Calf rearing is a very important aspect of livestock farming, particularly in dairy herds where the majority of calves are reared away from their dams. They are reared by artificial methods rather than the natural methods of the cow. In beef herds, the cow calves down and then rears her calf for 6 – 7 months until it is weaned. She feeds it, looks after it, and generally keeps the calf out of trouble. This is how young animals are reared in the wild, and this method is the best because the calf can help itself to small amounts of milk whenever it is hungry. The milk is clean and at the right temperature for the calf. In dairy herds, this cannot be done because the cow is being kept for milk production. The calf is taken away from the cow at 4 days old, the cow is then milked by hand or by machine for the rest of her lactation, and the calf is taken away to another building where it is housed and fed milk from a bucket. This type of calf rearing is full of difficulties, and the death rate (mortality) among calves reared in this way is very high, usually between 10 and 20%. Most of the deaths occur in the first month of the calf’s life.

When this figure of 10 – 20% of deaths in dairy calves is compared to the figure of 2 – 3% for deaths in beef herds, where the calves are reared by the cows, it shows that the methods of rearing and the standards of management in many calf units are very poor. This course is intended to give you an idea of the various methods of calf rearing that can be used, and the things that must be done in order to achieve a high success in the artificial rearing of calves.


In the beef herd, the matter of selecting calves to rear does not arise, because the cow gives birth to her calf and that is the one which she rears. Unless the calf is very weak at birth, or is deformed, the cow is left to feed and mother the calf on her own. In the dairy herd, things are rather different, because of the high cost of rearing calves away from their mothers. The farmer can afford to rear only those calves which he requires to replace cows in the herd, and usually does not rear all the heifer calves born into the herd. He selects those calves which he is going to need and rears only those. The selection of the dairy calf is covered in the Animal Breeding Course, but we will go over it again here, just to make sure that it is clear.

Selection of the dairy calf is based on two things, the appearance of the calf which is called the Phenotype, and the genetic make-up of the calf which is called the Genotype: this is the genes and chromosomes which the calf has inherited from its parents. The other point which is important is the factor of Heritability: this is the likelihood of a characteristic being passed on from a parent to its offspring. Some factors are highly heritable, these being mainly beef characters such as live-mass gain, muscling, fat cover and such things as colour markings and horns. Most dairy characteristics, however, have a low heritability, with milk yield having the lowest and the amount of butterfat in the milk having the highest. This is important in the selection of dairy calves, because the farmer is normally looking for animals that will give good milk yields and be an improvement on the cows already in his herd.

Deformities (noun, plural): deformed part, especially of the body.  

Turning to selection of the calf based on its Phenotype, the farmer can assess this simply by looking at the calf just after it has been born; the things he is looking for are the following:

  1. The size and weight of the calf. A large calf will usually grow into a large cow, and, conversely, a small, undersized calf will end up as a small, undersized cow. For most of the dairy breeds, a heifer calf should weigh about 35kg at birth, although calves of the Jersey breed will weigh less than this.
  • Any deformities in the calf. Look particularly at the jaws to make sure they meet properly and are not undershot or overshot In addition, examine the calf for blindness, loss of hair, bent back, etc. Any calf that is abnormal at birth should be killed off and not kept for rearing.
  • Make a careful examination of the feet and legs of the calf, and make sure that they are straight and properly formed. Avoid calves that have back legs which are too bent, a condition known as sickle hocked because such animals will have trouble with their feet as they grow older. Feet and legs are important because animals have to walk backwards and forward to the milking shed, and also have to walk about camps or paddocks while they are grazing.

Figure 1: The Conformation of the Animals’ Legs

  1. Examine the teats of the young heifer calf carefully to make sure it has four teats that are well spaced out and not cramped together. This is most important when the animal is going to be milked, with a milking machine later on in life.
  • If the calf is a pedigree animal, check that the colour and markings are correct for the breed; e.g. a Friesland calf should be black and white, and a Hereford calf should be brown with a white face.

When considering a calf to rear as a replacement in the dairy herd, the things the farmer should look for are the following:

  • Milk yield: He wants a calf that will grow into a high-yielding cow, one that will do better than the cows already in his herd.
  • Speed of milking: A cow that will milk out quickly, particularly if it is going to be machine-milked.
  • Udder shape: A cow with a well-shaped udder which can be milked easily by a milking machine.
  • Longevity: Cows that pay the farmer best are those that have a long, useful and productive life. He will select those heifers whose records indicate this quality.
  • Total solids and butterfat: The farmer selects a cow with a good percentage butterfat in its milk, because milk is paid for according to the quality.

If you consider this list, you can see straight away that a farmer cannot tell by looking at a newly born calf if it is going to meet any of the above-mentioned criteria. The farmer cannot tell from the calf if it is going to be a quick milker, if it is going to be as good as its mother – it might be much worse. How then, does the farmer decide that he is going to select this particular calf as a herd replacement? He does it by considering the Genotype of the calf.

First of all he looks at the Heritability of the above factors, and the list is arranged with the lowest heritability, milk yield at the top, and the highest heritability, butterfat at the bottom; the other factors come between these two in descending order of heritability. The heritability of milk yield is 20% which means that 80% of a cow’s milk yield is affected by the management of that cow during its lactation. The heritability of butterfat is 50% which means that a cow is much more likely to pass on her ability to produce butterfat to her daughter. If the calf is  born from a cow with good butterfat, say 4% average, and by a bull whose dam was a good butterfat cow, then there is a 50% chance that that calf will grow up and be a good butterfat cow. In fact, the butterfat average in a herd can be improved quite quickly, in about four or five generations, by using bulls  born of good butterfat cows. Butterfat is highly heritable. It is much more difficult to improve the milk yield in a herd because milking ability has a low heritability.

Another problem a farmer has when selecting cows for his herd is that it is impossible to milk a bull. In the selection of beef animals, you can look at a beef bull and assess his beef characteristics; his size, weight, muscling, fat cover and his general conformation, and you know that, because beef characteristics are highly heritable, there is a good chance that he will pass some of these onto his offspring. You cannot look at a dairy bull and tell anything at all about how his daughters are going to milk. You can look at the milk and butterfat records of the calf’s dam, but you cannot do this for the calf’s sire.

Another point to remember is that, in any breeding programme, there is always a tendency for animals to produce offspring which are about average for the breed, (the breed average). For any breed, there is an average size, weight, milk yield and butterfat for that breed. Friesland cows are large animals, their average weight is about 650kg, their average milk production is 4500kg per lactation, and their average butterfat is 3.5%. This is the average of all the cows in the breed. Jersey cows are small animals, their average weight is 380kg, their average milk production is 3500kg, and their average butterfat is 4.8%. It is seldom that one sees a very small Friesland cow or a very large Jersey cow. This ‘pull’ towards the breed average for any group of animals is something that occurs naturally. It is nature’s way of avoiding animals that are above or below the average for that group. If you see a herd of buck, you will notice that they are all about the same size, and they all run at about the same speed, which is the breed average for that species. Any individual that is exceptionally fast or slow will be separated from the group, and will likely to be taken by a predator. This ‘pull’ towards the breed average operates when a farmer is trying to increase the milk yield of his herd by increasing the genetic potential of his cows, their natural ability to produce milk. The way in which a farmer can overcome this is by looking at the ‘family groups’ in his herd rather than by simply looking at individual animals.

The idea of the family group is best explained by looking at animals that produce more than one offspring at a time; animals that produce litters of young such as dogs or pigs. If you look at a litter of pigs or dogs, there is nearly always one in the litter that is bigger than the rest, and one that is smaller than the rest, the one that is called the runt. The rest of the litter fall somewhere in between these two extremes, and the whole litter adds up to the breed average. In the case of dairy cows, which produce only one calf at a time, one must look at the family group of the calf’s dam; her sisters, and half-sisters who are in the herd and whose milk records will be available. The farmer is looking for the family whose milk average is above the average for the breed. He looks at the best cow in the family, but also looks at the worst cow, so that a true family average can be calculated. The farmer must also look at the family group of the bull. He does not just look at the milk yield of his dam but also at her sisters and half-sisters. If the average milk yield of the bull’s family and the cow’s family is above the breed average then the chances are very good that the calf will grow up to be a good milker, above the breed average and well worth rearing as a herd replacement. This calf will have the genetic potential to be a good milker, because it has a good genotype for milk, and (provided that it is well reared and well managed as a cow) it will fulfil that genetic potential. If the feeding and management are poor, it will never produce the milk of which it is capable. It will end up just as another moderate cow.


Beef calves can be selected on their appearance and their sire, because beef characteristics are highly heritable. Dairy calves have to be selected from the best families in the herd rather than the best individual, as the heritability of the milk yield in the best individual may be low.