Gortleigh - 35 years of recording

A few words from Gill Trace, owner of the Gortleigh flock of performance recorded Dorset sheep.

Breed	Flock Name	First year of weight recording	Weight recorded lambs	Ultrasound scanned lambs
Dorset	Gortleigh	1988	11,533	3,914

Flock facts:

The Gortleigh Dorset flock was established by Gill and Richard Trace in 1986 on a 330-acre farm in North-West Devon. The breed was chosen for its ability to lamb naturally out of season, its versatility, adaptability and docility.

The Gortleigh flock has always been pro-actively managed using Estimated Breeding Values (EBV’s) and has been a member of the Centurion Dorset breeders group since 1997. In 2016 it was awarded the AHDB Beef and Lamb Better Returns Programme Improved Flock Award for Dorset sheep, having previously been frequent runners up.

To improve the accuracy the Gortleigh flock scans approximately 100 lambs each year, supplies pre-tupping shearling weights to Signet and uses some stock rams over a number of years to strengthen genetic comparisons. 

Originally lambed in September of each year, a major farm diversification of 85 acres of cider orchards required lambing to move to November due to labour demand. The sheep are lambed indoors due to weather conditions and high risk of bird predation outdoors. Gortleigh breeding stock are sold as shearlings, mostly from the farm. 

Terminal Sire selection:

Considering terminal traits, historically the Gortleigh flock selected for improving muscling to achieve a good conformation ewe that could rear 2 lambs on a forage based diet.  In the last few years selection has been emphasising higher growth rates and this has significantly reduced the finishing time of the lambs going for slaughter. Now lambs are being scanned 30 days younger at similar weights than earlier years of the flock recording. The average 8 week weight has increased by 9.15kg since 1988. The 2002 foot and mouth outbreak resulted in the 2000 head flock being slaughtered as a contiguous cull.  The farm restocked, sourcing sheep mainly from performance recording breeders.  The flock has continued to make significant genetic gains, as highlighted in the graph below.   

When buying unrecorded rams there is no way to assess the potential growth rates that a ram may pass on to its progeny.

This is particularly illustrated by an analysis of the latest Gortleigh flock Progeny Report (Sire summary) produced by Signet in December 2022.  This shows the Terminal Sire Indexes of current and historic rams, in descending index order (from over 300 down to 32), of the 88 rams used in the Gortleigh flock between 2012 and 2022:

• The top 9 rankings are occupied by home-bred rams.
• Purchased recorded rams from other Centurion members, prefix letters D, W and C, occupy rankings 10 – 12 respectively.
• Only 6 rams with no Signet recording figures have been used and they occupy rankings 50, 74, 82, 84, 85 and 88.
• The ram at ranking 88 (bottom) looked lovely and was purchased at Mayfair. However, when his progeny were evaluated in the Signet analysis the EBV’s attributed to this ram were:
  • 8 week Growth Rate -1.49;
  • Scan Growth Rate  - 4.16
  • Overall Terminal Index only 32
  • No progeny were kept

Future flock aims:

The future aims for maternal traits are to maintain prolificacy and slightly improve milking ability.  An additional aim is to take the ewes slightly fatter to help maintain condition during this improving lactation.  For the terminal traits there is plenty of scope to improve the growth rates and muscling across most of the flock, although this year 3 older home-bred rams which all have lower growth rates have been selected to maintain our wide genetic base.