Drying off is a key period in dairy cycle
With milk quotas a distant memory, dry periods are likely to be shorter than in previous years - but this should not pose a problem with good management
It's that time of year again and spring calving dairy herds are starting to look at drying off. This is more than just a rest period from milking; proper management and nutrition of the dry cow is critical to maximising dry-matter intake, herd health, reproductive efficiency and milk production in the subsequent lactation. This period of preparation for the next lactation is a key period in a dairy cow's cycle.
The procedure for successful drying off
It normally commences 60 days prior to calving. With milk quotas now gone, it is likely that dry periods will be shorter than previous years. This is not a problem once cows are in an appropriate body condition at the dry-off date. With good management, dry periods can be as short as 45-50 days. Lower yielding cows doing 10-12l per day are relatively easy to dry off, with an abrupt cessation of milking not causing any problems.
Higher yielding cows can be more difficult, but a strategy of providing less feed of lower nutritive value works well. However, withholding water is not recommended. Feeding straw for the 24 hours before drying and 72 hours afterwards is an excellent way of reducing milk production rapidly. Dry cow antibiotics and, in most cases, a sealer are used. Regular monitoring of udder health after drying off is critical to ensure that mastitis does not occur.
The aims of good dry cow management should include:
* adjust and maintain body condition score (BCS);
* repair the rumen wall;
* complete the involution of the udder after drying off;
* regenerate the mammary gland for the next lactation;
* prime the immune system to minimise disease;
* ensure good fertility rates by promoting the production of quality follicles that will be released during the breeding season;
* stimulate appetite after calving;
* allow for easy calving and a healthy calf;
* minimise pre- and post-calving metabolic disorders;
* drive colostrum production to enable sufficient antibodies to be passed to the newborn calf;
* maximise milk solid production in the next lactation by maintaining a healthy rumen.
Cows should be dried off at a body condition score (BCS) of 3.0-3.5 and maintained at this right through to calving. Although it has been common practice to feed cows to gain weight during the dry period, this can have negative consequences.
Dry cows only put on fat when fed for condition and this fat melts off their back after calving, leading to metabolic problems. If cows are thin in late lactation, it is best to try and regain some of that condition while the cow is still milking. Management of condition score should be an all-year round job, not just at drying off when it is often too late.
Prior to drying off, cows could be eating 3pc of body-weight on a dry-matter basis, which falls rapidly to 2pc once dried off. The developing calf requires additional nutrients as the cow moves to complete the final third of pregnancy. This increased demand is modest, but the increased proportion of the cow's abdominal cavity being occupied by the calf has a major effect on space available for the rumen and thus intake potential.
Dry cow feeding
Feeding good quality straw with restricted silage provides good physical fill and helps to control potassium levels in the diet. Straw intakes should be encouraged to reduce the energy density of the diet. Remember that silage with a dry-matter digestibility (DMD) of over 70DMD is often too good for dry cows, since it can result in excessive body condition gains. Precision-chop silage also provides very little structure to promote cud chewing as it is often too short. However, provision of a small amount of concentrates during the dry period will help to promote rumen bug populations in preparation for nutrient-rich diets in early lactation.
Straw promotes good rumen function that helps to promote extra dry-matter intakes after calving. Straw encourages active cud chewing that produces calcium for the cow to metabolise, which improves her muscle tone.
The calcium metabolised by the cow has a role in preventing milk fever at calving. The provision of straw in the dry period often helps to dilute possible negative effects of typical grass silage such as excessive potassium and chloride. It will also help to prevent excessive weight gain where very good silage is being fed.
A good-quality dry cow mineral is also an essential part of successful dry cow nutrition and management. Try to look at the quality of the mineral rather than buying it on price alone. If you have a mineral analysis for your silage, then get help to match the correct mineral so that any deficits in your silage are filled. Dry cow minerals should always have a high magnesium level and chelated trace elements to optimise mineral availability. It is also important that sufficient vitamin E is fed to dry cows to promote the cow's immune response around calving.
A transition dry cow ration is recommended for higher yielding herds to ensure a smooth change from the dry period to early lactation.
The cow's nutrient requirements in the last two weeks of the dry period are increasing due to colostrum production and the increasing size of the rapidly growing calf. The cow's appetite is also declining due to the hormonal changes. To ensure all the nutrient requirements are met, a target of 9.5-10.5kgDM/cow/day, with energy intakes of 110MJ/day is required.
The best way to achieve this is by offering the transition cows some additional concentrates along with the diet that they have been eating throughout the dry period. The protein content of the transition diet should be increased to at least 14pc from the target 13pc in the early dry period. The additional protein helps promote intakes as well as increasing colostrum yield and bagging down. The in-calf heifers will also benefit from the additional protein before calving as they are the ones that are most likely to suffer from poorer intakes as they approach their calving date.
Use condition score and dry cow tube withdrawal period to determine the length of the dry period
Don't over condition cows in the dry period.
Supply an appropriate top quality dry cow mineral throughout
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