The first trial flock comparing Irish and New Zealand genetics in a common environment is in the final stages of lambing. The Ireland and New Zealand Across Country (INZAC) genetic flock was established in Teagasc, Mellows Campus, Athenry, during 2015.

While the trial only began in mid-2015, it has already gained a strong following, with sheep farmers eager to see how New Zealand genetics perform in an Irish setting.

Explaining its background, lead researcher of the trial Noirin McHugh said: “Research has shown the rate of genetic gain in the New Zealand sheep industry is almost three times higher than the Irish sheep industry.

“Putting it in economic terms, the rate of genetic gain on New Zealand sheep farms on the maternal index is €1.16 compared with €0.27 in Irish flocks. The same gap is evident in the terminal index, so it is no surprise that Irish producers look favourably on their [New Zealand] genetics.

“However, we must remember that these genetics have never been compared in a common environment and therefore it is difficult to assess the compatibility of the New Zealand ewe to Irish grass-based production systems. This trial will answer this question and many more, such as should we be incorporating New Zealand genetics in Irish breeding programmes?”

The flocks

The INZAC flock consists of 180 ewes, with Suffolk and Texels selected as they are the most common breeds across the two countries.

The ewes are split into three sub-flocks – a flock of 60 New Zealand Suffolk and Texel ewes with elite genetics, 60 Irish Suffolk and Texel ewes with elite genetics and 60 Irish low genetic-merit Suffolk and Texel ewes.

While the elite groups will allow for benchmarking genetics across countries, it will also serve as an important tool to validate the Sheep Ireland replacement index. This is the main reasoning behind the incorporation of a low-index group into the trial.

Important parameters

Fiona McGovern has joined the INZAC trial in a post-doctorate position, having recently completed a PhD in sheep nutrition at UCD Lyons Research Farm. Fiona says the trial will focus on analysing important production traits.

“We will be collecting a lot of data over the next four to five years that has the potential to deliver for farmers in a number of areas,” she said.

“We have measured birth assistance, lamb viability and mothering ability at lambing and we will be collecting milk yield records starting on Tuesday. This will also give us information on milk composition.

“As well as normal production data, such as lamb performance, ewe condition score and litter size, etc, we will also be measuring grass intake and as lambs reach drafting weight, we will have detailed records on muscle and fat scores.”

The farm is set up with a stocking rate of 12 ewes per hectare, ie each group has access to 5ha of land, with four paddocks assigned to each group, taking account of any potential differences in land quality or soil type.

Fiona says paddocks will be subdivided to give each group access to eight paddocks over the main grazing season.

“We will start splitting paddocks next week to ensure optimum grassland management and access to grass at the recommended pre- and post-grazing heights,” she said.

Grass supplies

Teagasc technician Henry Walsh reports that the flock is in a better position than initially feared a week to 10 days ago.

“At the start of lambing, we looked to be in a good position with grass reserves, but we couldn’t get fertiliser applied due to very poor ground conditions. Reserves started to disappear, but in the last few days, growth has responded to fertiliser applied a few weeks ago and it now looks like we might be OK,” he said.

“We were lucky to miss out on the heavy rainfall a lot of places got over the weekend and this helped with ewes being able to graze down to 3.5cm and achieve good utilisation. Growth was recorded at 20kg DM/ha over the last week and weather will be the dominant factor in keeping grass ahead of ewes.”

Early signals

It was reported previously that the New Zealand Texel ewes were performing slightly ahead of their Irish counterparts by achieving a higher litter size of about 1.8 lambs per ewe to the ram.

However, Noirin points out that early data stemming from the trial should be treated with caution as there are relatively small numbers and it will take two to three years to develop an accurate and fair picture.

Commenting on lambing performance, Henry said the New Zealand ewes are probably the front-runners in terms of mothering ability after year one.

“The Suffolk ewes were wilder than all other ewes up to lambing, but it’s remarkable how they quietened down once lambed, with lambs up quick to suckle.

“The New Zealand Texel ewes have also performed well and looked like very good mothers in their first year lambing and it will be interesting to see how they perform during the grazing season.”

Lambs will remain in the production system until they reach 45kg liveweight. The best-performing and most-suitable lambs will be retained as potential replacement rams and the ewes with lambs not making the grade will be slaughtered.

The trial will run for four to five years, with regular updates from Teagasc.