High-index sheep produce less greenhouse gas (GHG) emissions per kilo of carcass produced, according to Alan Bohan of Sheep Ireland.

Alan spoke last week the Sheep Ireland industry meeting. He compared 5-star ewes to 1-star ewes and explained how the latter, during a study carried out between Sheep Ireland and Teagasc, was found to produce more GHG per kilo of carcass produced.

The model used was a 20ha farm, stocked at 12 ewes/ha. 257 ewes were joined to the ram, while a lot of central progeny testing (CPT) background data was used.

The premise of the study was to compare 1-star ewes joined with 1-star rams, and 5-star ewes joined with 5-star rams, and to then look at the results from the concluding progeny.

Some ewes were joined to replacement sires and others were joined to terminal sires, with data collected for 1-star replacements and 2-star terminal lambs, and likewise with 5-star replacements and 4-star terminal lambs.

sheep study
Data source: Sheep Ireland

The 1-star flock, consisting of 257 ewes on 20/ha, weaned 1.6 lambs per ewe, with an average days to slaughter of 200.

While the 5-star flock of 257 ewes on 20/ha also, weaned 1.74 lambs per ewe and had an average days to slaughter of 192.

Alan said that even though the differences are small, that they all combine to make a significant distinction.

In terms of physical outputs, in which there were a lot of figures, Alan highlighted a couple of important ones which saw the 5-star ewes stand above their 1-star counterparts.

These included: Scanning rate; numbers of lambs born per ewe lambing; lamb survival percentage; weaned lambs per ewe joined; 40 day weight; weaning weight and scan weight (150 days) – all of which 5-star ewes were superior when to compared to 1-star ewes.

Alan then spoke about the lamb drafting pattern and noted how more 5-star lambs were drafted each month for slaughter in comparison to the 1-star lambs.

Alan said that the earlier lambs are drafted helps to keep costs down in the system, which means less lambs at the tail end of the year – where concentrate feeding tending to be introduced and possibly even housing to get those lambs finished.

sheep study figures
Data source: Sheep Ireland

Lamb sales were €3,711 greater for the 5-star flock in comparison to the 1-star flock, with the total farm costs also greater for the 5-star flock by 636.

Although, the farm net profit for the 5-star flock was greater by just over €3,000.

On a per hectare and ewe basis, the 1-star flock had a net profit of €439/ha and €34/ewe, while the 5-star flock had a net profit of €593/ha and €46/ewe.

In essence, the 5-star ewes were more profitable and more productive than the 1-star ewes.

Data source: Sheep Ireland

However, as Alan highlighted, it is what effect these two flocks had on the environment which was also very important.

Environmental impact

Using lifecycle assessment to look at the carbon equivalent of the output of the flocks.

This took into consideration everything from fertiliser; concentrates fed; methane output from each animal; right down to diesel use and electricity on the farm.

It was found that the 1-star flock was producing 9.35t/ha of CO2 versus 9.32t/ha of C02 for the 5-star flock.

When broken down further on a per kilo of caracss basis, the 1-star flock had a carbon output of 22.1kg, verus the 5-star flock that had a carbon output of 21kg.

This would equate to a 5% reduction in CO2 output per kilo of carcass by the 5-star flock, Alan highlighted.

Choosing high €urostar animals will help to increase profit and reduce carbon output, Alan concluded.

Data source: Sheep Ireland