In The Paddock
Seasonal sheep flock management tips for July 2001

Silage for the ewes
Just what the doctor ordered?

Key points

Feeding silage to sheep is quite rare in the North Island and the northern half of the South Island. But it's standard practice on many sheep farms in Otago and Southland, and is the most commonly used supplement on dairy farms.

In autumn, silage is good for flushing ewes, and in winter it's a useful tool to help build up pasture cover for when it's needed in late pregnancy.

Because settled weather and complete drying of the crop is not needed when making silage, it can be made earlier in the growing season than hay. This means it is usually made with less mature pasture than hay, which means it has a higher feed value.

Also, because this earlier harvesting is generally completed before the onset of the summer dry, continued grass growth means there is more pasture cover going into the summer. Often, after hay is cut, there is very little pasture recovery before the autumn rains.

In the 1970s and early 1980s there was a series of severe droughts in many parts of the country. Farmers and researchers were forced to look at ways to survive a drought.

Silage feeding trials during this period showed ryegrass-white clover pasture was a good supplement for breeding ewes – especially as a flushing feed before mating.

This led to widespread feeding of silage to sheep especially in Northland, Hawkes Bay, Canterbury, the pumice country and the drier parts of the South Auckland-Waikato areas. But as the incidence and severity of droughts lessened so too did the practice.

How do sheep perform?

In a feed pinch, ewes readily eat silage. Trials in the 1970s and 1980s at Ruakura, Waikato and Templeton, Canterbury, showed wilting (32–37 per cent vs. 16–18 per cent DM) or chopping of the pasture before ensiling resulted in large increases in dry matter intake.

When wilted silage was fed to appetite, intakes were mainly in the range of 0.8 to 1.5 kg DM/ewe/day. This was in addition to any pasture eaten.

Ewes gained 3.5–4 kg liveweight during the four to six week trials. Some did even better.

Increases in ewe liveweights were accompanied by improvements in body condition scores, so the silage result was not just a gut fill effect. In one of the Templeton trials, ewes on wilted silage did as well as those grazing high levels of irrigated pasture.

All the trials showed some substitution of silage for pasture in the ewe's diet. The first Ruakura trial demonstrated this very clearly.

As silage intake increased from 0 to 1.0 kg DM/ewe/day the pasture intake declined 1.2 to 0.8 kg DM/ewe/day. These reduced pasture intakes led to increases in post-grazing pasture levels, from 500 to 900 kg DM/ha. In other trials the pasture sparing effect was greater than this.

This shows the very important role that a supplement has in preventing overgrazing, thus allowing some build-up of pasture as an aid to future feed planning.

In those trials where wool growth was measured, silage feeding invariably led to higher wool growth. Indeed, some ad lib silage groups grew 40 per cent more wool than sheep fed pasture only.

Reproduction responses, where measured, were variable. But increases in ovulation rates, conception rates and lambing percentages invariably occurred. Templeton research suggested 17 days feeding of silage was a minimum to achieve a flushing effect.

It's easy

It's easy to teach ewes to eat silage. They readily accept it if a bit of grazing pressure is applied.

To get a mob started, feed out a little on the last day in a paddock. Once most appear to be eating it, silage can be offered daily.

Some farmers feed grain on top of silage to introduce stock to either feed, and/or to reduce wastage of grain.

WoolPro advises sheep farmers buying silage to pay for it on the basis of its dry matter content. Lincoln University and AgResearch provide testing services.

AgResearch data indicates that the dry matter should range from 15-20 per cent, crude protein from 12-20 per cent and energy from 8.4–9.5 MJME/kg DM."

More information?

For more information, refer to these published research papers, or search 'silage' on the AgResearch website http://www.agresearch.co.nz/.

Rattray, P.V. (1983), Use of pasture as a summer supplement for ewes, Proceedings NZ Grasslands Association, 44:188-195.

Haymond, J.M. & Munro, J.M. (1983), Silage for flushing ewes, Proceedings NZ Grassland Association, 44:196-202.

Your local farm consultant or veterinarian will also be able to help. Alternatively, contact your local WoolPro extension specialist:

Northern North Island: Sally Hobson tel 07-823 3321 or 025-924 751
Hawkes Bay/East Coast: Lew Willougby tel 06-835 1888 or 025-434 417
Southern North Island: Richard Gavigan tel 06-376 0006 or 025-499 851
Nelson/Marlborough/Canterbury: Alan Marshall tel 03-343 7913 025 329 399
South Canterbury: Julia Mackenzie, tel 03-680 6782 or 025-782 353
Otago: Robert Pattison, tel 03-489 9021 or 025-323 094
Southland: Aaron Meikle, tel 03-203 9071 or 025-846 377