IT'S THE COMBINATION: SCIENTIFIC DATA REVIEW OF THE FIRST CORN SILAGE TO BRING TOGETHER FIBER AND STARCH DIGESTIBILITY

摘要

Lactating dairy cows require highly digestible forages with the correct mix of fermentable fiber and non-fiber carbohydrates to ensure efficient rumen fermentation, optimal feed intake, and high output of milk solids. With lower fiber digestibility, rumen fill constraints may limit dry matter intake (DMI) and productive capabilities of dairy cattle fed higher forage diets (Allen, 2000). Brown midrib (bm3) corn silage contains lower lignin content than conventional corn silage, resulting in improved NDF digestibility and greater DMI before rumen fill limitations are encountered (Ebling and Kung, 2004). But, starch digestibility is often lower for diets containing bm3 rather than conventional corn silage. For example, Ferraretto and Shaver (2015) measured a 6%-unit reduction in rumen starch digestibility and a 1.4%-unit reduction in total tract starch digestibility for cows fed bm3 versus conventional corn silage. The lower dietary starch digestibility with bm3 corn silage may be related to: 1) greater passage rate of digesta driven by higher DMI (Moharrery et al., 2014), and(or) 2) greater kernel vitreousness of bm3 corn hybrids compared with other commercially available corn hybrids (Ferraretto and Shaver, 2015).