Abstract: Embodiments of the present invention relate to the use of tannin-containing wood products in animal feed to improve production efficiency and health of ruminants (e.g., sheep, goats, and cattle) by reducing internal parasite load, reducing methane and ammonia production in the rumen, and decreasing phosphor emissions from fecal waste. Embodiments include a domesticated ruminant feed comprising a condensed tannin. Certain embodiments relate to methods comprising administering condensed tannins to ruminant animals by incorporating pine bark or other suitable condensed tannin-containing wood products into regular animal feed.