Feeding sheep - The Accidental Smallholder

Digestive system in sheep

Sheep are herbivores i.e. animals that live on grass and other plant material, and ruminants i.e. animals that have complex digestive tracts that include a rumen. Cattle and sheep are ruminant herbivores; horses are non-ruminant herbivores.

The rumen is the first stomach. It is a large vessel that contains vast numbers of bacteria that break down chewed material into fatty acids, methane and heat. The fatty acids are absorbed into the blood stream, the methane is excreted as gas and the heat maintains body temperature.

As prey animals, ruminants consume plants quickly when it’s safe to do so, hardly seeming to stop for breath. This plant material goes into the rumen where digestion starts. At a time when predators are least likely to strike, the ruminant will lie down and start to regurgitate the rumen contents, chew them again then swallow them into the second stomach for digestion to continue.

This is called chewing the cud or cudding. By developing this complex digestive system and harnessing the useful rumen bacteria, the ruminant species can digest plant material more efficiently that non-ruminant ones.

Nutritional requirements

Like us, sheep need protein, carbohydrates, fats, fibre, vitamins, minerals and trace elements in the correct proportions to make up a healthy diet. A ewe’s nutritional requirements are to a large extent determined by the stage of the breeding cycle.

So sheep have evolved to live on plant material and, even in domestic situations where we may require higher levels of production than from a wild sheep, for some of the year, your sheep will be able to live quite happily on grass.

However, grass doesn’t grow all year so there are times of the year when the sheep’s diet needs to be supplemented, because the nutritional demands of getting pregnant, carrying a lamb and feeding a lamb or lambs outstrip what can be provided by grass alone.

In basic terms, grass starts growing in spring, grows well until mid-summer when both growth rate and nutritional value falls; it has a growth spurt in September then stops growing over winter. How well it grows, in terms of quantity and nutritional value, depends on a number of factors – species, soil type and condition, geography, climate.

When grass is not enough – supplementary feeding

Ruminants must have long fibre i.e. grass, hay, haylage, silage in their diets to keep them healthy. They cannot thrive on cereals alone. During the winter, when the grass is not growing, the sheep’s diet will have to be supplemented with hay, silage or haylage. The merits of each type of forage are covered in the Grassland Management guide.

There are two periods in the year when ewes are usually given a concentrate (cereal based) feed, in addition to the forage element of their diet:

• For a few weeks before the tups go in, during tupping and for a few weeks after the tups come out. This is called flushing.
• In the final trimester of pregnancy (7 or 8 weeks pre-lambing) if the ewe is carrying multiple lambs.

These cereal based feeds come in two forms; in a bag, as pellets or a coarse mix or as a feed block. As well as cereals for protein and energy, both the bagged feed and the blocks contain vitamins and minerals, and usually molasses to improve palatability.

The main advantage of feed blocks is that the sheep just help themselves, so they feed little and often. Shy feeders also get good access (if enough blocks are put out) and the “little and often” feeding is closer to the sheep’s natural way of feeding. However, feeding pellets or mix gives you a good chance to inspect your sheep and. bucket- friendly sheep are usually quite easy to move from place to place.

Weaning

When the lambs are weaned in late summer, the ewe is usually put on poor grazing so that her milk supply dries up quickly. Because she has been feeding a lamb or lambs, her body condition might be quite poor, so once her milk supply has dried up, she can be put on better grazing to improve it.

Pre-tupping

A couple of weeks before the tups go in, she may be offered a supplementary cereal-based feed; this encourages the ewe’s body to produce eggs and should increase the number of multiple births. Continuing the supplementation for a couple of weeks after mating helps to ensure good implantation of the fertilized egg.

If ewes go to the tup in November, say, for an April lambing, they will normally require only a forage supplement over winter – hay, haylage or silage. Grass has stopped growing and what there is will be of limited nutritional value. However, once the ewe is pregnant, her nutritional requirements are quite low until the final third of the pregnancy, when the lambs start to grow in size. Up until then, the lamb is developing but remains quite small.

Final trimester of pregnancy

In the final trimester (third) of pregnancy, about 50 days before lambing, the demands on the ewe of the lambs’ rapid growth increase dramatically. Not only this, but as the lambs grow, physical pressure on the rumen increases, making it difficult for the ewe to eat sufficient forage to meet her and the lambs’ nutritional requirements.

Most sheep keepers will feed a supplementary feed from about six weeks before lambing, particularly to ewes carrying multiple lambs. However, it’s equally important not to overfeed the pregnant ewe, particularly those carrying single lambs, as the additional feed can give rise to an overlarge lamb that a fat ewe will struggle to give birth to.

Post-lambing

After lambing, unless lambing late, into May, it is unlikely that grass alone will be able to provide enough nutrients for a ewe with twin or more lambs. The sheep keeper can either supplement the ewe’s diet or the lamb’s or both.

Once the grass is growing well, the need for supplementation will pass and ewes and lambs will do well on good, sufficient pasture.

Minerals and trace elements

The “chemical” part of the sheep’s diet is divided into minerals and trace elements. Minerals, such as calcium, magnesium and phosphorus, are required in relatively large amounts; trace elements, such as selenium, cobalt and manganese, are only required in very small amounts. Both, however, are critical to sheep health and wellbeing.

Some soils, and therefore the grass that grows on them, are deficient in certain minerals and trace elements. You can have your soil or your forage tested and your vet will be able to advise you on any known problems in your area. If you have soil or forage tests done, get a knowledgeable person to interpret them for you – a high concentration of some elements is a bad thing as it can inhibit the uptake of others.

It is possible to top dress your grassland with a mineral / trace element compound to address deficiencies,

Concentrate feeds, both bagged and in blocks, contain minerals and trace elements, but these are only generally fed at certain times of the year. Alternatives are to make rock salt and a mineral lick available all year round or to speak to your vet about drenches, injections and boluses if there are serious deficiencies.