Strategies to improve forage fiber digestibility can increase dairy sustainability. Reducing lignin content through natural breeding or genetic engineering can improve DMI, neutral detergent fiber (NDF) digestibility and feed efficiency. A 60 mid-lactating cow experiment was carried out to compare production and nutrient digestibility responses to low-lignin vs. conventional alfalfa hay. The 3 treatments provided 0% (conventional), 50% (blend) and 100% low-lignin alfalfa; all diets contained 31.8% alfalfa on a dry matter (DM) basis. Low-lignin alfalfa decreased total-tract NDF digestibility and milk fat concentration in a dose-dependent manner. All other nutrient and production parameters were unaffected. Therefore, observed NDF digestibility and milk fat results suggest that the low-lignin alfalfa provided less physically effective fiber, failing to demonstrate obvious benefits. Another strategy for improving NDF digestibility involves use of different trace mineral supplements. In a small meta-analysis that included 8 studies and 12 comparisons in both sectors, beef and dairy, effects of hydroxy vs. sulfate trace minerals (TM) on nutrient digestibility and DM intake were investigated. Study design, sector and method of digestibility analysis were the factors included in the analysis. Hydroxy TM increased DM digestibility only in beef cattle and NDF digestibility, which was affected by digestibility analysis method. Total collection studies showed the greatest benefit, followed by use of undigested NDF as a digestibility marker, but 24-h in situ approaches did not show any significant response. In conclusion, adopting multiple strategies for optimizing fiber digestibility might help the dairy industry achieve greater feed efficiency goals.
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