Processed barley grain mitigates the adverse effects of starch-rich diets in lactating Holstein cows

High-starch diets, commonly formulated with barley grain (BG), can impair ruminal function and trigger systemic inflammation in lactating dairy cows.

The present study investigated the effects of different forms of BG on rumen fermentation, immune-related gene expression, and systemic inflammation in Holstein cows fed starch-rich diets.

Twenty-seven lactating Holstein cows (three fistulated and six non-fistulated per treatment) were randomly assigned to three dietary groups: untreated BG (BG_CTRL), BG processed with 5% lactic acid (BG_LA), or BG processed with sugar beet pulp extract (BG_SBPE). Cows received a basal total mixed ration for two weeks, followed by one week of high-starch experimental diets.

Cows fed BG_LA (5.97) and BG_SBPE (5.85) had significantly higher ruminal pH compared to BG_CTRL (5.55; P<0.05), along with shorter durations of pH<5.8 (61.35, 182.93, and 362.98 min/day for BG_LA, BG_SBPE, and BG_CTRL, respectively; P<0.05). The acidosis index was reduced from 18.10 in BG_CTRL to 8.13 in BG_SBPE and 3.05 in BG_LA. Also, BG_LA reduced ruminal E. coli abundance (P<0.001), while Megasphaera elsdenii was lower in BG_SBPE than in BG_CTRL (P<0.001). Both processed BG diets significantly decreased serum haptoglobin and serum amyloid A, and reduced mRNA expression of CD14, TLR4, and MD2.

Processing BG with lactic acid or sugar beet pulp extract mitigates the adverse effects of high-starch diets on rumen health and systemic inflammation in lactating dairy cows.