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Management of dry cows
Afrikaans | Xhosa
The dry period extends from the end of lactation until the cow calves again. In the production cycle of the cow this is a critical period, since she is now heavily pregnant with a fast growing foetus. During this period the nourishment of dry cows should not be neglected.
The purpose of the dry period is to provide the milk producing tissue in the udder with the opportunity to regenerate. This process lasts for about six weeks. In cases where the ewes are not allowed a dry period, the decrease in milk production during the subsequent lactation can be as high as 30%. The dry period also provides the rumen with an opportunity to recover. During the dry period the condition of cows must be maintained. An effort may be made to improve the condition of cows that are very weak.
The gestation period of cows lasts for nine months, and in the last eight weeks before calving the foetus grows exceptionally fast. About 60% of the increase resulting in the birth mass of the calf takes place during this period. The nutrition supplied to the cow during the dry period must at least ensure that foetal growth takes place.
Duration of the dry period
The dry period must last from about 42 to 60 days. Both a short as well as a very long dry period will have an adverse effect upon the milk production of cows during the next lactation.
The drying up date
In order to determine the drying up date, the expected calving date must be known. This is calculated from the servicing date, once it has been confirmed that the cow is pregnant. The average gestation period of cows varies from 275 to 283 days. To determine the drying up date, sixty days are subtracted from the expected calving date.
Drying up method
Prior to drying up, the milk production of cows must be reduced. The feeding of concentrates must cease, while cows may also be fed straw. Cows are dried up in the following way:
- Cows are dried up by suspending milking. If a cow has a high milk production of 20 kg or more, she must be milked only once per day during the last two to three days before drying up. The cow may also be fed straw to reduce her milk production. Although the water intake may also be limited, this must not be done during very hot weather conditions.
- At the last milking a long-lasting dry cow antibiotic must be administered to each of the four quarters to ensure that during the dry period the udder will not be infected by bacteria causing mastitis. For the first week after drying up, cows must be watched carefully. The pressure of milk in an udder that is not drained causes the gradual re-absorption of the milk, and this in turn suppresses milk production. The result is that the cow dries up, after which she can be moved to the dry cow group.
Feeding during the dry period
The last 2 to 3 weeks before calving seems to be a critical period for the dry cow. At this time her hormonal status undergoes a dramatic change in anticipation of the imminent calving process and subsequent lactation. The cow usually loses her appetite with the result that she eats less, especially in the days just before calving. After calving this may result in disease conditions such as ketosis, fat livers, displaced abomasums, and stuck placentas.
There is a strong relationship between the intake of dry material before and after calving. This means that cows that are poor feeders before calving, will also be inclined to feed poorly after calving. The result is that the production of such cows will be below par, and that they will also present increased physiological and reproductive problems.
It is important that cows should be in a good condition when they are dried up. Lean cows do not have sufficient energy reserves to maintain high production during early lactation, since their energy needs exceed their energy intake. Excessive fat in cows is also undesirable, since excessively fat cows eat less and are more inclined to present metabolic and reproductive problems.
It is important that cows be given coarse fodder of a good quality and rough texture during the first four to six weeks of the dry period. During this period maize silage, grass hay, small grain hay or silage, and grass pasture or grass and clover pasture may be successfully used as food sources for dry cows. Restrict the intake of maize silage to prevent cows becoming too fat. A suitable lick must always be supplied together with the coarse fodder to ensure that the mineral and trace element status of the cow is built up.
The last three weeks of the dry period can be used to accustom the cow to concentrates. The feeding of concentrates can commence with 1kg/cow/day, and be increased systematically to about 3kg/day just before calving. Only coarse fodder with a low potassium content should be supplied during this period. Good examples of such fodder are maize silage and small grain hay or silage. Coarse fodder with high potassium levels such as kikuyu, rye-grass and clovers results in the suppression of calcium mobilisation, which causes problems such as lacteal fever and stuck placentas.
Given the importance of the cow's trace element status during calving to prevent stuck placentas and mastitis infections after calving, vitamin A and E with injectable zinc and selenium can be administered to milkers 14 days before calving.
CJC Muller
ELSENBURG / Research
