The high protein content in ensiled alfalfa is not all usable by ruminant animals. In feeding and research trials, even red clover made into silage has a higher level of protein recovery in animals than alfalfa.
“Factors that affect forage protein utilization in alfalfa include the speed of fermentation and rapid lowering of pH,” said Allan Macaulay, provincial silage system specialist with Alberta Agriculture in Barrhead.
He said research from Kansas State University recommends alfalfa be wilted down in the windrow to minimize its buffering effect, which enhances the quality of alfalfa silage. Wilting also reduces proteolysis, which contributes to ammonia buildup and subsequent reduction of protein use in the feed by the ruminant.
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Wilt the crop to the maximum level that still allows the ensiling process to occur. This is likely in the range of 55 to 60 percent moisture. Activities and additives used to speed the ensiling process, rapidly lower the pH and stabilize the material. This reduces protein degradation and enhances protein recovery in ruminants.
Glen Broderick, from the U.S. Forage Research Center, compared alfalfa put up as silage with that put up as dry hay. Alternate windrows were used to minimize variables. He found that microbial protein formation in the rumen was 29 percent higher with the hay than with the silage. Ruminate ammonia was almost twice as high from the silage than the hay. Animals eating the hay produced more milk fat and protein than those on silage.
