Supplementing grape marc to cows fed a pasture-based diet as a method to alter nitrogen partitioning and excretion
The inclusion of the grape marc into livestock rations provides an opportunity not only to use a waste byproduct resourcefully, but also to induce beneficial metabolic changes in animals. Grape marc contains condensed tannins that could alter N metabolism, which would be beneficial from an environmental perspective. The objective was to determine if dietary grape marc could decrease urinary N excretion from nonlactating dairy cattle. Eighteen multiparous cows were randomly divided into 2 equal groups, receiving either (1) pasture + 2 kg of dry matter (DM)/d energy pellet per cow (control group) or (2) pasture + 2 kg of DM/d energy pellet per cow + 3 kg of DM/d grape marc per cow. Urine, fecal, and blood samples were collected at baseline (d 0) and at d 9. Cows receiving grape marc excreted 22% more N in feces compared with the control group. Cows offered grape marc had lower plasma urea nitrogen concentrations (2.42 and 2.97 ± 0.1 mmol/L from treatment and control cows, respectively), but had no significant difference in urine urea concentration compared with control animals (84.24 and 114.1 ± 17.62 mmol/L from treatment and control cows, respectively). Overall, the potential exists to alter N metabolism in dairy cows using dietary grape marc. The exact mechanisms causing this shift in N metabolism require further investigation.... [Show full abstract]
Keywordsgrape marc; dairy cattle; nitrogen metabolism; supplement; Dairy & Animal Science; Feces; Animals; Cattle; Vitis; Fruit; Nitrogen; Blood Urea Nitrogen; Diet; Dietary Supplements; Female
- Metadata-only (no full-text) 
Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.