Reduced age at first calving: effects on lifetime production, longevity, and profitability
Kansas Agricultural Experiment Station Research Reports
M. J. Meyer
Amburgh M.E. Van
Follow this and additional works at: https://newprairiepress.org/kaesrr Part of the Dairy Science Commons Recommended Citation Meyer, M. J.; Everett, R.W.; and Van, Amburgh M.E. (2004) "Reduced age at first calving: effects on lifetime production, longevity, and profitability," Kansas Agricultural Experiment Station Research Reports: Vol. 0:
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Reduced age at first calving: effects on lifetime production, longevity, and
profitability
Abstract
The primary advantages of reducing age at first calving (AFC) include reducing rearing costs as well as
reducing time in which the heifer is only a capital drain on farm resources. The primary disadvantage of
reducing AFC is that it is frequently associated with a reduction in first-lactation milk yield. Despite this
reduction in first-lactation milk yield, production per year of herd life is typically increased by reduced AFC.
Furthermore, although the first lactation yield may be influenced by AFC, future lactations are decidedly
not. In addition, stayability and health of cows are not influenced by reduced AFC as long as heifers
freshen at an adequate weight. Most analyses indicate that the financial advantage afforded from heifers
that freshen at a low AFC seems to at the least offset any milk lost during the first lactation. Furthermore,
when the time value of money is considered in this analysis, a reduced AFC (~22 months) seems likely to
represent a more fiscally sound management decision. When applying these ideas on the farm, a properly
managed feeding and breeding program should permit a firstlactation cow to weigh ~1,210 lb after
freshening at 22 months of age. The National Research Council recommends a postpartum weight equal
to 82% of her mature body weight. This can be achieved with a maximal prepubertal average daily gain
(ADG) of 2 lb/day when a traditional preweaning program is employed or 1.8 lb/day when an intensified
preweaning program is employed. Because of the well defined link between inadequate body weight at
calving and increased mortality and morbidity in first-lactation cows, achieving this target post-calving
body weight is of critical importance.; Dairy Day, 2004, Kansas State University, Manhattan, KS, 2004;
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Dairy Day 2004
REDUCED AGE AT FIRST CALVING: EFFECTS ON LIFETIME
PRODUCTION, LONGEVITY, AND PROFITABILITY
Summary
The primary advantages of reducing age at
first calving (AFC) include reducing rearing
costs as well as reducing time in which the
heifer is only a capital drain on farm
resources. The primary disadvantage of
reducing AFC is that it is frequently associated with
a reduction in first-lactation milk yield.
Despite this reduction in first-lactation milk
yield, production per year of herd life is
typically increased by reduced AFC. Furthermore,
although the first lactation yield may be
influenced by AFC, future lactations are decidedly
not. In addition, stayability and health of cows
are not influenced by reduced AFC as long as
heifers freshen at an adequate weight. Most
analyses indicate that the financial advantage
afforded from heifers that freshen at a low
AFC seems to at the least offset any milk lost
during the first lactation. Furthermore, when
the time value of money is considered in this
analysis, a reduced AFC (~22 months) seems
likely to represent a more fiscally sound
management decision. When applying these ideas
on the farm, a properly managed feeding and
breeding program should permit a
firstlactation cow to weigh ~1,210 lb after
freshening at 22 months of age. The National
Research Council recommends a postpartum
weight equal to 82% of her mature body
weight. This can be achieved with a maximal
prepubertal average daily gain (ADG) of 2
lb/day when a traditional preweaning program
is employed or 1.8 lb/day when an intensified
preweaning program is employed. Because of
the well defined link between inadequate body
weight at calving and increased mortality and
morbidity in first-lactation cows, achieving
t (...truncated)