Robert E. James
Extension Dairy Scientist
Virginia Tech
Limit Feeding to Lower Cost and
Promote Early Weaning is Not
Cost Effective?
Historically, dairy calves have been limit-fed approximately 4
quarts of milk or the equivalent of 0.45 kg of milk replacer powder
per day. The most common milk replacer powder has contained
20% protein and 20% fat. The logic behind “limit-feeding” is to
make the calves hungry and encourage early consumption of dry
calf starter feeds thereby promoting early weaning and reducing
costs. This practice has been widely adopted in spite of the fact
that milk with 3.8% fat and 3.2% protein contains the equivalent
of 30% fat and 25% protein on a powder basis and the fresh cow
routinely produces more than 4 quarts of milk per day during
early lactation. In fact nearly every other mammalian species
consumes considerably more nutrients in early life than the
limit-fed calf. Has limit feeding impaired calf growth and subsequent biological potential?
Nutrient requirements for growth
More recent research indicates significant advantages of more liberal
feeding recommendations which consider requirements for maintenance and a reasonable rate of growth and factor in the influence
of environment on maintenance nutrient requirements. Nutrient
needs of calves can be partitioned into maintenance and growth.
When calves are limit-fed, they must devote a greater portion of their
daily intake to maintenance, resulting in decreased availability of
nutrients to support growth and lower feed efficiency. When the
temperature drops, more energy is needed to stay warm and even
less is available for growth.
As an example, a 36 kg calf housed at 50°F (10°C) requires 0.4 kg
of milk replacer or milk dry matter to maintain body weight. When
the temperature drops to 5°F (-15°C), maintenance requirements
increase to 0.6 kg of dry matter. If the calf is housed in a wet
environment, maintenance requirements are even higher because
the hair coat has lost its insulating ability and fewer nutrients are
available to support growth. The impact of environment on calf
growth is even more critical when one considers that the newborn
calf has low levels of body fat (3-4%) to draw upon during periods
of high energy demand such as cold weather or illness.
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Nutrition and calf health
Economics of calf rearing programs
Field studies in Virginia, Minnesota and California have demonstrated
that more liberally fed calves exhibited lower mortality and less
illness during the first two months of life. The relationship of diet to
calf health was best demonstrated in a controlled study conducted
at the University of Minnesota in which over 400 calves were fed
either 4 quarts of pasteurized whole milk or 20:20 milk replacer
containing 0.45 kg of dry matter. A summary of growth and health
is shown in the table below.
Traditional calf feeding programs which involve feeding approximately
1 gallon of milk or an equivalent amount of dry matter from a 20:20
milk replacer have been appealing to the producer due to low cost. In the
examples which follow the 2001 NRC was used to estimate expected
gains at different environmental temperature. Two milk replacer feeding
programs are compared using current market prices.
Pasteurized
Whole Milk
20:20 Milk
Replacer
Average daily gain (kg)
0.47
0.34
Treatment rate – all months
12%
32%
Treatment rate – winter months
20%
52%
Mortality – all months
2.3%
11.6%
Mortality – winter months
2.8%
21%
Measure
(Godden, et al., JAVMA, 2005)
Improvements in body weight gain and health could be attributed
to the fact that calves fed whole milk received 50 g more fat and
30 g more protein daily than calves fed the milk replacer. Virginia
Tech research has also shown that smaller calves (<29.5 kg) require
proportionately more nutrients than larger calves due to their proportionately larger surface area and the propensity for greater heat loss.
Nutrition and mammary development
Research over the past 10 years indicates that a more biologically
normal growth rate (>0.45 to 0.9 kg/day) may have an influence on
mammary development and later lactation yield. Studies in Israel,
Denmark, Illinois and New York have demonstrated that calves fed
more liberally prior to weaning produced as much as 907 kg more
milk during their first lactation. Growth of the mammary fat pad and
in some cases mammary secretory tissue is enhanced in Holstein
calves fed diets which enable gains exceeding 0.68 to 0.9 kg/day. These
differences suggest a developmental advantage for more liberally
fed calves. A retrospective study of preweaning calf growth in nearly
800 calves at Cornell University showed that each kg of preweaning
average daily gain was associated with the production of over 453.6
kg more milk during the first lactation. Their study also attributed
25% of the differences in 1st lactation milk yield to calf growth
prior to weaning. Although there are indications for differences in
mammary development, it is also conceivable that other factors
such as improved health during the early rearing period might
enhance the animal’s ability to achieve higher milk yield during
later life.
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Conventional
0.45 kg of a 20:20 milk replacer powder fed in a total volume of
1 gallon. Daily intake is 0.09 kg of protein and 0.09 kg of fat.
At 68oF (20°C) this program provides sufficient nutrients to
support approximately 0.23 kg of gain.
At 32oF (0°C) this program does not provide enough energy
to support any gain. The animal must use all the energy to
maintain body temperature and will still lose weight.
Intensive
0.9 kg of a 26:16 milk replacer powder fed in a total daily volume
of 2 gallons. Daily intake is 0.24 kg of protein and 0.15 kg of fat.
At 68oF (20°C) this program provides sufficient nutrients to
support nearly 0.81 kg of gain
At 32oF (0°C) this program still provides enough energy to
support 0.54 kg of gain.
The difference in daily feed cost between the two feeding programs
is $1.42/day. If calves are weaned at 6 weeks of age, the added cost
for the more intensive feeding program is $60. At first glance this
appears to be a significant increase in feed cost which cannot be
tolerated in today’s economic climate.
However, additional factors should be considered. If cost per unit
of gain is calculated, the limit-feeding program is actually more
expensive costing $4.71/kg of gain while the cost is only $2.98/kg
of gain for the faster growing, more intensively fed calves. These
differences occur because the limit-fed calves use a larger
proportion of their nutrient intake to support maintenance with
little left over for growth. The differences become even more
accentuated with young calves (less than 21 days of age) that
become cold stressed at temperatures below 59oF (15°C)!
Results of the Minnesota study indicated a 10% reduction in mortality
when more protein and fat were fed from milk as compared to a
20:20 milk replacer. The higher protein and fat intake found in more
intensive milk replacer feeding programs mimics the benefits found
in feeding whole milk. The additional feed cost of a more intensive
feeding program for 100 calves is about $6,000 given our example
above. Assuming a value of $500 each at birth, $5,000 is recovered
in lower death loss. Additional benefits will be obtained due to reduced
expenses for treating sick calves although these are more difficult
to estimate.
There is sufficient research to suggest that more liberal feeding
programs support higher first lactation milk yield. Using a conservative
estimate of 226.8 kg more milk in the first lactation, 100 calves will
generate an additional $8,000 in gross income during the first
lactation using an average milk price of $16/cwt.
Granted these are estimates, but there is sufficient economic and
practical evidence to justify more liberal feeding programs for dairy
calves. Intensive calf feeding programs are probably better termed
more “biologically normal” as they now resemble how other mammalian
species are fed.
1. Colostrum intake is critical. A gallon in the first 6 hours of life
of high IgG colostrum is requisite to success of any calf feeding
program. Illinois research suggests that calves failing to absorb
sufficient colostrum antibodies will not respond well to improved
nutrition. Additionally, evidence suggests that the colostrum should
have low bacteria counts. High bacterial growth (>100,000 cfu
standard plate count) caused by delayed feeding or delays in
refrigeration has been associated with failure of passive transfer.
Colostrum should be treated in much the same manner as milk
that is destined for human consumption. It should be rapidly
cooled to <40oF (4.4°C) as quickly as possible to limit microbial
growth. This is achieved by placing clean frozen bottle of water
into colostrum to achieve rapid chilling.
Milk replacers are a practical and
economical alternative on many
dairies. Products with at least
26% protein and fat levels
between 15 and 25% promote
more cost-effective gains. Milk
replacer powder should be
diluted with warm water (110oF
(43°C)) to achieve total solids levels between 12 and
17% depending upon manufacturer’s recommendations. More liberal
feeding programs encourage growth which more nearly reflects the
animal’s genetic potential for growth, is more natural and is more
conducive to improved animal welfare.
2. High quality liquid diet fed at the appropriate dilution is essential.
While calves will grow well when fed 6 – 8 quarts of whole milk per
day, failure to pasteurize it successfully exposes calves to risks of
infection by Johne’s organisms, Mycoplasma, E. coli and a host of
other potential pathogens. Successful use of waste milk requires
careful consideration of investment in equipment, additional labor
and quality control testing to assure successful pasteurization.
3. Provide plenty of fresh, clean water.
4. Offer a palatable calf starter containing 18 to 22% crude protein
during the first week and keep it fresh. The calf starter should
contain an anticoccidial such as Bovatec, Rumensin or Deccox.
5. Wean calves when they are eating 0.9 kg of starter per day.
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