EBVs help with maternal selection

Using rams with superior Estimated Breeding Values (EBVs) is paying dividends for Cornwall-based commercial Poll Dorset producer Jim Hext.

Over the past eight years prolificacy has been maintained and carcass traits enhanced through the selection of rams with superior litter size, scan weight and muscle depth EBVs.

And Mr Hext, who runs 600 ewes, believes carcass weights have increased by at least 1kg and finishing times have reduced. But carcass weights could be taken heavier if required.

“Having a contract with Waitrose means lambs can be selected in peak condition, rather than selection decisions being influenced by fluctuations in lamb prices,” he explains.

Using high index rams has increased consistency and uniformity of the farm’s lamb crop and enhanced the flock’s ability to meet market specifications.

In recent weeks all of his lambs have hit market specifications, a fact he credits to the use of the right genetics, particularly the flexibility provided through use of rams with low fat depth EBVs.

The flock’s physical and financial performance is equally impressive, with ewes leaving the lambing shed with an average of 1.81 lambs each, having scanned at 1.92.

With average carcass weights just short of 19kg, it is no surprise the average output per ewe mated is £99.87.

When selecting tups Mr Hext is keen to consult EBVs, particularly when it comes to the selection of rams with superior maternal genetics, as he believes these traits can’t be judged by eye.

Rams are purchased in batches of three or four and they run together, so it is easy to see improvements in performance that correspond to sire selection.

However, he admits it is difficult to put a precise financial figure on these benefits, as they arise in different ways, including improved growth rates, better carcass conformation and outstanding maternal performance in the ewe flock.

Mr Hext’s belief in the use of EBVs is backed up by Sam Boon of MLC’s Signet Breeding Services.

“Production levels like these show what can be achieved in lowland sheep production through careful ram selection.

“The selection of maternal sires is nearly impossible without the use of EBVs, because traits such as prolificacy and milking ability are impossible to identify simply by looking at a ram, but they can be the most important traits to consider.

“These genetics will be expressed year after year by breeding females within the flock and so the impact of a ram’s breeding potential may still be being expressed a decade after he was purchased.”

These are messages that will feature strongly in the next phase of the EBLEX Better Returns Programme.

“The programme aims to demonstrate that for an average UK flock of 210 ewes, which is self replacing, this lift in flock productivity due to careful ram selection could be worth an extra £1000 a year,” says Mr Boon.

High selection pressure is also applied to female replacements, as ewe lambs retained or sold for breeding are selected at birth.
Replacements must be twins or triplets, out of ewes with good characteristics, particularly feet, udder shape and ability to lamb unaided.

When these criteria are satisfied the ewe lamb is ear notched according to the group of rams which have sired it.

After weaning Mr Hext goes through these pre-selected ewe lambs again, culling any which don’t posses the conformation or breed type he is looking for.

“This strict selection policy has also helped keep lambing percentage high.

This is important when dealing with a trait such as litter size, which has a low heritability,” he adds.