Lack of colostrum increased lamb losses tenfold, study shows

Lamb mortalities on a Welsh sheep farm were 10 times more likely when the animals had not received adequate colostrum in the crucial first 24 hours of life, a study has found.

Nigel Bowyer and his family run a flock of 270 Aberfield and Lleyn ewes at Ty Coch, Llanbado, near Usk, lambing indoors in February and March and selling finished lambs.

Historically, they suffered lamb losses of about 15% from birth to weaning, with more deaths than expected occurring after turnout.

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Previous research by Welsh red meat levy body Hybu Cig Cymru had concluded that most deaths among pre-weaned lambs on Welsh farms occurred within the first week of life.

Despite ongoing improvements to ewe nutrition and the eradication of maedi visna virus from the flock, losses remained stubbornly high and above the industry target of less than 10%.

The Bowyers suspected that poor lamb colostrum intake was partly to blame for this.

As part of their work as a Farming Connect Our Farms monitor farm, they decided to investigate the influence ewe colostrum quality and quantity had on lamb survival and growth rates in the 2024 lambing season, with the help of Hilary Jones of Farm First Vets.

Ewe nutrition

Hilary formulated a pregnant ewe ration plan for ewes to receive in the six weeks before their due lambing date.

This ration was based on red clover silage with metabolisable energy of 11.5MJ/kg dry matter, and a mix of home-grown wheat and barley supplemented with beans and wheat distillers.

All the ewes were fed the same ration, with those carrying triplets fed for at least six weeks before lambing, twin-bearing lambs for four weeks and singles for two weeks.

Blood samples were then taken two weeks before the expected start of lambing to ensure intakes of protein and energy matched ewes’ needs – which they did.

The study followed a cohort of 34 sets of twins and four sets of triplets from birth – a total of 80 lambs. These were tagged, weighed and assessed for stomach fill within 24 hours of birth.

The body condition scores (BCS) of the dams were recorded, and colostrum quality at birth was assessed using a Brix refractometer – a score above 26% is considered good.

Any other issues such as mastitis or ill-health were noted.

Nigel Bowyer © Debbie James

Passive transfer

Lambs that have good levels of passive transfer of antibodies from colostrum have high protein levels (above 9%), while those lacking sufficient colostrum have low levels (below 8%).

To assess this, the lambs were blood tested at 24-48 hours old. The samples were tested at the Farm First Vets veterinary practice, also using a Brix refractometer.

As part of the follow-up, any incidence of health issues such as watery mouth was recorded, and a post-mortem was carried out on any lambs that died among the 80.

Many of the lambs that died had shown signs of having pneumonia.

Surviving lambs were weighed again at eight weeks, at weaning and at finishing, to calculate a daily liveweight gain.

Colostrum intake

The project showed that the percentage of lambs reared averaged 138% a ewe, compared with the flock’s scanning percentage of 163%, showing a loss of 15.3%.

The results also confirmed the vital role of colostrum, as 40% of lambs that had had inadequate colostrum intakes died before weaning, compared with only 4% of those whose consumption was sufficient.

Lambs that had been recorded as having full stomachs at the first assessment generally had higher Brix scores than those that appeared empty, suggesting they had had better colostrum intakes.

Triplets tended to have a lower Brix score than twins, indicating poor passive transfer as a result of poorer intakes.

Ewes in the Bowyers’ flock that lambed at BCS 3 – which is considered optimal for their breed of sheep – were slightly more likely to have good-quality colostrum than thinner ewes.

Farming Connect red meat sector manager Lisa Roberts, who oversaw the project, says the results are not surprising as they indicate that ewes in optimal condition at lambing are likely to produce better colostrum – but that is incidental if the colostrum does not get into the lambs.

Those that do not learn to suck, or triplets that have to compete for colostrum, need to be topped up, she says.

“Lambs that didn’t get enough colostrum were 10 times more likely to die than their well-fed counterparts,” she adds.

Lasting impact

With losses continuing to occur at Ty Coch after those initial few weeks, the study concluded that the effect of colostrum intakes appeared to last as lambs got older.

Calculations showed that if losses had been reduced by 5.5%, to bring it in line with the industry target, the Bowyers would have generated an extra £2,000-£2,500 in lamb sales, at 2024 prices.

This, Hilary evaluates, is equivalent in cost to paying for more than 150 hours of casual labour.

This could be used to check lambs in the first 24 hours, supplementing any that receive inadequate colostrum, and therefore reduce losses.

Daily liveweight gain was also assessed as part of the project, but a direct link between growth and colostrum intake was not established.

However, the lambs with the best Brix scores appeared slightly better grown at eight weeks and at weaning.

In the 2025 lambing season, the Bowyers have acted on the findings of the project, recruiting a member of staff to help during the lambing period.

“We have so many things to do on the farm as well as lambing that a failing in the past was not spending enough time with the lambs,” says Nigel.

“Having that extra pair of hands to look after the lambing shed has made all the difference.

“Our losses have been noticeably down: of the 280 lambs born, we had 19 losses, and the lambs look fitter than they have ever looked before.”