The Cutting Edge - Article 31 - Available energy in starter is dependent upon previous NFC intakes

Operators To OWNERS

Estimates of calf starter energy affected by consumption of nutrients. 2. Evaluation of models to predict changing digestion on energy content in calf starters

Big 3 Infographic at otovets.com/cuttingedge

Link: https://www.journalofdairyscience.org/article/S0022-0302(19)30082-7/fulltext

Big Take Away #1 Let’s open with a great quote, “Estimates of energy in CS in young calves should consider rumen development and changing digestion with advancing GI maturity.”

When we calculate daily DE or ME in calves we use an NRC model for CS that accounts for adult digestion NOT neonatal immature digestive tracts. And as you would expect these immature tracts are not really ready to using energy in the CS form.

Big Take Away #2: The big key the researchers did find was that the MEratio, or when ME of CS in the calf over ME of the NRC estimate came close to 1, was usually reached when 15 kg of NFC were consumed and MEnrc actually overestimated ME until this occurred.

This ratio persisted in weaned calves fed starter and 5% forage as well suggesting accurate predictions of ME even in TMR calves.

Big Take Away #3: When the researchers looked for an average age at which this 15kg of NFC was reached they found a range from 51 days of age up to 63 days of age in trial calves. This clearly disputes the industry norm of weaning at a specific age.

Also, the current industry recommendation for weaning at a specific intake volume of CS, such as 1kg CS/day, does not mean that that amount of feed can be used by the calf’s GI tract if the 15kg NFC limit has not been reached.

Estimates of calf starter energy affected by consumption of nutrients. 2. Evaluation of models to predict changing digestion on energy content in calf starters

Published by J. Quigley, W. Hu, J. Knapp, T. Dennis, F. Suarez-Mena, T. Hill, Jan 2019

Location: Cargill Animal Nurition, Brookville, Ohio

Objective: The objective of this study was to evaluate methods to calculate energy values of dry feeds (NRC, 2001) fed to young calves during the first 4 mo of life utilizing estimates of total-tract nutrient digestion.