Effects of Supplemental Virgin Coconut Oil and Condensed Tannin Extract from Pine Bark in Lactation Dairy Diets on Ruminal Fermentation in a Dual-flow Continuous Culture System

Abstract

The objective of our study was to investigate effects of virgin coconut oil (VCO) and condensed tannin extract from pine bark (PCT), either separately or in combination, as supplements to lactation dairy diets on in vitro ruminal fermentation profiles in a completely randomized design with four independent runs of continuous cultures. Four dietary treatments included: 1) control [CONT; total mixed ration (TMR) without supplement], 2) TMR with VCO (VCOT), 3) TMR with PCT (PCTT) and 4) TMR with VCO and PCT (VPT). Results showed that culture pH was maintained at least at 6.13 across dietary treatments, and supplementing VCO and/or PBE did not influence culture pH. Total volatile fatty acid concentration was similar in response to the supplements. Supplementing PCT decreased ammonia-nitrogen concentration both in PCTT and VPT (P<0.01), while VCO supplementation resulted in no effect on ammonia-nitrogen concentration. Cultures offered VCO and PCT supplementation, either separately or in combination, showed no response on methane production. The decrease in ammonia-nitrogen concentration when PCT-containing diets (PCTT and VPT) were offered is likely attributed to condensed tannins in PCT, which indicates that PCT can affect dietary nitrogen utilization efficiency in vivo through condensed tannins on ruminal nitrogen metabolism. However, dietary concentration of VCO used in this study may have not been enough to manipulate ruminal fermentation.