Group Housing and Feeding
of Milk-Fed Calves:
Moving Closer to Nature's Way
Table of Contents
- Introduction and Concepts
- Why this Topic now?
- Calf Behaviour And Choice Of A Feeding
- Free-Access or Ad Libitum Feeding
- Delivery Systems for Acidified Milk
- Biosecurity and Cleanliness
- Housing - Group Size and Pens
- Weaning Strategies
- Setting up the System
- Training Calves to Free-Access Feeding or
- Avoiding Practices that put Calves off Suckling
- Milk Intake
- Water, Grain And Forage
- Reading List
Introduction and Concepts
Choices in feeding systems, housing and management affect health,
growth and behaviour of calves and farm profit. Ontario producers
traditionally rear milk-fed dairy calves in individual pens and
feed milk in two or three meals per day. However, there has been
significant adoption of a Finnish feeding system in a relatively
short time. Finnish farmers have 18 years and Ontario farmers have
seven years of practical experience with free-access feeding of
milk acidified with formic acid. Producers claim less labour, inexpensive
equipment and efficient use of surplus colostrum, transition cow
milk or milk from cows under treatment. They also report calves
achieve excellent health and diarrhea is a rare event for calves
fed free-access acidified milk. For Finnish farmers, free-choice
feeding is an easier feeding method for substitute workers. Free-access
feeding systems enhance a calf's feeding experience by allowing
individual calves to achieve their biological growth in addition
to meeting their physiological and behavioural needs, for example
suckling, eating to appetite and socialization. Free-access feeding
may be the new standard for accelerated feeding because ad libitum
feeding and group housing systems mimic more closely Nature's way.
The components of a basic free-access feeding system include a
reservoir to contain the milk or milk replacer, a plastic tube,
a check valve and a nipple. (Figure 1) Acidification with formic
acid preserves the milk for storage at room temperature and allows
producers to mix batches at one- to three-day intervals to save
labour. Traditionally, the milk is fed cool (20-24°C in winter)
to slow the speed of intake and reduce the chance of gorge feeding.
Since they began using the system in June 2005, Ontario producers
have been very successful at finding what does and what does not
work. This presentation looks at a few practical aspects of free-access
feeding of acidified milk in its various forms.
Figure 1. A simple free-access feeding system includes
a nipple, plastic line, check valve, milk reservoir, and preserved
milk. Image courtesy of Valio Dairy, Finland
Why this Topic now?
Enhanced feeding and group rearing are important topics at this
time because of calf health and welfare, economics, labor efficiency,
and public advocacy. Recent innovations have made group feeding
and rearing a practical alternative to traditional rearing in individual
pens or hutches.
Welfare - Producer and Public Interest
Hunger (De Paula Vieira et al., 2008) and the biological need to
suckle may have been under-recognized in conventional calf rearing.
Traditionally, caregivers interpreted loud bawls from calves as
signs of good health and appetite rather than protests about hunger.
Additionally, caregivers strive to assure passive transfer, cleanliness,
biosecurity, or identification-control-treatment of diarrhea-causing
pathogens while perhaps being less sensitive to or ignoring physiological,
behavioral or welfare challenges associated with conventional restricted-milk-feeding
systems. Happily for calves and their caregivers, bawling is being
recognized as a sign of hunger and the natural benefits of suckling
are being adopted for milk delivery systems. Recent changes to milk
feeding and rearing practices may be motivated by producer interests
in calf well-being, dairy profitability, or responses to advocacy
by consumers, milk processors and retailers.
Benefits of Suckling
Our ancient contract with calves is a barter of food, shelter and
welfare in exchange for future considerations, primarily milk for
sale. In exchange for the loss of suckling its dam, we should provide
an alternative milk delivery system that mimics Nature's way (Anderson,
2008). An imitation system should deliver milk on demand to satisfy
a calf's inborn needs for suckling, small volumes per meal, several
meals per day (Ahmed et al., 2002), and increasing daily volumes
to satisfy health, maintenance and growth. A system that mimics
Nature's way should prevent the risk of ruminal acidosis and the
rumenitis-omasitis-abomasitis complex associated with bucket, esophageal
feeder, or gorge-feeding (Gentile, 2004).
Health, Growth, and Economics
Calf health may be another impetus for accelerated adoption of
free-access feeding strategies. Diarrhea is the most common disease
of milk-fed calves and accounts for the majority of pre-weaned heifer
calf deaths. Pneumonia is the most common disease of recently weaned
calves (USDA, 2010). Prevention of hunger may reduce the risk of
diarrhea. With enhanced feeding, calves may be weaned at heavier
weights and at an earlier age. Enhanced or ad libitum feeding permits
normal growth and development and reduced age at breeding and calving.
Because of quicker throughput, overhead costs related to buildings
and infrastructure may be reduced on a per calf basis. In recent
times in the United States, producers may have adopted accelerated
rearing of heifer calves because of a greater demand, limited supply,
and favorable pricing for bred heifers. In addition, US researchers
have shown greater first-lactation milk production by heifers reared
on accelerated milk-feeding programs compared to heifers reared
on restricted-milk diets (Davis Rincker et al., 2011).
Group Rearing - Opportunities
Group housing and free-access or automated feeding compliment an
accelerated feeding scheme. The package contributes to decreases
in labor (Gleeson et al., 2008); Kung et al., 1997) and facilitates
adoption of precision farming technology available through automation.
Although hutch-rearing has advantages for calf health, labour and
worker comfort may be reasons for leaving the hutch system and adopting
group feeding and rearing. Loneliness has been under-recognized
as a stressor in calves reared in hutches or individual pens with
solid sides. Socialization in pairs or small groups benefits calves.
Group housing allows calves to see and mimic behaviour, including
suckling, and may be the reason for greater milk intakes and gain
compared to calves reared in single pens (Hepola, 2003). In some
European countries, legislation has forced the adoption of group
rearing systems. In Canada, a recommended best practice calls for
a minimum total daily intake of 20% of body weight in whole milk
(or equivalent nutrient delivery via milk replacer) until 28 days
of age. Since body weight increases with daily gain, free-access
feeding or use of automated feeders with simulated free-access programming
may be the easiest way to adopt the new feeding recommendations.
Producers using restricted feeding or buckets often avoid group
housing because of cross-suckling. Intersuckling is a hunger-related
behavior - hunger for milk and for suckling. Caregivers are preventing
the unwanted behaviour by meeting the calf's needs for milk and
nipple feeding. At weaning, intersuckling may be alleviated by gradual
reductions in milk over a 15-day-interval and provision of grains
with higher concentrations of protein.
Calf Behaviour And Choice Of A Feeding
An understanding of behaviour of calves and their caregivers is
useful to design or choose feeding and housing for milk-fed calves.
It's reasonable to provide feeding and housing that promote positive
interactions between calves and caregivers. To do so, we must be
familiar with normal, sensitized to abnormal, and aware of the consequences
of compromises and coping. Normal feeding behaviour meets physiological
functions and social needs of the calf. Suckling, eating, resting
and playing are group activities and they follow a pattern with
a daily rhythm. Suckling events cluster near dawn and evening and
may be related to hunger or changes in light. With free-access feeding
of acidified milk, dairy calves may suckle an average of seven meals
per day and meals may last for seven minutes for a total of 49 minutes
suckling per day. The youngest calves may have inter-meal intervals
of four hours while older calves suckle at less frequent intervals.
Overall, young milk-fed calves seldom choose 14- or 16-hour intervals
between meals, common intervals with twice daily feeding schedules.
In addition, calves compete for what they perceive to be limited
resources such as a nipple at a nipple bar or space at a grain feeder.
Since suckling and eating grain follow a cyclic pattern within a
day, a group of calves should have enough nipples and feed trough
space for several calves to suckle or eat at the same time.
Free-Access or Ad Libitum Feeding
Nature's way of feeding calves includes free access, nursing until
satiated, frequent meals per day and suckling. Free-access milk-feeding
systems include housing with a nurse cow or unrestricted access
to a container of milk. An automatic feeder programmed for a generous
total daily volume or free-access feeding may still restrict access
because of the calf-to-nipple ratio. The origins of free-access
feeding of milk may have been from producers noticing improved health,
greater feed conversion, rate of gain and growth in calves nursing
cows or fed in ways that mimic nature. No doubt they also are looking
for methods to decrease labour and to make feeding calves easier.
Free-access feeding includes the principles of enhanced biological
growth, normal suckling activity and social behaviour. This feeding
strategy prevents hunger, weight loss or stress and allows for optimum
growth and future milk potential. Frequent small meals moderate
pH fluctuations in the abomasum (Ahmed et al., 2002). Producers
use whole milk, conventional milk replacer or accelerated milk replacer
for free-access acidified milk feeding.
Unpreserved milk may be a hazard in free-access feeding because
of rapid proliferation of bacteria. In Finland, other Nordic and
European countries, Canada, and some States in the USA, producers
feed milk preserved with formic acid to groups of calves (Anderson,
2008; Todd, 2011). Formic acid preserves milk by inhibiting the
growth of or killing bacteria and allows milk to be stored at ambient
temperatures for a few days without refrigeration. Acidification
decreases a calf's exposure to bacteria in milk.
Loose stool may be associated with consumption of greater volumes
of milk. The frequency of occurrence may be greater with free-access
feeding. A stockperson needs to differentiate between sick calves
and healthy calves with loose stool. Clinically ill calves may be
removed from a group for nursing care.
Delivery Systems for Acidified Milk
Acidified milk or milk replacer may be fed with a nipple bottle,
a nipple bucket, a barrel with nipples, a milk line with nipple
bars, or an automated feeder. A few Ontario producers successfully
discovered that their calves refused to drink acidified milk from
buckets and that this may be related to an odour. I am unaware of
anyone feeding acidified milk in a trough. An ideal milk delivery
system should meet a calf's needs for inter-meal intervals, suckling
minutes, meals per day, volume per meal, and stress-free access
Nipple Bottles or Nipple Buckets
Bottles or buckets are common containers for feeding calves housed
in single pens. The nipple provides the benefits of normal suckling.
A conventional feeding system may be enhanced by providing a greater
volume per day and more meals per day. Acidified milk may be fed
with nipple bottles or nipple buckets.
The origins of the name mob feeding become obvious when you watch
a gang of hungry calves swarm the nipples of a feeder filled with
milk. Mob feeding systems are common in regions where cows calve
in groups and produce many calves in a short time. In general, mobs
of calves are grouped together and fed milk in containers with multiple
nipples. In Europe and North America, mobs may consist of fewer
calves than in New Zealand and be housed indoors in cool and cold
months or outdoors in summer. The container may be filled with a
fixed volume (e.g., four litres) per calf at each of two daily feedings.
Mob feeders may be used for conventional restricted, classic accelerated
or acidified-milk feeding. The volume consumed by a calf will vary
with the suckling speed of the individual. The feeder usually has
a nipple for each calf in the group.
Milk Barrels and Milk Trolleys
Plastic or stainless steel reservoirs are common containers for
holding acidified milk. Stainless steel has an advantage for ease
of cleaning over plastic but recycled 200-litre barrels are inexpensive
and easy to obtain. Some trolleys serve multiple purposes as mixers,
transporters, agitators and reservoirs for nipple bars. The capacity
of the milk reservoir varies with the number of calves in the group
and how often it will be refilled. Nipples may be attached directly
to the container or mounted on a nipple bar on a wall or gate. A
plastic line attaches to the nipple and feeds off the bottom of
the container. Milk will stay in the plastic line when an appropriate
check valve is attached to the end of the line in the container.
An automated feeder provides the technology to monitor daily milk
intakes of individual calves. Forster, Urban and Holm & Laue
are the most common machines in Canada. Some producers are storing
cold acidified milk or milk replacer in functioning bulk milk tanks
and connecting these tanks to their automated feeders. The automated
feeder warms the acidified milk and dispenses it to the calf in
the feeding station. The automated feeder may be programmed to feed
calves for restricted, accelerated, or free-access feeding (Borderas
et al., 2009). Milk may be delivered according to preprogrammed
feeding curves or adjusted manually. The feeding station has a reader
for an electronic identification tag carried by each calf. Base
models will store individual calf data for two days and there are
options to store and retrieve data for a calf's entire milk-feeding
period. Action lists alert managers to examine calves that may not
have consumed their daily milk allowance. Gradual weaning is possible
by programming the machine to decrease the milk allowance over a
short or long interval of days. Generous programming of three litres
per meal and 10 to 12 litres per day move feeding closer to Nature's
way. Calves may enter the group at three days of age and receive
these allowances from the day of entry until the start of weaning.
A "Powder Maid Milk Maker" is a recent Finnish innovation
built by Finnlacto. The machine prepares milk powder in four to
seven litre batches and will automatically dose acid into the milk
for acidification. Hoses connect the milk container to a nipple
bar and the machine mixes a fresh batch when the container empties.
The machine has modular components, for example, one collects data
for monitoring daily milk intake of individual calves. This latter
device may be attached to existing 'warm box' systems being sold
Several producers use milk lines to transfer milk from a central
storage tank to nipple bars mounted at pens in a group housing barn.
Initially, foaming of the milk or milk replacer, the formation of
butterballs or cottage cheese, leaking or plugging of nipples, or
cleaning were challenges to producers. However, these have been
overcome and now there are calf barns with milk lines mounted beneath
floors, on top of floors and at various convenient or practical
heights. Milk may be distributed by gravity flow or by pump. For
pump-assisted systems, an air-operated peristaltic pump has become
the pump of choice for circulating the milk with minimal foaming.
In the pump-assisted systems, a check valve is mounted at the nipple
to prevent leaking. Early milk line systems were designed to keep
the acidified milk at about 70ºF while in the storage tank.
In these systems, reverse flow heat exchangers took the chill off
the milk as it returned to the tank. In cold barns the milk may
cool quickly while traveling in a loop back to the tank and calves
may reduce their milk intakes. An alternative system is gaining
favor for practical reasons. With these, acidified milk is kept
cold and a plate warmer (an adapted plate cooler, heat exchanger)
warms the milk leaving the tank and entering the milk line. Figure
4 shows a schematic of the system. Milk line systems may be washed
with automated clean in place equipment.
Nipples may provide gratification, frustration or a hazard to milk-fed
calves. Therefore, nipples merit careful consideration when choosing
a milk delivery system and routine inspection during our investigations
of calf sickness.
Peach Teats® have become a popular choice with Ontario farmers
for free-access feeding of acidified milk. They have a unique ergonomic
shape, a built-in pinch valve, and two small slits placed on the
sides rather than a hole at the end. The correct orientation places
the slits at the top and bottom so milk squirts upon the palate
and tongue. Other nipples have an opening on the end, either a round
orifice or an X-shaped opening. These are common with automated
feeders, nipple bottles or mob feeders.
Producers complain about calves not wanting to suckle on some types
of nipples. Calves may have trouble suckling because of hardness
of the rubber, diameter and length, or restrictive orifice. Drinking
speed may be a function of the calf's ability and / or the nipple.
Nipple surgery with a pocket knife is a common practice by those
feeding calves in hutches because a larger opening reduces suckling
time, accelerates calf feeding and decreases the caregiver's exposure
to harsh weather.
Enlargement of the opening also is common with automated feeders
because caregivers believe that line ups at the feeding station
are due to small nipple openings that slow drinking speed. Alternatively,
queues may happen because calves are hungry when offered small volumes
per meal. Unwittingly, large orifices permit rapid ingestion of
milk and may encourage calves to loiter to satisfy their need to
suckle. Long suckling times also may be due to worn out or collapsed
nipples, a common finding. Like milk liners, the rubber becomes
tired after repeated use and does not return to its shape. Large
openings permit rapid ingestion, reduce suckling time and saliva
production and may be an under-recognized hazard for aspiration
pneumonia or digestive upsets.
Nipple bars are practical because they provide access to more calves
at one time than a single nipple because feeding events are group
activities and cluster around early morning and evening hours.
Figure 2. A cluster of nipples. Top left, new red
and white nipples. Top right, a white nipple that has had surgery
and modest use. Bottom left, a surgically modified, well- used nipple
from a nipple bottle used to feed colostrum. Bottom right, a new
Biosecurity and Cleanliness
Free-access acidified milk systems require regular cleaning. Proper
acidification prevents the formation of slimes in the lines. A black,
green or pink slime in clear plastic lines is an indication of inadequate
acidification. In general, slimes and moulds do not grow at pH 4.0
However, reservoirs need cleaning on a regular schedule, and twice
per week is common practice. Cleaning involves the use of detergents,
acid and alkaline cleaners, and sanitizers. With milk hoses dead-ending
to a nipple, hoses need to be removed and cleaned. Since plastic
hose is readily available and inexpensive, some producers replace
the hoses on a regular schedule.
Suckling is a messy, slobbery activity because of the production
of lots of saliva. Surfaces around and below nipples become covered
in saliva and spilled milk. Floor drains and water hoses at feeding
stations and nipple bars make cleaning and disinfection an easy
and timely chore. Floor drains and sloped floors are useful design
features in new barns or renovations. It's common for good caretakers
to clean and disinfect these areas daily. Slobbered milk is very
attractive to cats, rodents, and flies. Disease may spread between
calves by means of contaminated nipples. There is scant information
to quantify the risk.
Housing - Group Size and Pens
For our average-sized dairies milking 75 cows and with three or
four heifer calves born each month, four pens are common. At any
time, the barn may have a clean, disinfected pen that is sitting
idle, a pen that houses recently weaned calves, a pen with a full
compliment of suckling calves, and a pen being filled with calves.
A dairy milking 600 cows may be able to fill a pen with eight calves
in ten days and require 12 or more pens for calves from birth to
post-weaning. The size and weight of a calf at weaning should be
used to determine the pen area allocated per calf in a group. Forty
square feet per calf may be a reasonable minimum for Holstein calves
weaned at 42 to 60 days or less of age. To maintain stable groups,
producers may choose group sizes in proportion to their herd size.
Ontario producers using free-access acidified milk systems have
been advised to house eight or less calves in a group based on findings
about group housing and disease from Sweden (Svensson & Liberg,
2006). Through personal communication, a US dairyman reported his
observations after rearing calves in groups of six through 14 per
pen. With about 600 calves on free-access acidified milk each day,
he found that a group of eight calves was ideal for his housing
For automated feeders, small groups of six to 12 calves are being
recommended to minimize disease, to achieve good weight gains, and
to assure satisfactory social behaviour (Svensson & Liberg,
2006). Stable groups are preferable to moving calves in and out
(Engelbrecht-Pedersen et al., 2009). All-in all-out management may
be practical for large herds but more difficult to achieve for small
dairies. Advice from researchers is at odds with the recommendations
from manufacturers of automated feeders. Manufacturers and their
sales persons recommend 20 to 30 calves per nipple and advertise
machines that can feed 40 to 120 calves. In Ontario, pens with 10
calves are common while at least one producer manages 30 calves
in a group pen with two feeding stations.
The weaning process introduces calves to grain or forage while
milk is being removed from their diet. Weaning is complete when
the calf no longer receives milk. Briefly, weaning involves a change
in diet over a period of time. Three methods may be used to wean
calves from free-access acidified milk - abrupt, step and gradual.
Sudden removal of milk is the defining characteristic of abrupt
weaning. When done at a young age or when calves are consuming large
volumes of milk, there will be a rapid reduction in daily nutrient
intake. Calves may experience a loss in weight during this time
because their nutrient intake from solid feed may not compensate
for the nutrients removed by weaning off milk. Abrupt weaning is
stressful to the calf and their hunger may lead to intersuckling.
Reductions in the volume of milk by several stages over several
days are characteristics of step weaning. Each stage may be over
a few or several days. The process allows calves to increase their
intake of grain or forage to replace nutrients withdrawn with the
milk. This weaning process is less stressful than abrupt weaning
but it also may lead to intersuckling amongst hungry calves.
Gradual weaning includes small daily reductions in milk over a
prolonged period of time. A reduction in volume is often recommended
as the preferred technique but producers claim excellent results
by gradually diluting the milk with water. In practice, the time
period may be 14 days.
With free-access milk feeding, calves often eat less grain or forage
than calves on restricted milk diets. For calves on these systems,
gradual weaning is the method of choice. Practical implementation
of gradual weaning requires some ingenuity. In groups with wide
ranges of age, calves may be removed to another pen for gradual
weaning. With milk-line systems, producers may reduce milk intake
by restricting access to the nipple for more hours each day until
weaning is complete. In contrast, some choose a gentler weaning
by shutting off the valves on the milk line, removing the nipples
and providing milk at a nipple bar supplied from a container of
Automated feeders are marvellous machines for implementing gradual
weaning. In general, milk is reduced gradually over 15 days for
a relatively stress-free weaning. During weaning, the daily intake
of dry feed and water increases as milk is removed from the diet
(Sweeney et al., 2010).
Keeping the Chill Off the Milk
In cold housing during winter months, producers adopt innovative
ways to keep the chill off the milk. Some warming devices have been
ineffective with the milk being too cold resulting in calves refusing
to drink adequate volumes and suffering as a consequence. Other
devices have been too hot resulting in milk baking on heating elements
or making a container of cottage cheese.
Winding River Farms in Nova Scotia invented a practical solution,
a warm box with devices to maintain the inside of the box at about
70ºF (21ºC). Warmth comes from a thermostatically controlled,
electric base board heater. An agitator on a timer stirs the milk
at predetermined intervals. The designers had the wisdom to recess
the nipples inside the box to prevent them from freezing. The box
is not intended to warm cold milk to feeding temperature. However,
it does an excellent job of maintaining the temperature of a container
of acidified milk. The plans and list of materials for building
a warm box are available on the OMAFRA website. Use your internet
browser and type in the following words to get the plans: Stewiacke
Warm-Box Milk Bars Free-Access Milk Feeding in Cold Calf Barns.
Advanced Dairy Systems in Wellesley, Ontario build a box based upon
the Winding River plans. The company builds their warm box with
plastic and stainless steel. (See Figure 3) Complete units or the
components are sold in Ontario, across Canada and into the USA.
The company also sells components for milk line systems.
Figure 3. A warm box milk bar may have nipples mounted
on three sides. The other side has a door for access to the barrel
of acidified milk.
A warm room has been adopted on many farms with the walls providing
mounts for the nipple bars to feed calves in adjacent pens. A warm
room provides space for the equipment needed for a free-access acidified
milk system using milk lines or for barrel and nipple systems.
Milk-line systems may include a reverse-flow heat exchanger to
take the chill off the milk. The heat exchanger may be purpose-built
or adapted from a plate cooler. Figure 4 shows the basic configuration
with a plate warmer on the outgoing side of the milk line. With
this system, there is no remixing of milk back into the cold acidified
milk in the main storage tank. 'Warmed' milk not suckled by the
calves returns to a small sink where it mixes with cold milk from
the bulk tank. This system has been in use for about two years on
a farm where cold acidified milk is being warmed to about 100ºF
(38ºC) without the formation of cottage cheese. An alternate
setup warms milk on the return line just before entering a main
bulk tank. In effect, it attempts to keep the chill off a large
volume of milk. Placement of the warmer on the outgoing milk line
has inherent advantages and some Ontario producers are changing
to this design.
Figure 4. A plate 'warmer' takes the chill off cold
acidified milk before the milk goes to the nipple bars. The return
line empties into a small sink where the 'warmed' milk mixes with
cold acidified milk flowing from the storage tank.
Setting up the System
OMAFRA's website has a document (revised in 2008) that describes
setting up a free-access feeding system using formic acid. To access
the document, type the following words into your web browser: free-access
feeding of acidified milk setting up the system. The document was
written for Canadian dairy producers and some information may not
be applicable to the USA. For example, formic acid may not be an
approved product in the USA. Comments about temperatures for mixing
acid into milk replacer may not apply to American readers because
your milk replacer may not contain skim milk powder. Another section
describes the addition of milk replacer powder to whole milk to
avoid formation of cottage cheese in milk line systems. When the
document was written, we were challenged by foaming and curd formation
caused by pumps in milk line systems or agitators in barrel systems.
An astute producer minimized the problem by adding milk replacer
to his whole milk. In the past year we've found that an air-operated
peristaltic pump solves the problem and there is no need to add
milk powder to whole milk. Nonetheless, it's now apparent that we
can mix whole milk and milk replacer without doing harm to calves.
In addition, there are descriptions about ways to keep the chill
off milk that may or may not be useful or applicable in light of
recent on-farm experience. At the time of writing this paper, the
document prepared in 2008 is undergoing a revision with deletions
and additions and corrections. Therefore, check the site for the
Cautions and Safety
Formic Acid 85% is hazardous to skin, eyes and lungs. Appropriate
safety equipment (goggles, gloves, and clothing) is essential for
handling this acid. For safety, dilute one part Formic Acid 85%
into nine parts water to make a 9.8% product and work with this
weaker acid. Store acids safely and keep them out of reach of children.
A commercially prepared, dilute (9.8%) formic acid is available
to Ontario farmers and many choose to buy this even though it costs
more. You will find more safety precautions listed in the information
sheet posted on our website. Although infrequent, sometimes producers
add concentrated acid to water and then do not stir the contents
of the barrel. Next they pump from the bottom where the acid settled
and encounter problems with pH when mixing it into milk. To avoid
this problem, stir well once and you may not need to stir the dilute
Preparing and Feeding Acidified Whole Milk or Colostrum or Milk
Mix dilute acid into cool (68 to 75°F, 20 to 24°C) milk
replacer* or cold (e.g., plate cooler temperature) whole milk to
avoid gelation, coagulation or clot formation. (*Note: this caution
about temperature applies to milk replacers that contain skim milk
as a protein source. It may not apply to American milk replacers.)
Add 30 mL (cc) dilute acid (Formic Acid 9.8%) into each litre of
milk or milk replacer. Stir vigorously while adding the acid into
the milk, again within the first hour, and several times each day.
Check for the target pH of 4.0 to 4.5. Use narrow range (3.0 to
5.5) litmus paper or a pH meter. Feed at ambient temperature in
summer and at 20 to 24°C in winter. Please see the notes above
about keeping the chill off milk and a plate 'warmer' used in milk
line systems. Provide free-choice water and calf starter and hay.
Mount the nipples at a calf's shoulder height or lower for ease
About Hot or Warm Colostrum or Milk or Milk Replacer
It's easy to make cottage cheese by adding acid to freshly harvested
warm milk or by adding acid to cold milk and heating the mixture
and holding it at a warm or hot temperature. The same is true for
milk replacer powders that contain skim milk powder. Since most
milk replacers sold in Canada contain skim milk powder, we mix the
powder with part hot water and then add the remaining water as cold
to produce a mixture at about 68 to 75°F (22 to 24°C), and
then we add acid to this mix. Because we can make cottage cheese
by heating cool acidified milk replacer, we acidify and feed our
milk replacers at 22 to 24°C.
Since most milk replacers sold in the USA do not contain skim milk
powder, this caution about temperature and making cottage cheese
may not apply. Briefly, the precautions about feeding cool (not
cold, not body temperature) milk or milk replacer focus on the prevention
of curd formation. You may be successful at warming cold acidified
whole milk (or milk replacer containing skim milk powder) to 100°F
(38°C) and feeding it immediately. Or, you may make lots of
cottage cheese by keeping a volume of acidified milk at warm or
hot temperatures for several hours. You may make cottage cheese
by focusing a heat source on one area of a barrel of acidified milk.
An American milk replacer based upon whey protein concentrate may
be acidified and warmed successfully without forming cottage cheese.
It's best to read the label on the milk replacer, mix a small volume
as a test batch and do some experiments with the powder of your
Do Not Feed Cold Milk or Milk Replacer. Do Not Make Cottage Cheese
In winter when I'm told about low intakes of acidified milk, thin
calves or diarrhea, the temperature of the acidified milk is the
first item on my checklist. Usually, it is too cold and calves decrease
their intakes. A thermometer is a handy tool. Use it to check the
feeding temperature of the milk. In temperate climates during summer,
we feed acidified milk at ambient temperatures. Sometimes, producers
ruin batches of milk by exposing the containers to direct sunlight
where the milk can quickly get too hot. Therefore, keep acidified
milk in the shade.
pH and Contact Time for Killing Bacteria
pH paper is of little use to folks who are red-green color blind
and pH meters lose their calibration. Meters should be checked and
calibrated often. False readings can lead to adding too much acid
and calves refuse to drink the acidified milk. (Yes, it has happened
too many times.) Or, you may not add enough acid to preserve the
milk. Acidification does not kill all bacteria. A pH of 4.0 to 4.5
with formic acid and contact time of eight to 12 hours should produce
acidified whole milk that meets or exceeds quality targets. Because
coliforms will be the most common contaminant in milk replacer,
and since coliforms die quickly (e.g., one hour) upon acidification
with formic acid, acidified milk replacer may be fed immediately.
In experiments with whole fresh milk, acidified with formic acid,
we found no growth of coliforms after a contact time of one hour
at pH 4.1. We found no growth of Staphylococcus aureus after a contact
time of 4 to 6 hours at pH 4.1 in whole milk acidified with formic
acid. During a study of 24 farms feeding acidified milk during the
summer of 2006, we found 81% of 46 milk samples were in the target
pH range of 4.0 to 4.5. On bacterial culture, the majority of samples
had no growth or less than 10,000 colony-forming units per millilitre
(cfu/mL) of milk. Thirty-one of 48 samples had no coliform growth.
We found environmental Staphylococcus and Streptococcus in less
than half the samples and at levels of less than 5,000 colony forming
units per millilitre. One research report from the University of
Guelph claimed that formic acid killed Mycobacterium avium subsp.
Paratuberculosis (MAP) (Johne's bacterium) but another study from
Iowa State claimed that it did not.
Agitating Acidified Milk or Milk Replacer
Since acidified whole milk and milk replacers made with skim milk
powder separate over time, agitation is essential. A vigorous stir
for a short duration will achieve excellent mixing. Too much mixing
will make butter. Therefore, choose slow, short-duration, and frequent
agitation. In addition, whole milk separates naturally with fat
rising to the top. Therefore, agitation is a practical consideration
when drawing milk from storage tanks.
Training Calves to Free-Access Feeding
or Automated Feeders
Ontario producers reported and researchers confirmed that newborn
calves may not consume sufficient quantities of free-access acidified
colostrum (Collings et all, 2011). Refusals or slow drinking may
be related to age (less than four hours old), an acidic taste or
weak suckling ability.
Strong suckling ability should be the decisive factor for introduction
of a calf to free-access feeding or an automated feeder. With free-access
acidified milk feeding systems, caregivers may introduce their calves
at two to four days of age. Producers want their calves to bond
to the nipple-barrel or nipple bar and not to someone hand-feeding
with nipple bottles or buckets. Contrastingly, the age of introduction
to an automated feeder may vary from three to 21 days depending
upon advice given by salespersons or choices made by producers.
Bottle-feeding until 10 to 14 days of age seems to be a common recommendation
because calves may fit into groups better when they are two weeks
old compared to calves less than a week of age (Jensen, 2007). Contrarians
disagree with existing recommendations for age at introduction to
automated feeders. As an example, owners of an Ontario farm invested
in an automated feeder and took full advantage of its labour-saving
features by introducing a calf when it suckled strongly. They admit
80% of their calves to the feeder at three days or less of age.
Tutor calves may assist with training of new entrants to automated
or free-access feeders. A tutor calf is already trained to the system
and new entrants follow it to the nipples. A nipple bar may facilitate
tutoring compared to feeding stations with access for a single calf.
Some caregivers feed two litres by nipple bottle prior to introducing
a calf. Others find that training is easier and quicker when a calf
is hungry upon entry. An automated feeder may have a pump to assure
milk is at the nipple when calves are being trained to the machine.
With two feeding stations, a pen may be subdivided into a training
pen for calves being trained to the nipples. This pen facilitates
easy identification and handling of the youngest and newest additions
to the automated feeder. When trained, calves are released into
the main pen.
Data about daily intakes of colostrum, bottle milk and milk from
automated feeders for each calf may be useful when investigating
neonatal calf problems. Sometimes a nutritional deficiency, excess,
or abrupt change may be identified as a predisposing cause of ill-thrift
or disease. For example, at a study farm calves became very unthrifty
shortly after introduction to an automated feeder. Bottle-feeding
was eight litres per day divided into three meals prior to moving
calves at 21 days of age to their automated feeder. However, a check
of the feeder showed that it was programmed to provide five litres
per day and at less total solids content. The calves experienced
two stressors at the transition, commingling in groups and a substantial
abrupt decrease of nutrient intake.
Avoiding Practices that put Calves off
Accelerated colostrum feeding may put some calves off suckling
and delay an easy or early transition to free-access feeding or
automated feeders (Anderson, 2011). A defining characteristic of
accelerated colostrum feeding may be a single feeding of four litres
by esophageal feeder within a few hours of birth. Features are speed
and method of delivery, quantity of nutrients, volume delivered
or labour devoted to the task. Force-feeding differs from suckling
in many ways. Does the volume of colostrum or method of delivery4
do harm and should we consider the welfare aspects of the practice?
For example, rapid administration of colostrum by esophageal feeder
at a dose of 10 to 11% of birth weight differs from Holstein calves
suckling nine to 21% of their birth weight (Lineweaver & Hafez,
1969) in several relatively smaller meals. Granted, there are challenges
with bottle feeding but the hazards of rapid administration using
an esophageal feeder that directs colostrum to the reticulo-rumen
also merit our consideration (Gentile, 2004).
Some producers who followed the force-feeding advice complained
about calves not suckling at their next meal or being slow drinkers
afterwards. Non- or slow-drinkers make calf-feeding frustrating
and time consuming for caregivers. Some abandon force-feeding except
for exceptional cases whereas others carry on while accepting but
questioning the practice. When looking for ways to get calves onto
bottle or free-access feeding or automated feeders, the first step
may be avoiding practices that put calves off suckling. The next
steps may include feeding smaller volumes per meal and more meals
to achieve four litres total volume. And lastly, some calves are
not ready to suckle in the first hour of their life and delaying
bottle feeding for two to four hours may be successful for them.
There are practical alternatives to force-feeding four litres of
colostrum to every newborn calf, alternatives that assure high probability
of successful passive transfer (Chigerwe et al, 2009). Briefly,
the strategy includes ingestion of 3L of colostrum at the first
meal (1, 2, 3 or 4 h of age) and another one L at the second meal
(prior to 12 h of age).
Producers often ask how much calves will drink when offered free
access to milk. Unpublished data from research at the University
of Guelph (Cindy Todd) compared calves suckling free-access acidified
milk replacer to calves suckling free-access non-acidified milk
replacer. Average intakes were 10 litres per day with acidified
milk replacer compared to 11 litres per day with sweet milk replacer.
There were no differences for weaning weight. In another trial,
Emily Miller-Cushon found ad libitum intakes of milk averaged 12
litres per day with a peak of about 16 litres at week six prior
The major manufacturers of milk replacers sold in Ontario enhanced
the mixing and feeding schedules of their products in the past two
years. For example, one popular brand recommends mixing 150 grams
per litre and feeding six litres per day at five to seven days of
age and six to eight litres per day for 45 kilogram calves at eight
to 42 days of age. These may be considered conservative feeding
levels compared to what calves want. Calves vary in birth weight
and when given a chance they tell us clearly that their wants and
needs vary and that they want more than offered conventionally.
Here are some data to illustrate the point above. From summer
2009 to spring 2012, we recorded daily milk replacer intake for
Holstein heifer calves using an Urban® automatic calf feeder
that was programmed to mimic some aspects of free-choice feeding.
At our study farm, the milk replacer contained 20% protein and 15%
fat and the mixing ratio was 15% on a weight to weight ratio (e.g.,
150 grams of powder into 1000 grams of water), or about 13% total
solids. From entry to the start of weaning, the machine provided
each calf a maximum of 12 litres per day. Maximum volume per meal
was initially set at two litres but this was soon increased to 2.5
during 2010 and then to three litres in 2011. Eighty percent of
the calves were three days of age or younger upon admission to the
feeder and data for three days of age may be considered training
day intakes. Calves were penned in groups of 10 in naturally-ventilated
cold housing with straw bedding in winter and sawdust in summer.
Water and calf starter were available free-choice. Milk replacer
consumption has been recorded for about 400 calves to date.
Figure 5 summarizes the data in chart form and includes standard
error bars on the columns. The chart shows a linear increase in
average daily milk replacer consumption from 4.8 litres per day
at three days of age to 9.2 litres per day at 17 days of age. In
this 14-day period, the calves increased their intakes by 4.4 litres
or about 315 millilitres per day. Consumption increased an average
of one litre from three days old to five days old. During the six
day interval from eight to 14 days old, milk intakes increased an
average of 1.9 litres, from a daily intake of 6.5 litres to 8.4
Figure 5. The chart shows the linear increase in
average daily milk replacer intake from three to 17 days of age
for calves using an automated feeder.
Equivalent of Graphic
Although averages are interesting, the distributions of consumptions
by calves of the same age may be more useful. As shown in Figure
6, at 11 days of age, the top 25% of calves were suckling more than
nine litres each day and 50% were suckling more than 7.5 litres.
Clearly, a fixed volume of six litres per day would not have met
the needs of the majority of calves. These data may be useful for
comparison to feeding guidelines on milk replacer labels or to recommendations
for programming automated feeders.
It's interesting to compare what calves want to milk allocations
programmed into automated feeders. For example, it's common enough
to find calves bottle-fed and then entered onto automated feeders
at 10 to 14 days of age and offered six litres of milk replacer,
far less than they want or require for their age. More generous
feeding allowances during the first 28 days of life should help
calves meet their potential.
Figure 6. The chart shows the distribution of milk
replacer intakes for 11-day old calves offered 12 litres of milk
replacer per day. One half the calves suckled greater than 7.5 litres
per day and 25% of them suckled nine litres or more.
Equivalent of Graphic
The design of automated feeders or feeding stations may limit
milk intakes because they ignore group feeding behaviour of calves.
For example, an automated feeder typically supplies four nipples
but only one calf can receive milk at a time. At our study farm,
after modifying the feeder so calves could suckle at the same time,
intakes were 1.2 to 1.4 L greater per day. Figure 7 shows the historical
comparison of average daily intakes. The data were from April 4
to August 15, 2011 for the original feeding station (75 calves)
and from April 5 to August 12, 2012 for the updated feeding station
(60 calves). (Anderson, 2012).
Figure 7. The chart shows greater intakes of milk
replacer after updating feeding stations for an Urban 40 automated
feeder to permit simultaneous suckling and receipt of milk at the
Equivalent of Graphic
The owners report much easier training and introduction, greater
daily intakes at younger ages, and more satisfied calves. The data
do not show the change in contentment of the calves. Bullying, bunting
at dry nipples, and stepping back and forth in the feed stall were
common events with the old configuration but are rare with the new.
Milk is readily available at the nipple and there is almost instant
satisfaction when a calf arrives for feeding. Potential differences
(e.g., weather) between 2011 and 2012 may mislead us to believe
the new feeding stations had a positive effect. Testimonials and
historical comparisons may be viewed as weak evidence to adopt new
technology. Nonetheless, an investment in the new feeding stations
merits consideration for calf well-being. We will have to wait for
an appropriately designed research trial to confirm or disprove
our clinical impressions. At this farm, the owners are convinced.
Water, Grain And Forage
Calves using a free-access acidified milk system drink scant amounts
of water until weaning when water intake increases rapidly upon
withdrawal of milk (Hepola et al, 2008). Nonetheless, water should
be available at all times to calves on the feeding system.
It's common advice to feed grain and withhold roughage to stimulate
rumen development in milk-fed, dairy replacement calves. Some producers
follow the advice while others ignore it and feed hay like grandpa
did because he knew how to feed calves. What's old is new again
because research has caught up to the old ways. Dry grass hay in
the diet results in normal development of rumen mucosa in all calves
whereas only grain, grain plus corn silage or grain plus free-access
straw bedding results in normal development in 62-75% of calves
(Suarez et al., 2007). Producers should question the dogma about
feeding grain only to milk-fed calves. For sure, grain facilitates
rumen development but some dry hay assures development of a healthy
rumen (Khan et al, 2011). Rumination and cud-chewing activities
by 14-day old calves are common observations when calves are offered
hay or when they eat straw bedding.
The ingestion of manure is the route of infection for enteric diseases
of concern in dairy calves. Bedding should be considered contaminated
and a source of infectious agents. Therefore, for reasons of biosecurity,
calves should be fed forage in a clean trough. Feed in sweep-in
mangers may be contaminated with manure from the boots of caregivers.
Our ancient contract with calves is a barter of nourishment and
welfare in exchange for future considerations, primarily milk for
sale. Free-access feeding with acidified milk or novel programming
of an automated feeder allows us to feed calves closer to Nature's
way. Milk can be delivered on demand to satisfy a calf's inborn
needs for suckling, small volumes per meal, several meals per day,
and increasing daily volumes to satisfy health, maintenance and
growth. Group housing compliments the feeding systems and allows
calves to exhibit or develop normal social behaviours. Producer
interest in calf well-being, dairy profitability, labour savings,
caregiver comfort and protection of milk's good image has accelerated
the successful implementation of group feeding and rearing.
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- Free-Access Feeding of Acidified Milk - Setting Up the System
Using Formic Acid
- Stewiacke Warm-Box Milk Bars Free-Access Milk Feeding in Cold