Canola Meal Replacing Dried Distillers Grains with Solubles in Diets for Lactating Dairy Cows

The objective of the study was to determine the response to feeding diets containing canola meal (CM) as a protein supplement in place of all or portions of dried distillers grains with solubles (DOGS). Twelve lactating Holstein cows (four primiparous and eight multiparous) were fed in a 4 x 4 Latin square design with 4 wk periods. Data were collected wk 3 and 4 of each period. Diets were formulated with decreasing amounts of canola meal at 100, 66, 33 and 0% of the source of supplemental protein. All diets contained a forage to concentrate ratio of 55:45, with forage being 50% corn silage and 50% alfalfa hay. Diets were formulated to be similar in crude protein (16.0%) and ether extract (4.7%). No difference (P \u3e 0.05) was found among treatments for dry matter intake. An increase in CM had no effect on milk production. Milk protein concentration, protein yield, fat concentration and fat yield were similar for all diets. Lactose concentrations tended (P \u3c 0.10) to be lower with combination diets and tended to be higher for primiparous cows. There was no effect of treatment on lactose yield. Dietary treatments had no effect on feed efficiency. Increasing canola meal concentrations in the diet resulted in-a quadratic response (P \u3c 0.05) of milk urea nitrogen concentrations. The extraction efficiency of His, Phe, Tyr, and Val all indicated significant linear effects of treatments, increasing as more CM was added to the diet. There was no affect of adding CM to the diets on ammonia concentrations in the rumen. Varying concentrations of CM had a cubic effect on acetate, propionate, and butyrate concentrations in the rumen as well as a linear effect on butyrate. Canola meal is a suitable replacement for DOGS in dairy cow diets