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Friday, February 22, 2002
FULL TEXT PAPER
Soyhulls as a Replacement for Corn in the Diet of Lactating Dairy Cows
by Ignacio R. Ipharraguerre, Rodolfo R. Ipharraguerre, and Jimmy H. Clark
TAKE HOME MESSAGES
- Soyhulls can supply 20 to 30 percent of the dry matter intake of midlactation cows producing about 65 lb of milk per day without negatively affecting animal performance.
- Feeding 20 to 30 percent soyhulls in the diet may increase milk fat percentage and yield.
- Replacing a portion of the corn in the diet with soyhulls may help to reduce feed costs when soyhulls can be purchased at a more competitive price than corn.
The physico-chemical characteristics of soyhulls, which have a high content of highly digestible NDF, low content of lignin and relatively high energy concentration, make this byproduct a suitable feed for dairy cattle. The substitution of soyhulls for ground corn in high grain diets decreases starch intake and might maintain a higher or more consistent dry matter intake and reduce the metabolic disturbances associated with low ruminal pH. The objective of this study was to investigate the effects of substitution of soyhulls for ground shelled corn on yields of milk and milk components by cows in midlactation.
MATERIALS AND METHODS
Fifteen multiparous Holstein cows that averaged 112 days in milk were used in the trial. Cows were randomly assigned to five treatments in a triplicated Latin square design with 5 animals and 5 periods of 21 days each. Pelleted soyhulls replaced ground shelled corn in the experimental diets to supply 0, 10, 20, 30, or 40 percent of the dietary dry matter. The diets consisted of 23 percent alfalfa silage, 23 percent corn silage, and 54 percent concentrate on a dry matter basis. The diets were fed for ad libitum intake twice daily as total mixed rations. Cows were adjusted to the diets for 14 days in each period. Dietary dry matter intake, milk yield, and milk composition were measured during the last 7 days of each experimental period.
Total dry matter intake tended to decrease (P = 0.06) linearly whereas ADF and NDF intake increased (P < 0.01) linearly as the substitution of soyhulls for ground shelled corn increased from 0 to 40 percent (Table 1). Crude protein intake was not affected by treatments. Production of milk and 3.5 percent FCM, crude protein and true protein percentage and yield, total milk solids yield, and milk urea nitrogen (MUN) concentration were not affected by treatments. Increasing the percentage of soyhulls in the diet increased (P < 0.01) linearly milk fat percentage and yield, and the concentration of total solids in milk. Body weight change decreased (P < 0.01) linearly as the percentage of soyhulls increased from 0 to 40 percent of dietary dry matter. However, body weight losses only occurred when soyhulls replaced 30 and 40 percent of the ground shelled corn.
Table 1. Least squares means for intake, milk production, milk composition, and body weight change.
|Crude protein, %
|Crude protein, lb/d
|True protein, %
|True protein, lb/d
|Total solids, %
|Total solids, lb/d
|3.5% FCM, lb/d
|BW change, lb/d
1Level of dietary dry matter substitution of soyhulls for ground shelled corn.
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