Partial replacement of canola meal with dried dairy waste as a protein source in the diet of dairy cow: Effects on lactation performance, ruminal measurements, nutrient digestibility, and nitrogen balance

The potential nutritive values and in vivo responses of dried dairy waste (DDW) as a protein substitution for canola meal (CM) in the diet of early lactating Holstein dairy cows were evaluated. Twenty-four dairy cows were assigned to three treatments in a complete randomized design with eight replicates for 35 days. The treatments consisted of a control (without DDW), a low level of DDW (50% of dietary CM content was replaced by DDW), and a high level of DDW (100%). Dry matter intakes averaged 26.9 and 24.9 kg per day for control and DDW supplemented diets. Cows showed similar total-tract digestibility values for dry matter, organic matter, neutral detergent fiber, and ether extract. Ruminal pH and individual volatile fatty acids were not affected by the inclusion of DDW. There were no significant differences among the treatments for raw milk, fat, or energy corrected milk, as well as milk fat and protein yield by dietary replacement of CM with DDW. When compared to the control, feeding DDW enhanced feed efficiencies determined using raw milk and milk that has had its fat or calorie content adjusted. As the quantity of dietary DDW increased, urinary urea-N (g/d) decreased. Reduced urinary urea and manure nitrogen excretion are based on reduced dry matter intake, and 0.42 kg less crude protein intake when DDW replaced CM. DDW, as an alternative available protein source, could replace 50% of dietary CM. If milk production is maintained, DDW may be an eco-friendly supplement in lactating dairy cows by reducing feed and crude protein intake.