NRC Overview – Vitamins and Minerals – Dr. Bill Weiss and Dr. Rich Erdman

Posted: November 9, 2021


Dr. Bill Weiss, The Ohio State University

Dr. Rich Erdman, University of Maryland

Co-host: Dr. Clay Zimmerman, Balchem

Episode 30: NRC Series: Vitamins and Minerals

Podcast Topic

Tonight we finish the conversation on the new NRC with two legends in the industry. We’ll first focus on macro minerals, trace minerals and vitamins, but then we’ll also put a bow on the NRC series and wrap it up for our listeners tonight.


Dr. Bill Weiss says the new NRC defines “requirements” which was never done in past NRCs. They give a specific number for a specific population which is a large improvement for the reader. (9:55) 

Dr. Rich Erdman discusses the animal’s needs or requirements in order to maintain herself. He discusses the availability of vitamins, trace minerals and macros as well. (19:50)

Dr. Bill Weiss discusses trace minerals and the factorial system used in the new NRC for these minerals such as manganese, iron, selenium and iodine. He discusses the copper and zinc data found in the 2021 version are based on the maintenance requirements of the cow. (33:33)

Dr. Rich Erdman stresses there is still a need for more specific data on the availability of supplements and feed. (50:10)

Dr. Bill Weiss discusses challenges for the next editions of the NRC (now NASEM) such as finding young scientists specializing in minerals, funding and the USDA recognizing that minerals are important and should be focused on. (1:05:53)

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 and click on the NRC series for a link and the discount code. 

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