Effects of phenolic compounds on ruminal protozoa population, ruminal fermentation, and digestion in water buffaloes

• Phenolic compounds from honey bee propolis were identified and quantified.
• Phenolic compounds were dosed in the rumen of water buffaloes up to 50.8 mg/d.
• Phenolic compounds significantly changed ruminal protozoa population.
• Phenolic compounds linearly reduced ruminal Entodinium population in water buffaloes.
• Phenolic compounds quadratically increased ruminal acetate in water buffaloes.

The objective of this study was to evaluate different doses of phenolic compounds extracted from honey bees propolis on ruminal protozoa population, microbial protein synthesis, ruminal fermentation, solids’ passage rate, and total tract digestibility in water buffaloes. Four crossbred non-lactating female water buffaloes averaging 543.9±32.1 kg of body weight fitted with rumen cannulas were used in a 4×4 latin square design. The phenolic compounds were dosed in the rumen via rumen cannula in four doses: 0, 16.95, 33.9, and 50.85 mg/d; respectively. The total mixed ration consisted of 800 g/kg corn silage and 200 g/kg concentrate. Phenolic compounds linearly reduced the Entodinium protozoa population (P<0.01) and quadratically increased ruminal acetate concentration (P<0.05) and there was a trend to increase microbial protein synthesis in the rumen (P=0.07). Phenolic compounds did not change total digestibility of dry matter and nutrients, solids' passage rate, and the efficiency of microbial protein synthesis (P>0.05). It can be concluded that phenolic compounds reduce the Entodinium protozoa population in water buffaloes and change ruminal fermentation pattern, favoring acetate fermentation.