Effect of dried extracts of Aspergillus oryzae and their association with Saccharomyces cerevisiae on mid lactation dairy cattle productivity under moderate heat stress conditions.

A trial was conducted in Parmigiano Reggiano area with the aim to study the effects of Aspergillus Oryzae fermentation extract pure or in association with Saccharomyces cerevisiae yeast as direct feed microbials on the productivity and milk quality of dairy cattle diet during moderate heat stress. Twelve Holstein multiparous cows with average parity of 2.7 and average DIM of 193, were involved in sequential study design of three periods of 21 days including 14 days of adaptation and 7 days of measurements and sampling. During the first period animals were treated with 7 g/d of a commercial product containing 50% of Saccharomyces cerevisiae yeast as direct feed microbials and 50% of fermentation extracts of Aspergillus oryzae –treatment “SC+AO”-. During the second period animals were fed the base diet –“CON”- while during the third period the diet included 7 g/cow/d of fermentation extracts of Aspergillus oryzae –treatment “AO”-. Diet was composed of a mix of hays, straw, soybean meal and a commercial protein mix including mineral and vitamin supplement and was administered as Total Mixed Ration (36.18% NDF, 14.18% CP, 24.07% Starch). Measurements included environmental temperature and humidity (to calculate Thermal Humidity Index –THI-), group feed intake and orts, individual milk production (daily), BCS, fecal score (FS) and rectal temperature (RT) (twice weekly). Sampling included diet collection, individual faeces and individual milk (twice a week). Milk composition, diet composition and indigestible NDF (uNDF) and faeces uNDFwere determined to calculate in vivo NDF digestibility (NDFD) and dry matter digestibility (DMD). Statistical analysis of data was performed using the SPSS for windows (vers.21); the repeated measures procedure of the GLM model was adopted using THI as covariate. The treatment AO induced an increase of dry matter intake (25.55 vs. 23.93 and 22.12 kg of CON and SC+AO thesis; P<0.001), of in vivo NDFD (53.18 vs. 48.49 and 49.23 %NDF; P<0.05) compared to the other treatments and of in vivo DMD with respect to the CON group (70.50 vs. 69.06; P<0.05). AO has also been observed to decrease rectal temperature (38.31 vs. 38.77 and 38.80°C; P<0.01). Energy Corrected Milk production such as the percentage of protein and LDG parameters (r and A30) appeared improved. Dried extracts of Aspergillus orizae had some beneficial effects on DMI, showing a higher activity if compared with SC+AO, but did not heavily affected milk production and quality