What to consider before keeping sheep on tack at your dairy farm

Tack grazing is a valuable source of winter forage for sheep farmers and it generates an income for dairy farmers at one of the most expensive times of the year.

But, as spring calving systems become more commonplace and awareness grows of the potential risk of disease spread between species, there are fewer opportunities for winter tack.

Dairy grazing consultants sometimes refer to sheep as woolly parasites that should never be allowed near dairy farms, especially in winter.

See also: The 1,400-head dairy grazing all year round

But for systems that don’t rely on early spring grazing for milk production, sheep can be a good management tool for enhancing grass quality and growth.

Pros and cons of keeping sheep on tack

Warmer winters mean grass continues growing late into the season in some regions, affecting quality, says independent grassland specialist Chris Duller.

“Heavier farms can find themselves with strong covers and carrying too much grass through the autumn and winter, particularly in cases when the last cut of silage was in October,’’ he says.

Disease

“It can mean that by February there is a foot of grass cover and at this level it is susceptible to rusts, drechslera and other diseases of grass.’’

These diseases feed on the plant’s energy, making grass less palatable and reducing yield. In more extreme cases they can kill the plant.

Some types of grass are more prone to disease than others – Italian ryegrass, for example, can often be susceptible to both rust infections and rhyncosporium.

Heavy winter covers also result in poor-quality spring swards, with an accumulation of dead material caused by shading at the base of the plant.

“You can reduce the risk by having lighter covers. Sheep can be a means of achieving this,’’ says Mr Duller.

Slurry contamination

Some dairy farmers experienced difficulties with slurry contamination last spring because they had carried heavy grass covers through the winter.

A dry spring meant very little rainfall to wash the slurry into the soil, leaving it to contaminate the leaf. It was still there when the first crops of silage were cut, says Mr Duller.

Benefits

An argument in favour of tack grazing is that it encourages ryegrass to tiller and thicken.

Swards will be very open in fields where four or five crops of silage are cut and this will also be the case in systems where pasture is not grazed correctly, with high covers and low stocking rates resulting in opening covers of 3,400kg DM or more.

Another benefit of mixed grazing is that sheep are useful for controlling worms on pasture and a good tool for managing problem fields, such as those that have been reseeded and where growth is strong.

“It might be good to use sheep to keep on top of that, or there might be a wetter field that won’t be grazed until the end of the first grazing round. That could be targeted with sheep,’’ says Mr Duller.

Sheep are also useful for clearing up weeds, he advises. “It might be that a field has been reseeded in October and, as sprays are not as effective in the autumn, weeds take hold.

“I know of farmers who use sheep to clear up chickweed, perhaps in small groups of about 60.’’

How to decide if sheep are right for you

In Mr Duller’s view there is a simple rule for determining if sheep have a place on a dairy farm in the winter.

“If you are turning cows out in the second week in February, after calving, you shouldn’t have sheep.

“If you have a heavier farm, and have a different calving pattern and cows are not going out until March, it is not an issue to have sheep on the farm until the first week of January.’’

Silage quality

However, even farmers who don’t turn cows out to grass early should approach tack grazing with caution, because it can affect the quality and quantity of that all-important first cut of silage.

“One way or another, quality or quantity will be compromised,’’ warns Mr Duller.

“We are trying to encourage farmers to make high-quality silage to reduce concentrate costs and that in itself means starting the silage process that bit earlier in the season.

“If you are aiming to cut silage at a certain growth rate to get the quality, the quantity is going to be compromised by leaving sheep on the leys too late in the season.

“It is vital the ewes are gone on time, otherwise first-cut yield can be very severely undermined.’’

A tonne of silage dry matter is worth about £125. Keeping sheep on the farm for an extra month could result in a loss of up to 0.5t DM/ha.

Research has shown the effect of late-winter grazing on grass yields can extend as late as June, says Mr Duller.

“Even if the grass doesn’t appear to be growing much through January and February it is still photosynthesising and sustaining itself.

“If it has sheep nibbling away at it and reducing the leaf area it means it has to come from a standing start rather than a running start when the ground temperature warms up.’’

But if grass diseases are an issue because of heavy covers, this can also affect the quality of first-cut silage.

Instead Mr Duller says sheep can be rotationally grazed to create a grass wedge for March, instead of letting them graze every field.

Setting up contracts

The most important term in the contract between the host farmer and the grazier is a firm date when sheep must be removed, says Paul Macer of Kite Consulting.

“It can work very well for both parties if there is a good agreement whereby sheep arrive when the cows are housed and are moved off promptly,” Mr Macer advises.

“If sheep overstay their welcome you can get a situation where the tail is wagging the dog and some dairy farmers lose sight of the amount of potential grass growth they are sacrificing by keeping the sheep on for an extra three or four weeks.

“At that point in time they might just see the prospect of cold, hard cash without taking the loss of growth into account.’’

But he says the contract should also:

• stipulate the maximum stocking density so the sheep don’t make a mess
• make clear who is responsible for shepherding and fencing

What fees to charge

Spring block-calving has resulted in greater competition between sheep and dairy stock, with sheep farmers having to look to new geographical areas and a bit further east.

Fees for winter grazing can vary significantly, depending on location. The further east, the lower the rate, says Mr Macer.

“If you are in close proximity to a high concentration of sheep – in Wales and the north-east of England, for instance – rates are quite a bit higher.’’

Typically payments can range from 25p a head a week to 70p in areas where competition is greatest.