Ewe nutrition impacts immunity of newborn lambs

Veterinary researchers have identified key risk factors that could influence lamb production in lowland sheep flocks in the UK. 

Their findings could improve management of flocks and lamb health, to support survival in a sector in which approximately one in 10 newborn animals on average die each year.

Researchers studied a lowland flock of UK sheep to investigate how ewes’ condition and management influenced their lambs’ health, through the transfer of immunity in antibodies in colostrum, or first milk, from mothers to their offspring.

They measured key aspects of maternal nutrition and management on lamb outcomes during a lambing season. 

These included ewes’ nutrition during late pregnancy, together with levels of transferred immunity to the lambs, and growth rate, disease and survival in lambs up to weaning.

The team, led by the Royal (Dick) School of Veterinary Studies, identified through blood tests that low levels of the blood marker albumin in ewes – considered to be a marker of long-term protein status – was associated with lamb losses in the last weeks of pregnancy. 

The researchers also found that high levels of another marker, beta-hydroxybutyrate (BOHB), in ewes – a marker of short-term energy status – was associated with failure of transfer of immunity via colostrum to lambs. 

Low levels of albumin and high levels of BOHB can be associated with poor ewe nutrition or health and can impact on pregnancy and lactation. 

Subsequently, lambs with low levels of immunity had increased odds of reduced growth within the flock. 

These results highlight the opportunities in lowland farming systems to improve ewe health and nutrition for the benefits of lamb survival and production, the team reports. 

The team also discovered that administering oral antibiotics to newborn lambs at birth had no significant effect on lamb outcomes. This highlights the importance of evidence-based flock health planning as a partnership between farmer and vet, to decide when antibiotics are necessary. 

In the same project, the team also found that an on-farm diagnostic blood-based test, measuring total protein in blood, could be used instead of conventional lab tests for antibody levels, to assess adequate transfer of immunity via colostrum from ewes to lambs. 

The blood-based diagnostic technique is widely used in calves but has not commonly been applied to lambs in commercial settings. 

Their findings highlight the potential of on-farm diagnostic to assess lambs for their colostrum uptake.

Further work is needed to define a level of sufficient protein in test results for lambs across different production systems in the UK, the team says.

Results from the project, published in two articles in Vet Record, are being used to inform professional development materials for farm vets.

The research was carried out in collaboration with the Universities of Liverpool and Nottingham along with Synergy Farm Health, Dorchester. It was supported by the Agricultural and Horticultural Development Board England, Quality Meat Scotland, and Hyb Cig Cymru, Wales.