Dose–response effect of a pine bark extract on in vitro ruminal ammonia and methane formation kinetics

ABSTRACT

This study assessed the potential of a pine bark extract (PBE) to decrease methane (CH₄) and ammonia nitrogen (NH₃-N) production in vitro. Dietary substrates, mixed hay, soybean meal and corn grain, were supplemented 0, 2, 4 and 6% of PBE and incubated in an in vitro batch culture for 24-h. Incubations were run three times. Total gas production (GP) was determined at 6, 12 and 24-h and gas samples were analysed for CH₄. Samples were collected for volatile fatty acids (VFA) and NH₃-N analysis. Treatments were compared by polynomial contrasts for PBE concentration. Increasing PBE caused linear decreases in NH₃-N, microbial biomass production and digestibility, whereas the degradation rate was quadratically reduced. Total VFA were decreased but total GP and CH₄ production and kinetics were unaffected. The inclusion of 2% PBE in ruminant feed has the capability to reduce NH₃-N concentration by 50%, without affecting diet digestibility or CH₄ production.