5 June 1998

Assisted births responsible for higher mortality

MOST lambs dying in an EU survey of mortality had been assisted by humans at birth, with low birth weight, infection and trauma being the biggest causes of death.

Jenny Anderson, MLC sheep scientist, says of a total of 2809 lamb births recorded in Scotland, Belgium, Holland and Germany as part of a survey on fecund sheep, 423 lambs – 15% – died.

"Birth weight had a significant effect on mortality, with average weight of surviving lambs being 4kg, while lambs that died averaged 3.5kg. In the study, 58% of lambs died between 24 hours and six weeks old, with 25% dying at birth."

According to Dr Anderson, most deaths (35%) were due to infection, while trauma killed 26% of lambs; triplets and quads were more likely to die from infection (22% of deaths) and trauma (15%) than singles at 2% and 3% mortality, respectively.

"We also found that lambs from young dams – one and two years old – are more likely to die of trauma than those from older ewes."

Overall, the survey found that most lambs which died had been assisted by humans at birth although they were in the correct position. Only small numbers of lambs born with legs or heads back or backwards subsequently died.

"This shows how important it is to allow the sheep to have as much time as possible to lamb naturally to keep mortality rates low." &#42