NRC Overview – Dry Cows, Calves & Heifers, Dr. Jim Drackley, Dr. Bill Weiss, Dr. Mike VandeHaar
Dr. Jim Drackley, University of Illinois
Dr. Bill Weiss, The Ohio State University
Dr. Mike VandeHaar, Michigan State University
Episode 28: NRC Series: Dry Cows, Calves & Heifers
Tonight, we continue our discussions with the authors of each chapter of the new NASEM, formerly the dairy NRC. We’re focusing on dry cows, calves and heifers for our conversation and it should be a lively one. Here is a link to the webinar on the new report. Also, we’ve got a new co-host tonight with Dr. Jeff Elliott joining us.
Dr. Bill Weiss discusses changes in the chapter regarding dry cows and transition cows. The biggest update was the changes in intake prediction, which changes every day substantially as the cow gets close to calving, making intake prediction difficult to model. There is also up-to-date discussion on all the metabolic problems within the text that doesn’t all show up in the software but is great for users to have as a reference. (7:08)
Dr. Jim Drackley discusses steam-up rations and high energy density diets. He explains there are large steps from the dry cow to the close-up cow but not a large step to the fresh cow. That is part of the problem and why they took a more moderate steam-up approach. The other problem is that cows are becoming catabolic the last few days before calving. So adjustments are made to focus on metabolism and divert nutrients to the mammary gland. (12.05)
Dr. Mike VanderHaar discussed a big change in the composition of gain. They used data from Holstein cattle instead of growing beef cattle. By doing this the intake equations are better than the last model. They also include feed factors and are size scaled. (41:44)
Dr. Jim Drackley discusses updates to the calf chapter. The requirements on the conversion of nutrients into gain are much improved because of better data based on Holstein and Jersey calf studies. (58:14)
As a reminder, we will continue breaking down the new 2021 8th Revised Edition of the Nutrient Requirements of Animals in podcasts releasing over the coming weeks. Be sure to subscribe so you don’t miss any of the new episodes. If you’d like to pre-order a copy and receive a 25% discount, visit Balchem.com/realscience and click on the NRC series for a link and the discount code.
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