Brian Reidy: Dry cow diets — a steady transition into the next lactation
Many silages are again low in protein this year so extra protein may be necessary this coming spring.
In spring-calving dairy herds, most have a proportion of the herd dried off at the moment, with a view of all being dry over the coming weeks.
Some will also be milking on a proportion of the herd through the winter. There is no right or wrong when it comes to milking cows through the winter or drying them all off.
For many, the cash flow, particularly with the current lower milk prices, is welcome, and it allows cows to complete a full lactation. Facilities and labour will determine if this is practical from farm to farm.
Many will have noted over the years that future cow performance can be negatively affected where individual cows or groups of cows have a dry period in excess of 10 weeks.
There is nothing wrong with individual cows only being dry for five or six weeks. Obviously, body condition and dry cow tube withdrawal will also be factors that must be considered when deciding on dry off dates.
Let’s look at them as cows we are preparing for their next lactation and not just dry cows, as this is a key period in their production cycle. Any problems during the last dry period and the most recent lactation can be addressed now.
It is an opportunity to adjust and maintain body condition score. Ideally, dry cows off in the condition you want to calve them down in and maintain them right through to calving with a controlled energy diet and appropriate mineral supplementation.
Any cows that had digestive upsets during the last lactation also have an opportunity to repair the rumen wall during the dry period.
The dry period allows for complete involution of the udder after drying off, and an opportunity to regenerate the mammary gland for the next lactation. A key part of this regeneration process is correct protein supplementation in the dry cow diet, particularly as cows approach calving, which will also improve colostrum yield and quality.
Many silages are again low in protein this year so extra protein may be necessary this coming spring. Many 2025 silages are also too low in energy to even maintain a dry cow, and as a result, may need supplementation in advance of calving.
This is particularly true for second cuts, as a large proportion of them are too dry, over-wilted and not well preserved. Many of these second cuts are below maintenance for dry cows.
Calving is a stressful event for the cow or first calving heifer and priming the immune system to minimise disease in early lactation is critical. As part of this a targeted mineral strategy with sufficient vitamin E and selenium will drive the immune system around the calving event.
A good dry cow strategy can ensure good subsequent fertility rates by promoting the production of quality follicles that will be released during the next breeding season.
How you feed cows during their dry period will stimulate good appetite post calving and will really pay off in the next lactation as it will minimise stress and weight-loss post calving. Sufficient fibre in diets with adequate protein (13%-14%) in the dry period will promote intakes post calving. This will aid milk production and help with milk quality.
Any preparation for the next lactation must obviously aim for easy calving and a healthy calf, as a well implemented dry cow diet will keep cows fit rather than fat, resulting in easier calving’s in general.
Minimising pre- and post-calving metabolic disorders will also be essential for a successful transition to milking and increase overall milk yield, milk quality, fertility performance and feed efficiency, predominantly from grazed grass. All of which adds up to a cow that is almost unnoticed in the herd but delivers a profit.
Grass silage alone may have nutrient and mineral imbalances, resulting in potential metabolic disorders around calving and in the early weeks of lactation. An accurate forage mineral analysis will help to devise your dry cow diet strategy, particularly if you have had issues around the transition cow in the past.
For some, the option of feeding straw if available, while restricting silage, provides good physical fill and helps to control potassium levels in the diet. Straw intakes can also be encouraged to reduce the diet energy density.
Silages (68 Plus DMD) are too good for dry cows, resulting in excess body condition gains. The feeding of a small amount of balanced concentrates during the dry period will help to promote rumen bug populations in preparation for nutrient-rich diets in early lactation, and also may be required to boost protein supply.
A quality dry cow mineral is an important element of a successful dry cow nutrition and management strategy in preparation for the next lactation. Look at the quality of the mineral, rather than buying it on price alone. Dry cow minerals should always have a high magnesium level and organic/protected trace elements to optimise mineral availability.
As I mentioned above, it is also important that sufficient vitamin E is fed to dry cows to promote the cow’s immune response around calving. Phosphorus also needs to be supplied in sufficient volume to ensure good saliva production for thorough digestion and rumen buffering.
One group of dry cows should be sufficient in most yards, as it is not practical to be constantly moving cows from batch to batch, and may prove more stressful than it is worth for farmer and cow.
In some cases, a special diet may be necessary for the last three weeks dry if historical issues have been recorded or the silage has particular mineral characteristics requiring attention.
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.
It is good practice to spec dry cow diets at 9.5 to 10 ME and 13.5 to 14% for all dry cows for the entire dry period, as separate diets can complicate things and are generally unnecessary.
The additional protein helps promote intakes as well as increasing colostrum yield and help bagging down. In-calf heifers will benefit from the additional protein pre-calving as they are the ones that are most likely to suffer from poorer intakes as they approach their calving date.
Dairy blends/nuts should not be fed to cows before calving as they contain calcium.
Once calved, take care to introduce the milking diet carefully. Obviously, concentrate levels can be introduced faster through a mixed ration than they can in the parlour.
