Nutritional value of commercial broiler feed supplemented with olive mill waste fermented with probiotic Rhizopus oryzae strains.

AIMS: The changes in chemical composition and metabolizable energy (ME) of both olive mill waste (OMW) upon fermentation by three potential probiotic Rhizopus oryzae strains and commercial feed (CF) upon its supplementation by fermented olive mill waste (FOMW) were investigated. The objective was to test whether there will be an enhancement in the nutritional value of OMW after fermentation and/or commercial broiler feed upon supplementation by potentially probiotic filamentous fungi. METHODS AND RESULTS: A three Rhizopus oryzae strains (92/1, 236/2 and 284) isolated from agricultural soil that were proven to have good probiotic properties (non-toxic, antimicrobial activity, antioxidant capacity and gastrointestinal tolerance) were used to ferment OMW, then the chemical composition was analysed after 7 and 14 days of fermentation. The FOMW with the R. oryzae 284 strain, which gave the best results, was added to a commercial broiler feed at 20%, 30% and 40% supplementation ratios. Then proximal analyses were done to compare non-supplemented with supplemented CF. Chemical analyses included dry weight, crude protein, crude fats, crude fibres, crude ash, sugars and starch, and then ME was calculated from the given values. CONCLUSIONS: Compared to non-fermented OMW, the best results were obtained by the R. oryzae 284 strain allowing an increase in crude protein content by 23.4% after 7 days of fermentation, a decrease in crude fibre content by 9.8% after 14 days of fermentation and an increase in ME by 3.6% after 7 days of fermentation. Compared to non-supplemented CF, the ME changes of 20%, 30% and 40% supplementation increased by 8.38%, 2.83% and decreased by 4.27%, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: FOMW can be incorporated into broiler feed rations until 30% without causing any decrease in metabolizable energy. It can be a cheaper alternative with promising productivity and chicken health improvements.

Functional properties of Rhizopus oryzae strains isolated from agricultural soils as a potential probiotic for broiler feed fermentation.

The most crucial and expensive fragment in the broiler chicken production industry is the feed. Because of the rising demand, finding a cheap and effective feed is an urgent necessity. Fermentation of broiler feed by probiotic fungal starters can enhance the nutrient's availability and digestibility while preventing pathogenic growth. In this study different Rhizopus spp. have been isolated from agricultural soils around Izmir, Turkey, and tested for their probiotic potential and fermentative capacity. The isolated Rhizopus strains first underwent microscopical fluorescent investigation to exclude endofungal bacterial presence, then, those without endofungal bacteria (totally 82) were tested for antimicrobial activity counter bacterial and fungal pathogens. The ones with wide-spectrum antimicrobial activity (totally 10) were tested for gastrointestinal tolerance and antioxidant ability. Upon phenotypic and genotypic identification, the 10 isolates were found to belong to Rhizopus oryzae species. While all 10 strains showed variable gastrointestinal tolerance and antioxidant activities, three of them (92/1, 236/2, and 284) had relatively high antioxidant activity. Upon fermentative capacity assay, compared to unfermented commercial feed, there was a general decrease in crude fiber content by 56% after fermentation by 92/1 isolate for 4 days and 236/2 isolate for 2 days. The highest increase in crude protein content (by 14.5%) occurred after a 4-day fermentation period by 236/2 isolate. The highest increase in metabolizable energy was 8.64%, by the 284 isolate after 2 days of fermentation. In conclusion, the three strains showed good probiotic properties and fermentative capacities hence can be beneficial for the poultry industry.