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The feeding of replacement heifers up to the first calving
Afrikaans | Xhosa
Most milk producers raise their own replacement heifers. This practice is preferred to that of buying heifers from other producers for the following reasons:
- The origins of the bought heifers are often poor and/or unknown.
- Bought animals may be contaminated with infectious diseases such as contagious abortion and bovine tuberculosis.
- The purchase price of heifers is often disproportionate to their production abilities.
- Heifers are not always available at times when they are needed.
Heifers must come into production as soon as possible, since this is the only way to save on the cost of raising them. But care must be taken to prevent heifers from getting fat. However, as heifers get older, fat deposits increase. Fat deposits in the udder before puberty will adversely affect milk production.
The faster an animal grows, the more efficient the process whereby food is converted into body mass, since a smaller proportion of the food goes to maintenance and a larger proportion to growth. Heifers must therefore grow to maturity and reach covering weight as quickly as possible, within a given age constraint. Covering before the appropriate age will result in low production and increased calving problems. Heifers should preferably not calve when they are younger than 22 months, nor when they are older than 27 months. The size and condition of heifers at the first calving have a marked effect on their production during the first three lactations.
The heavier a heifer is at the first calving, in other words the closer she is to her mature body mass, the higher her milk production during the first three lactations will be. Moreover, the heavier heifer usually has greater reserves of body-fat to provide for her energy needs during the first three months of lactation. This is of particular importance, since it is during this stage that the amount of energy in the feed alone is not sufficient to meet her requirements for the production of milk. More grown-up heifers require less energy during the first lactation to achieve their mature weight, with the result that there is more energy available for milk production. This effect remains through to the third lactation.
The reason why some heifers are less productive is that fatty tissue rather than udder tissue is deposited in the udder. This process occurs during or even before puberty.
FEEDING
The factor that plays the principle role in the growth of heifers is feeding. Both over-feeding and under-feeding have an adverse effect. The nutritional needs of heifers change as they grow older. Consequently their feeding programme must be adapted according to the following age groups:
- 3 to 6 months
- 6 to 12 months
- 12 months to calving.
Three to six months
During this phase heifers of comparable age groups can be placed together in sheds or small pens. The age difference within any group should preferably not be greater than two months. At this stage the rumen is not yet fully developed, and the heifers should be given only the best quality coarse fodder in the form of grazing and/or legume hay. Straw, chaff, stubble-fields, and poor fallow lands or stubble grazing will have an adverse effect on the growth of the animals. A whole fodder of this composition and supplied ad lib, or a good quality coarse fodder (lucerne hay, grass or legume hay, or grass and clover grazing) together with 1,5 kg calf growth meal, will meet the calf's requirements.
Six to twelve months
At this stage the rumen has been fully developed and the calf is able to effectively utilise coarse fodder. The most important source of nutrition should be a good quality coarse fodder in the form of grazing, silage and/or hay. At this stage coarse fodder of a poor quality, and a low and deficient feed intake are the foremost causes of poor growth and malnutrition.
Twelve months to calving
Depending on the kind, quantity and quality of the available coarse fodder, any of the following feeding programmes may be followed during this stage:
- Programme 1 - with very high quality hay
Supply high quality legume hay (lucerne) or young planted grazing, plus 1 kg maize meal (or small grains) per day up to the covering stage. Concentrates are now discontinued until three months before calving, after which the heifer must once more receive 1 kg of dairy meal per day.
- Programme 2 - with medium quality hay
Supply hay of an average quality plus 2 kg of coarse protein concentrate per day up to the covering stage.
After impregnation: 1 kg grain meal per day plus rough fodder
From 3 months before calving: 2 kg dairy meal per day plus rough fodder
Since the nutritional requirements of the heifer increase appreciably due to the growth of the foetus and the placenta, the extra concentrates during the last three months before calving are important.
When heifers are inclined to grow too fat, the supply of concentrates must be reduced.
MANAGEMENT
- Heifers must be divided into groups according to age, particularly when they are being fed. Any age differences in a group should preferably be limited to a maximum of two months.
- Expensive housing is not necessary, but any flocking together in wet and dirty pens must be prevented. It is necessary, however, to provide protection against extreme temperatures. During hot summer days, in particular, it is essential to provide shading.
- In order to prevent waste, effective troughs must be provided where feeding takes place.
- Calves and heifers must be weighed or measured every month to determine their growth. A chart on which the weight of each calf at each weighing is recorded, is to be recommended. In this way adjustments of feeding programmes can be made in time, before the growth of the animal is affected permanently and detrimentally.
- Keep the heifers tame and calm. Move about among them on a regular basis. If practically possible they can be accustomed to the stable routine during the last three months before calving.
- Heifers must be de-horned with a branding iron before the age of one month, and any supernumerary teats must be removed.
- Follow a disease control programme which has been drawn up in collaboration with a veterinarian or an animal health technician.
- It is essential and compulsory by law to vaccinate the heifer against contagious abortion at five months. After this age it is no longer possible to immunise a cow against the disease.
CJC Muller
ELSENBURG / Research
