Infection and dystocia are the two main causes of lamb mortality, accounting for 38% and 15%, respectively, according to a study carried out by Teagasc in Athenry.
Lamb mortality impacts on ewe productivity (number of lambs reared per ewe joined), and farm profitability. Therefore, ewe nutrition and good practices prior to and after lambing will go a long way in reducing lamb mortality rates.
Most lamb mortality occurs within the first few days after birth. A study at Teagasc Athenry has shown that 52% of lambs that die, died either prior to or at birth. A further 21% of lamb mortality occurred between birth and 24 hours. Thus 73% of all neonatal lamb mortality occurs within 24 hours of birth.
Causes of lamb mortality
According to Teagasc, infection and dystocia were the two main causes of lamb mortality, accounting for 38% and 15%, respectively. Accidents accounted for 8% of lamb mortality.
The cause of death was not identified in 28% of the lambs that died. The two main causes of neonatal lamb mortality are potentially preventable through the implementation of best-known practices prior to and during lambing.
Management practices on sheep farms
Approximately 50% of lamb mortality (infection and dystocia) on Irish sheep farms is potentially preventable. The main cause of lamb mortality is infection. Key on-farm issues impacting infection are hygiene, colostrum intake and an adequate vaccination programme.
Natural colostrum contains IgG which is critical for the transfer of passive immunity to many diseases and infection to newborn lambs. Nutrition management in late-pregnancy influences colostrum supply.
On 10% of sheep farms, artificial colostrum is the only colostrum that is administered to lambs when adequate supply is not available from the mother.
Post-lambing, ewes and their lambs are placed in individual pens on 88% of sheep farms. However, on many farms, there are poor hygiene practices in the management of individual pens. Only 41% of Irish farms clean and disinfect individual pens after each ewe vacates.
The main cause of dystocia is inadequate nutrition management which results in lambs been either over or underweight at birth.
Only 60% of farmers raddle their rams during the joining period and of these only 70% change the colour every two weeks or more frequently.
Only 69% of farmers’ pregnancy scan their ewes. Consequently, many farmers are unable to implement an effective pregnancy nutrition plan as they do not know the expected lambing date and/or litter size.
Lamb mortality on your farm
Lamb mortality includes all lambs that die up to weaning including abortions and stillbirths. All lambs that die should be recorded on a record sheet.
Other information recorded should include date of death, age at death, litter size, symptoms/cause of death.
This information will identify if there is a lamb mortality issue, the potential causes and can be used by veterinary practitioners to develop a flock health plan to reduce mortality in future lambing seasons and thus increase flock profitability.