- MANAGEMENT OF THE DAIRY COW
The term ‘management’ is one that is used a lot in agriculture and means the way in which a farmer looks after his crops, his finances and his animals. The good farmer maintains a high standard of management and remembers that good managing is a combination of knowledge, attention to detail, with the ability to spot a problem in its infancy and correct it intelligently.
Management is very important with all cattle but mostly with dairy cattle, although all dairy cows are selected for milk production, and have what is called a good “Genetic Potential”. In other words, they are capable of producing high yields and ought to produce such yields. Whether they milk well or badly will depend on their management by the farmer. In other parts of the course, notably in the Animal Breeding Course, we have talked about Heritability which is the way that characteristics like coat colour, horns, etc. are passed on from the parents to the offspring. The heritability of some characteristics, especially those relating to beef production, is high, but the heritability of milk yield is low; only 20%. This means that 80% of the milk which a cow yields depends on how she is managed by the farmer; how she is fed, milked and generally looked after.
Management can be divided into two main areas: that concerned with the general health of the cows in the herd, and that concerned with the production of the cows; that is, the milk and butterfat yields of the herd.
Dairy Cattle should be free of ticks, and this can be achieved by dipping. Dipping frequency will depend on:
- Where the farm is – some areas have much greater tick problems than others;
- The severity of the problem on the farm affected. i.e. the number of ticks
Dipping should be done in a spray-race or hand-spray or using a pour-on dip. Plunge dips are not suitable for dairy cows – the stress causes a drop in milk production for that day, and cows with big udders are likely to injure their udders. Tick control is very important because they transmit several diseases, the most serious being redwater, gallsickness and heartwater.
Depending on the area, some routine injections are given to dairy cattle. Injections against Rift Valley Fever and Lumpy Skin are given at the beginning of the rains in October. Young stock are injected against Contagious Abortion and Quarter Evil. Normally animals are injected against such diseases as Rabies, Anthrax and Foot and Mouth disease, only if cases have been reported in the area.
The aim of the farmer with a dairy herd should be to see that his cows produce a calf each year, giving a calving Index of 365 days. The Calving Index is the time in days between a cow calving down and producing the next calf. This is not easy to achieve, and good farmers are happy with a Calving Index below 390 days.
A Calving Index for a herd, which is the average of all the calvings in the herd, which is over 400 days,
means that the herd has an infertility problem and the cows are not conceiving properly. They are having too long in their dry period and not producing milk. The ideal is for a cow to calve down, milk for 10 months, have a dry period of 2 months and then calve down again. Cows normally come on heat 60 days after calving and then every 21 days unless they have been served by a bull or by Artificial Insemination (A.I.), and have conceived (i.e. have become pregnant). As the gestation period for a cow is 9 months or 270 days (the time between being served and producing a calf) it follows that the best time to put the cow to the bull will be about 3 months after she has
calved. This means she will produce her next calf 12 months or 1 year after her last calf. Because cows do not always conceive the first time they are bulled, the usual practice on dairy farms is to bull the cow at about 60 days after calving, depending on her heat period, so that if she fails to conceive, she can be put to the bull 21 days later and still calve down in good time.
Calving Index of 365 days
One of the most important management points in dairy farming is to make sure that cows are served by the bull at the right time. It means that the herd has to be carefully watched to see when cows come on heat. The signs of this are that the cows ‘ride’ each other by jumping on the back of the cow that is bulling. The cow which stands still and allows the others to ride it is the one that is on heat. Other signs of heat are excitability in the cow, and often a discharge of thin, clear mucus from the vulva. Having seen that a cow is on heat, the next step is to identify the cow and then check her milking records to see how many days she has been in milk – i.e. from her last calving. If she has been milking for less than 60 days, it is better not to serve her as this means that she will calve down too early, without allowing her to have 2 months (60 days) rest period between lactations. If she has been milking for 60 days or more, put her to the bull and record the date bulled and the bull used. This is most important and very necessary to keep records for the whole herd; dates of calving, coming on heat, and of bulling. It is a good idea to keep a book with one page for each cow in the herd, and record all these things immediately so as to keep the records in order. Always record these things immediately, otherwise you forget to do it, and your records become just a muddle.
If a cow comes on heat 21 days after being served, it means that she has not conceived and must be served again. If she keeps doing this, it means there is something wrong with her and she should be examined by the vet.
Do not serve any cow that is producing a thick white discharge or mucus from the vulva, because this means she has an infection of the uterus and will not be able to conceive. She can also infect the bull.
The usual practice with a dairy herd is to keep the bull in a pen or paddock separate from the herd. Do not run the bull with the herd, because he will serve some cows too early and will also serve when the herdsman is not looking, so that no record of that service can be made. It is most important to record all services so that the farmer knows when a cow is due to calve down again and can dry her off in time to give her a rest. A practice often followed is to keep the bull in a paddock pen which the cows have to pass when coming into the cowshed to be milked and going back to the field after milking. Any cow that is on heat will stand at the fence beside the bull and can be seen by the herdsman.
Good, accurate records are more important in dairy farming than in any other type of agriculture. The farmer should know how much milk a cow has given each day so that she can be fed properly, because cows are fed according to their daily milk yield. He must know when cows have calved down, when they come on heat and when they have been served so that he can dry them off and give them a rest between lactations. He should know how much milk each cow has given during her past lactations and what her butterfat production has been because he can get a higher price for milk with a high butterfat content. Cows which have poor butterfat (3% or less) should be culled from the herd. A record should also be kept of all cows treated for illness in the herd, especially Mastitis. Any cow which continually has to be treated should be culled from the herd.
The average life of a dairy cow in a herd is four lactations, which means that if she calved down with her first calf at 2 ½ years old, she will be 6 ½ years old when she is culled from the herd. Compare this with the average life of a cow in a beef herd which is 8 – 9 years. The two main reasons for having to cull cows from the dairy herd are:
- Infertility – failing to get the cow in calf;
- Mastitis – This is the commonest disease of all dairy cattle worldwide.
If these two problems can be kept to a minimum in your herd, you will make better profits, and the best way to reduce these problems is by keeping good and accurate records.
3. FACTORS AFFECTING MILK YIELDS
A number of factors combine to affect the milk yield that a cow will give over her lactation period of 10 months or 300 days, and as we have already discussed, most of these factors are:
This can be controlled by the farmer or herdsman. The cow is born with a genetic potential for milk production, but whether or not she achieves this potential depends on how she is managed by the farmer. A good Friesland cow may have the ability or genetic potential to produce 5 000 kg of milk during her 300 day lactation, but, because of poor management, she may produce only 3 000 kg.
If the daily milk yield of a cow is plotted on a graph, it would look something like this:
Figure 1: Shows the lactation curve
She should reach her highest daily yield at about 30 days after calving, maintain peak yield until the 50th day, and then begin a gradual decline until she is dried off at 300 days. This gives her the 2 months rest (65 days) required before she calves again. The rate of decline of her daily yield will depend on a number of factors, including the cow herself, the season of the year (winter or summer), how she is fed, her age and when she is bulled and conceived. Once a cow conceives (i.e. becomes pregnant) her milk yield is reduced as food goes to nourish the calf growing inside her, (the foetus).
The breed of the cow affects her milk yield; for example, a Friesland cow will give more milk usually than a Jersey cow. The average milk yields for the main dairy breeds are:
- Friesland/Holstein – 5000kg’s per lactation
- Guernsey – 4300kg’s per lactation
- Ayrshire – 4000kg’s per lactation
- Jersey – 3500kg’s per lactation
Butterfat is also affected by breed, but in this case, it works the opposite way around. Jerseys have the highest Butterfat with a breed average of 5.0% and Frieslands the lowest with 3.5%. In other words, although Jerseys give less milk, it is much creamier milk than Friesland milk.
Cows are normally milked twice a day, but some cows are milked three times a day at intervals of 8 hours. These cows will show an increase in milk yield of between 10% and 25% over the cows which are milked twice daily.
A dairy cow will normally give her highest yield at her 5th lactation, and after this, her yield will drop. The great pity with dairy cows is that most of them stay in the herd for 4 lactations and then have to be culled, usually because of infertility or mastitis, so that they never reach their peak yield.
Cows that are badly milked through the use of an inefficient milking machine will give less milk. Each time they are milked, some milk is left behind in the udder and this tends to reduce their yield and causes them to go dry more quickly.
The time of the year when the cow calves is quite important to her milk yield. The best time to calve a cow is just before the rains so that she reaches her peak daily yield on Summer grass. The worst time for a cow to calve is towards the end of the grazing season, when the drop in her daily yield will be made worse by the change to Winter feed.
This is by far the most important factor in milk yield and the one to which the farmer should pay the most attention. It has been dealt with earlier in the course and in the Foods and Feeding Course. The important thing to remember is to calculate the Nutrient Requirements of the cow according to her Maintenance and daily Milk Production, and then feed a ration that is balanced for Dry Matter, Protein (D.C.P.) and Energy (T.D.N.). It is important not to overfeed as the surplus nutrients will be laid down as fat and this is a waste of expensive concentrate feed.