The €uro-Star genetic index values generated in 2026 will be based on updated economic values and the addition of two new traits – a new health trait for faecal egg count (FEC) and a new carbon trait for methane production. The changes were announced at a Sheep Ireland industry stakeholder meeting held last week in Tullamore.

Each genetic index has an economic value and a genetic component or breeding value. Teagasc researcher Edel O’Connor explained how the economic values are derived. The Teagasc Bio-economic or lamb production model is used. This is a computer simulation of a sheep farm using physical performance figures and production costs collated from Teagasc reports, CSO, Co-ops, service providers etc.

The system modelled is 107 ewes stocked at 7.5 ewes/ha and scanning at an average litter size of 1.7 lambs per ewe joined to the ram. Lambing date is early March and the weaning rate is 1.48 lambs per ewe joined. Current costs are based on figures collated from 2010 to 2014, while the new costs are based on the average costs from 2020 to 2023.

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The system modelled a one-unit increase in each individual trait independently, while holding all other traits constant. For example, the number of lambs born is a measurement of all the lambs the ewe gives birth to including live and dead lambs per lambing and, in particular, looks at the value of one additional lamb surviving past 48 hours.

This encompasses aspects such as the physical number of lambs, sales, concentrate costs, veterinary costs, fertiliser costs, etc. Edel summarised that increased production costs and lamb price are driving the increase across all economic values.

Economic values

Nóirín McHugh, Teagasc geneticist picked up the mantle from here and presented the new economic values, outlined in Table 1. A minus figure is desirable for all the figures with a negative value and vice versa a plus figure is desirable for traits such as lamb survival to birth, lamb vigour etc.

The number of lambs born is taken as a positive figure up until a litter size of about 2.18 lambs per ewe, with the figure remaining static above this.

The addition of two new traits as mentioned above brings about changes to the weighting or make up of the terminal and replacement index. The current breakdown of the terminal and replacement indexes and the new indexes incorporating the two new traits are demonstrated in Figure 1 and Figure 2.

The methane and faecal egg count still make up a small percentage of the overall index and as such will not alter the current evaluations of individual animals to any great extent.

These new traits will not be reflected in how genetic evaluations are displayed, but breeders/farmers will be able to see this data through the ram search facility.

Nóirín presented analysis which looks at how the changes in the new index will influence the future trajectory of key traits. In terms of terminal traits she said the changes will drive faster progress in genetic gain in lamb survival, lambing ease (singles and twins) and lamb vigour. Lamb growth will be maintained, while methane production will slow. Combined, Nóirín says this will add an additional €15m in profit to the sheep sector over the next 10 years.

Replacement index

In terms of the replacement index, an analysis of future performance shows the change in the index will lead to a national flock of ewes that on average have an improved milk yield and mothering ability.

Lambs will be faster growing and there is no change predicted in ewe mature size, while ewes are predicted to emit lower levels of methane. The changes are worth €20m over the next decade.

Nóirín summarised the changes as leading the replacement index on a trajectory that will deliver more live lambs on the ground, more productive ewes, ewes with a higher milk yield, faster-finished lambs and ewes with a similar mature size, which will produce less methane.

Star ratings

Thierry Pabiou, Sheep Ireland geneticist, outlined that there is a very strong correlation within breed between the current and new indexes.

He said that 90% of rams (4,656) keep/increase their current terminal star rating, while 8% of rams experience a reduction in their star rating.

The level of movement is similar for ram lambs, with approximately 10% of rams moving up or down by one star rating.

He added that there is also very little re-ranking expected on the replacement index. Some 86% of active rams from 13 breeds retain their star rating, with 8% reducing and 6% increasing.

With regards ram lambs, 13% o are expected to increase (6%) or decrease (7%) by one star rating.

Thierry concluded by saying that every breed is expected to achieve faster genetic gain under the new indexes.