7 considerations when formulating the heifer’s first TMR

By Dr. Lucas Mitchell
On many farms, a TMR presents an effective and efficient way to provide heifers with a complete and balanced ration.  TMRs boost efficiency through nutrient synchronization and reduced labor with easier feedstuff handling.

However, if formulated improperly, TMRs can be detrimental to heifer growth and development.  Put the following seven concepts to work to ensure effective formulation of the heifer’s first TMR.

1. Age
Penn State University research has shown heifers may be offered a TMR as early as two months of age without detrimental effects on growth.  Heifers at two months of age are still developing their rumens and have much smaller rumen capacity compared to heifers at four or six months of age.  Farms must accommodate this smaller capacity when formulating TMRs for heifers two to four months of age.

2. Transitioning feeds
Diet transitions should be made gradually because feed changes are expected to alter rumen microflora.  If made too quickly, both animal and rumen microflora growth and development may be stunted.  Slowly introduce heifers to any new TMR ingredients that they have not been exposed to previously.

In many situations, forage is the primary ingredient that is new to heifers.  To allow the rumen microflora time to adapt to this new ingredient, consider offering heifers free-choice forage one to two weeks prior to transitioning to a TMR or topdress the TMR with starter for one to two weeks.

3. Batch size
In many situations, the primary issue for implementation of a TMR for heifers less than four to six months of age is that the batch size is too small relative to the mixer, which may impair the quality of the mix.

4. Dry matter
A TMR for heifers less than four months of age should be around 65% dry matter (DM).  Consider this example:  A 300-pound heifer needs to eat 10 pounds of DM.  If the TMR is 65% DM, she needs to eat 15.4 pounds of feed as-fed.  If the TMR is 40% DM, she needs to eat 25 pounds of feed as-fed.  It is unlikely this heifer would be able to consume enough feed at that lower DM to meet her needs.

5. Ensiled forages
Research has shown that heifers as young as two months will consume ensiled forages without detrimental impacts to their growth or health.  The primary issue with feeding ensiled forages is that these feeds are prone to heating and spoilage.  Therefore, manage feedbunks carefully if including ensiled forages as part of the heifer’s first TMR.

6. NDFhttps:/vitaplus.com/blog/articles/reduce-spoilage-fe
Research from the University of Wisconsin showed heifers ranging from 400 to 1,400 pounds will consistently consume 1% of their bodyweight as NDF.  That means a 400-pound heifer will consume 4 pounds of NDF.  If she needs to consume 13.5 pounds of DM, the TMR should not contain greater than 30% NDF.

Penn State research has shown the 1% of bodyweight as NDF does not apply to smaller heifers.  This is likely due to the fact they are still developing and expanding their rumen capacity.  That research suggests TMRs for heifers two to four months old should not contain greater than 15% grass hay or 20% corn silage or alfalfa haylage.

7. Poor-quality forages
On many farms, “problem forages” make their way into heifer rations, but these forages can cause some real issues, especially if used in a heifer’s first TMR.  Problem forages can disrupt the rumen microflora and will reduce intakes.  These feed disruptions often manifest into more health-related events.  It is best to avoid putting problem forages into a heifer’s first TMR.

Judge the success of a TMR formulation according to how the animals perform.  It is especially critical to evaluate and track the performance of heifers that are being exposed to a TMR for the first time.  Heifers consuming a properly formulated TMR should have consistent manure, healthy-looking hair coats and minimal health challenges.  They should also be hitting the farm’s predetermined benchmarks for weight and frame growth.

This article was originally written for the January 10, 2022, issue of Hoard’s Dairyman.

About the author:  Dr. Lucas Mitchell is a Vita Plus calf and heifer specialist.  He grew up working on his family’s dairy farm in Indiana and attended Purdue University, where he received his bachelor’s degree in food science in 2013.  He worked in the food industry before returning to academics to pursue a Ph.D. in animal science, with a focus on dairy nutrition, at Penn State University.  His research focused on the impacts forage type and quantity have on growth, intake, and metabolism of recently weaned calves.  Mitchell provides on-farm support in Michigan, Indiana, and Ohio.  He also works closely with the Vita Plus calf team to apply current research and provide custom solutions to meet the needs of calf and heifer raisers.