palatability, a tough texture, and low digestibility. This study evaluated the potential of solid-state fermentation using locally available starter cultures (Saccharomyces cerevisiae and Lactiplantibacillus plantarum; LAB) to enhance the nutritional value, digestibility, and palatability of Sporobolus pyramidalis as goat feed. The experiment comprised four treatments: an unfermented control (T1), yeast fermentation (T2), LAB fermentation (T3), and yeast-LAB co-culture (T4), with proximate composition, fiber fractions, pH, digestibility, texture scores, and aroma profiles assessed following fermentation. Results demonstrated that yeast fermentation (T2) was the singularly most effective treatment, producing the highest crude protein content (7.26 ± 0.01%) exceeding the reported 7% crude protein benchmark for goat maintenance. T2 also resulted in the lowest fiber fractions (CF: 32.8 ± 0.03%; NDF: 69.10 ± 0.01%), the lowest pH (4.70 ± 0.17) as well as the highest in vitro dry matter digestibility (58.01 ± 1.10%). In addition, T2 resulted in the softest physical texture, alongside a desirable fruity and alcoholic aroma. In contrast, LAB (T3) and co-culture (T4) treatments failed to improve CP or reduce fiber, yielding values statistically similar to the control (CP ~5.3%; CF ~34-36%; NDF ~72.1%), with the co-culture demonstrating clear antagonistic interactions. A significant reduction in ash content was observed across all fermented treatments (lowest in T3 at 2.88 ± 0.01%), raising concerns about potential mineral losses. The study concludes that yeast fermentation alone is an effective, low-cost biological strategy for upgrading S. pyramidalis for goat production. The validation of these findings through comprehensive in vivo feeding trials will be instrumental in developing practical and sustainable strategies for improving forage quality in resource-limited tropical production systems.