Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/1999
Publication Date: N/A
Citation: Interpretive Summary: Ease of mechanization and lower field and weather damage losses have made ensiling the favored way to harvest and store alfalfa for feeding dairy cows in the Northeast and Midwest U.S. Increasing alfalfa's energy content would be as beneficial as feeding more grain. Maceration, a method of mechanical conditioning alfalfa originally developed to increase drying rates in the field, was found also to increase alfalfa's energy content. The objective of this research was to determine quantify by which maceration improved the nutritional value of alfalfa for dairy cows. Four large scale feeding trials and one smaller digestibility trial were conducted using alfalfa silage harvested during two consecutive years. The smaller trial indicated that maceration increased fiber digestibility; energy digestibility was greater in the large scale feeding trials. Over all four large scale trials, macerating alfalfa increased production of milk, protein and lactose (milk sugar), but did not change fat production. These increases in milk production were equivalent to feeding cows about 5% more corn in their diets. This means that macerated alfalfa silage has about 5% more nutritional value for milking cows than conventional alfalfa silage. A commercial maceration machine is being developed by an American farm equipment manufacturer. Farmers can use the information from this research to determine the economic value of such machines for macerating alfalfa silage, and whether maceration will pay for itself at the grain prices that are current in any given year.
Technical Abstract: Five feeding studies were conducted with lactating Holstein cows comparing macerated and control alfalfa silage harvested at two cuttings in each of two years. Overall, silage made from macerated alfalfa contained more ash, suggesting greater soil contamination, as well as more fiber and less NPN, suggesting greater fermentation in the silo. In a digestion study, two diets were fed containing [dry matter (DM) basis] 72% of either control or macerated second cutting alfalfa. Apparent digestibility of NDF and ADF was increased by maceration, with similar changes in digestibility observed using either Yb or indigestible ADF as marker; indigestible ADF was used as marker in later studies. In each lactation study, mean composition of diets formulated from alfalfa silage plus concentrate based on high moisture ear corn were (DM basis): Negative Control (61% control alfalfa silage), Macerated (61% macerated alfalfa silage), and Positive Control (50% control alfalfa silage). Diets were made isonitrogenous by adding soybean meal; about 2 percentage units CP from either roasted soybeans or low-solubles fish meal were added to each diet. Milk yield was greater on Macerated than Negative Control in two of four trials; milk and milk component yield were not different between Macerated and Positive Control in one of four trials. Overall performance on Macerated versus Negative Control indicated greater OM digestibility, greater yield of milk, protein and SNF, but lower milk fat content. Yield of milk and milk components was greater overall on Positive Control versus Macerated. Estimation of NEL from maintenance, milk yield and BW gain indicated that control and macerated alfalfa silage contained, respectively, 1.36 and 1.42 Mcal NEL/kg OM, an increase of about 5% due to maceration of alfalfa in these trials.