R. Bras. Zootec.01/Jul/2017;46(7):599-605.
In vitro fermentation characteristics of ruminant diets using ethanol extract of brown propolis as a nutritional additive
The addition of levels of ethanol extract of brown propolis was evaluated by assessing diet degradation in rumen fluid and predicting cumulative in vitro gas production by nonlinear (dual pool logistic and exponential) models. A total of 35 g of crude propolis were extracted in 65 mL of cereal alcohol (95% ethanol). In a completely randomized factorial design, the experimental diets combined four concentrations of extracted propolis diluted in cereal alcohol (0, 50, 70, and 100% of propolis extract) and supplementation doses (4, 8, 12, 16, and 20 mL/kg dry matter), tested in triplicate. Diet (400 g/kg Tifton hay and 600 g/kg concentrate) was incubated for 96 h carried out three times in three different weeks. There was significant interaction between extract concentration and dose on the dry matter (DM) degradability. Dry matter degradability of diet decreased exponentially as a function of the increase in dose (y = 678.55×dose–0.271). Pure alcohol treatment showed a negative exponential effect, with degradability of 303.61 g/kg when administered at a dose of 20 mL/kg DM. Treatment 100% ethanol extract reached the greatest degradability, estimated at 18.93 mL/kg DM. The treatment with 70% extract showed 6.35 mL/kg DM and the 50% extract, 7.65 mL/kg DM of minimum degradability. The reduction potential of pure ethanol was –0.32 mL gas/mL. Estimates of maximum gas production by dual pool logistic and exponential models were 13.10 mL and 12.07 mL for 100% extract, respectively. The 100% extract produced the highest gas production estimates, above 30 mL gas/100 mg DM of fermented diet. The degradation and fermentation of ruminant diet can be improved using 13 mL/DM kg of ethanol extract of propolis.