Animals perform a useful and necessary role in agriculture for the following reasons:
- Animals provide protein and some minerals and vitamins which are necessary to human health, and which balance other nutrients that man obtains from plant foods. Animal protein in the form of meat contains the amino acids which are essential to the growth and development of humans. In general, children cannot grow properly nor can adults lead a healthy life, without the protein obtained from the consumption of meat, milk and eggs. Vegetarians can survive without eating meat, but they have to be extremely careful about their diets.
- Animal products are always in demand to satisfy human appetites. People like the taste of meat, and as the standard of living and income rises in a country, the demand for animal products also rise. Per head of the population, the developed countries eat the most meat while the underdeveloped countries eat the least meat.
|Ruminants: an even-toed ungulate mammal that chews the cud regurgitated from its rumen.
- Farm animals can be divided into two groups – those that convert human foods into protein and those that convert non-human foods into protein. In the first group there are pigs and poultry which eat mainly the cereals, such as maize or wheat, which are staple human foods. These animals produce protein in the form of meat and eggs, but the efficiency of that production is not very high. In a well-run pig unit the efficiency is about 3 – 1, this means that 3kg of meal is required to produce 1kg of pig meat.
- Animals in the second group are the ruminants, which convert grass and roughage into high quality human food. Although the efficiency of this conversion is also not very high, these animals perform a very valuable function in agriculture, because they convert something that cannot be eaten by man, into a form that is a valuable human food. Animals in this group are cattle, sheep and goats.
- Ruminants are necessary on a farm in order to utilise veld and pasture grass and the by-products from arable crops such as straw, stover and haulms. These products which cannot be sold by the farmer are converted into saleable products by processing them through the ruminant animal.
- Animals in both groups produce manure which is necessary to feed the soil and maintain soil structure. This increases the production of the arable crops on the farm.
- Although the greatest demand is for the high energy plant foods such as cereals and oil seeds, the area of arable land in the world is limited. Crop production is being increased but this is not keeping pace with the demand for food. Many people throughout the world live at the level of starvation. Areas of marginal land that are unsuitable for arable cropping can be used for meat production, and small stock such as pigs and poultry can be kept under intensive systems almost without any land at all.
The systems used in animal production are divided into:
Extensive System: This makes use of the natural veld, and is supplemented with veld hay and drought resistant trees and shrubs to see the animals through lean periods caused by summer droughts. This system is used for cattle breeding herds, with some cattle being finished and sold fat off the veld.
|Arable: used or suitable for growing crops
Semi-extensive System: Natural veld supplemented during the winter dry period by some roughage from arable by-products on the farm or ranch. Fat cattle can be sold off the farm, either steers bred on the farm or those bought in to clean the arable lands of their crop residues.
Semi-intensive System: Natural veld supplemented with roughage and concentrate produced from arable land. This is the system used for dairy cattle, many beef breeding and fattening enterprises and for stud breeding.
Intensive System: No veld involved, although grass pastures are used in this system. Food produced from arable land or bought in from outside the farm. In fully intensive systems such as feedlots, (pigs and poultry), the animals are housed and all food carried to them.
The type of system used on any farm will depend on a number of factors, the main ones being:
- The size of farm. Small farms have to use semi-intensive or intensive systems for animal production in order to be viable economically;
- Location of the farm and the natural area where it lies;
- Climate in the farms location. Humidity, rainfall and temperature all affect the type of livestock suited to a farm and the type of system used for their production. In general, the effects of high temperatures are offset by low humidity, causing hot days and cool nights, which allow the animal to recover and feed during the night. Animals from breeds that are adapted to this type of climate mature more slowly than temperate breeds, and this will determine the type of animal produced on the farm and the age of marketing;
- Soils on the farm will determine the amount of arable land, and also the land left over as non-arable or grazing. On a well-developed arable farm the non-arable land will be vleie, kopies and areas that are too rocky or shallow to allow for ploughing;
- Available markets and transport facilities will affect the type of livestock production carried out on a farm. Milk and eggs are produced near to their markets, whereas, cattle can be transported over long distances, although this can be an expensive operation; and
- The personal wishes of the farmer, which is an important consideration. Some farmers dislike certain types of livestock, and prefer other animals for their farming operations. If a farmer dislikes for example, pigs, he will not really be interested in their welfare, and they will not be a profitable enterprise.
|Oestrus: a recurring period of sexual receptivity and fertility in many female mammals; heat.
The best system of animal production is the one which takes into account both the environment and the economic factors. If the environment is not considered, the system can be only short term, as it will be destroyed by adverse conditions, which the farmer cannot control, or which are too expensive to control. Animal production systems which fit into the environment are based on a long term policy. While such a policy might bring small returns immediately, it does ensure security and better ultimate returns because both the natural resources and the animals remain in better condition and suffer much less damage.
One of the major factors limiting increased productivity of the ranch cattle of Southern Africa is poor reproductive performance.
The Calving Percentage of a beef herd is calculated by:
Number of calves born X 100
Number of cows bulled
The average calving percentage for ranch herds in this part of the world is about 50%, which means that most cows are producing a calf every other year, instead of every year. If the average for the area could be increased to 80% more beef would be produced, and the farmers and ranchers would make more money.
The number of calves born and weaned each year, is the most important single factor in determining the profitability of any beef breeding herd.
|Polyoestrus: having more than one period of oestrus per year.
Where disease is not a factor, this low reproductive capacity of cows is due to poor female fertility, in the period after they have calved. Cattle, unlike sheep, are polyoestrus in their sexual behaviour, and have lost their seasonality of reproduction. Under reasonably good conditions of feeding and management, the beef cow will breed during any time of the year, although sexual activity is at a low level during mid-winter and increases rapidly during the summer. Where bulls are run with the cows all the time, peak conception occurs January to March. This follows the natural breeding habit of cattle with mating taking place in late summer, when the cow has built up her body reserves, and the cows calving in the following spring. The cows then follow the natural pattern of the grass, producing their first milk as the grass starts to grow and building up to peak production as the grass becomes more plentiful.
Lactation (i.e. milk production) delays the resumption of sexual activity, and since the gestation period of a cow is 9 months, it is not easy to get a cow to calve down every 12 months, which is the ideal situation in a beef herd. Cows that lose their calves soon after calving quickly come on heat again, while the temporary removal of the calf 10 weeks after calving increases the activity of the ovaries in lactating cows. The time of conception is earlier with dry cows and heifers, and in addition, the rate of conception is much higher – in some cases up to 60% higher. The tendency in any herd is for the dry cows and heifers to come on heat and be bulled soon after the bulls have been put into the herd.
The early calvers are the next to conceive, and finally the late calvers are bulled right at the end of the bulling season. In fact, some of the late calvers do not come on heat in time to be bulled, if a restricted bulling season is practiced.
This means that many cows are taking a rest of one year, are not conceiving and are not producing a calf. Having taken a rest and built up their body reserves, they will be among the first to conceive during the following bulling season.
LENGTH OF MATING SEASON
Most beef farmers use a mating season of 3 months i.e. the bulls run with the cows for 3 months. It has been found that there is very little, if any, increase in the calving rate obtained by extending the bulling season beyond 3 months. The latest tendency is to limit the bulling period to 65 days, as this provides sufficient time for 3 oestrus (heat) periods and makes the calving period much easier to handle.
DISTRIBUTION OF CALVING
The management of the beef herd during the calving period is made much easier, if a high proportion of the cows are bulled during the first 40 days of the breeding season, so that most of the calves are born together. A calving season that shows a pattern of calvings taking place towards the end of the season, is a sign that the nutrition of the herd is poor. Cows are not building up their body reserves that have been depleted during pregnancy and early lactation, and the cows are not coming on heat until the end of the mating period. Cows should not be allowed to lose too much bodymass after calving.
TIME OF WEANING
The age at which the calves are weaned is an important factor in the management of the beef herd.
Calves that are weaned too early will be small, and unless they are fed very well after weaning, they will always be poor growers and have had a bad start in life. If weaning is too late, the calf will be a good size, but there will be a tremendous strain on the cow. She will use up more body reserves in producing the extra milk, and this makes it difficult for her to come on heat and conceive; she could fail to conceive and produce a calf the following year so that her overall productivity in the herd has been lowered. In commercial herds it is normal to wean the calves at 7 – 8 months old. If the calving season has been compact, the calves can be weaned in large batches, but if the calving has been drawn out, weaning may have to take place every week as the calves reach the right age.
NUTRITION OF THE COW
Scientists have found that with most species of farm animals, the females will conceive more easily if they are well fed during the period just before they are mated. This ‘flushing’ as it is called works with ewes and sows, and results in better conception and more offspring. The problem with both beef and dairy cattle, is that, the cows are losing condition just before the mating period, because of the milk which they are producing. If they lose too much condition, they do not come on heat at all. Cows that calve on sour veld in spring commonly lose 50 – 100kg in live-mass during the first three months after calving. If the cows were being flushed in the same way as ewes and sows, they would be gaining weight during this period. If the farmer wants a good calving percentage from his herd, he must see that his cows are in good condition at calving, and that they do not lose too much weight in the first 100 days after calving.
This can be done by supplementary feeding, but how much feed is required will depend on the calving season. Cows calving in the spring will require less supplementary feed than those calving at the beginning of the winter.
When considering the nutritional requirements of beef cows, the following points are important:
- The reproductive mechanism of the cow is more sensitive to under-nutrition than any other body process;
- A cow weighing 500kg should gain 45kg between weaning her calf and calving again if she is to conceive again after her calving. This means that both the cow and the calf, are in good condition at calving, and gives the cow a good start for her lactation;
- Cows that are producing milk must be fed for both maintenance and production, and the ration, whether grass only or grass plus supplements, must be balanced for energy, protein, minerals and vitamins. The nutrition of cattle is covered in the Feeds and Feeding Course; and
- If cows are underfed, particularly during their first three lactations when the cow is developing and maturing, they will gradually lose condition and body-mass, until they fail to conceive and have a year’s rest without a calf.
NUTRITION OF THE HEIFER
In general, heifers have a high conception rate during their first mating season, and a calving percentage of up to 90%. However, during the second mating season, when the heifer is feeding her first calf, the conception rates are often very low. This is due to poor feeding and the failure to recognise that a heifer has not only produced a calf and is producing milk, but also the fact that she is still growing and developing. Heifers require special attention in order to:
- Limit the unproductive period before their first calf is produced;
- Ensure that they reconceive after their first calf; and
- Make sure that they grow out to their mature size and do not become stunted.
One important factor is the age at which a heifer can be bulled, and in fact, size is more important than age. This will vary according to the breed or cross of the heifer, but for most breeds, heifers are bulled when they weigh 65% of mature mass. The age at which they reach this weight will depend on the level of feeding during their rearing period, and under ranch conditions with no supplementary feed, very few heifers calve down before they are 3 years old. Good feeding can produce earlier calving and one extra calf in the lifetime of the cow.
Birth weight is closely associated with the daily live-mass gain of calves during the suckling period. In other words, calves that are the heaviest at birth are the heaviest at weaning. It has been found that each 1kg increase in the birth weight of a calf, results in 3 kg more weight at weaning. The heavy calf at birth takes more milk from the cow and, in turn, stimulates the production of even more milk throughout the lactation. Each additional 1kg of weight at birth causes the calf to consume about 1,5kg more milk at each feed when the calf is one week old. This increases the production of the cow so that for each 1kg of extra birth weight the calf will consume the following:
- 6kg more milk up to 1 month old
- 16kg more milk up to 2 months old
- 20kg more milk up to 3 months old
In this way the heavy calf at birth becomes the heavy weaner, because it has had more milk than the lighter calf. Birthweights in calves are influenced by the age of the dam. Birth weights increase with the age of the dam, until the heaviest calves are produced when the dam is 6 – 8 years old; after that, they remain about the same and may decline slightly with very old cows. The heaviest weaners are produced by cows that are 6 – 8 years old, because these cows produce the heaviest calves at birth, and the most milk during their lactations.
The normal milk production of a beef cow shows a fairly rapid rise in daily yield during the first 4 – 6 weeks after calving, and then gradually declines. Provided that the levels of feeding are satisfactory, the maximum amount of milk produced by a beef cow is limited by the appetite of the calf, rather than the productive ability of the cow. If the calf consumes only a portion of the milk available during the first few weeks of the lactation, the excess milk is re-absorbed by the cow, and her production will decrease until it is just enough to satisfy the appetite of the calf.
The amount of the milk produced by beef cows varies a great deal according to such factors as levels of feeding, size of calf, breed or cross of the cow etc. Hereford cows have been shown to produce between 400 kg and 2000kg, and Afrikaner cows between 600 and 2300kg of milk during a lactation of 240 days or 8 months. Range cows show a marked increase in production as the feeding value of the veld increases in early summer, and this will happen even if the cow is towards the end of her lactation.
Each bull in a herd will have some effect on the calves which he sires. The effect is small until weaning, but it has been said that 11% of the variation in the weaning weights of calves can be due to the effects of the sire. It is possible to increase weaning weights by selecting animals that have had high weaning weights themselves. However, in most herds it is seldom practical to cull cows that have produced calves with low weaning weights. After replacing old, infertile cows, it is not advisable to cull more than 5 – 10% of the herd females because of poor weaning weights of their calves. Selection of the best heifers and bulls can increase weaning weights in a commercial herd by 8 – 9kg per generation.
Inbreeding will affect adversely both the calf and the dam and can have a very marked effect on the weight of the calves at weaning.
SEASON OF BIRTH
Under natural conditions the beef cow calves in the spring and her milk production rises in line with the production of grass from the veld.
The cow produces enough milk for the calf, and is also able to maintain her own body condition, so that she is able to come on heat, and conceive again three months after calving. This situation is ideally suited to the cow, and a good general rule with a commercial herd is to calve the cows at the start of the rains on the farm. The rains stimulate the growth of grass, although the start of the rains will vary from district to district, and even from farm to farm.
The Advantages of spring Calving are:
- Milk production by the cows is higher on green grass than on dry winter field. It is much cheaper;
- Calves are weaned before winter and the dry cow can be winterfed inexpensively;
- The early calf can withstand the winter cold better than the late calf;
- Calves can be sold at weaning with no winter feeding, or as yearlings after having fed them for only one winter; and
- Cows are mated on green grazing when they are being ‘flushed’ and more likely to conceive.
The Advantages of autumn Calving are:
- The cows are in good condition when they calve down, and the calves are likely to be strong;
- The young calves are spared the heat, flies and other parasites; and
- Calves are weaned onto grazing and not onto a dry paddock where they will require extra feeding.
The time of calving is largely determined by the available food. Spring calving has a clear advantage under extensive conditions, but under intensive conditions where supplementary feeding can be supplied, the tendency is to move towards autumn calving. Under either system there will always be a range of 2 – 3 months between the first and last calves, so that some extra food may have to be provided for the early calving cow or the late born calf.
AGE OF WEANING
The main reason for weaning calves is to reduce seasonal stress on the cows. Weaning should be carried out when the calves are old enough to fend for themselves, and the cows have sufficient reserves to withstand the dry season. The time of year can be more important than the age of the calf. It is not advised to wean calves later than 8 months old, and heifer’s calves should be weaned at 6 months old. The normal practice with cows is to wean at 7 – 8 months old. By that time the calves are eating some grass to compensate for the lower milk production of the cow. If calves are weaned earlier, or if maximum growth is required, the calves should be given a creep feed from 1 month of age.
A factor that can affect the age of weaning is the market price for weaners and whether or not the calves are going to be sold at, or shortly after weaning.
REDUCING THE SHOCK OF WEANING
Any inoculations, dosing, castrations and/or ear marking should be done well before weaning (e.g. at least 2 weeks) so that these operations do not add to the shock of weaning. The size of the weaning herd is important, and preferably the herd should not exceed 100 calves.
Systems of weaning are:
- The removal of the cows from the paddock leaving the calves behind;
- The temporary removal of the calves from the paddock and the removal of the cows to the far side of the farm;
- Interchanging the cows of two herds;
|Inoculations: the action of inoculating or of being inoculated; vaccination. Castrations: remove the testicles of a male animal or man.
Removing the cows, but leaving a few dry cows behind to act as foster mothers;
- The use of weaner plates for 2 weeks before separating the cows and calves; and
- This is probably the most humane and least noisy way of weaning. Whenever separation is involved, the objective should be to avoid either party knowing where to look for the other, which means moving out of earshot.