Level II Agricultural Business Operations. Overview of the production cycle of a ewe Appropriate...
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Transcript of Level II Agricultural Business Operations. Overview of the production cycle of a ewe Appropriate...
Overview of the production cycle of a ewe
Appropriate management of the flock pre mating to achieve optimum performance
Identify the most suitable option for selecting replacements
Unlike cattle sheep have a distinct breeding season linked to day length
As day length decreases sheep begin to come on heat
Different breeds will cycle at slightly different times
Breeding season affects choice of breed
Lowland breeds and crosses cycle – Aug – Feb
Hill breeds – Oct – Jan
Some breeds, e.g., Dorset Horn can breed almost any time of year (for early lambing systems, mate in July)
When in season a ewe comes on heat every 16 – 17 days
Each heat lasts for 24-36 hours
Gestation period 147 days (21 weeks)
The number of eggs shed at each ovulation
Affects number of lambs born to the ewe
A number of factors affect the ovulation rate
◦Breed – in general terms ewes of hill breeds have lower ovulation rates than those of low ground breeds
◦Nutrition
Age – ovulation rate is low in the ewe lamb, rises to peak at about 4 years of age, stays the same for a few years and then drops.
Body condition – ewes in poor condition have lower ovulation rates
Stage of breeding season – ovulation rate is low at the beginning and end of the breeding season and highest at the midpoint
Starts at weaning
Ensure ewes have enough time to recover between weaning and mating
Assess ewe body condition
Condition scoring is method of estimating the condition or 'nutritional well being' of a ewe
It requires an assessment of the amount of muscle and fat covering the backbone and the short ribs of each sheep
This gives a picture of the sheep’s store of energy
Use body condition scoring to guide your feeding management pre-mating and throughout pregnancy.
Wean lowland ewes July-mid August
Hill ewes no later than end of September
This give ewes time to gradually gain condition
Ensure ewes are appropriately dried off
May sort off culls at this stage for marketing◦ Bad udders etc.
Reassess body condition ideally 8-6 weeks before mating date
Feed ewes accordingly to achieve desired BCS
Check udders/teeth/feet etc
Treatments
Cast/culls
Ewe body condition score
Sward height
DM intake Kg per day
Low 2.5 or below 5 – 7 1.3 – 1.4
Optimum 3.0 – 3.5 4 0.8 – 0.9
High 4 + 3 0.7
• Monitor condition regularly until rams go in and adjust feeding to avoid excessive loss or gain in condition
Not needed for ewes BS >3.0
Very fat ewes = increased barrenness
Very thin ewes = low lamb numbers
Increase by 1 body score takes about 6 weeks on good grass at 7-9 cm ◦ (appox. 8-12kg for mature lowland ewe)
If grass is short can offer additional feed
Check feet, footbath, cull persistently lame sheep
Crutch dirty/long tailed ewes Dose for liver fluke as per vet advice Vaccinations If dipping, do this 1 month before tupping
Where possible carry out all management tasks at least 2 weeks prior to tupping
Clostridial & Pasteurella (Hep P+) Initially two vaccines given 4-6 weeks apart
then an annual booster 4-6 weeks pre lambing
Toxoplasa abortion Live vaccine –up to 1 month prior to tupping.
Lasts 2-3 years (Toxovax)
Enzootic abortion Live vaccine – up to 1 month prior to tupping.
(Enzovax, Chlamydophila)
• Assess mineral status of ewes• Blood sample 6-8 weeks before mating (Selenium,
Cobalt, Iodine)• AFBI research found 50% hill ewes sampled had
inadequate selenium (Se) status
• Benefits of Se supplementation of ewes– Se supplementation 4-6 weeks before mating improves
ewe fertility– Higher growth rates, heavier lambs at weaning – Ewe body weight and condition maintained more
efficiently, higher overall lamb output
• Methods of supplementation – Injectable, boluses, drenches and feed additives
On average 10% of ewes in a flock fail to rear lambs
Ewe and lamb deaths contribute to the biggest loss in productivity (37%)
Older ewes are more prone to ewe deaths, abortion/stillbirths, lamb deaths
Hence replacing/culling these ewes becomes necessary
A ewe should be replaced before she has an unproductive season
Typically after 5 crops
Important to record and identify problem ewes so they don’t get a reprieve◦ Ear notch/tag
Replacement rate◦ Typically 20% for lowland flock◦ Potentially 25 – 30% on a hill farm
Prolific Strong maternal ability Good milker (lamb growth) Produce quality lambs with good growth rate Hardy / disease resistance Reasonable size / conformation Minimum cost to feed and treat Easy lambing Durable
Advantages Disease risks are lower
Quality – greater control over management
Potential to improve ewe type - maternal sires
Good records
Cheaper?
Disadvantages Management can be
complex
Breeding policy must be planned
Cheaper?
Advantages Replacements can be
bought as shearlings
Hybrid vigour
Less complex recording?
Less time consuming
Disadvantages Higher risk of disease
No control over the rearing phase
No prior knowledge
Autumn sales are fixed
Little time for introduction to flock
Conception rates are lower ◦ 90% or less ◦ average litter size of 1.0-1.2
Lamb mortality can be high due to ◦ Lambing difficulties, small lambs, lack of milk etc
There is a greater risk of mismothering
Good feeding is essential to ◦ Sustain growth of the ewe lamb◦ Enable the production of adequately sized lambs and
sufficient milk.
May be cheaper than gimmers/hoggets
Extra crop of lambs (if lambed)◦ Harder to lamb/manage◦ Easier to manage following year if lambed
Need to be 60-70% of mature weight going to the ram
Can stunt growth Extended lambing season
Two aspects of flock health must be considered when introducing replacements
1. If bought in – must not be allowed to bring diseases such as scab or enzootic abortion into the flock
2. They have to be protected against the main causes of losses, such as clostridial diseases, pneumonia and infectious abortion
1. Yard all sheep (rams and ewes) on arrival for 24-48 hours
2. Treat asap Worm treatment Fluke treatment Treatment for sheep scab Vaccination – Clostridial diseases, Toxovax, Enzovax Foot care – Inspection and footbath
3. Quarantine – turn out to pasture previously grazed by own flock and keep isolated for 3 weeks
Size, length, conformation Legs and feet Mouth and teeth Wool Reproductive organs Breed characteristics EBVs (Scan weight)
Body score 3.5 – 4 (Feed meal 8 - 10 weeks prior to tupping)
Handle testicles – Should be hard without bumps or lumps, check for epididymis
Mouth – Check for broken mouth
Temperature and wellbeing
Feet
Brisket sores
Management of the mating period
1. Select mating date so that lambing coincides with spring grass!
http://www.tvsp.org/gestation.html
2. Restrict mating period to 35-42 days to reduce lambing period and minimise lamb weight variation
1 mature ram: 40 ewes(A fit, 2 shear, ram will cope with more as will certain breeds – e.g. Highlander/Primera)
Ram pool, 3 rams – 150 -200 ewes
Raddle/harness crayon colour should be changed regularly◦ More frequent changes gives more control of feeding
Excessive repeats (25-30%+) indicates a problem with ram fertility
Vasectomise at least 8 weeks before they are needed
Use one teaser for 100 -150 ewes Put teasers in for 17 days max Remove before fertile rams are introduced
Alternatively:
Run entire rams on opposite side of secure fence line for 14 days before introducing to ewes
Maintain body score (3.5)
Embryo floats about in uterus
Don’t dramatically increase or decrease feeding
Avoid unnecessary handling and stress
Ewes served at the correct body score is the 1st step in achieving a high lambing percentage
Carry out a ram MOT early and use rams at correct ratio
Manage nutrition carefully after mating
Remove culls and obtain replacements
Use appropriate vaccines and drenches