|Distended: swollen due to pressure inside, bloated.
The feeding of a calf begins before it is born, because a cow that is underfed cannot feed the calf, or the foetus as it is called, which is inside her. The farmer must remember that cows that are getting near to calving must be fed enough to supply the cow herself, and the calf.
In general, the smaller the calf at birth, the slower will be its growth rate for the first six months of its life. The faster growth rate of bull calves is due to their greater size at birth; heifer calves are smaller and grow more slowly. The average birth weight of bull calves is about 10% higher than heifer calves.
Within a breed, there is a slight relationship between the weight of a cow and the weight of her calf; the larger cow will tend to produce a larger calf, provided that she has been fed properly. In the case of cross-breeding, the weight of the calf will be related to the size and weight of the dam rather than the bull. This is important because it sometimes happens in cross-breeding that a bull from a large breed is mated with cows of a smaller breed, and if the weight of the calf was governed by the weight of the bull, the cows would have extremely difficult calvings with many problems. The calf takes its size from the uterus of the cow. To illustrate this point, take the extreme case of the South Devon crossed with a Dexter. The South Devon breed is one of the largest breeds of cattle, with cows that weight up to 700kg and the Dexter is the smallest breed of cattle, with the cows weighing 300kg. If a South Devon Bull is mated to a Dexter cow, the average weight of the calf will be about 26kg. If the Dexter bull is mated to the South Devon cow, the weight of the calf will be about 33kg. The size of the calf has been governed by the size of the dam rather than the size of the sire.
The weight of the calf at birth can be reduced by poor feeding of the cow in late pregnancy, and by giving the cow a short dry period between her lactations. The normal dry period for a dairy cow is two months, in order to give her a rest between lactations, and allow her to be brought into good condition for calving, and subsequent milk production. If this dry period is reduced, say to three or four weeks, this can reduce the size of the calf that the cow is carrying.
On the other hand good feeding in late pregnancy and particularly good ‘steaming up’ (see Foods and Feeding Course) before the cow calves, can increase the size of the calf, but this increase is small – about 2 – 4kg. If a cow is well fed before calving, some of the extra food will go to nourish her calf, but most if it will be converted into fat, and stored by the cow for use after she has calved and is producing milk. Most cows lose weight during the first 100 days of their lactation because they use up body reserves of fat to produce milk. The demands of the foetus during the last month of the cow’s pregnancy are equal to the nutrients required to produce 5 litres of milk.
The signs that a cow is about to calve are as follows:
- The udder is distended and swollen, and sometimes milk will drip from the teats, especially in a high yielding dairy cow;
- The vulva becomes distended and a discharge of thick mucus can be seen;
- The ligaments between the tail head and the pelvis drop and the whole area appears to open up;
- The cow appears to be ‘flat sided’ because the calf has moved from the body of the uterus into the cervix; and
- The cow appears to be restless, and will usually move away from the rest of the herd, and go off by herself into a corner of the paddock.
In the case of dairy cows, it is good practice to put cows that are near to calving into a small paddock where they can be watched. Always be sure to keep a good eye on dairy cows that are near to calving, even during the night, because dairy cows, and particularly Friesland cows can have problems and the calf can easily be lost. Even if the cow calves without any assistance in the paddock, someone should be there to make sure that the calf breathes at once, and has no mucous across its nose and mouth; a calf can die in three minutes if its nose and mouth are covered at birth.
If the cow is having difficulty in calving, she should be brought into a loosebox or the milking shed or parlour, tied up with a halter so that the herdsman can give her some assistance. Two nylon calving ropes, warm water, soap and a towel should be available. In a normal presentation the water bag appears first, and once this has been broken, the two front feet and the nose of the calf should appear. Provided these are presented and can either be seen or felt with the hand, the cow can be calved quite easily. Some examples of abnormal presentation are given in the Animal Structure and Function Course; some of these can be dealt with by an experienced herdsman, but, in the case of difficulty, a veterinary surgeon should be called on to calve the animal. An inexperienced person can do severe damage to a cow, resulting in the death of both the cow and the calf.
After the calf has been born, any mucous should be removed from the nose and mouth, and the calf should be helped to draw that vital first breath of air by massaging the area of its lungs. Once the calf is breathing, allow the cow to lick the calf dry. This not only dries the calf but stimulates it and helps its breathing and circulation; it also helps to calm the cow and make her content. The calf’s navel cord should be dressed with a 20% solution of iodine as a precaution against Joint Ill. Remain with the cow and calf until the calf has got onto its feet and suckled the cow; you should also watch for the cleansing, or lining of the uterus, which should be discharged from the cow between 1 and 2 hours after calving, although it sometimes takes longer than this. Once the cleansing has been discharged, it should be removed because cows will often attempt to eat their cleansing, and they can choke to death while doing so. If the cleansing is not discharged shortly after calving, this is a sign of infection inside the cow; it should be left for 3 days, and then removed by an experienced herdsman or Veterinary Surgeon. A pessary can be inserted into the uterus on each of the 3 days to assist the cleansing to come away.
|Pessary: a small soluble block that can be inserted into the uterus to treat infection.
The normal practice is to leave the calf with the cow for 3 to 4 days, allowing it to suckle the cow, and bringing the cow into the milking shed to milk out any surplus milk at the normal milking times. It is most important that the calf receives this first milk from the cow. The calf will take about 6 litres of milk on the first day, and 10 litres on the fourth day.
It is important to remember that Colostrum is not milk and cannot be sold as milk. It becomes true milk only four days after calving, and can be sold as milk on the fifth day after calving. For the same reason, cows that are being recorded under the National Milk Recording scheme officially begin their lactation on the fifth day after calving, and any milk produced before that is not recorded.
Colostrum is a mixture of true milk and other constituents of blood plasma which appears in the cow’s udder between 3 and 9 days before the cow calves. The actual analysis of colostrum and milk is compared below.
|TABLE 1: SHOWS AN ANALYSIS OF COLOSTRUM
|Lactose (Milk Sugar)
The remainder of both colostrum and milk is made up of water. One big difference between colostrum and milk which is not shown on the above analysis is the colour. Colostrum is a rich yellow colour, and the reason for this is that it contains more carotene than milk does. Carotene is the yellow pigment which gives the colour to carrots, and is contained in nearly all vegetables and grass; it is associated with the production of Vitamin A (see the Foods and Feeding Course). Colostrum is higher in Vitamins A, D and E than milk and these are important vitamins for the very young animal. The amount of these three vitamins in colostrum can be increased, by feeding the cow a vitamin supplement before the calves are born.
Looking at the analysis of both colostrum and milk you can see straight away that the main difference is in the amount of the Solids-not-fat, or S.N.F. as it is commonly called. The S.N.F. content of colostrum is much higher than that of milk. S.N.F. consists of the protein, lactose and minerals in the milk; in other words, the solids in the milk apart from the butterfat. You can see that the reason for the S.N.F. content of colostrum being higher than milk is that the protein content is much higher; 14.3% in colostrum as against 3.3% in milk. The protein in colostrum contains substances called lacto-globulins and antibodies which pass from the cow, through the colostrum and into the calf’s bloodstream via its stomach. Once inside the calf’s bloodstream, they give the calf what is called passive immunity to certain diseases, notably calf scour caused by the bacteria e.coli. This is a very important factor in the survival of the calf during the first two weeks of its life. The blood of a new born calf does not contain any antibodies at all, and the calf has no natural resistance to disease, especially scours. Resistance to disease is acquired by the calf when it drinks the colostrum from its mother and the antibodies pass into its bloodstream. If the calf becomes infected, the bacteria causing the infection are attacked by these antibodies; this is called passive immunity. The calf starts to acquire what is called active immunity when it is about 10 days old, because it is then beginning to produce its own antibodies, and it will continue to produce these antibodies for the rest of its life.
The amount of protein in colostrum falls quite quickly as the colostrum is taken from the cow, either by milking, or by the calf suckling. It follows therefore that the number of antibodies also falls at the same time.
Protein falls from:
- 18% after the 1st milking
- 12% after the 2nd milking
- 6% after the 3rd milking
- 4% after the 4th milking
One of the most important things in calf rearing is to make sure that the calf gets the colostrum from its dam. The best way of doing this is to allow the calf to suckle for 4 days, before being taken away from the cow. If, for any reason, the calf is not being allowed to suckle, the cow must be milked and the colostrum fed to her calf. If a calf does not receive the Colostrum from its dam, it has no defence against infection and is very likely to die within the first two weeks of its life.
Colostrum may not be available for a newly born calf. This occurs when a cow dies giving birth to a live calf. The following mixture can be fed to the calf:
- 1 egg in 0.5 litres of water
- ½ teaspoonful of castor oil
- 0.5 litres of whole milk
This mixture should be fed to the calf three times a day for four days. After this, it can be fed on normal milk. It is important to remember that the mixture should be fed at blood heat (38°C).