The Principles and Importance of Sheep Production

National Importance  Sheep production accounts for about 4 – 6% of agricultural production in Ireland.  Wool, milk and cheese production are of minor importance. The main product of the industry is sheepmeat.  We export sheepmeat to France, Germany, Italy, Belgium and the Middle East.  Lamb is slaughtered at age 3-12 months and is leaner than hogget mutton which is slaughtered over 12 months.

Production Systems  Mountain and Hill –Extensive –Uses rough grazing and heather –Mortality can be high if management is poor –Low production targets –Products are breeding stock and some lambs for fattening  Lowland –Intensive –Better land –Well defined management –High production targets –Products are lambs for slaughter

Sheep Breeds  Blackface Mountain – horned, black or black and white faces and legs. Small carcass. Hardy.

Sheep Breeds  Wicklow Cheviot – polled, white wool, mountain breed but not as hardy as Blackface Mountain.

Sheep Breeds  Galway – polled, long white wool, lowland sheep.  Border Leicester – polled, long white wool, very prolific breed.  Belclare Improver – very prolific breed.  Down Breeds (Oxford, Suffolk) – polled, short white wool, very fast growing and good conformation  Texel – polled, long white wool, excellent carcass conformation.

Galway

Texel

Suffolk Ram & Belclare Ewes

Breeding Strategies  Mountain sheep farmers use ewes of a mountain breed and cross them with rams of the same breed. Lambs are used as replacements or sold to the Italian market as they like a small carcass.  Hill sheep farmers use “culled for age” ewes off the mountain and cross them with prolific breeds such as the Border Leicester to produce crossbreds.  Lowland sheep farmers use these crossbred ewes and Suffolk or Texel rams. This results in a large numbers of good conformation lambs ready for slaughter.

Birth, Growth Rates and Puberty  Lambs weigh 3 – 5kg at birth.  They are slaughtered at 30 – 40kg depending on breed and age.  Ewe lambs reach puberty at about 40kg

Reproduction  Sheep are seasonally polyoestrous. This means they only come into heat during a certain period of the year, September to February.  The oestrous cycle is 17 days and oestrous lasts for 36 hours.  The gestation period is 149 days.

Synchronised Breeding  Traditionally rams go in with ewes in early September and stay there for 6 – 8 weeks. This leads to a very drawn out lambing season.  Oestrous can be synchronised artificially leading to shorter breeding season and therefore compact lambing which eases flock management.  Progesterone impregnated sponges are placed in the ewes’ vagina and left for 12 – 16 days. This prolongs the life of the corpus luteum.  When the sponges are removed all at the same time the sheep come into oestrous all at the same time within a few days.

Breeding out of Season  This is breeding sheep in July/August to ensure lambs are born early enough to have them ready for slaughter for the Easter market when prices are highest.  Place sponges in vagina the same as for synchronised breeding but when they are removed give the sheep an injection of another hormone called Pregnant Mare Serum Gonadotrophin (PMSG).  If synchronised ram ratio to sheep is 1:10 but if not synchronised it is 1:40.

Mixed Grazing  Cattle and sheep grazing the same area together.  Both animals have higher growth rates.  Sheep grazing close to the ground encourage tillering of grass.  Sheep eat grass that cattle do not (around dung and urine patches) so there is better utilisation of the grass.  Dung and urine of sheep and cattle is different and this leads to better recycling of nutrients.

Wool and Wool Quality  Wool fibres are solid whereas hair is hollow.  A wool fleece yields about 2 – 4kg per animal per year.  Wool quality is determined by fineness of fibre.  Merino sheep have the finest wool.  The Bradford Count is the standard measure of wool quality.