September 16, 2021

Interpretive Summary: Digestibility Reduced Lignin Alfalfa Horses

Interpretive Summary: Digestibility Reduced Lignin Alfalfa Horses 

By: Caitlin Vonderohe

Alfalfa is a commonly used forage for horses with high nutritional requirements, but some of its utility as a highly digestible feedsource may be negatively affected by lignin content. Lignin is a complex phenolic polymer that increases plant rigidity and growth, but negatively interacts gastrointestinal microbial populations, limiting the total tract digestibility of the forage. Recently, reduced lignin-alfalfa cultivars were developed with the intention of improving digestibility, but limited work has been done to assess the utility of these cultivars as a forage for equines. Grev et al. recently published “ Apparent digestibility, fecal particle size, and mean retention time of reduced lignin alfalfa hay fed to horses” in the Journal of Animal Science, which assessed the potential benefits of feeding reduced-lignin hay to horses. 

Six horses were used to assess the digestibility of traditional and lignin-reduced alfalfa hay in a crossover design.  Horses received the experimental diets in hay nets. Experimental periods consisted of a 9-day adaptation phase, followed by a 5-day total fecal collection phase. Horses received Co-EDTA and Yb-labeled NDF residue as indigestible markers of mean retention time of solute and particulate phase digesta, on the second day of total collection. Nutrient composition was similar between both types of alfalfa, except for lignin levels, which were, as expected, lower in the lignin-reduced cultivar. Dry matter digestibility improved by 3% when horses were fed reduced-lignin alfalfa, but fiber digestibility (ADFD, NDFD, ADLD) did not statistically differ between diets. Retention time and particle size also did not differ between diets. 

Overall, this study demonstrated that feeding reduced-lignin alfalfa can improve dry matter digestibility in adult horses without affecting dietary intake, nutrient profile, fecal particle size or GI tract retention time, but more research should be done to further explore the potential benefits of reduced-lignin alfalfa fed to horses.