Performance Recording

We have been recording with Signet Breeding Services (part of AHDB) since 2009. They are the nationally recognised provider of this service and around 50 Lleyn flocks annually record about 20,000 lambs with them.

 

As well as all the usual pedigree information we record litter size, birth weights, lambing ease, 8 week weights, 20 week weights and mature size. In addition to this all of our lambs are also scanned for muscle and fat depth and 20/21 weeks and for the last two years we have also been taking individual Faecal Egg Counts to help identify lambs more resistant to worms.

 

Signet Breeding Services analyse all of this information and produce Estimated Breeding Values which allow us to identify the sheep with the best genetic potential within our flock. These can then be used by anyone looking for sheep from us to help identify those that would best suit their breeding objectives as shown below.

 

8 week weight          Selecting for high 8 week weight EBVs will     EBV (Kg)              give faster growing lambs to weaning 

 

Litter size EBV          Positive figures should increase the               (lambs/ewe)            number of lambs born in a flock 

 

Scan weight              Selecting for high scan weight EBVs will       EBV (Kg)                 increase growth weight to 21 weeks of age

  

Muscle depth           Selecting for high muscle depth will              EBV (mm)                increase the lean meat content  of                                                carcases by increasing lamb muscularity.

 

Fat Depth                 Choosing sheep with negative fat depth    EBV (mm)                EBVs will allow lambs to be taken to higher                       higher carcase weights without becoming                                     too fat.

 

Mature size               The mature size of a flock can be         EBV (Kg)                   influenced by using this trait.

 

FEC EBV                  Sheep with negative FEC EBVs are more                                    resistant to worms and excrete less worms                                  on to pasture.

 

Our latest genetic trends can be seen in a word document here.

 

EBVs and pedigrees for all of our sheep are available on the Signet data  website and if you have any questions please get in touch.

  

Estimated Breeding Values  EBVs

Estimated Breeding Values (EBVs) provide a measure of the breeding potential of individual animals for a particular trait such as muscle depth, weight at 8 weeks or litter size.

 

As well as an animal’s own performance, records of known relatives, the relationship between traits and the degree to which traits are inherited from one generation to the next are all taken in to account in the calculating of EBVs.

 

They are analysed using a procedure called Best Linear Unbiased Prediction (BLUP). This system can calculate how much of an animal’s performance is down to its breeding potential rather than the environment in which it has been raised. The EBVs produced can then be used to make comparisons between animals in different flocks. A sheep will only pass on half of its genes to its progeny so the EBVs must be halved in order to estimate the average genetic worth of its progeny.

 

EBVs are expressed in the units in which they are measured (eg Kg for 8 week weight) and related to a common baseline of zero, which represents the average of lambs in the first year of across flock analysis.  This makes EBVs simple to interpret. For example, compared to the baseline, a ram with an 8 week weight EBV of +3 has the potential to be 3kg heavier at 8 weeks.

 

While EBVs are useful when selecting for a particular trait they can also be combined to produce breeding indexes. In these traits are weighted, usually according to their economic importance, and can help breeders to rank their sheep. For recorded Lleyn sheep we used to have a Maternal Index and a Carcase + index but these have now been combined into a single index which also takes into account an 'optimum' litter size and  is weighted against higher mature size. 

 

Accuracy values, ranging from 0 to 99 are given beside each EBV. These indicate how close the EBV is to its true breeding value. These figures increase as more performance information is added.