There are many different breeds of sheep from rare breeds to coloured wool, longwool, dairy and meat breeds. Different breeds of sheep have been bred for different terrains and uses and have an average life expectancy of 10 - 12 years.
Sheep are ruminants and therefore require a forage based diet. In the absence of upper incisors, sheep use a hard dental pad (in front of the palate) and lower incisor teeth, lips and tongue to select food. Food is swallowed with minimal chewing, relying on the process of rumination (regurgitation and remastication) to break food down further at a later point.
Ruminants have a 4 chambered stomach; the rumen; reticulum; omasum and abomasum.
The main function of the reticulum is to break down large food particles for rumination.
The rumen is a large fermentation chamber populated by microorganisms which break down ingested food. Fibre (complex carbohydrate) is broken down by the microbial population to produce volatile fatty acids (VFA’s) which are used as the ruminant’s primary energy source.
The omasum is made up of many folds of tissue which help to break up ingested food.
The abomasum is often referred to as the ‘true stomach’ because it is where digestive enzymes and hydrochloric acid breakdown small particles of food before they enter the small intestine, where the majority of nutrients are absorbed. Any indigestible or unabsorbed nutrients pass through to the large intestine where they are further digested and absorbed before being excreted.
Dietary requirements vary depending on the breed, age and reproductive status of the sheep. Highland breeds tend to do better than lowland breeds from a small amount of concentrate feed. Typically additional feed is only given either to provide vitamins and minerals or to meet the higher energy requirements of breeding or growing animals.
Sheep are grazing animals; grass is quickly grazed and ruminated at a later point when the sheep is at rest. Grazing should be the basis of the diet with additional forage (hay, straw, grass silage) supplied when grazing is limited. The use of concentrate feeds is generally reserved for ewes in late pregnancy, lactation, growing lambs, or for dairy sheep, which may need feeding year round.
Feeding Guidelines for Pedigree Sheep Mix and Country Sheep Nuts:
Lambs: Introduce gradually as soon as an interest is shown, increase quantity by a maximum of 0.5kg per day (healthy lambs tend to show an interest in food at around 10 days old)
Adult sheep: 0.5-0.75kg per sheep per day
In-lamb and lactating ewes: 0.5-1.25kg per sheep per day. The amount of concentrate feed required will depend on the forage quantity and quality available, the amount of time before lambing and the number of lambs
Rams: at rest 0.5-0.75kg per sheep per day increasing to 1.5kg per sheep per day when in work
If feeding more than 0.4kg per sheep per day of concentrate feed this should be divided across at least two feeds
Any change in feed should be made gradually over at least 10-14 days
Fresh, clean water should be available at all times
Sheep should only ever be fed specific sheep feeds as they are very susceptible to copper toxicity and the copper level in most feeds is unsuitable for sheep
Condition scoring of sheep is vital to ensure that they are in good condition and allows the diet to then be adjusted accordingly
The stocking density per acre varies depending on a number of factors such as breed and size of sheep, quality of grass, type of land and how much of the year sheep will be turned out for. As a guide, one acre would support 3-4 sheep and up to 6 on very fertile land.
Breeding and Management
The time of year that sheep will come into season is dependent on their breed, although tupping (where ewes are running with a ram) typically occurs from August onwards, aiming for a March or April lambing. The gestation period for sheep is about 5 months.
A higher plane of nutrition is introduced prior to tupping (mating) to ensure maximum ovulation. The use of this practise is only suitable providing ewes are not carrying too much condition in the first place. A similar technique can also be used for rams to ensure that they are in the best condition prior to tupping. Sperm production takes 7 weeks and can be responsive to nutrition, therefore an improvement in the ram’s nutrition 7 weeks prior to tupping may help to improve sperm production.
Feeding amounts are typically increased in the last 6-8 weeks of pregnancy where the majority of foetal growth occurs and building up to 1-1.25kg per ewe per day for the last 2-3 weeks of pregnancy and during lactation is recommended. The ewe’s appetite can decrease in late pregnancy meaning that smaller quantities of feed with a higher nutritional content are required. Poor nutrition during late pregnancy can affect birth weight, the ewe’s milk production and overall lamb viability. Lactation peaks 2-3 weeks post lambing and therefore the higher rate of feeding can be continued 4-5 weeks after lambing to help support milk production.
While the amount of wool produced by sheep is influenced by breed and genetics, nutrition is also a factor to consider. Wool fibres are almost entirely made up of the protein keratin and for this reason wool follicles require a good supply of sulphur-containing amino acids. Wool continues to grow even when sheep are chronically undernourished, although when a sheep is fed a balanced, nutritious diet the rate of wool production increases.
Wool quality is also influenced by nutrition. The diameter (thickness) of wool fibres increase as good quality feed is given, finer wools coming from sheep in nutritionally deprived areas. Copper deficiency in sheep can cause a loss of waviness in the wool and a general reduction in quality, whereas Zinc deficiency causes the production of brittle wool fibres. Many vitamin deficiencies affect wool and hair follicles in sheep, therefore it is essential that animals raised and kept for wool are fed a balanaced ration.