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Value of Aspen Sawdust as a Roughage Replacement in High-Concentrate Dairy Rations¹

Dairy Science Department, University of Wisconsin, Madison 53706
and Forest Products Laboratory, Madison, Wisconsin 53705

ABSTRACT

In two lactation trials we determined if aspen sawdust could be a roughage replacement in high-concentrate dairy rations. In Experiment 1, 20 lactating Holstein cows were separated into four equal groups and fed ad libitum one of the following four all-pelleted rations for a 6-wk experimental period: (1) grain mix with 10% sawdust; (2) grain mix with 10% sawdust, 5% sodium bentonite, and 2% sodium bicarbonate; (3) grain mix with 20% sawdust; or (4) grain mix with 30% sawdust. The four rations did not produce significant differences in milk production, percent milk protein, percent milk solids-not-fat, feed intake, or body weight. Milk fat percent, rumination time (h/day), and ruminal acetate-to-propionate ratios were affected and averaged 2.1, 2.0, 1.24; 2.6, 1.6, 1.75; 2.8, 3.2, 1.58; and 3.7, 4.1, 2.60 for each of the four groups. Experiment 2 was similar to Experiment 1 except 12 lactating cows were separated into three equal groups; each group was fed one of the following three rations during the experimental period: (1) grain mix with 2.3 kg alfalfa hay; (2) grain mix with 12% sawdust and 2.3 kg hay; or (3) grain mix with 12% sawdust, 5% sodium bentonite, 2% sodium bicarbonate, and 2.3 kg hay. Effects of treatment were not significant on milk production or composition, feed intake, or body weight. Milk fat percent, rumination time (h/day) ,and ruminal acetate-to-propionate ratios averaged 3.4, 5.1, 1.81; 3.5, 6.3, 2.17; and 3.6, 5.1, 3.43, respectively. Aspen sawdust can be a partial roughage substitute in lactating dairy cow rations, and it is helpful in maintaining near-normal milk fat content in high-concentrate rations. The sawdust cannot, however, serve as the only source of roughage for lactating cows because of the irregular feed intake that results if no other forage is fed.

¹ Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, and the Forest Products Laboratory, Forest Sewioe, V.S. Department of Agriculture.

² Forest Products Laboratory, Forest Service, U.S. Department of Agriculture. The Laboratory is maintained at Madison (North Walnut St. 53705) in cooperation with the University of Wisconsin.