Evaluation of whole flaxseed and the use of tannin-containing fava beans as an alternative to peas in a co-extruded flaxseed product on ruminal fermentation, selected milk fatty acids, and production in dairy cows

This study evaluated the effects of whole versus extruded flaxseed and the use of tannin-containing fava beans as a replacement for peas in an extruded flaxseed-based supplement on rumen fermentation, selected milk fatty acids, and production in dairy cows. Eight Holstein cows were used in a replicated 4 × 4 Latin square consisting of 28-d periods. Cows were fed a control diet (CONT) or 1 of 3 diets that contained a whole flaxseed supplement (FLX), an extruded flaxseed and pea supplement (EXT; linPRO-R, O&T Farms Ltd., Regina, SK, Canada), or an extruded flaxseed and tannin-containing fava bean supplement (EXTT). Dry matter intake was less in cows fed FLX, EXT, and EXTT compared with those fed CONT (P = 0.006). Milk yield was greater in cows fed EXT (44.4 kg/d) compared with those fed FLX (42.3 kg/d; P = 0.023) and tended to be greater in cows fed FLX, EXT, and EXTT (average 43.5 kg/d) compared with those fed CONT (41.9 kg/d; P = 0.073). Milk fat percentage was less in cows fed FLX, EXT, and EXTT compared with those fed CONT (P = 0.033); however, milk fat yield was unaffected. The C18:3n-3 and cis-9, trans-11 conjugated linoleic acid fatty acids were greater in milk of cows fed EXT compared with those fed FLX (P = 0.001). No differences in milk fatty acid composition were observed between EXT and EXTT. These results demonstrate that feeding extruded flaxseed supplements containing peas or tannin-containing fava beans effectively improve milk yield and milk fatty acid profile when compared with whole flaxseed.