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

BACKGROUND

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

AIMS: 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.

METHODS

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

RESULTS

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

CONCLUSION

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.