Perspectives - Winter 2016 - 27

THE FIRST TRANSITION PERIOD

MANAGING WEANING IN REPLACEMENT HEIFERS
by Tana Dennis, MS, PAS

Calf and Heifer Specialist, Provimi

W

hen a nutritionist starts talking about
managing the transition period, most dairy
producers automatically think about their lactating
herd. But, the very first transition period occurs
much sooner than the onset of lactation for the cow.
The weaning transition period is often overlooked
on farms, but is an important period in a replacement
heifer rearing program. Abrupt and drastic changes
in rumen function and digestive development occur
during this time and proper management is crucial to
avoid post-weaning "slumps" in growth. However,
successful heifer rearing programs are usually only
judged by high growth rates before weaning and not
performance of calves immediately post-weaning to
4 months of age.
MILK FEEDING PROGRAM INFLUENCES STARTER
INTAKE AND DIGESTIBILITY AFTER WEANING
Evaluation of the milk feeding program is key
to planning for a successful weaning transition
period. There are several schools of thought
regarding milk feeding programs, all with the goal
of developing healthy replacements that reach their
genetic potential for milk production in a costeffective manner. However, some programs place
heavy emphasis on growth performance to 56
days of age, which is typically the time at which
milk is removed from the diet. These programs
encourage high feeding rates in excess of 2 lb of
solids per calf per day, which has been shown to
reduce calf starter intake when compared to calves
fed less aggressive milk programs. The general rule
of thumb for weaning has been to begin removing
milk from the diet when starter intake reaches 2
lb per day for 2 to 3 consecutive days. In a more

conventional milk feeding program (1 lb of solids
per day), by the time calves consume 2 lb of starter
per day they have already consumed a significant
accumulated amount of starter. In aggressive milk
feeding programs, calves do not consume much
starter until the weaning transition begins; however,
once milk is removed from the diet, starter intake
increases quickly. Calves can be eating 2 lb per day
in just a few days, but accumulated starter intake
would be very low. For this reason, rumen digestive
capacity in aggressively-fed calves may not be
developed enough to efficiently utilize dry feeds
when using this weaning criteria. When compared

"In aggressive milk feeding
programs, calves do not consume much
starter until the weaning transition
begins"

to conventional and moderate (1.5 lb of solids per
day) milk replacer feeding programs, digestibility
of total dietary organic matter at 56 days of age has
been shown to decline about 12.5% for calves fed
an aggressive milk replacer program. This reduction
in diet digestibility immediately after weaning may
partially explain the post-weaning "slump" often
seen with aggressive milk feeding programs. Rumen
capacity may be restricted due to less dry feed intake
before weaning in aggressively-fed calves, which
would limit retention time in the rumen and increase
passage rate, thereby reducing starter digestibility.
A more appropriate metric would be to have calves
consuming at least 100 lb of calf starter from birth
to 56 days of age to ensure a successful weaning
transition, which would be equivalent to 1.8 lb per
day of starter intake on an as-fed basis.
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Perspectives Magazine

27


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Perspectives - Winter 2016

Table of Contents for the Digital Edition of Perspectives - Winter 2016

Contents
Perspectives - Winter 2016 - Cover1
Perspectives - Winter 2016 - Cover2
Perspectives - Winter 2016 - Contents
Perspectives - Winter 2016 - 4
Perspectives - Winter 2016 - 5
Perspectives - Winter 2016 - 6
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Perspectives - Winter 2016 - Cover3
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