New methods for maternal ability assessment set to benefit sheep industry

Changes following EBLEX research acknowledge array of influences on lamb's eight-week weight

EBLEX Breeding Services Manager Sam Boon
EBLEX Breeding Services Manager Sam Boon

EBLEX-commissioned research is set to lead to major improvements in the accuracy with which sheep producers can assess their flocks’ genetic potential for maternal ability.

Studies using data for the Lleyn and Dorset breeds have identified the need for a better way to do so, with the updated approach being rolled out to all breeds recorded by Signet Breeding Services in 2015.

The new method acknowledges both direct and maternal genetic influences on a lamb’s eight-week weight simultaneously, as well as environmental influences.

The analysis also takes into account:

* the contemporary group in which lambs are reared, incorporating their flock, year of birth, and sex;

* the number of lambs being reared by each ewe;

* the age of the ewe;

* the direct genetic influence on lamb growth rate from sire and dam, with this becoming the Eight-Week Weight EBV;

* maternal genetic influence on lamb growth rate from dam, with this becoming the Maternal Ability EBV;

* temporary environmental influences on the lamb and;

* permanent environmental influences.

The maternal ability EBV is designed to identify breeding lines where ewes express superior performance as mothers, in terms of their ability to influence lamb growth rate in early life. Key components include their milk production and maternal care.

It is expressed independently of prolificacy, although it does take into account the number of lambs a ewe is rearing. Hence, the maternal ability EBVs of ewes producing singles/multiples are not biased in any way.

Breeders wishing to change the prolificacy of their flocks are advised to use the Litter Size EBV when making selection decisions.

EBLEX breeding specialist Sam Boon said: “Without access to detailed lamb weight records it is very difficult to assess a ewe’s genetic merit for traits like milk production and maternal care, and virtually impossible when selecting rams.

“The maternal ability EBV provides producers with a way to assess this commercially important trait.

“This will help them avoid the purchase of rams whose daughters are likely to express poorer levels of milk production and rear lighter lambs as a result.”

Signet Breeding Services is part of EBLEX, the organisation for beef and lamb levy payers in England, which is itself a division of the Agriculture and Horticulture Development Board (AHDB).

EBLEX exists to enhance the profitability of the English beef and lamb sector.

It aims to help the beef and lamb supply chain become more efficient and to add value to the industry as a whole.

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