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 on animal performance. However, results from different sources are inconsistent due to variations in types of diets or other factors across experiments. Therefore, our main goal was to evaluate the effects of feeding a fermentation product derived from the fungus Aspergillus oryzae (AO) on dairy cows’ performance through a meta-analysis from published literature. A database from experiments involving AO supplementation to dairy cows was built. In vivo experiments reported in selected peer-review papers published from 1984 to 2019 and 1 unpublished record were included. A total of 26 studies comprising 76 treatment means were pooled in the database. Data were analyzed by the means procedure of SAS (SAS 9.0, SAS Institute Inc., Cary, NC). When dairy cows 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, was enhanced by AO supplementation (P < 0.0001). As the increase in dry matter intake from AO treatment does not fully explain the rise in milk production, it is likely that AO also influences nutrient bioavailability and partitioning for productive purposes. Our results indicate that AO shows a consistent response in milk production across feeding situations (season and feeding systems) and diets (forage type and level of concentrate), partly boosted by an increase in dry matter intake and by improvements in dry matter digestibility. Future work should focus on improving our understanding of the mode of action and, especially, how AO can affect the immune response in high-producing dairy cows.