Abstract
Background:
Palm kernel meal (PKM) is a by-product of the palm oil industry with considerable potential as a poultry feed ingredient. However, its utilization is limited due to its high crude fiber content and relatively low nutritional value.
Microbial fermentation has been widely recognized as an effective strategy to improve feed quality through fiber degradation and enhanced nutrient availability. Previous studies have demonstrated that Bacillus subtilis and Saccharomyces cerevisiae individually improve the nutritional characteristics of feed materials through enzymatic activity and microbial protein synthesis. Nevertheless, studies evaluating the combined fermentation of palm kernel meal using these microorganisms remain limited, particularly regarding their potential synergistic effects on nutrient enhancement and fiber reduction for poultry feed utilization.

Aim:
This study aimed to evaluate the effects of fermenting palm kernel meal using Bacillus subtilis and Saccharomyces cerevisiae, either individually or in combination, on its nutritional value for poultry feed application.

Methods:
A completely randomized design with four treatments and five replicates was employed. The treatments consisted of: A (unfermented palm kernel meal), B (fermentation with Bacillus subtilis), C (fermentation with Saccharomyces cerevisiae) and D (combined fermentation with Bacillus subtilis and Saccharomyces cerevisiae). The evaluated parameters included dry matter, gross energy, crude protein, crude fiber, crude fat, calcium and phosphorus. Data were analyzed using analysis of variance (ANOVA) and Duncan’s multiple range test was applied when significant differences were detected at P < 0.05.

Results:
Fermentation significantly improved the nutritional profile of palm kernel meal by increasing gross energy and crude protein content, while decreasing dry matter, crude fiber and crude fat levels (P < 0.05). No significant differences were observed in calcium and phosphorus content (P > 0.05).

Conclusion:
Combined fermentation using Bacillus subtilis and Saccharomyces cerevisiae resulted in higher crude protein and lower crude fiber content, indicating improved nutritional quality of palm kernel meal. These findings suggest its potential for further development as an alternative poultry feed resource.

Key words: Bacillus subtilis; Fermentation; Palm kernel meal; Poultry feed; Saccharomyces cerevisiae.