Calf growth targets

The estimated birth weight for Holstein calves is around 6.25% of Mature Body Weight (MBW). So, for a Holstein cow weighing 650kg, the newborn calf will should around 40.6kg.

To achieve high standards of pre-weaning weight gain, it is important to focus on colostrum management is key as well as hygiene, housing and feeding management.

Day 1 – 3
Weight at birth, % Mature Body Weight
Weight at birth, kg*
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Why Colostrum?

Colostrum is the first milk from a cow that has just calved. It contains high levels of quality nutrients like fat and protein. It also delivers essential antibodies to the calf. Calves are born without fully developed immune systems so the antibodies provided through the colostrum are essential in fighting off pathogens.

Feed colostrum during the first three days of life. Good colostrum management can be achieved by taking into account the 3Qs

Quickly – Quantity – Quality


The first feed should be as soon as possible after birth. The capacity of the intestines to take up antibodies decreases rapidly after birth and by about 50% in 12 hours


Aim to feed 6 litres of colostrum (three feeds of two litres) within the first 24 hours of life


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Feeding schedule

Feed colostrum during the first three days of life. Start the first feed as soon as possible after birth.

Day 1

Feed 6 litres of colostrum within the first 24 hours of life:

Feed 2 to 3 litres per feeding time, taking into account the capacity of the abomasum.

Click here to learn more about the importance of supplying colostrum

Day 2 – 3

Feed colostrum in days two and three as it has a high immunological and nutritional value.

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Colostrum quality

What is good quality colostrum?

High nutritional value

Table 1. Difference in composition between colostrum from the first, second and third milking and normal milk

1st  colostrum
2nd  colostrum
3rd  colostrum
Normal milk
Dy matter, %
Fat, %
Protein, %
Lactose, %
Vitamin A, µg/dL
Immunoglobulins, %

Adapted from Godden, 2008

Stored and fed at the right temperature

Clean and hygienic


Measure colostrum quality with colostrometer

 The most important quality factor in colostrum is the amount of IgG. A young calf needs a plasma IgG level of approximately 10 to 15 g/l, and that means colostrum should contain between 50 and 100 g IgG/l.

colostrometerTo measure colostrum quality, a colostrometer can be used and these instructions followed:



 Measure colostrum quality with refractometer

The most important quality factor in colostrum is the amount of IgG. A young calf needs a plasma IgG level of approximately 10 to 15 g/l, and that means colostrum should contain between 50 and 100 g IgG/l.

To measure colostrum quality, the refractometer can be used and these instructions followed:

First calibrate the Brix refractometer:
Place two drops of distilled water on the radical of the refractometer and use the calibration screw to set the scale in the refractometer to zero. Remove the water.

Measure colostrum:
Place two drops of colostrum on the radical of the refractometer. Look into the light and measure the IgG concentration using the Brix scale on the refractometer.

A Brix reading greater than 21% indicates that the colostrum has sufficient IgG, so greater than 50g/l.

Targets for colostrum:refractometer





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Freezing and thawing colostrum

Spare colostrum can be stored in the fridge for a few days or frozen for about a year. It should be stored in the fridge or freezer within one hour after collection, and collected and stored in a clean bucket/container. Colostrum from sick cows or cows with mastitis should not be fed.

Colostrum from the freezer is best thawed in a warm water bath with a maximum temperature of 50°C. Temperature above 55-60 °C will denature the proteins.

Colostrum storage bad Colostrum storage good


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General considerations

Good housing conditions contribute to efficient youngstock rearing and ensures their potential growth from the nutrients in the diet is achieved and not wasted by spending energy on staying warm or fighting off high pathogen loads. Poor housing conditions, such as poor ventilation, can lead to poor feed intakes, low growth rates and poor feed efficiencies. It can also have serious long term effects on lifetime lactation.

In general terms there are three simple principles for good housing conditions for each stage of the rearing period

(Low) Moisture

Excess moisture, originating from the animals and bedding, combined with heat is an ideal breeding ground for pathogens. This increases the risk of pneumonia so should be avoided. Excess moisture from leaking gutters, water troughs or broken buckets should also be avoided.

Fresh Air

The air around calves should be similar to the outside air. Stale air has a much higher viable airborne pathogen load.

Air speed

Fresh air is important but draughts are very dangerous. The right air speed will depend on the age and number of animals in the building. The air speed itself, within a barn, is the product of the air inlet and air outlet size and position. A smoke test will help to determine air movement in buildings.

All three principles can be controlled by The Stack Effect

The Stack Effect

The stack effect works by air flowing past the animals, which is warmed up through heat generated by the animals, and rising to the top where it leaves the building through the outlet. As the warm air leaves, negative pressure draws in fresh air from the inlets.

However, this only works if there is enough heat generated by the animals to create the effect. Youngstock create less heat than adult dairy cows and this needs to be taken into account. If, for example, the building is too wide for the number of stock being housed, the cool air can drop instead of leaving through the outlet. A smoke test can help determine whether the stack effect is working.


Appropriate lighting is important, especially during the breeding phase to stimulate the oestrus cycle. For housed animals, 10% of the natural light should be able to reach the pens from clear roofing panels. For artificial lighting conditions, the intensity should be between 100 and 200 lux. Artificial light should resemble natural lighting and follow the daily pattern of natural light.

Housing requirements for calves

Hygiene and pens space regulations

Hygiene is very important, especially in the first months of life when the calf is more susceptible to pathogens. To keep the pathogen load low, regular cleaning of feeding materials is essential.

Staying warm

Young calves lose relatively more heat and have a lower tolerance to cold than older heifers or cows. The temperature at which the calf needs to spend extra energy on keeping warm is referred to as the Lower Critical Temperature (LCT). LCT is dependent on body weight, air speed and moisture level as illustrated in the table below.

Calf Weight (kg)
Wind speed (m/s)
LCT (ºC)

If the calf stays warm then energy consumed can be used for growth rather than for staying warm.

Summary of the practical considerations to keep calves warm:


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Key element in phase
Target % MBW
Acquire passive immunity
Day 1 – 3
Initaite rumen development
Day 3 – 56
Maximise dry matter intake
Month 3
Optimise growth rate
Month 4 – 9
Control growth to improve fertility
Month 10 – 15
55 – 60
Maintain growth and nutrition
Month 16 – 23
Prepare for calving and lactation
Month 24
94 (7 days pre-calving)

*Mature Body Weight (MBW) of Holstein heifers is 650kg