A meta-analysis of the impact of an Aspergillus oryzae fermentation product on ruminal fermentation and dairy cow performance

Abstract

There is evidence that some fermentation products from yeast and fungi have positive effects onanimal performance. However, results from different sources are inconsistent due to variations intypes of diets or other factors across experiments. Therefore, our main goal was to evaluate theeffects of feeding a fermentation product derived from the fungus Aspergillus oryzae (AO) on dairycows’ performance through a meta-analysis from published literature. A database from experimentsinvolving AO supplementation to dairy cows was built. In vivo experiments reported inselected peer-review papers published from 1984 to 2019 and 1 unpublished record wereincluded. A total of 26 studies comprising 76 treatment means were pooled in the database. Datawere analyzed by the means procedure of SAS (SAS 9.0, SAS Institute Inc., Cary, NC). When dairycows received AO as a supplement, milk yield and fat corrected milk were significantly(P < 0.0001) increased. Decreased milk fat and protein content was also found (P < 0.0001),probably because of the increased milk yield. Nutrient digestion, except for crude protein, wasenhanced by AO supplementation (P < 0.0001). As the increase in dry matter intake from AOtreatment does not fully explain the rise in milk production, it is likely that AO also influencesnutrient bioavailability and partitioning for productive purposes. Our results indicate that AOshows a consistent response in milk production across feeding situations (season and feedingsystems) and diets (forage type and level of concentrate), partly boosted by an increase in drymatter intake and by improvements in dry matter digestibility. Future work should focus onimproving our understanding of the mode of action and, especially, how AO can affect the immuneresponse in high-producing dairy cows.