Generating EBVS for postnatal lamb survival

Results:

1. New knowledge has been gained relating to genetics of lamb survival in the Blackface breed e.g. genetic and phenotypic parameters, and influence of key environmental factors (or fixed effects, e.g. sex of lamb, age of ewe) on lamb survival.

2. Two Lamb Survival EBVs have been developed; one as a direct trait of the lamb and the other relating to maternal influence of the dam.

3. Investigation in to the parameters within the cleaned data set revealed further examination across the full data set is required. This will be carried out in 2013. The two new Lamb Survival EBVs will be introduced once that has been completed.

4. A final project report has been produced by SAC. Copy attached.

5. A technical note for use by breeders and for knowledge transfer purposes has also been produced; copy attached.

Planned Activity:

1. A teleconference meeting between SAC & Signet (Kim Matthews, Sam Boon, Alison Glasgow, Jo Conington, Kirsty Moore) took place at the project end to discuss its findings and agree on the steps required for introduction of the new EBVs.

2. Signet will circulate the breeder note to those concerned within the Blackface and Woolshedding evaluations, along with guidance about capturing dead lamb records from 2013 onwards.

3. Egenes will add the Blackface breed to its list of breeds for full parameter review in 2013.

4. Discussions will be held once this has been completed – between Signet and SAC – to agree on appropriate adoption of the Lamb Survival EBVs.

The Problem:

Excluding costs associated with feeding and managing sickly lambs, postnatal lamb mortality in the UK is estimated to cost the industry in the region of £181 million per annum (SAC). It has been shown that there is a genetic component to the survival of lambs with heritabilities significantly greater than zero (eg Sawalha et al, 2007). This means that there is the potential to incorporate lamb survival in breeding programmes if the trait can be easily recorded and assessed.

Project Aims:

The purpose of this initiative is to evaluate the possibility of generating meaningful estimated breeding values for lamb survival using existing recorded data.

Approach:

1. To collate industry data from the BASCO database for the Scottish Blackface breed and to edit for outlying records for key records (e.g. records recently extracted for another breed has data showing age at 21 week weight to be up to 522 days and such anomalies require editing to obtain sensible parameters)
2. To run connectedness software to determine if it is appropriate that all flocks can be evaluated together and combined to form a single dataset for parameter estimation
3. To investigate the trait survival from live birth to 8 weeks and using information from scan weights to catch additional data that could be lost if only 8 week weight is used (this is due to imperfect gathering of lambs for hill flocks at this time, and other lambs that are missed at the 1st weighing occasion); this includes documentation of rules to be applied for data extraction and evaluation to avoid allocating false lamb deaths
4. To quantify this trait (estimate univariate predictions of phenotypic and genetic variances) for direct and maternal components for these data; the work will include testing the most relevant model for genetic evaluations (i.e. determine which key fixed and random effect data are required for the best predictions of parameter estimates)
5. Using existing data for current genetic evaluations, estimate genetic and phenotypic variances and co-variance parameters (genetic correlations) for the existing breeding goat traits with lamb survival, in readiness for the multivariate commercial implementation of EBVs for lamb survival; this exercise will update existing parameters used for the genetic evaluations thereby negating the need for Signet to do this for the Blackface breed in the near future
6. 6Compare results from records where birth weight is available vs unavailable, and (where possible) for flocks that either do, or do not lamb out of doors (this will involve Signet to provide SAC with such information)
7. Hold two half-day meetings with Signet before and after the work is completed
8. Write final report and a technical note in layman’s language to explain the derivation of lamb survival EBV and how to interpret the information; this can then be edited by Signet for use in farmer training sessions
9. The final report will outline all required information to implement the lamb survival EBV so that EGENES can then replicate it in the live system