THE CARE AND HANDLING OF DAIRY CATTLE

P G Stewart
Cedara Agricultural Development Institute

INTRODUCTION

A high-producing dairy cow has been called a "genetic monster" meaning that she is capable of producing far more milk than ever would be required by her calf. In order for her to express her full genetic potential, she must be kept as contented and comfortable as possible so that she experience's as little stress as possible.

The dairy animal's environment has profound effects on her productivity through its effects on her growth rate while young, and on her reproduction and milk production as a cow. Environmental factors can be conveniently separated into three distinct subdivisions. First, the way in which the cow interacts with her herd mates; second, the interactions with the farmer and his labour, which can be referred to as stockmanship; and third, the physical environment, which includes the farm's facilities, climate and weather. This leaflet looks briefly at the ways in which a good stockman should handle dairy cattle, and also at those environmental factors which must be considered to reduce stress to a minimum.

BETWEEN ANIMAL INTERACTIONS

Dairy cattle are gregarious animals which, by nature, need the company of other animals. Experiments have shown that calves reared in isolation do not grow as well as calves which can merely see each other. Cattle have a need to socialize, and within each group there is a dominance hierarchy. Provided that groups are not too large, and that animals are not moved from group to group too frequently, each animal gets to know her herd mates and her place in the hierarchy. As a result, there is very little social stress. But, each time a new animal joins a group, there can be considerable social interaction, and even severe bullying of the new arrival. Bullying is far less prevalent amongst young animals than amongst mature cows, and is also a function of space, housing system and even breed. It is not possible to lay down hard and fast rules for minimizing social stress, but some general guidelines are set out in the next section.

MINIMIZING SOCIAL STRESS

Horns

Horns have no function on the head of a dairy animal and, if present, MUST be removed. It is preferable to prevent them from growing, by means of an appropriate procedure while the animal is still a calf. Just one cow with horns can completely dominate a feed manger otherwise adequate for ten.

 

Group size - calves

Calves should never be reared in isolation and, if kept in hutches or individual pens for the first few weeks of life, they must be able to see and hear other calves. Calves can be reared in small groups from a very early age. As a general rule, group size until six months of age should not be greater than ten. More important than the absolute size of the group, is that calves within a group should be more or less of an age. Animals significantly smaller than their herd mates cannot compete successfully for food and shelter, and simply do not do as well as they should, even when the group pen or camp is quite large and access to feed troughs appears to be adequate. Fortnightly weighing will soon reveal if there are any problems. Do not simply move poor doers down a group. Try to find out why the animal has not done well and rectify the problem. Animals which remain small for their age should be culled. For practical purposes a heifer that is "small for her age" is more than 15% lighter than the average heifer of the same age in the herd.

 

Group size - heifers

Provided that there really is ample pasture area and that concentrates are fed individually, heifers older than six months can be run in groups of up to about 40. However, they should still be grouped by age for regular weighing, and growth rates should be checked against breed targets. In feedlot systems, where heifers are kept in small camps and group fed, the maximum group size should not exceed 15, and the animals within a group should be very much of the same age and weight, i.e. no more than two months between the oldest and the youngest in a group. Heifers more than a year old can be run with the dry cows. This is especially necessary when a follower herd is needed to clean up the pasture left by the milking herd; DO NOT USE HEIFERS AS MOWING MACHINES, they must continue to grow at the target growth rates for the breed, even if this means a lot of supplementation.

 

Group size - cows

Some dairy farmers successfully run groups of as many as 200 cows. Observation of these large groups will show more frequent social interactions, such as head pushing, than in smaller groups. These interactions not only use up time that could be better used eating or resting and ruminating, but they also result in unnecessary trampling of pastures. Furthermore, the time taken to move large groups to and from the milking parlour, and milking time itself, can become unacceptably long. But, on the other hand, the group size at which cows instantly recognize each other may be as small as 50 to 70, and this is rather impracticable on most farms. As a compromise, it is suggested that groups should not be larger than 150, and, ideally, that the group size is maintained at about 90 to 120. The important principle is that there should be enough space in the pasture, or at the feed trough, for every cow to have free access to the food.

In feedlot systems cows are usually grouped by production and stage of lactation. This is very necessary where total mixed rations are fed, since feeding economy dictates that cows should be grouped according to their feed requirements. North American dairymen refer to grouping as "stringing". Diligent stringing into four or more feed groups is considered essential for maximum profitability. Grouping by stage of lactation can also facilitate heat spotting, since only a certain group or groups may need to be closely observed. Grouping by stage of lactation is an absolute necessity when bulls are run with the herd.

In pasture systems, grouping by production is not usually a good idea. However, farmers persist in grouping the high producers separate from the low producers, with the high producers getting the best pasture, and the lower producers either following the high producers on the same pasture, or getting a distinctly poorer pasture. The high producers are usually also receiving quite a large amount of concentrates. Therefore, it can be argued that the high producers should get the poorer or less abundant grazing. In fact, neither group should be punished in any way. The high producers must be encouraged to eat as much roughage as possible to minimize the risk of acidosis and maximize nutrient intake, while the lower producers must also eat their fill of roughage in order to reduce their need for concentrates to a minimum, and to ensure that they recover adequate body reserves before being dried off for the next lactation.

Depending on herd size, several grouping strategies are possible. Some suggestions are :

• If pasture is very limited, as in the winter with limited irrigation, send only the highest requirement cows (early lactation, high producers) out to the pasture, but ensure that those remaining behind get ample silage and hay.

• If there is ample pasture but some pastures are much further from the dairy than others, consider grouping into early-lactation, high-producers plus the cows with pendulous udders or otherwise sick, lame and lazy, and graze them on the closer pastures, while sending the rest to the more remote pasture.

• If no pasture is more than a kilometre from the dairy, and there is ample pasture, then consider grouping into first-calvers and the rest. Any sick, lame and lazy cows or cows known to be very low in the pecking order can also be put into the first-calver group. First-calvers are subject to bullying in large herds, and this grouping ensures that they get their fair share of the food, especially as the first-calver group will be about half the size of the other group.

 

Group size and the milking parlour

Top dairymen and women ensure that their cows spend as little time as possible in the waiting areas immediately around the milking parlour. When not actually being milked, cows should either be eating or resting and ruminating. More than three hours per day away from food or rest will adversely affect milk production. Therefore, the milking herd must be split into groups, so that no group spends more than three to four hours at the parlour (1½ to 2 hours per milking for twice daily milking). If the cows must spend more than three hours per day at milking, then waiting yards must be large and very good hay and/or silage should be provided. Areas required for waiting yards and other useful standards for dairy facilities are detailed in KwaZulu-Natal Dairy Leaflet 7.1.

Grouping and the dry cow

Neither cows nor heifers should be permitted to calve among the cows in milk. The curiosity and excitement generated by a calving within a large herd of cows in milk can overwhelm a new mother, and result in the calf being trampled or stolen and thus, either being injured or not getting its mother's colostrum.

The nutritional needs of the dry cow are also very much less than the cow in milk. Thus, in all the preceding discussion, it was assumed that the dry cows and close to calving heifers would be run separate from the cows in milk. But, the newly calved heifer, now a cow, has many new experiences at calving and is frequently unsteady on her legs due to pressure on the obturator nerve during calving. If the stress of finding her place in the social hierarchy of the cow herd is added to the stresses of parturition, the new cow may hardly eat at all for the first few days, resulting in loss of condition, and subsequent milk production. In order to reduce post-calving bullying, heifers must be introduced to the cows in milk before they calve. This can best be done by running the heifer with her milking group for two weeks from three weeks before her due date. A week before the expected calving date, the heifer should be removed from the milking herd. In small herds, where a particularly close watch is kept on the cows, the heifer can even run with the cows until observed in labour. Post-calving bullying won't be entirely eliminated but will certainly be very much reduced if these precautions are taken.

STOCKMAN COW INTERACTIONS

Some years ago (circa 1970) an English research worker named Martin Seabrook investigated the relationship between the personality of the herdsman/woman and milk yield of the herd. Not only did he find good correlations between the personality of the stockman and milk yield of the herd, but that two personality traits were particularly important. Amongst other traits, he classified the subjects of his study on the basis of their self-confidence, or lack thereof, and whether the person was an introvert or extrovert. No one is a complete extrovert or complete introvert, nor totally self-confident or lacking in self-confidence. Yet, as illustrated by Figure 1, he found that self-confident introverts tended to get the most milk out of their cows.

Figure 1. The relationship between personality and milk yield

 

Self-confident introverts

Obviously, farmers cannot take every prospective employee for psychological testing and, even if that was possible, there may not be enough self-confident introverts to go around. Therefore, what was it about these stockmen and women which enabled them to get more milk? In brief: "Quiet, confident handling". Self-confidence meant that the herdsman was completely unafraid and communicated this lack of fear to the animals, thus giving the animals confidence, and dominating them by sheer force of personality. The introvert did not need to chatter constantly with other people, and hence took time to pat and chat to the cows. Experienced beef farmers reading this are going to think that the author is quite mad, but ignore these findings at the cost of a lot of milk. In other words, the stockman who handled his animals quietly and gently and took time to talk to and touch them actually got significantly more milk, and as a corollary, took significantly less time over milking than any other personality type. The dairy farmer must strive to emulate this style of behaviour and train his labourers accordingly.

Sticks, whips & prodders

It follows from the previous section that there is no place on a dairy farm for sticks, whips or electric prodders. Patient, unhurried herding, using voice, or at most a well-trained dog, to assist, will pay dividends. When training cows to a crush for weighing, push rather than prod, and by the third weighing it may not even be necessary to close the gate on the scale.

 

Heifer training

Be extremely patient when bringing heifers into the parlour for the first few times. Begin doing this several weeks before calving. Allow them to stand in the parlour while the machine is being washed. Test dip them, talk to them, use the most experienced and quietest milker to train them. Let them know there is nothing to fear. Under no circumstances approach the newly calved heifer hesitantly, bearing a hissing milking machine, and attempt to put it directly onto her teats. Pat her on the rump, handle her udder, talk to her, and if possible have her calf at her head during the first few milkings, and the chances are that she will not even lift a foot off the floor.

 

Sensitivity to training

Experienced stockmen will have noticed that individual cows which usually ignore the farm dogs, may suddenly begin chasing them just before calving and especially just after calving. This is indicative that the normally docile and phlegmatic dairy cow still has a strong instinct of preservation before and after calving time. If one could measure the sensitivity of a cow to other environmental stimuli, it would be found that her sensitivity to nearly all stimuli is heightened in the few days before and after calving. This is illustrated in Figure 2. If the cow, or heifer, has good experiences during this time, she will milk far better than if she had a traumatic calving followed by a fight to get her into the parlour. The reason for this is that milk let down is a controlled by a hormone, oxytocin, which is released involuntarily in response to the stimulus of the suckling calf. The effect lasts only a few minutes and adrenaline, the hormone of flight and fear, is strongly antagonistic to oxytocin. Observe the conditions under which beef cows allow their calves to suckle. The mother stands quietly, placidly chewing her cud in an atmosphere of complete relaxation. The dairy farmer must strive for the same atmosphere in the parlour.

 

Figure 2. Sensitivity to training and the intercalving period

 

The cow's heightened sensitivity to stimuli at calving time has a corollary. If training has been bad, the cow may have to calve again before she can be taught to change a bad habit. A true story serves as an example: a herd in the KwaZulu-Natal Midlands experienced a change of manager and within six weeks the milk yield dropped by 5 kg per cow per day. Numerous experts examined the feed, the pastures, the water supply and even the weather patterns. Finally another farmer suggested investigating the milking routine in the otherwise immaculate and apparently well-run tandem side-gate parlour. This study showed that there was no milking machine routine. Machines were being applied
and removed in a random manner. There was a great deal of udder stress, as evidenced by a somatic cell count in excess of 1.5 million, caused mainly by machines being left on for far too long. The cows were reluctant to enter the parlour, and milk flow rates (poor oxytocin release) were slow. It took six months from identification of the problem until milk production was fully restored (the herd had to be retrained). The estimated loss, in this herd of 150 cows, was in excess of 100 000 litres of milk.

STRESS

STRESS DEFINED

For the purposes of this section, stress will be considered to be any factor which prevents the dairy animal from expressing its full genetic potential.

UDDER STRESS

Any stress on the udder is particularly detrimental to milk production. The common causes of udder stress are poor hygiene, tissue damage through poor milking machine maintenance or management, hurrying the cows on their walk to and from the pasture, mud and dirt. It is best measured through somatic cell counts (SCC). Somatic means "body" and these cells are part of the body's self-defence mechanism and are a normal component of milk. Thus, their numbers increase dramatically, pouring in from the blood stream, if there is any challenge to the udder, whether it be from bacterial invasions or simply tissue damage. If the SCC's are carried out on a regular basis, they are the best indicators of udder health. There is also a standard on-farm test, the California Mastitis Test (CMT), which can be used. Table 1 shows what can be expected in bulk milk samples. The SCC of individual healthy cows will vary with age and stage of lactation, but should be in the range 20 000 to 200 000. A count of over 300 000 indicates that there is a mastitis problem. This economically important topic is dealt with further in KwaZulu-Natal Dairy Leaflet 8.1.

Table1. Incidence of mastitis and milk losses estimated from somatic cell counts of bulk milk samples

Cell count/ml	Mastitis and management problems	% of cows affected	Lost milk production	Milk quality
< 250 000 250 000 - 499 000 500 000 - 749 000 750 000 - 999 000 > 1 000 000	Low Moderate Unsatisfactory Serious Very serious	< 20 % < 20 % 20 - 40 % 40 - 60 % 60 - 80 %	< 5 % 10 % 12 % 15 % > 18 %	Very good to good Moderate to suspect Unsatisfactory Unfit Unfit

Table 2. Ideal, acceptable and maximum temperatures for dairy cows

Ideal temperature Acceptable range Holstein-Frieslands Jerseys Brahmans < -15° C > 21 - 24° C > 38° C > 32-35° C

Feed intake up and milk production down Feed intake drops Feed intake ceases Severe milk loss and fertility drops

-1 to + 15° C -15 to + 27° C Maximum + 27° C + 30° C + 35° C

CLIMATE

High temperatures - heat stress

The process of roughage fermentation and breakdown in the rumen generates a great deal of heat. For this reason, the dairy cow functions best in the temperature range of -1 to +15° C. Unlike the horse, the cow is a homeothermic animal, that is, cattle attempt to maintain a fairly constant body temperature of about 38,6° C. Environmental temperatures up to 27° C are acceptable, but above this temperature cows must eat less to reduce heat production. If the cow cannot maintain body temperature by giving off excess heat, the body temperature will rise and adversely affect reproduction, primarily through causing early foetal death. Humidity plays a role and high humidity, combined with high temperatures, is obviously more stressful than the same temperature at a lower humidity. Indices which combine temperature and humidity can be used to estimate the degree of heat stress. A formula for estimating the temperature humidity index (THI) from dry and wet bulb temperatures is:

THI = 0.4(T_db + T_wb) + 4.61
where T_db and T_wb are the dry and wet bulb temperatures respectively.

A THI over 23° C is considered to be the upper limit before a Holstein-Friesland cow's production is affected. Cows can withstand hot midday temperatures much better if the nights are cool. The most stressful environments are areas such as the northern KwaZulu-Natal Coast, in summer, when both day and night can be hot and humid. Table 2 summarizes the effect of temperature.

It will be noted that Jersey are more resistant to heat than are Holstein-Frieslands. This is a function of genetics, body size and colour. Light coloured cattle do not get as hot as do black cattle. Watch a herd of Holstein-Frieslands on a hot sunny day; the mostly black cattle will invariably seek shade sooner than the mostly white cattle. Cattle have a limited ability to sweat (the skin of the nose being an exception) and must shed a lot of their heat through the lungs.

With housed cows, water sprays (not mists, this merely increases humidity and reduces evaporative cooling), fans, adequate shade, and other techniques can be used to facilitate evaporative cooling. There are several specialist publications on this topic and further remarks here will be confined to the grazing animal.

The normal respiration rate of resting cattle is 30 to 60 breaths per minute. Once this reaches over 60, the cow begins to feel the heat and at 180 per minute, she feels severe stress.

Practical steps that can be taken to reduce heat stress in hot weather are:

• Milk very early in the morning (finish by 05:30) so that the herd can get out to graze while the day is still cool. Provide shade, and even a spray in the waiting yards and milk early in the afternoon (14:00) so that the cows can cool down when the day is still very hot.

• Make sure that the night grazing is very good. Cows will tend to graze two thirds of their intake during the day and a third at night, but in hot weather this will change to half during the day and half night, provided that the night grazing is good.

• Provide ample cool water wherever the cows are grazing. This may mean putting roofs over the water troughs. Some studies have shown that it even pays to refrigerate the water.

• Shade trees in pastures are not necessarily a good idea. There are seldom enough, and so cows tend to crowd under the limited area with the result that mud and hence mastitis is increased, and valuable land on which grass could be growing is wasted. In general it is better to bring the cows in early in the afternoon, and to let them cool down before milking.

• Consider milking three times per day, and feeding silage in the shade during the midday milking.

• Set up an irrigation line in the pasture, and run it for an hour until all the cows have enjoyed a cool off.

• Try and give the cows as digestible a feed as possible. Poor quality roughage generates a lot more heat than highly digestible rations.

• If you must farm in a very hot area such as the Lowveld, then consider farming with a heat tolerant breed. The Australians have two breeds, the Australian Milking Zebu (AMZ) and the Australian Friesian Sahiwal (AFS), in addition to Jerseys, which they have bred for hot climates.

Low temperatures - cold stress

The effect of cold is strongly correlated with the amount of wind and wetness experienced with the cold. The effect of rain and wind at 3° C will be as severe as at -20° C with little air movement. Cold weather is not normally a problem in southern Africa, and no special precautions need be taken except to keep calves in draught-free and dry housing, and to have good windbreaks established along the boundaries of several pastures which can be used when severe winter or spring weather is experienced. Thin cows will shiver sooner than cows in good condition. It is a good idea to have a maternity stall available for use in bad weather and at other times when a cow close to calving needs close observation.

A fodder bank is essential in areas where snow can be experienced since the animals must have food to keep them warm and the most severe snow usually comes in Spring just when the normal winter feed is exhausted.

 

Mud and dirt

Mud leads to mastitis, foot rot, and stress (animals are reluctant to lie down and rest if the only place available is muddy). The cynic will remark that, no matter how much concrete is thrown, there will always be mud. If roads are confined as far as possible to crests and are well drained and hardened, then mud should not be a major problem, provided that there is sufficient concrete at the waiting area around the parlour (a minimum of 1,4 m²/cow). Clean mangers, food without mould or rancidity, and other common sense precautions will all reduce stress.

WATER AVAILABILITY

The water requirements of dairy cattle

The amount of water required by a dairy cow depends on the physiological state of the animal. Age, rate of gain, livemass, whether the animal is lactating or dry and even her breed all affect her water needs. The weather plays an important role in how much will be drunk. In hot weather, drinking will increase, both to cool the animal and to make up for the water lost by evaporation. As a very rough guide, an animal needs from four to seven litres of water for each kilogram of dry matter eaten. The water content of feeds varies from less than 10 to more than 93%. The wetter the feed, the less water that will be drunk. The British

Agricultural Research Council (ARC, 1980) gives the following equation for water requirement:

I_w = 12.3 + 2.15I_d + 0.73M
where I_w = water intake, I_d = dry matter intake and M = Livemass.

Table 3 compares the water budget of a lactating cow with that of a dry cow. Exchange water is the water released through the breakdown of organic compounds. The breakdown of fat releases quite large volumes of water (camels are particularly well adapted to the exploitation of this metabolic water). Note also that in this study, evaporative water exceeded the water in the milk, and that more water was excreted in the faeces than in the urine.

 

Table 3. Daily water balance of Holstein-Friesland legume hay (Georgievskii et al, 1981)

Water balance (l)	Dry cow	Lactating cow
Absorbed: from the drinking trough with the feed exchange water TOTAL	26 1 2 -- 29	51 2 3 -- 56
Eliminated: with faeces with urine by evaporation with milk TOTAL	12 7 10 0 -- 29	19 11 14 12 -- 56

Cows at pasture, given day and night access to water, will drink throughout the day with a marked peak after the afternoon milking. Up to 30% of the day's intake could occur in the hour following afternoon milking. Cows will drink very little from midnight until after the morning milking. To be safe, a 100 cow herd would have a minimum requirement of 3000 litres in the peak hour and the water troughs must have adequate volume and length.

 

Water troughs and water quality

Water must be clean, cool and freely available. Total dissolved solids should not exceed 0,5%. Ducks must not have access to water troughs. In cool weather (below 24° C) cows do not need constant access to water, but should never be away from water for more than three hours. If the herd is going to a pasture where there is no water, then it is essential that all cows have adequate opportunity to drink before leaving the parlour area. It is good stockmanship not to open the waiting area gates until the last group that was milked has had a chance to drink. If this is not done, the last group to emerge from the parlour will set off after their herd mates and may not stop to drink.

At least 10% of the herd should be able to drink at one time from the water trough and each cow needs about 450mm of drinking space. Thus a 1,8m trough would be long enough for an 80 cow herd provided they had access to both sides.

Water trough design is a compromise between inflow rate and trough size. The trough must never empty. Large troughs can have slow inflow rates, but heat up in warm weather and so should be shaded. Small troughs need large diameter pipes leading to them. In a pasture layout never use piping smaller than 20mm internal diameter for even with a big head, the inflow rate will be too slow. At best, an empty trough results in impatient cows breaking ball valves and, at worst, in considerable loss of milk. The ideal is a relatively small capacity trough with a very high inflow rate since this ensures clean, cool water. The water surface should not be more than 900mm above the level on which the cows stand. One cow can drink about 16 to 27 litres per minute and will commonly drink 20 litres at a time. A reasonable rule of thumb is an inflow rate of 700 l/hour/100 cows if the troughs have a large capacity (2,5m³) and 2500 l/hour/100 cows for low volume troughs.

FLIES, TICKS AND PARASITES

Flies can cause a great deal of stress simply through the irritation they cause. Flies can also spread diseases, especially eye infections, and therefore flies must be controlled. This is an area where an ounce of prevention is worth several pounds of cure. Calves should not be reared on deep litter on earth floors since this makes a perfect hatching place for fly larvae. All dairy effluent must be run into an anaerobic lagoon unless (and this is very unusual) effluent is disposed of through slurry irrigation. Spray for flies regularly with appropriate insecticides.

If necessary, cattle dusters can be used. A very simple dusting system is to hang a sack containing an insecticidal powder at the entrance or exit to the parlour just low enough so that it rubs the back of the shortest cow.

Tick control measures are very specific to bioclimatic area and farm. In the cooler dairy areas no more than an occasional dosing with a modern pour-on acaracide may be needed. In warmer areas where ticks are more abundant, a spray race may be the most economical control method. Never put valuable dairy cows through a plunge dip. Consult a local veterinarian about tick-borne diseases in the area and the precautions that should be taken.

Young cattle need regular dosing to control internal parasites which can seriously affect their growth rates, but adult cattle do not normally require dosing, one possible exception being liver fluke. The farmer should consult his veterinarian for a suitable dosing programme for his specific area and farm.

RATION BALANCING

While incorrect ration balancing is not a common cause of stress, farmers should be aware of a few points. Excess nitrogen, usually called crude protein, can cause a variety of problems. This topic is discussed in detail in KwaZulu-Natal Dairy Leaflet 5.2 and will only be touched on here.

Excess N can cause a drop in dry matter intake, can affect fertility, needs energy for its excretion, can interfere with vitamin A metabolism and, if the cows are hungry, can result in death through bloat. Therefore, rations must be properly balanced. The most obvious symptom of excess nitrogen is a distinct lack of appetite for well fertilized pasture and a tendency to select for the yellowest and poorest parts of the pasture.

Excess energy in the form of readily fermentable carbohydrates can lead to acidosis and other metabolic problems. For this reason diets should not contain less than 40% roughage and a minimum of rapidly fermentable constituents. KwaZulu-Natal Dairy Leaflet 5.5 has guidelines for ration formulation.

Mineral nutrition can be very important, especially in pasture systems where excess potassium can induce magnesium and calcium deficiencies. Deficiencies, imbalances or excesses may not be immediately apparent but must be avoided as a range of problems from foot rot to infertility can be due to poor mineral nutrition.

A chronic imbalance between calcium and phosphorus manifests itself through cows walking with their hind feet tucked forward under the body. The cattle should be observed walking on a hard surface and any abnormalities noted. This sickle-hocked walk will persist even after the problem has been corrected and leads to injuries to the bulbs of the hoof and impairs the herd's ability to walk to and from pastures. This topic is detailed in KwaZulu-Natal Dairy Leaflet 5.3.

ADAPTATION AND ACCLIMATIZATION

Cattle need time to adapt to changes in their routine, and the population of ruminal micro-organisms need approximately fourteen days to adapt to a change in diet. The stockman must be sensitive to these problems and not expect the 40 litre cow which he has just brought home from the sale to continue giving 40 litres on his farm. Ideally new animals should be brought onto the farm when they are dry, or in late lactation, and thus have time to adapt to the new routines and find their places in the dominance hierarchy before they begin their next lactation.

Acclimatization is an altogether different problem. Purchasers need to consider the diseases prevalent in their area, and not bring in cattle from areas where these diseases do not occur. This is especially true of heartwater, redwater and gallsickness. Another example is the common intestinal bacterium, Escherichia coli, which can cause scours in calves and acute mastitis in cows. E. coli has many strains, and cattle resistant to the strain occurring on the farm of their birth can be susceptible to other strains.

To sum up; ruminal micro-organisms need approximately 14 days to adapt to changes in diet, and cattle need time to adapt to changes in routine and climate, and may never acclimatize to diseases foreign to the area of their birth.

WALKING AND CLIMBING

The actual energy cost of walking and climbing is quite small, nevertheless it can be significant. A three kilometre walk and a fifty metre climb will burn up the energy equivalent of about 0,6 litres of milk (See KwaZulu-Natal Dairy Leaflet 5.12). The real cost of walking and climbing is the time taken that could be better used resting or ruminating. A long walk is also tiring, and tired cows might not graze as well as they would otherwise.

As a general rule, do not walk cows more than 1,5 kilometres from parlour to pasture, especially if there is a difference in elevation of more than 30 metres. Beyond 1,5 km (a 3 km round trip) significant milk losses will occur which cannot be made up simply by feeding more concentrate. Even a 1,5 km walk may be too much for cows with bad feet or large and/or pendulous udders.

FURTHER READING

ARC., 1980. The nutrient requirements of ruminant livestock. Farnham Royal: Commonwealth Agricultural Bureaux.

GEORGIEVSKII., ANNENKOV, B.N. & SAMOKHIN, V.I., 1981. Mineral nutrition of animals (Studies in the agricultural and food sciences) London: Butterworths.