Prolificacy and stocking rate drive sheep farm performance

The link between better prolificacy, stocking rate, and profitability, on sheep farms has been investigated as part of a major research project at the Teagasc Mellows Campus in Athenry, Co. Galway.

Since 2012, Teagasc researchers have been working to identify the most appropriate stocking rates and prolificacy levels to maximise the profitability on mid-season lambing Irish sheep flocks.

Teagasc’s Philip Creighton presented an overview of the key findings of the study at the recent Irish Grassland Association Sheep Conference.

What was investigated?

“The project looked at the effect of stocking rate and prolificacy level within a grass-based system on animal performance, grassland performance and ultimately the economic performance,” the Teagasc Research Officer said.

To do this, three stocking rates (10 ewes/ha, 12 ewes/ha and 14 ewes/ha) at two levels of prolificacy (high and medium) were investigated.

“The aim was to wean 1.5 lambs/ewe in the medium-prolificacy groups and 1.8 lambs/ewe in the high-prolificacy groups,” he said.

Information was gathered across these contrasting systems on grass supply and demand, drafting patterns, carcass output from grass, and profitability.

Our aim was to look at a mid-season lambing flock producing as much lamb as we could from grass.

“We wanted to push the systems as hard as we could with grass without including any sort of meal supplementation until it was absolutely necessary at the end of the year.

“We wanted to see what’s achievable, what’s not achievable and to identify the challenges,” he said.

Key results

Stocking rate and prolificacy

Across prolificacy groups, Creighton said there was no difference in the lifetime average daily weight gain of the lambs.

However, the number of lambs weaned from the high-prolificacy group was lower than expected at 1.7 lambs/ewe joined.

There was no difference in terms of the number of days it took to get the lambs to slaughter.

“There was a difference in terms of stocking rate. As the stocking rate increased, the individual animal (lamb) performance was reduced.”

When it came to finishing the lambs off grass, Creighton said there was no difference between the high and medium-prolificacy groups.

“We finished 85% of the lambs on a grass-based diet. About 15% of the lambs in both groups did have to be supplemented with concentrates.

“The real effect was stocking rate. As we moved towards the higher stocking rate groups, we had to supplement more lambs.

“There was no difference in the days to slaughter figure for the 10 ewes/ha and 12 ewes/ha groups, but it was significantly higher for lambs produced from the 14 ewes/ha group,” he said.

Source: Teagasc (red lettering denotes significant differences)

But, this was balanced by the higher number of lambs sold from the higher stocking rate groups.

“By increasing the stocking rate by two ewes/ha (going from 10 ewes/ha to 12 ewes/ha) we produced an extra 55kg of lamb carcass/ha.

“When we compared the 10 ewes/ha and 14 ewes/ha groups, the higher stocking group produced an extra 102kg of carcass/ha.”

Economics

The Teagasc research officer also touched on the economic performance of the various groups under the trial.

“For most of the way through this trial, the 12 ewes/ha high-prolificacy group was coming out on top in terms of economics.

“It has changed slightly in that the 14 ewe/ha high-prolificacy group is now the most profitable,” he said.

This occurred as data from the 2015 and 2016 trial years have been added into the equation.

“2015 was pretty much a perfect year in terms of growing and utilising grass in Athenry – even the high stocking rate groups didn’t require a whole lot of meal.”

This, he said, helped to boost the profitability of the 14 ewes/ha high-prolificacy group.

In addition, he said, lamb performance across all of the groups was terrible last year – as had been the case on many sheep farms throughout Ireland.

“We had to put a lot of concentrates into the high stocking rate groups, but we also had to put more concentrates than usual into the other groups as well.

“The gains we would normally have made in the 10 ewe/ha and 12 ewe/ha groups, in terms of concentrate supplementation, weren’t actually made,” he said.

What should farmers do?

Increasing prolificacy levels and then stocking rate, in combination with increasing grass production and utilisation, is key to increasing profit, Creighton said.

“By increasing the prolificacy, we have the greatest impact on increasing our profitability.”

According to Creighton, increasing prolificacy had a much bigger impact on improving performance than stocking rate.

“Increase the prolificacy first, then look at your stocking rate and do so while increasing the amount of grass grown and utilised,” he said.

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