The rules and principles for feeding dry cows

Spring dairy farmers are just beginning to think about drying off cows. Some year-round producers or block autumn-calving producers have some tail-end cows still to calve. Some are getting too fat and the importance of the technical detail in this article will not be lost on these farmers.

Good nutrition management during the autumn dry period will significantly reduce the risk of metabolic problems at calving.

There are three main points to consider.

Firstly, keep body condition score at calving to a maximum of around 3.5. Allowing condition to build higher than this greatly increases the risks of metabolic disease and calving problems.

In the next few weeks, some spring producers will dry off the first-calvers that are calving again next February and some farmers graze them behind the milking group in the early dry period before moving off to the calving area.

One of the most important nutrition aspects when feeding dry cows is to feed a low potassium diet (<2% of dry matter) in the last few weeks before calving.

It is best to avoid feeding real high-quality lush grass at this time. If cows are calving outdoors, they can be strip-grazed on stemmy grass and supplemented with low potassium haylage or silage.

The other key nutrition aspect during the dry period is to feed a good-quality dry cow mineral from six weeks pre-calving. Magnesium (Mg) is critical for milk fever prevention. Supplement to reach levels of 0.4% of the total diet (Table 2). Add extra Mg in the last two weeks pre-calving if needed.

Minerals

Inadequate mineral supplementation during the dry period can cause problems with perinatal calf health, as well as a greater risk of problems with cow health. These include clinical and subclinical milk fever, ketosis, retained cleanings, low dry matter intake, displaced abomasum and fertility problems.

Pre-calving minerals should be fed to dry cows for at least six weeks pre-calving. The correct feeding level should be offered. Typically, mineral specifications are formulated to a 120g/cow/day feeding rate.

If easy feeding silage, as most farmers are doing, it is advisable to dust minerals on silage twice daily (60g/cow in two feeds) to try to ensure that intake is controlled and that all cows can have access to minerals. This is especially important where feed space is limited.

For herds with a history of mineral-related issues, a farm-specific mineral mix may be required.

I know some farmers who will have tested grass and silage and typically find out it is low in selenium, for example, and will feed a high selenium mineral mix.

Body condition score

Having cows in the correct body condition score (BCS) at calving is essential to ensure trouble-free calving, good milk yields and good subsequent fertility performance next year.

This is much more valuable than squeezing a few extra litres from thin cows milked into November and December. Grouping and feeding dry cows based on BCS is not always practical, but should be attempted if at all possible.

It may be easier to meet BCS targets by management in late lactation. The sooner you put a plan in place to deal with thin cows, the more options you have.

Acting in October will allow you to use the option of an extended dry period for early-calving cows.

As a rule, there is plenty of silage around this autumn for winter feeding. Some of it may be of questionable quality.

I’ve seen some silage taken in the last few days (October silage) that will definitely be minimal feed value.

Dry cows on 62% DMD silage for eight weeks would be expected to lose BCS (-0.15), while those on 68% DMD silage would gain around 0.20 units.

To put condition on cows, you need real high-quality silage or else you need to extend the dry period.

Thin cows (less than 2.5) will require extra days dry, once-a-day milking, extra dry-period feeding or a combination of measures to make the targets.

Ketosis – is it an issue for your cows?

I was up north this week on dairy farms and on one of the farms the vet was just leaving the yard after treating a case of suspected ketosis.

This example clearly shows the problems that can occur when a cow becomes too thin or fat.

The cow in the crush was a fifth-calver who had been dried off in late July and had calved down five days ago.

She came in for milking and the farmer had noticed she was off form – slow to move around the yard and standing at the back of the collecting yard in a world of her own, so to speak.

What is ketosis?

Ketosis is a signal that the cow is in negative energy balance and this happens when output exceeds input or, in other words, when she is milking more than the energy she is consuming.

Clinical ketosis (cows actually showing signs like the cow above) is reported to be less than 2% to 5%, but vets often suggest that prevalence of sub-clinical ketosis (no sign of sickness) can suppress the immune system and open the door to other problems such as retained placentas, metritis and displaced abomasums.

How to prevent?

One of the most important issues in freshly calved cows is to try to keep feed intakes up after calving.

This can be very difficult on cows that calve down over-fat, so with quality silage on some farms, be very careful not to feed too much high-quality feed to November- and December-calving cows or late March or April spring-calving cows. Fat cows reduce intakes considerably before calving.

Another very simple thing you can do is to ensure dry cows have enough feed space, because if you have limited feed space it can often be the trigger for reducing intakes and hence lower energy.

Indicators of negative energy balance include high incidence of ketosis, retained placentas, displaced abomasums, high milk fat to milk protein ratio (over 1.5 ratio - so this means results such as a fat of 4.5% and protein of 3% should send an alarm signal) and low milk yield post-calving.

Previously, blood samples were the key to testing for ketosis, but now there are some individual testing kits that test milk from fresh cows. High-risk cattle are cows that have twins, fat cows and heifers calving down for the first time at 28 to 30 months old.

Treatment

For the farm I was on this week, the vet recommended drenching the cows with propylene glycol to try to improve energy levels.

They also advised taking the sick cow out into a paddock near the yard where they had access to grass and forage and not be in competition for feed with other fresh calvers.

Research suggests drenching cows with glycol increases insulin by 200% to 400% within 30 minutes after drenching.

It also increases plasma glucose. There are also slow release boluses available to treat.

Read more

What to do when silage is running low

Meal time: what's on the menu for beef cattle this winter?

What can my silage do for me this winter?

How far will my silage go this winter?