Small stock production: Back to basics with sheep nutrition


By Digital team | 1 November 2018
sheep
Photo: Pieter Bosch

What sheep eat has a great impact on their condition and performance. These basic feeding principles can help you improve their nutritional status.

Feed is the single biggest budgetary item associated with raising ruminants, such as sheep. It usually accounts for at least 60% of the total production costs in commercial flocks.

Dr. Dave Midgley, animal health specialist, says nutrition has a huge influence on flock production and reproduction. Better nutrition can also lead to higher milk production and improved lamb growth.

If animals receive unbalanced diets, they become more prone to disease and fail to reach their genetic potential.

Midgley explains that a ruminant’s nutritional needs change at the various production stages, be it a young growing animal or a pregnant ewe.

The sheep’s diet, however, should always contain appropriate quantities of energy (carbohydrates), protein, minerals, vitamins, fats, fibre and water.

THE BUILDING BLOCKS

Carbohydrates are responsible for the maintenance and growth functions of the animal, and for the generation of heat. “Heat generation occurs as a result of food breakdown or fermentation in the rumen,” Midgley explains. Maize, barley, triticale, wheat fodder, oats, grass and rye are good sources of energy.

You can also feed animals silage, which is produced from forage or grain crops. Farmers should only feed a good-quality product, as mouldy silage can cause listeriosis or “circling disease”. As with fresh forage, a high-producing animal sometimes cannot consume enough high-moisture silage to meet its nutritional needs.

Also read:
The secret to making good silage
Listeriosis in animals

Protein grows muscle (meat) and tissue. It also performs other vital immune system functions. Lucerne, hay, lupins, oilcake meal and fishmeal are good protein sources. Livestock don’t store excess protein.

It’s burned as energy or eliminated as nitrogen by the kidneys. Since parasites often cause blood loss in smaller ruminants, higher protein levels in the diet may enhance the animal’s immune response.

Also read: Lucerne – top-quality feed for your animals

Fibre should also form part of a ruminant’s diet as it maintains a healthy rumenand prevents the incidence of digestive upsets. Fibre sources such as grass or lucerne also contain other building blocks, carbohydrates and protein, for instance.

Also read: Manage the rumen for profit

The most important vitamins and minerals are salt, calcium, and phosphorus. The ratio of calcium to phosphorus should be kept at 2:1 to prevent metabolic conditions such as urinary calculi. Small ruminants require vitamins A, D and E.

“In Europe, vitamin D is referred to as the “sunlight” vitamin, but we have enough sunlight here to not really need extra vitamin D,” Midgley says. Most vitamins already occur in feed, but vitamins K and B are manufactured in the rumen.

Water’s the cheapest feed ingredient and a shortage can cause health problems in animals. Sheep should always have access to clean, fresh water. A mature animal will consume 2.8 to 5.6 litres water per day. Remember that water requirements and intake increase during late gestation and lactation.

SUPPLEMENTS

At times farmers have to feed supplements to provide the nutrients that forage alone cannot provide, particularly for high-producing animals.

Some experts believe that a free choice salt-vitamin-mineral premix should be available to small ruminants at all times (unless a premix has been incorporated into the grain ration or total mixed ration).

The controlled application of minerals and vitamins may be more effective, however. The danger of free choice is that animals might not consume the minerals they need, or they could consume too much.

Midgley says the way supplements are administered to animals is what does the trick.

  • If supplements are fed daily, substitution occurs and there is a danger that sheep won’t graze.
  • Feeding in the afternoon, instead of the morning, will ensure that they have a more uniform intake of supplements.
  • Later in the day, sheep will have grazed and the need for food is less.

Many feed companies offer “complete” sheep feed in pelleted or textured form. These are balanced for the needs of animals at particular production phases. The advantage is that animals cannot sort feed ingredients. But remember that such feeds are more expensive.

PASTURE & BROWSING

This is considered a primary and most economical source of nutrients for sheep. Sometimes pasture feeding alone can meet a small ruminant’s nutritional requirements.

Pasture is high in energy and protein when in a vegetative or growing state. However, a high moisture content in pasture may lead to insufficient intake where the animals feel “full” but do not meet their daily requirements – especially in high-producing animals.

Also read:
How to establish forage crops and pastures
Get the most out of natural or planted pastures

HAY

In the dry season, hay is the primary source of nutrients for small ruminants. “Hay is a feed that is planted and while it is still growing, farmers cut, dry it to remove moisture and bale it,” Midgley explains.

Hay varies in quality and farmers can test its nutritional content by having a sample analysed by a forage-testing laboratory. It is a moderate source of protein and energy for sheep. Studies have found that legume hay such as alfalfa (lucerne), clover and lespedeza tend to be higher in protein, vitamins and minerals than grass hays.

The energy and protein content of hay depends on the maturity of the forage when harvested. Proper curing and storage are also necessary to maintain its nutritional quality.

SHEEP MAINTENANCE

Maintenance covers what an animal requires to live and maintain its weight without extra needs. There are standard guidelines for the requirements of sheep at the various production stages.

Factors such as maintenance, growth, pregnancy, lactation, fibre production and environment affect the nutritional requirements of sheep. Midgley says that, as a rule of thumb, sheep will consume 2% to 4% of their body weight on a dry matter basis. The exact percentage depends on the weight and production stage of the animal.

Maintenance requirements increase with the level of activity. For example, a sheep that has to walk further for feed and water will have a higher maintenance requirement than animals in a feedlot.

Environmental conditions also affect maintenance requirements. In cold weather, sheep require more feed to maintain body heat. Pregnancy, lactation and growth also increase nutrient requirements.

FEEDING TOO MUCH CEREAL GRAINS

  • Grains can cause acid stomach (acidosis) in sheep.
  • Farmers can prevent this by adding slaked lime to the grain (1 kg lime for every 100 kg grain) they supply as sheep feed.
  • Lime-treated grain will also improve the grain intake of animals.
  • Provide small quantities of grain at first, to allow animals to adapt gradually.

FEED PALATABILITY

Palatability refers to the flavour and texture of feed.

Animals have taste buds and can distinguish between different feeds, textures and tastes. Ruminants like green succulent feed, as opposed to dry feeds. Sheep have short tongues and cannot clean their nostrils as cattle do. Hence, they don’t like “dusty” feed, such as meal.

  • This article was written by Wilma den Hartigh and firswt appeared in Farming SA.