REARING DAIRY REPLACEMENT HEIFERS

 

 

 

 

INTRODUCTION

 

 

Rearing calves and heifers as replacement milkers, is a serious business and the replacement stock are one aspect of dairying no dairy farmer can afford to overlook. In brief, successful calf- and heifer-rearing depends on animals attaining target weights and heights for age, using a cost-effective system. While it is true that the milking herd generates the income, calves and heifers are just as valuable to the dairy’s future as the current milking herd. Remember, today’s calves will enter the milking herd in two years time. Raising calves takes special skills and knowledge. While the responsibilities of calf care are great, so are the rewards. Assuming that anyone can successfully raise calves is as costly as assuming the end is closed on the bulk tank. Poor calf management allows future profits to slip away. Following a few basic, but very important steps, will help ensure that every calf matures into a profit-generating cow.

 

 

To successfully raise calves, emphasis should be placed on the following: -

 

·         minimise stress by good management - only trained, reliable staff who enjoy and take an interest in the calves should do calf chores.

 

·         When more than one person feeds calves, it is vital that all communications are clear and that the same procedures are followed daily.

 

·         Plan ahead and prepare thoroughly before calves arrive at the calf barn/shed.

 

·         Select calves that will grow well (bought-in calves).

 

·         Use shelter effectively to protect calves from the weather, while minimising disease problems.

 

·         Use the right feed balance at the right time for maximum benefit.

 

·         Start preparing the calves for the dairy-feeding system early, i.e. TEACH THEM TO EAT.

 

·         Keep live-weight gain as high as economically possible up to and past weaning.

 

·         Disease management – appropriate prevention, detection and treatment.

 


1.  MATERNITY AREA

 

 

A clean maternity area is vital to both the cow and newborn calf. The pen or enclosure should: -

 

·         be a clean, dry environment with good ventilation (not in a draft)

 

·         be separate from other livestock

 

·         have firm, slip-resistant footing

 

·         have good lighting.

 

·         Stables or pens must be disinfected after each calving. Burn the used bedding and supply fresh hay / straw / wood-shavings / untreated sawdust.

 

·         Where outdoor paddocks are used, these should be rotated to avoid an excessive bacterial build-up.

 

 

The cow should have access to: -

 

·         feedstuffs found in the milking herd ration (cows at this stage, on most South African farms, are called “steam-ups” and are separate from the main dry herd)

 

·         free-choice fresh water.

 

 

The use of a special “dry cow” ration, incorporating anionic salts, can be beneficial to both cow and calf. This should be fed for at least 3 weeks pre-calving. Although originally intended to reduce the incidence of milk fever and sub-clinical milk fever, a beneficial side effect is an increase in the muscle tone of the cow resulting in an increase in ease and speed of calving, hence, less stress on the calf.

 

 

 

2.  CALVING CHECKLIST

 

 

Once a cow has calved :-

 

·         Check that the calf is breathing. If the calf does not begin breathing, stimulate the inside of the nostril by tickling with a piece of clean straw, sneezing will force the calf to take a breath!  Massaging the calf’s chest also stimulates breathing.

 

·         Allow the cow to lick the calf, thereby stimulating the new-born’s circulatory system and drying the calf’s coat.

 

·         Milk the cow for colostrum (see section 3).

 

·         Dip the calf’s navel cord in a 7% tincture of iodine solution. Completely cover the cord and the hair on the belly. Only use an iodine preparation specifically for dipping navels. Teat dip and preparations for humans are NOT strong enough to disinfect a calf’s navel effectively.

 


3.  COLOSTRUM

 

 

3.1  WHAT IS COLOSTRUM?

 

The importance of colostrum cannot be over-emphasised. Colostrum is the thick, creamy, yellow secretion collected from the cow’s udder after calving. By definition, only milk from the FIRST milking after calving can be referred to as COLOSTRUM. Milk secretions from the second to the eighth milking (5 days post-partum) are called transitional milk, as the composition gradually becomes similar to that of milk. Refer to table 1.

 

 

 

TABLE 1 : COMPOSITION OF COLOSTRUM

 

 

 

DRY MATTER

%

FAT

%

TOTAL PROTEIN

%

CASEIN

%

ANTIBODIES

%

LACTOSE

%

MINERALS%

1st colostrum

21.1

6.7

14.0

5.72

7.33

2.9

1.1

After 24 hours

19.3

5.5

9.2

4.78

4.52

3.5

1.0

After 48 hours

15.5

5.4

5.0

3.38

1.62

4.2

0.8

After 72 hours

14.5

5.0

4.4

3.27

1.13

4.4

0.8

 

 

 

 

 

 

 

 

20th day : milk

12.9

4.1

3.4

2.66

0.74

4.9

0.7

 

 

 

Colostrum has a high nutritive value, plus provides the calf with ANTIBODIES needed to protect the newborn calf from infections that may cause diarrhoea and/or death. Antibodies, or immunoglobulins are proteins normally found in the bloodstream and are vital components of the immune system. They help identify and destroy bacteria and other foreign particles (antigens) that have invaded the body. Antibodies are not present in the newborn calf’s bloodstream because they cannot cross the placenta during pregnancy. The antibodies are transferred to the calf via the colostrum, where they are then absorbed through the intestine.

 

Quality of the colostrum is determined by three factors:-

 

·         Length of the dry period : A short dry period (less than 4 weeks), premature calving, milking before calving and milk leakage before calving will lower the concentration of antibodies in the colostrum.

 

·         Age of the cow : Generally, the concentration of antibodies is higher in older cows than in first-calf heifers. Older cows also produce colostrum with a more diverse antibody population than younger cows because of the length of time they have had to build immunity to diseases existing in the herd.

 

·         Breed of dairy cow : Holsteins have a lower antibody concentration in their colostrum than breeds such as Ayrshire, Brown Swiss, Guernsey and Jersey.

 

 

Do not rely on the cow to nurse for colostrum, as the calf may suckle but not ingest colostrum, especially in cows with pendulous udders or excessively large teats. The more high quality colostrum one can get into the calf, when it can be best absorbed, the better…don’t worry about overfeeding colostrum at the first feed. High mortality rates are linked to too little quality colostrum intake, not too much. Most calves that die, do so because they do not have the ability to resist a virus challenge and fight common infectious diseases.

 

The amount of colostrum fed and time of feeding in relation to birth considerably influences calf survival. Immediately after birth, ABSORPTION of antibodies is highest, with a rapid decline in the efficiency of absorption of antibodies as soon as 6 hours after birth. Thereafter, DIGESTION of antibodies increases and intestinal cells rapidly become impermeable to antibodies. Approximately 24 hours after birth, calves lose the ability to absorb intact antibodies. It is still beneficial to feed excess colostrum to calves as the antibodies (gamma globulins), although they will not be absorbed, still have a valuable disease-controlling potential by neutralising pathogens locally in the gastric mucosa (stomach lining).

 

 

Colostrum has a laxative effect and stimulates the normal function of the intestinal tract.

 

 

 

3.2  THE FIRST FEEDING

 

Collect colostrum from the mother soon after calving, after the udder and equipment has been properly cleaned and sanitised. For the best results in transferring maternal immunity to the calf via the colostrum, feed about 5% of calf’s bodyweight, 15 minutes after birth (use a nipple bottle). Only use an oesophageal tube if the calf is too weak (e.g. difficult birth) to suckle. To prevent digestive disorders, colostrum should be fed at body temperature. It is not recommended to force the calf’s head into an open bucket because this method may also lead to digestive disorders.

 

As a guideline, feed :-

 

·         2.25 to 2.5 litres for a Holstein or Brown Swiss calf (birth mass >40kg)

1.25 to 1.5 litres for a Jersey calf (birth mass <30kg)

1.5 to 2 litres for Ayrshires, Guernseys and Dual-Purpose breeds (birth mass 30 to 40kg).

 

·         feed again within 8 hours and thereafter 3 times per day at 10% of body mass, for the first 3 days.

 

 

Clean the equipment thoroughly after each use to minimise bacterial growth and the risk of transferring pathogens.

 

 

 

3.3  SURPLUS COLOSTRUM

 

·         Can be stored for future use by freezing in flat trays. Storage temperature of –20 oC.

 

·         Defrost in a microwave as needed.

 

·         It is wise to keep some colostrum from older cows as their antibody levels are higher than those of first- calvers.

 

·         Do not store colostrum from cows that have been treated with antibiotics.

 


4.  SEPARATE COW AND CALF

 

 

The longer cow and calf are left together, the stronger the bond that forms between them, making the eventual separation more traumatic for both calf and cow. Calves allowed to nurse take longer to accept bottle- or bucket- feeding. The calf can also ingest dirt from the cow’s udder, legs or belly.

 

Make sure the calf is completely dry before moving it to the calf barn or hutch. Calves can withstand cold temperatures well when their coats are dry.

 

Identify the calf, record the date of birth, dam’s identification, sire and sex of the calf. (Don’t rely on memory!) Also record any special notes/details, such as assisted calving, milk fever etc

 

 

 

5.      HOUSING

 

 

To rear a calf away from its dam and other cows, is to deprive it of its natural form of nutrition, protection, warmth and shelter. For this we substitute a bucket, a building and a stockman! The person/s caring for the calves and overall level of management is infinitely more important than the type of housing used. It is essential to create an environment for the calf which gives the optimal conditions for disease-free growth and comfort.

 

 

Some basic considerations to apply to existing housing or to the construction of new housing include :-

 

5.1    SITE

 

·         Easily accessible.

 

·         Preferably not close to older stock.

 

·         Sheltered, but not surrounded by other buildings.

 

·         In South Africa, long walls should face in a North-South direction to avoid excessive heat in the calf-house due to direct sunlight.

 

 

 

5.2    TEMPERATURE

 

·         Recommended temperature in the calf-house when calves are placed is 15 oC.

 

·         Fit a thermometer to the calf-house and preferably a hygrometer as well. In South Africa, overheating and humidity are a common problem. In the colder areas, protective surrounds can be used for short periods.

 

 

 

5.3    HUMIDITY

 

Should be maintained above 50%, optimally at 70%. Low humidity tends to dry out the respiratory passages and predisposes the calves to infections. High humidity and high temperatures provide an ideal environment for bacterial multiplication.

 

 

 

5.4    VENTILATION

 

Effective ventilation without drafts is essential to prevent the build up of ammonia, carbon dioxide and humidity, which predispose the calves’ respiratory tracts to infection.

 

The following simple formula will provide sufficient ventilation without the use of fans :

 

Inlet                  0.045 m2/calf

Outlet               0.04 m2/calf, 1.5 to 2.5m above the inlet.

 

 

 

5.5    DRAINAGE

 

There are many different ways to provide a clean, dry place for calves to stand. A minimum fall of 1:20 is necessary to provide adequate drainage. Domed walkways are a great help in cleaning.

 

 

 

5.6    PENS

 

There are a number of effective designs for shelters. Choose a system that works for you. A guideline on the minimum space requirements is all that will be discussed here:

 

·         Individual pens      1.8 m2 (1.8 m x 1.0 m)

 

·         Group pens       1.5 m2 per calf, with feeding space of a minimum of 350 mm per calf.

 

 

 

6.  BIRTH TO 3 MONTHS

 

 

House individually in crates / pens / hutches that are warm, dry and free of draft. It makes no economic sense feeding calves well, only for much of the feed to be used keeping themselves warm, rather than growing!

 

 

6.1  GOALS OF FEEDING BEFORE WEANING

 

·         To feed for optimum health and strong immunity.

 

·         Encourage the intake of a starter as soon as possible.

 

·         Promote good skeletal development.

 

·         Develop the rumen.

 

·         Prepare the calf for weaning.

 

Providing for moderate gains and encouraging dry feed consumption before weaning then results in more economical gains, good rumen development and a healthy appetite for dry feed.

 


6.2  MILK FEEDING

 

Milk feeding systems fall into two broad categories: -

 

·         Ad-lib or high milk intake – calves are given high levels of milk and will grow rapidly up until weaning because milk is the perfect food for young animals. However, if the intake of solid feed has been limited, rumen development will be poor, leading to a check in growth after weaning. This is a waste of the advantage conferred by feeding expensive, highly nutritious milk previously.

 

·         Restricted milk intake – calves on restricted milk intakes require nutrients from another source if they are to match the growth rates of calves with ad lib milk intake. The introduction of a high quality calf starter from as early as day 1, will promote growth rates up to and past weaning.

 

 

Whichever policy is employed, the objective must be to have calves growing consistently to weaning and beyond, to avoid a post-weaning check in growth.

 

Colostrum / transition milk should be fed for the first 3 days after birth - feed at 10% of birth mass :

 

·         2 litres twice daily for a Holstein / Friesland, i.e. 4 litres a day

·         1.5 litres twice daily for a Jersey calf, i.e. 3 litres a day

·         1.5 to 2 litres for the other breeds, i.e. 3 to 4 litres a day.

 

 

From day 4, after colostrum, the calf should be offered milk that has the highest nutritional value to allow satisfactory growth for the lowest price. The following factors are important when feeding milk to young calves: -

 

6.2.1  Type of milk offered

 

·         Whole milk - can be fed until weaning. Limited amounts of whole milk, supplemented with a good quality calf starter are an excellent combination for dairy calves.

 

·         Extra / unsaleable milk, e.g. extra colostrum, transition milk

 

·         Mastitic milk - prevent contact between calves for at least 30 minutes after feeding to prevent infectious agents from being transmitted from calf to calf. Mastitic milk may increase the risk of health problems. Antibiotic residues may lead to the selection of drug-resistant bacteria, making antibiotic treatments less effective over time.

 

·         Milk containing antibiotics / anti-inflammatory drugs - as above.

 

·         Skim milk - derived from on-farm-processing - is relatively high in protein, but contains less energy and fat soluble vitamins (Vitamin A and Vitamin B) than whole milk because the fat has been removed. Use skim milk only when the calf is eating sufficient calf starter (about 3 weeks old). The calf starter will provide the vitamins and minerals that may be lacking in the skim milk. Feeding skim milk to calves in cold housing / during cold winters is not recommended as the calves need additional energy to protect themselves against low temperatures.

 

·         Milk replacer - may be used from 7 days of age. Replacers may contain less fat thus less energy than whole milk on a dry matter basis. Calves fed replacer may gain at a slower rate than those on whole milk.

 


6.2.2  Amount fed = meal size

 

·         8 to 10% of birth mass (as in 6.2 above) until weaning. By limiting milk consumption, calves are encouraged to consume solid feed at an early age.

 

 

6.2.3  Frequency of feeding

 

·         Preferably two equal meals per day.

 

·         Once a day feeding is possible only under strict and skilful management. When the amount of milk needed per day, is offered in one meal, the capacity of the abomasum is exceeded and the excess milk flows back into the rumen where it may cause digestive upset, e.g. bloating. Another problem with once a day feeding is the increased frequency of diarrhoea.

 

 

6.2.4  Method of feeding

 

·         Nipple feeding - forces the calf to drink more slowly and reduces the risk of digestive disturbances and diarrhoea. Strict equipment hygiene is imperative.

 

·         Bucket feeding - a calf can be taught how to drink from a bucket within a few days after birth. This technique is easy, rapid and requires less cleaning work.

 

 

6.2.5  Milk temperature

 

·         Ideally milk should be fed at body temperature, 37oC.

 

·         Cold milk can be used, but takes energy to heat in the stomach, which could better be used for growth.

 

·         A consistent temperature at every feeding and at the same time every day is essential.

 

A point to note: disease problems during milk rearing can reduce subsequent heifer growth rates and thereby increase the age at first calving.

 

 

 

6.3  HAY, CONCENTRATES AND WATER

 

6.3.1  Water

 

·         Make water available at the same time as calf starter is offered. It is important to withdraw water for at least half an hour before and half an hour after the milk or replacer is fed, in order to prevent milk going into the rumen, causing digestive upsets.

 

·         The intake of water stimulates the intake of dry feed, which leads to improved gains and reduced incidence of scours.

 

·         Bacteria in the rumen can only survive if they are in a water environment, i.e. that which comes from free water intake. Milk and replacer does not constitute free water - it bypasses the rumen via the oesophageal groove to the abomasum directly. (See below for detail.)

 


6.3.2  Solid feedstuffs - developing the rumen

 

At birth the rumen is small, underdeveloped and sterile. In the first few weeks of life, the size and proportion of the calf stomach compartments go through drastic developments. These changes are affected by diet. At birth, there are no microbes present and the digestive system functions as that of a monogastric (single-stomached) animal. The reticulum and rumen (fermentation vat) makes up some 30% of the stomach compartments, even though it is non-functional. The omasum makes up about 10% and the true stomach or abomasum makes up the remaining 60%. The abomasum is the only stomach fully developed and functional. As a result, only liquid feed (milk) can be utilised effectively by pre-ruminant calves, a few days old. By 12 weeks, the reticulo-rumen often makes up more than two-thirds of total stomach weight. It has then grown in size and function to the point where it is the major part of the stomach system. The rumen is most important to the animal because it acts as a fermentation vessel for microbes to digest complex carbohydrates and high-fibre feeds, which can then be utilised by the animal. Development of the rumen microflora and papilli (finger-like projections developed from the rumen wall) does not happen automatically. Microflora begin to grow as soon as the calf has a regular intake into the rumen of fibre (cellulose) and starch from dry, solid food.

 

The wall of the rumen of the newborn calf is thin and paperlike, with no visible papilli. Therefore the rumen has little surface area for absorption of nutrients. Young calves, fed primarily liquid diets, do not function as ruminants because they have only one functional stomach, the abomasum. When a calf is fed milk or replacer, closure of the oesophageal groove allows milk to by-pass the reticulo-rumen and flow directly into the abomasum. Solid / dry feeds go straight into the reticulo-rumen, as in older heifers and cows. As liquid feeds are decreased (weaning), the oesophageal groove gradually ceases to function. The rumen microflora become established in the rumen and rumen papilli development begins, allowing for a much greater surface area for absorption of the nutrients produced during rumen fermentation.

 

The most important objective in early rumen development is to provide the stimulus needed for EPITHELIAL TISSUE (papilli) development. The epithelial layer on the inside of the rumen is the area where nutrients are absorbed from the rumen. It is therefore crucial that as large a surface area as possible is developed here. This can be achieved by feeding a highly palatable calf starter (coarse grain mix or pellet) rather than hay. Rumen fermentation results in the production of various volatile fatty acids (and other components). When grains ferment in the rumen, some of the major end products of digestion are propionic and butyric acid. Forages are primarily digested into another volatile fatty acid, acetic acid.

 

If calves stay on diets consisting of only milk or replacer, the rumen will remain small and underdeveloped. Calves that receive grain from day 3 onwards have larger, more developed rumens. Calves fed only forages will have large rumens, but their papilli development will be limited. WHY? The butyric acid (from grains) produced in the rumen by the microbes is absorbed through the rumen walls as a normal part of rumen metabolism. It is this butyric acid which provides energy for the rumen wall hence providing energy for the growth and development of the papilli. The process is one that is self-generating, enabling the early grain-fed calf to have a tremendous amount of rumen development in 3 to 4 weeks.

 

One can tell that the rumen has become functional when cud chewing is observed, at 2 to 4 months old. Thus, the availability and early consumption of solid food allows rapid rumen development and early weaning. Note that milk and replacer supports the development of AEROBIC microbes, while dry food supports the growth of ANAEROBIC microbes. The type of dry feed will determine the type of microbes and the type of volatile fatty acids produced.

 

DO NOT WEAN A CALF UNTIL THE RUMEN IS FUNCTIONAL AND CAPABLE OF SUPPORTING ITS NUTRITIONAL NEEDS. The result will be rapid and consistent growth after weaning. Without a well-developed rumen at weaning, slow or little growth will be experienced for at least 3 to 5 weeks after weaning.

 


6.3.3  Calf Starter

 

A good calf starter should have the following specifications: -

 

·         18% crude protein with 13 MJ ME/kg energy.

 

Palatability is very important. Calves tend to prefer a coarse textured or pelleted feed. Offer small amounts frequently - keep it fresh. Overfilling the container is wasteful as the feed may go mouldy at the bottom, if not checked twice daily. Any “leftovers” can be fed to older calves.

 

Avoid contamination from birds or the calves themselves.

 

Ensure clean fresh water is available - consumption of dry feed is enhanced by increased water consumption.

 

By 6 weeks of age, the calf should be eating 650 to 750 grams (small breeds) and 1 to 1,25 kg (large breeds) of starter per day.

 

 

6.3.4  Hay

 

Making hay available to a young calf before weaning can significantly reduce energy intake. The fibre requirements of calves can be met without feeding any conventional forms of roughage. The suggested approach is to add highly digestible fibre to the starter in the form of bran or molasses meal. If none of these can be used, adding 5% good quality lucerne hay to the starter should be sufficient. Commercially available rations already include bran and molasses. Commercial complete calf rations should include lucerne meal. With a well-balanced starter, fed ad lib, it should not be necessary to feed any hay until 6 weeks of age. A limited amount - 0.5 kg per day can be offered from 6 weeks of age.

 

DO NOT WASTE GOOD QUALITY ROUGHAGE ON CALVES PRE-WEANING.

 

 

 

7.  WEANING

 

 

Weaning should take place when a calf is growing well and consuming the starter, as detailed above. Do not wean small or weak calves. When any changes are to be made, make them gradually.

 

Weaning later than 8 weeks of age is costly because the cost of milk or replacer is more expensive than forage and concentrates. Growth rates remain limited as long as calves are fed a liquid diet. Weight gain increases considerably after weaning, provided the calf is well adapted to a diet of solid food (starter and forages).

 


 

8.  FEEDING AND MANAGEMENT FROM WEANING ONWARDS

 

 

8.1  MANAGEMENT GOALS OF FEEDING POST- WEANING

 

 

8.1.1  Age at First Calving

 

Once a calf is weaned, the objectives from 3 months until breeding should be: -

 

·         to establish a desirable rate of growth

 

·         to feed the most economical sources of protein, energy, vitamins and minerals

 

·         ensure that the heifer does not get fat, thereby having a deleterious effect on subsequent milk production.

 

 

Sexual maturity and initiation of oestrus cycles are more dependent on: -

 

·         size and weight of the heifer as opposed to the age

 

·         rapid growth - will lower the age at which a heifer can be bred. It is now generally accepted that the ideal age for replacement heifers to calve for the first time is 24 months.

 

 

Increasing the age of first calving only leads to a 0.8% (for Frieslands) and 0.6% (for Jerseys) increase in 305 day milk production per month increase in calving age over 24 months. This small benefit in production is lost once the first calving exceeds 27 months.

 

The three main disadvantages of increasing first calving age to more than 24 months are: -

 

·         For every 1-month increase in average first calving age, an extra 2 to 3 heifers are needed per 100 cows. This means that the number of replacements that have to be managed and fed is also increased.

 

·         The entrance of genetically superior animals into the milking herd is delayed.

 

·         The cost of rearing a heifer is increased as the age at first calving increases. The reason being that a heifer having a lower daily gain makes less efficient use of feed because a larger portion of her feed intake is needed for maintenance. Growing heifers so that they calve younger than 24 months, although possible is not desirable as this leads to a reduction in milk yields in the first and even the second lactation. Calving difficulties (dystocia) can also be a problem.

 

 

8.1.2  Weight at First Calving

 

Body weight at first calving has a more significant effect on first lactation performance than age. A useful guideline is that directly after calving, (not including the weight of the calf and placenta) heifers should weigh 80 to 90% of the breed’s mature weight.

 

Refer to Table 2.

 


8.1.3  Growth Rates and Target Weights

 

In order for a heifer to reach 80 to 90% of its mature body weight by 24 months of age a minimum daily growth rate is required. The first important target weight-for-age after weaning is when the heifer reaches puberty. The onset of puberty is largely a function of body weight, usually reached when the heifer reaches 40 to 50% of mature weight.

 

Research has shown that a very high rate of gain pre-puberty leads to a reduction in the heifer’s subsequent lifetime milk production potential. The reason for this has to do with the development of the udder. The udder consists of three areas of milk secretion and storage: -

 

·         the teat and udder cistern

·         large and small ducts

·         the alveoli

 

 

About 70 to 80% of the milk is produced and stored in the alveoli and ducts and it is in this area that rapid pre-puberty growth rates have a very important effect. Growth and development of mammary cells occurs in phases related to reproductive development. These are: -

 

·         FOETAL STAGE TO 2 MONTHS OLD - basic udder structure is formed. No alveoli are present. During this period, the mammary cells are growing at the same rate as the rest of the body’s cells.

 

·         FROM 2 MONTHS TO PUBERTY - cell growth in the mammary tissue is double that of the rest of the body. At this stage the “fat pad” is laid down in the udder. Ducts are developing, but there are still no alveoli. The ducts need the fat pad for their development.

 

·         AFTER PUBERTY - cell growth in the udder returns to the same rate as the rest of the body. Alveoli formation begins and there is greater differentiation and numbers of cells, especially secretory cells. Milk production potential is directly related to the number of mammary cells, especially those of the alveoli. If pre-puberty growth is not controlled, then the space left available for the formation of the alveoli and small ducts, will be limited by the larger ducts and the large fat pad.

 

 

Poor pre-puberty growth also has a negative effect on heifers. Apart from the delay in getting heifers into calf and therefore into lactation, underfeeding heifers for prolonged periods pre-puberty leads to poor udder development and weak reproductive cycles.

 

Table 2 is a guideline for the different breeds’ weight for age targets.

 


TABLE 2: TARGET WEIGHT FOR AGE AND ADG

 

 

BREED

BIRTH MASS

Kg

MATING MASS

Kg

GROWTH RATE

Kg/day

WITHER HEIGHT

CM

CALVING MASS

Kg

GROWTH RATE

Kg/day

WITHER HEIGHT

CM

 

 

15 month mating

 

 

24 month calving

 

 

Holstein Friesland

40

310 – 360

0.6 – 0.7

120 – 130

510 - 560

0.7 - 0.8

135 - 140

Ayrshire

32

250 – 280

0.5 - 0.55

110 – 120

440 - 480

0.65 - 0.7

130 - 135

Guernsey

30

230 – 250

0.45 – 0.5

110 – 120

390 - 430

0.6 - 0.65

130 - 135

Jersey

25

230 – 250

0.4 - 0.45

100 – 110

350 - 390

0.55 - 0.6

120 - 125

 

 

18 month mating

 

 

27 month calving

 

 

Holstein Friesland

40

350 - 380

0.56 – 0.62

130 – 135

550 - 580

0.7 - 0.8

140 - 145

 

 

 

8.1.4  Other Growth Parameters

 

There are two other factors that can be used to monitor the feeding of replacement heifers, namely: -

 

·         Wither height (as per Table 2 above) – measuring wither height gives an indication of skeletal growth and development. Wither height is the highest point of the back located at the base of the neck and between the shoulder blades. The measuring tape/stick should be placed right next to the forelegs. As with weight-for-age parameters, heifers should attain a certain height. Heifers that attain target weight but not target height are an indication of nutritional imbalances.

 

·         Body condition score - is an indication of the deposition of fat. Table 3 gives the target body condition scores for heifers at different ages.

 

 

 

TABLE 3: TARGET HEIFER BODY CONDITION SCORES (BCS)

 

 

AGE months

3

6

9

12

15

18

21

24

BCS

2.2

2.3

2.4

2.8

2.9

3.2

3.4

3.5

 

SCALE: 1 = emaciated to 5 = obese.

 


8.2  FEEDING FROM WEANING TO 6 MONTHS

 

Once the calf is weaned, continue to house individually until 3 months old (space permitting). At 3 months, heifers may be moved to group pens (either in the calf barn or in small camps with shelters). Groups of 5 to 8 are a convenient, manageable size. If dehorning was not done at an early age (with the new “Buddex” machine), do not move and dehorn on the same day. Allow at least a week for the calf to adjust to the new environment. Minimise stresses.

 

 

The heifer ration at this age should contain: -

 

·         between 40 and 80 % forage

·         a calf growth meal or pellet  with at least 16% crude protein and 10.88 MJ ME /kg energy level.

 

 

Calves housed indoors in group-pens: -

 

·         ad lib good quality hay and some lucerne hay, if possible.

·         Growth meal: 2 to 3 kg per calf per day.

 

 

Calves on pastures: -

 

·         still provide good quality hay and some lucerne if possible.

·         Supplement concentrates at 2 kg per calf per day.

·         Poor pasture should preferably be avoided at this stage. A complete calf ration should be considered and fed ad lib.

·         Remember to rotate camps often to prevent worm and parasite build up.

 

 

 

8.3  6 to 9 MONTHS

 

Calves kept “indoors” can be moved on to pastures in groups of 10 to 16 even-sized heifers. Those already on pasture can be moved to bigger camps. Continue feeding as per the previous age group, but the amount of forage in the diet may vary from 50 to 90%.

 

As the heifers grow older, the concentration of protein in the diet can be decreased and the concentration of fibre can be increased. Maize silage and grass silage can be introduced from 8 months of age, allowing from 5 kg per heifer per day on an as is basis. Poor quality forages fed to this age group must be adequately complemented with concentrates and minerals. The crude protein in the concentrate will depend on the crude protein of the forage in the diet. In KwaZulu-Natal, heifers are traditionally raised on roughages that have a protein content ranging from 8 to 12% and energy values ranging from 7 to 10 MJ ME/kg dry matter. Therefore, heifers older than 6 months (fed primarily on these forages) will have a greater need for supplemental protein, than for energy. As a guideline the heifer meal should have a crude protein of 16% with 10.33 MJ ME/kg, supplemented at 2 kg per day. The concentrate must also provide adequate vitamins and minerals.

 

The use of ionophores in growing heifers can improve the efficiency of growth by up to 11%.

 


8.4  9 TO 15 MONTHS - PREMATING GROUP

 

Again 50 to 90% forage with 2 kg of a concentrate to balance the shortfalls of the roughages used. It is very important that the heifer does not get fat during this stage of growth.

 

 

 

8.5  15 TO 18 MONTHS - MATING GROUP

 

If practical, this group should be kept as close to the dairy as possible, so that heat spotting and bringing the heifer to the handling facility to be inseminated is made as simple and stress-free as possible. The concentrate fed should have a crude protein level of 17% and energy of 9.9 MJ ME/kg.

 

 

 

8.6  18 MONTHS TO CALVING

 

These heifers, once confirmed in calf, can join the dry-cow herd, provided there is no competition for forages. Preferably keep separate from cows and feed as per the dry cows, but not limiting the growth potential. For 8 weeks prior to calving, accustom the heifer to parlour routine and treat and feed her as a dry cow or “steam-up”.

 

 

 

8.7  CALCULATING REPLACEMENT HEIFER NUMBERS

 

Tables 4, 5 and 6 give a method of calculating how many heifers are required for a 100-cow unit.

 


TABLE 4: CALCULATING THE NUMBER OF REPLACEMENT HEIFERS AVAILABLE IN A 100 COW HERD

 

 

a)       Total number of heifers in the dairy herd

 

FACTOR

EXAMPLE

FORMULA

 

CALCULATION

TIME PERIOD*

 

2 YEARS

2

2

HERD SIZE

100

X No. OF COWS

X 100

X 100

CALVING INTERVAL

13 MONTHS

X 12/CALVING INTERVAL**

X 12/13

X 0.923

SEX RATIO

50%

X No. HEIFERS/No. OF CALVES BORN

X 0.5

X 0.5

CALF MORTALITY

10%

X (1-{%CALF MORTALITY/100})

X (1-0.1)

X 0.9

AGE AT FIRST CALVING

25 MONTHS

X AGE AT CALVING**/24

X 25/24

X 1.042

 

 

 

 

=87

 

 

b)       Number of first-calf heifers available for replacement per year

 

TIME PERIOD*

 

1 YEAR

 

 

HERD SIZE

100

x No. OF COWS

x 100

X  100

CALVING INTERVAL

13 MONTHS

x 12/CALVING INTERVAL**

X 12/13

X 0.923

SEX RATIO

50%

x No. HEIFERS/No. OF CALVES BORN

X 0.5

X 0.5

CALF MORTALITY

10%

X (1-{%CALF MORTALITY/100})

X (1-0.1)

X 0.9

AGE AT FIRST CALVING

25 MONTHS

X 24/AGE AT CALVING**

x 24/25

X 0.96

 

 

 

 

=40

 

 

* The time period needed to calculate the total number of heifers in the herd, at any time, is 2 years (24 months) and the time period to calculate the number of first-calf heifers available per year is one year.

** Must be expressed in months

 

 

 

TABLE 5: AVERAGE AFFECT OF CALVING INTERVAL, CALF MORTALITY AND INVOLUNTARY CULLING RATE AT FIRST CALVING ON ADDITIONAL NUMBER OF FIRST-CALF HEIFERS AVAILABLE PER YEAR IN A 100 COW HERD

 

FACTOR

RANGE

UNIT OF CHANGE WITHIN THE RANGE

ADDITIONAL FIRST CALF HEIFERS

CALVING INTERVAL

12 TO 18 MONTHS

MINUS 1 MONTH

+ 2 TO 3

CALF MORTALITY & INVOLUNTARY CULLING

0 TO 24 %

MINUS 10%

+ 3 TO 5

AGE AT FIRST CALVING

24 TO 36 MONTHS

MINUS 1 MONTH

+ 1 TO 2

 

 

 

TABLE 6: NUMBER OF HEIFERS AVAILABLE AS REPLACEMENT IN A 100 COW DAIRY HERD, ASSUMING A SEX RATIO OF 50 % AND 10% MORTALITY*

 

 

 

AGE AT FIRST CALVING

CI*

24

25

26

27

28

29

30

31

32

33

34

35

36

NUMBER OF HEIFERS IN THE REPLACEMENT HERD AT ANY TIME

12

90

94

98

101

105

109

113

116

120

124

128

131

125

13

83

87

90

93

97

100

104

107

111

114

118

121

125

14

77

80

84

87

90

93

96

100

103

106

109

113

116

15

72

75

78

81

84

87

90

93

96

99

102

105

108

16

68

70

73

76

79

82

84

87

90

93

96

98

101

17

64

66

69

71

74

77

79

82

85

87

90

93

95

18

60

63

65

68

70

73

75

78

80

83

85

88

90

NUMBER OF FIRST-CALF HEIFERS AVAILABLE FOR REPLACEMENT PER YEAR. (MAXIMUM POSSIBLE CULLING RATE TO MAINTAIN HERD SIZE)

12

45

43

42

40

39

37

36

35

34

33

32

31

30

13

42

40

38

37

36

35

34

33

32

31

30

29

28

14

39

37

36

34

33

32

31

30

29

28

27

26

26

15

36

35

33

32

31

30

29

28

27

26

25

25

24

16

34

32

31

30

29

28

27

26

25

25

24

23

23

17

32

30

29

28

27

26

25

25

24

23

22

22

21

18

30

29

28

27

26

25

24

23

23

22

21

21

20

 

*  CI = Calving Interval

 

 

 

To find the number of heifers available for a mortality rate different to 10 %, multiply the number found in the table by 1.11 and then again by (1-mortality fraction). E.g. The number of first-calf heifers available for a 14 month calving interval, 28 months of age at first calving and mortality rate of 5% is: - 32 x 1.11 x (1-0.05) = 33.8 or 34 heifers.

 

 

 

9.  TROUBLE SHOOTING

 

 

The key features of a good animal health plan are: -

 

·         prevention where possible

·         early detection of a problem

·         timely, appropriate treatment

·         When in doubt, consult your veterinarian!

 

 

9.1   SCOURS / DIARRHOEA

 

Scours is probably the most common and important calf disease. Scours is the calf’s response to a metabolic upset or imbalance in the digestive tract. Disease-causing organisms that infect the intestine often destroy cells which are then released into the intestine as cellular debris along with proteins, acids and minerals. When there is intestinal damage, the mineral balance of the intestine is upset and the calf responds by passing water into the intestine to re-establish equilibrium. The resulting combination of manure, mucous and sometimes blood is then called “scours”. In addition to water, there is a loss of the electrolytes sodium, chloride, potassium and bicarbonate which can cause acidosis (lowered blood pH) and death. Scours may be caused by toxins from infectious organisms or by incomplete digestion of nutrients. Poor quality protein, fat or carbohydrate in milk replacers or a change in concentration of components (e.g. changing from whole milk to transition milk) can cause scours.

 

 

Factors conducive to scours: -

 

·         irregular feeding

·         milk fed at varying temperatures

·         dirty buckets and utensils

·         mouldy hay / poor quality feed

·         calves suckling each other and spreading infection

 

Scours caused by infectious organisms are most common and most serious, because the cost of treatments (electrolytes and antibiotics) and labour are high and also the possible loss of the calf. It is important to be able to identify and recognise the organism causing disease in your calves. Some of the more common ones are: -

 

·         Salmonella – causes scours as early as 4 days old, but more commonly from 1 to 4 weeks of age.

Sources of infection – contaminated feed and infected animals. Hygiene and sanitation when dealing with infected calves is very important as Salmonella can be transmitted to humans. Prevention – vaccination and stringent hygiene. Treatment – antibiotics recommended by your vet.

 

·         E.coli – there are two distinct disease conditions caused by E.coli, namely septicaemia and enterotoxaemia. Septicaemia (bacteria in the blood) – occurs when the calf does not consume colostrum before the bacteria reach the small intestine. Disease occurs quickly i.e. within 24 to 36 hours after birth. Prevention – feed colostrum within the first hour after birth. Provide clean, dry calving areas.

Enterotoxaemia (bacterial toxins in the intestine) – occurs when bacteria attach to the intestinal wall of the calf and proliferate (usually within the first 7 days). The diarrhoea produced is profuse, watery and may contain blood. Prevention – vaccination and sanitation of calf facilities.

 

·         Coccidia – diseases caused by these organisms usually occur after 4 weeks. Infection occurs through ingestion of bedding or manure containing oocysts (eggs) which then multiply inside intestinal cells, causing damage to the intestinal wall, Prevention – use a coccidiostat in the feed. Commercial calf starters have this included.

 

 

 

9.2  NAVEL INFECTION

 

Caused by overcrowding and bruising of the navel cord early in life. Infection spreads from the cord to the liver, then the joints of the legs. The navel cord is hot, the leg joints swollen and painful. Treatment – antibiotic recommended by your vet for at least 5 days. Prevention – give calves enough space, soft bedding and use Iodine dip on the navel at birth.

 

 

 

9.3  CALF PNEUMONIA

 

Caused by poor ventilation and a build up of ammonia gas. Prevention is the best approach. Treatment – antibiotics.

 


9.4  PARASITES

 

Check with your vet for a sound dosing-programme to combat worm infestations.

Fly control is also a very important factor as they can be disease carriers.

 

 

 

9.5  VACCINATIONS AND INNOCULATIONS

 

Check with your vet for the most prevalent infectious organisms found in your area and work out a sound programme.

 

 

 

9.6  BLOAT

 

Type of bloat encountered depends on the age of the calf, i.e. whether it is weaned or not.

 

·         Overfeeding causes a mild gastritis and is generally not serious. Usually, a small amount of sodium bicarbonate will control this type of bloat.

 

·         Chronic respiratory infection: look for enlarged lymph nodes along the oesophagus that might interfere with the eructation of gas. This condition is common in calves over 1 month of age. Palpation of the lymph nodes in the pharynx region will indicate whether there is enlargement along the oesophagus and trachea. Possible causes of infection are from Actinomyces or Pasteurella species and will require antibiotic therapy.

 

·         Indiscriminate use of antibiotics can destroy the normal rumen microflora and thereby cause bloating. Inoculating the calf with a cud or bacterial culture from another calf can help cure the problem.

 

·         Milk that has remained in the rumen and deteriorated may be removed by dosing with a cup of mineral oil.

 

·         Fibre from bedding, hay or twine can accumulate in the rumen or abomasum as a fibre ball and cause bloat. This can be prevented by not feeding hay to calves while on milk or milk replacer.

 

·         Anatomical / physiological defects around the cardia, the opening to the oesophagus into the stomach, may prohibit eructation and thereby cause bloat.

 

·         Torsion of the abomasum is not common, but if not treated immediately, can be fatal. A vet should be consulted.

 

·         Peritonitis due to a ruptured abomasal ulcer. Ulcers can be caused by various Clostridia species. Again, consult a vet.

 


SUMMARY OF CALF – REARING GUIDELINES

 

MONTHS

WEEKS

MASS

FEED REQUIREMENTS

 

HEALTH PROGRAMME

HOUSING

MANAGEMENT

 

 

 

MILK

CONCENTRATES

ROUGHAGE

MINERALS

 

 

 

BIRTH

 

40

COLOSTRUM WITHIN 3 HOURS OF BIRTH +/- 4 litres

DISINFECT NAVEL WITH IODINE (7%) SOLUTION

CLEAN, DRY, DRAUGHT-FREE INDIVIDUAL PEN

REMOVE CALF FROM COW WITHIN 12 HOURS

1

1

 

WHOLE MILK

4 L/DAY

(2 BY 2L)

CALF STARTER PELLETS

 

INCLUDED IN STARTER

INNOCULATIONS AS PER VET RECOMMENDATIONS

AS ABOVE

WITH-HOLD WATER ½ HOUR BEFORE & AFTER MILK FEED

2

3

4

 

 

 

58

WHOLE MILK OR MILK SUBSTITUTE

(2 BY 2L)

CALF STARTER PELLETS. SEE SECTION 5.3.3

 

 

DOSE FOR MILK TAPEWORM

AS ABOVE

SEE SECTION 5.2 ON MILK  FEEDING

2

5

6

7

8

 

 

 

65

AS ABOVE

AS ABOVE

INTRODUCE HAY/LUCERNE

A,D,E INJECTION

DOSE FOR TAPEWORM

AS ABOVE

WEAN IF EATING 2 KG STARTER

3

4

5

6

 

97

118

139

160

 

NONE

CALF GROWTH PELLETS AD LIB

HIGH QUALITY HAY/LUCERNAD LIB

 

MULTISPECTRUM DEWORMER

MOVE TO GROUP PENS OF 4 TO 6

1.DEHORN.

NB.DO NOT WEAN, MOVE, DEHORN ON SAME DAY!

2.FRESH, CLEAN WATER!

7

8

9

 

180

200

225

NONE

DAIRY RATION @ 2KG/DAY DEPENDING ON ROUGHAGE QUALITY

PASTURE, HAY, SILAGE

MINERALS & PHOSPHATE/

SALT LICK

MULTISPECTRUM DEWORMER, 6 WEEKLY.

DIPPING FOR TICKS

MOVE TO PASTURES.

GROUPS OF 8 TO 12.

ROTATE CAMPS OFTEN.

1.FRESH, CLEAN WATER.

2.PROVIDE SHELTER FROM EXTREME WEATHER CONDITIONS.

10

11

12

13

14

15

 

240

265

280

300

330

350

NONE

SUPPLEMENT ACCORDING TO ROUGHAGE QUALITY

PASTERE, HAY, SILAGE.

TMR A GOOD OPTION.

AS ABOVE.

MULTIVITAMIN INJECTION PREMATING.

AS ABOVE

PASTURES IN GROUPS OF EQUAL SIZE/AGE.

SEE SECTION 7.

 


REFERENCES

 

SPESFEED :            Dairy Nutrition in South Africa : F Kleyn et al (1997)

 

SPESFEED NEWS :            ECONOMICAL HEIFER REARING

                                    By Shaun Storer and Helena van Rensburg

 

DAIRYING IN KWAZULU-NATAL :            Cedara College Publication

 

NRM NEW ZEALAND LTD :            CALF REARING – A Guide to Successful Calf Raising

 

HOARDS DAIRYMAN :-

 

January 10,1994 :            Veterinary Column : L.C.Allenstein, D.V.M.

                                    Determine Scours Cause

 

February 25,1994 :            Why Some Dairymen Have Better Luck With Calves

                                    By : James A. Jarrett, D.V.M.

 

Veterinary Column : L.C.Allenstein, D.V.M.

                                    Yellow Scours

 

March 25,1994 :            Colostrum Research Says ... Feed 4 Quarts for Healthier Calves

                                    By : Clive Gay

 

April 25,1994 :               YOUNG CALF GROWTH DEPENDS ON DRY FEED

                                    By : Jim Quigley

 

May 10,1994 :               WHY MANY NEWBORNS ARE AT RISK

                                    By : Jim Quigley

 

September 25,1994 :            WHAT IT TAKES TO FRESHEN HEIFERS EARLY

                                    By : Brian L. Perkins

 

                                    HIGH AND DRY HEIFERS ... FASTER GAINS, LOWER COST

                                    By : Sue Price, Pat Hoffman and Jim Barmore

 

October 10,1994 :            FARM FLASHES :            SALT AND WATER INTAKE AFFECT REPRODUCTION AND                                    HEALTH

 

                                                                        HAY IS NOT NECESSARY UNTIL AFTER WEANING

 

                                    TAILORED RATIONS HELP HEIFERS GROW

                                    By : Sue Price, Pat Hoffman and Jim Barmore

 

October 25,1994 :            GET CALVES AWAY FROM THEIR DAMS

                                    By : D.C.Sockett, D.V.M.

 

November,1994 :            WHERE AND HOW PEOPLE CALVE THEIR COWS

                                    By : Jim Quigley

 

 

 

VETERINARY COLUMN : L.C.Allenstein, D.V.M.

                                    MANY CALVES BLOAT

 

 

March 25,1995 :            WEANED CALVES WERE UNDER TOO MANY STRESSES

                                    By : James A Jarrett, D.V.M.

 

June,1995 :                   TOP OPERATORS MAKE SURE CALVES GET COLOSTRUM

                                    By : A..J.Heinrichs

 

September 10,1995 :            GIVE EVERY CALF THE RIGHT START

                                    By : Shelly A. Mayer

 

September 25,1995 :            KNOW THE ORGANISMS THAT CAUSE SCOURS

                                    By : Jim Quigley

 

                                    RAISING CALVES ISN’T JUST FOR KIDS

                                    By : Shelly A. Mayer

 

August 10,1996 :            VETERINARY COLUMN : L.C.Allenstein, D.V.M.

                                    THIS HOLSTEIN CALF SUDDENLY BLOATED AND DIED

 

January 10,1997 :            VETERINARY COLUMN : L.C.Allenstein, D.V.M.

                                    CALF IS CHRONIC BLOATER

 

January 25,1997 :           HERE ARE SAMPLE RATIONS FOR HEIFERS

                                    By : J.L.Morrill

 

March 25,1997 :            TOO MANY HEIFERS TOO FAT

                                    By : Brian L. Perkins (Nutrition consultant)

 

                                    DEVELOP A BLUE RIBBON FEEDING PROGRAM

                                    By : C.Vilter McDonald

 

April 10,1997m :            BOTH MILK AND REPLACER CAN WORK FOR CALVES

                                    By : J.L.Morrill

 

October 25,1997 :            MANAGEMENT CHANGE CUT COSTS, SAVED CALVES

                                    By : James A. Jarrett, D.V.M.

 

November,1997 :           A NEW LOOK AT OUR OLD HEIFER-RAISING RULES

                                    By : Patrick C. Hoffman

 

December,1997 :           A MUDDY START DIDN’T HELP THESE CALVES

                                    By : James A. Jarrett, D.V.M.

 

April 25,1999 :               WHY YOU SHOULD START FEEDING CALVES GRAIN EARLY

                                    BY : A.J. Heirichs

 

 

THE DAIRYMEN NEWSLETTER :            Reference to Feedstuffs 07/96

 

                                                            No. 2/95

                                                            No. 5/95

 

FARMERS WEEKLY            February 10, 1984            STRESS IN CALVES

                                                                        By : Anthony Phelps

 

AFMA FORUM              May 1998            FEEDING AND MANAGEMENT OF DAIRY CALVES

                                                            By : Dr Robert Elliott

 

June 1980 :       PREVENTIVE MEDICINE IN CALF REARING FOR REPLACEMENT STOCK IN DAIRY OR BEEF HERDS

                        By : G.W.Tedder (for BVSc V1/