Friday, September 4, 2015

Why TMR Works So Poorly
for Calves

Recently completed research compared growth rates among calves fed one of four rations in addition to their milk:
  • Silage-based TMR
  • Concentrate
  • Concentrate with chopped hay mixed in
  • Concentrate with chopped hay fed separately
Calves were offered up to 12.7 quarts per day of acidified milk daily free-access (12L)for the first 38 days and then they began weaning until no milk was fed at 50 days. For a resource on free-access feeding of acidified milk click HERE.

Preweaning - all calves gained about the same - about 2.4 pounds per day (1.1kg).

During Weaning:
  • The TMR calves dropped to about 0.4lbs/day.
  • The other three treatments dropped back to about 1.5lbs/day from 2.4lbs/day.
There was a big disadvantage for TMR calves.

After Weaning
  • The TMR calves improved coming up to 1.1 pounds a day from 0.4lbs/day.
  • The other three treatments averaged around 2.6 pounds a day up from 1.5lbs/day.
There was a big disadvantage for TMR calves. 

[By the way, no significant differences appeared in this study among the other three treatments - all offered free-choice along with free-choice water.]

Note - all four treatments had about the same "as-fed" level of intakes. The disadvantage for the TMR calves was that their ration was only 54 percent dry matter while all the other calves had rations that were 89-90 percent dry matter.

So, why does TMR work so poorly for calves? They have limited rumen volume capacity. Consuming high dry matter feeds provides them with more energy and protein than feeds with high moisture levels like silage-based TMR.

Reference: M. A. Overest and Others, "Effect of feed type and presentation on feeding behavior, intake,and growth of dairy calves fed a high level of milk." Journal of Dairy Science 98 Suppl 2, page 240, Abstract 154. 

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