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Estimated Breeding Values (EBVs)

Estimated Breeding Values

Pedigree and performance data is analysed to calculate how much of each animal’s performance is due to its breeding merit and how much is due to the environment in which it has been raised. This assessment of breeding potential is expressed as Estimated Breeding Values or EBVs.

The following EBVs are produced for Texel Sheep clients:

EBV Trait Raw Data
Eight Week Weight (kg) Growth rate to eight weeks of age. Maternal ability of ewe Weight at eight weeks of age. To achieve an adjusted eight week weight lambs must be weighed between 42 and 84 days of age.
Scan Weight (kg) Growth rate to 21 weeks of age Weight of lambs at time of scanning
Muscle Depth (mm) Carcase muscling Measured at 35 – 40kg or 21 weeks of age by a Signet-approved technician. Ultrasound measurements at the third lumbar vertebra. These traits will be adjusted by weight and not age with the introduction of CBA.
Fat Depth (mm) Leanness Measured at 35 – 40kg or 21 weeks of age by a Signet-approved technician. Three ultrasound measurements taken at the third lumbar vertebra. These traits will be adjusted by weight and not age with the introduction of CBA.
Maternal Ability (kg) Maternal ability of ewe, relates to milk production The component of a lamb’s growth to eight weeks of age that is influenced by the ewes breeding potential for milk production.
Mature Size (kg) Ewe efficiency Shearling ewe weight pre tupping (kg). More information below.
Birth Weight Potential to produce smaller than average lambs; high positive values indicate the genetic potential to produce larger lambs.
Litter Size Prolificacy This trait is defined as the total number of lambs born alive and dead when pregnancy reaches full term.
Lambing Ease The variation in a ram’s (or ewe’s) ability to produce lambs that are born without assistance. It is not intended as a measure of the ewe’s ability to give birth
EBVs only produced for flocks involved in CT scanning.

More information on this process can be found here.

Carcase Lean Weight (kg) Muscle yield Quantity of muscle tissue in the carcase assessed using Computed Tomography (CT) image analysis of breeding stock at 21 weeks of age.
Carcase Fat Weight (kg) Leanness Quantity of fat in the carcase assessed using Computed Tomography (CT) image analysis of breeding stock at 21 weeks of age.
Gigot Muscularity (mm) Carcase shape Thickness of the muscle tissue in the gigot assessed using Computed Tomography (CT) standardised to a fixed femur length.
NEW TO BE INTRODUCED: Intramuscular Fat
NEW TO BE INTRODUCED: Spine Length Vertebrae number
EBV only produced for flocks involved in FEC sampling
Faecal Egg Count (FEC) Worm resistance Faecal samples are taken from lambs at 21 weeks of age and submitted for laboratory analysis to measure the worm egg count in the sample. More detail on this trait below.


Further trait information

Lambing Ease

Lambing ease scores are determined by using a five point scale.

  1. No Assistance
  2. Slight Assistance by hand
  3. Severe Assistance
  4. Non-Surgical Vet Assistance
  5. Vet Assistance, surgery required
  6. Elective Caesarean

*Recording dead lamb information as well as a lambing ease score is vital to ensure accuracy.

Birth Weight

The birth weight of a lamb influences how easily it is born, hence this measurement is of interest in the analysis of lambing ease. Lambs should be weighed within 48 hours of birth and should be physically measured and not estimated.  For many breeders the easiest way to do this is to place lambs in a bucket hung by a spring balance.

This EBV is a guide to help breeders select sires that will suit their management system, ie lambing ewe lambs etc.

Ultrasound Scanning

It is now advised to scan lambs that weigh an average of 35kg-40kg (smallest being 30kg) rather than the traditional 21 weeks. Scanning is carried out on farm by a Signet Approved ultrasound technician who will submit the data as well as record the lambs weight.

TSS Ultrasound scanning booklet can be found here

NOTE* only animals that have been ultrasound scanned will be eligible to have EBVs appear in society prepared sale catalogues. Dont miss out on this valuable marketing opportunity

Mature Size

Weighing gimmers before putting to the tup for the first time can monitor and identify genetic potential for mature size. Selecting for growth rates in lambs can result in the increased size of the breeding female over time which can have a negative impact on the management system.

NOTE* Other sheep breeds now penalize females that are too heavy.

Worm Resistance

Worm resistance can be assessed by analysing the Faecal Egg Count (FEC) of lambs at around 21 weeks of age. Breeders send faecal samples to a laboratory, who send FEC scores to Signet for analysis to produce a FEC EBV – indicating resistance to worms.

Remember – before sampling: –

  • Lambs must be experiencing a worm challenge.
  • Test at least 15 lambs to provide a meaningful sample – preferably more
  • The lambs must not have been treated for worms within at least the last 4 weeks
  • Lambs should have grazed ‘dirty’ pastures for at least the last 4 weeks.
  • Don’t sample lambs given ‘long-acting’ or ‘persistent’ drenches. Samples can be sent once lambs are over 18 weeks of age
  • Samples must be submitted at least 5 days before the BLUP deadline

Eurion Thomas at Techion Group Ltd provides the service for the creation of EBVs.

Pre Monitoring Samples (to ensure a high enough FEC count before start) = £12.00 per sample.
3 X packs are provided in the event of first samples being too low.
Individual sheep FEC analysis – batch sizes are based on per farm basis.

  • If less than 99 samples = £6.50 / sample
  • If between 100 and 299 samples = £5.50 / sample
  • If more than 300 samples = £5.00 / sample

For more information go to their website or read this advertisement

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