Sheep
Background/history
UK sheep industry
Sheep farming year
Sheep reproduction
Sheep came to the UK 5000 years ago
Source of wealth in the past
1000 million sheep in the world, 30 million in the UK
800 different breeds in the world
86 breeds in the UK
Long wool breeds e.g. Blue faced Leicester
Cross breeds/Half breds e.g. Mule
Hill breeds e.g. Welsh mountain/Scottish Blackface
Down breeds e.g. Telex/Suffolk (terminal sire/meat breeds)
Hardy + strong mothering instincts
Low reproductive rate + poor carcass quality
Good milk production, large litter + body size
Cross of the above has both characteristics combined
Large size, meaty, fast growth
Medium litter size so cross with half breeds to produce lots of meaty lambs easily
Stratification: 3 integrated tiers related to altitude + quality of grazing**
Upland sheep production-produce half bred ewes + use upland ewes to cross with terminal sires for slaughter lambs
Lowland sheep production-produce slaughter lambs
Hill sheep production-produce purebred flocks
Advantages: allows for complementarity of breeds
Disadvantages: welfare of transport, disease spread, movement restrictions due to viruses
Seasonally polyoestrus in the Autumn/Winter-controlled by photoperiod
Oestrus cycle lasts 17 days with oestrus lasting 24-36 hours (most farmers use 2-3 cycle=length of lambing period)
Puberty at about 7 months/38kg
Conception rate=% ewes becoming pregnant in 1 cycle
Influenced by ram fertility-usually 1:30-100 ewes
Influenced by body condition score: 2.5-3.5 optimum
Also influenced by season, age + stress
Aim for >150% reproductive targets with <3% barren, <3% aborted, <10% mortality
Lambing %, scanning % + average litter size can be calculated by using the (data/total ewes)*100
Gestation is 147 days
Summer
Autumn
Spring
Winter
Rest better pastures
Move ewes closer/inside
Tailing lambs to decrease risk of fly strike at <7days old to use a rubber ring
Castration to prevent unwanted breeding at >7days old to use a rubber ring
Weaning at 12-16 weeks old
Shearing yearly
Sorting up/culling ewes with problems/>7 years
Selling lambs as store/to the abattoir
Flushing in the weeks leading up to tupping to increase bus to 3 for better fertility
Synchronise breeding using AI to lamb in batches
Use transabdominal ultrasound to pregnancy test ewes 45 days after tupping to separate according to how may foetuses they have to control feed intake + cull barren ewes
Inhousing for protection + control, but it does increase disease spread
Vaccinations-against lamb disease 4 weeks pre-lambing, against abortion pre-mating
Worming especially for young animals + late summer/autumn period
Dipping to control external parasites (welfare issues)
Nutrition
Finished lamb production
Sheep can be fed pasture/hay + silage/forage crops like sugar beet/concentrates all with 8-13 mJ ME/kg DM to intake 3% of body weight
Lambs should intake 300g per day from grass + ewes milk/concentrates
Poor nutrition=reduced growth rate, slaughter weight, increased time to slaughter+ poor carcass conformation =decrease in profit margin
Effects often due to disease as well as poor nutrition
Underfed ewe lambs have poorer ovulation rates as well
Carcass conformation E/U/R/O/P (E=best, R=most common)
Fatness over lumbar region + rump
Dead weight=half live weight
Use genetic variation to improve loin muscle, fat depths + conformation
Poor nutrition pre-mating=reduced pregnancy + ovulation rates
Poor nutrition in early pregnancy=foetal resorption/small lamb birth weight so lamb mortality more likely
Poor nutrition in late pregnancy=metabolic diseases, reduced colostrum production + quality leading to higher lamb mortality
Poor nutrition when lambs are born=reduced milk production so smaller lambs at weaning + loss of bcs that needs to be improved for next mating