Flock health plans hold the key to reducing lamb mortality

Most lamb mortality occurs within the first few days after birth.
Most lamb mortality occurs within the first few days after birth.

Dr Tim Keady and Dr Alan Bohan

Lamb mortality impacts on ewe productivity (number of lambs reared per ewe joined) and farm profitability.

It is estimated that each 1pc change in lamb  mort­ality nationally is valued at approximately €3m.

When does lamb mortality occur

Most lamb mortality occurs within the first few days after birth.

A recent study at Athenry has identified the timing of neonatal lamb mortality (died with seven days of birth) and the data is presented in Figure 1.

  • 52pc of lambs died prior to, or at birth.
  • 21pc of lamb mortality occurred between birth and 24 hours of age.

Causes of lamb mortality

The causes of lamb mortality are presented in Figure 2. Infection and dystocia were the two main causes of lamb mortality, accounting for 38pc and 15pc, respectively.

Accidents accounted for 8pc of lamb mortality.

The cause of death was not identified in 28pc of the lambs that died. The results of this study clearly show that infection and dystocia, both of which are potentially preventable, are the main causes of lamb mortality.

Management practices

A recent survey undertaken by Dwayne Shiels as part of his PhD studies, in conjunction with the National Farm Survey, has concluded that many farmers do not implement best practices prior to and during lambing on their farms.

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Considering that infection is the major cause of lamb mortality, 23pc of farmers do not clean or disinfect individual lambing pens.

Fifteen percent of farmers cleaned but did not disinfect individual pens after each ewe vacated, while 10pc of farmers disinfected but did not clean individual pens after each ewe vacated.

Nine percent of farmers do not apply iodine to lambs navels to prevent infection.

In relation to colostrum use, 68pc use artificial colostrum.

However, 9pc of farmers use artificial colostrum as their only source of colostrum (other than ewe colostrum) at lambing. Natural colostrum contains IgG which is critical for the transfer of passive immunity to many diseases and infection to newborn lambs

Considering that dystocia is the second main cause of lamb mortality, only 68pc of farmers pregnancy scan their ewes. Only 56pc of farmers raddle their rams. Thus many farmers cannot implement an effective nutrition plan as they do not know either the expected litter size or expected lambing date.

Lamb mortality on your farm

Prior to implementing a health plan to reduce lamb mortality you need to know how many lambs die and what are the causes.

Do you know the level of lamb mortality on your farm? Most probably you don't. Lamb mortality includes all lambs that die up to weaning including abortions.

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.

Having this information will enable the farmer to accurately quantify the level of lamb mortality on their farm and symptoms/causes of death.

Knowing this information the farmer will be informed if they have a lamb mortality issue, and the potential causes.

Then, with the help of his veterinary practitioner they can develop a flock health plan to reduce mortality in future lambing seasons and thus increase flock profitability.

Dr Tim Keady and Dr Alan Bohan are based at Teagasc's Animal and Grassland Research and Innovation Centre, Athenry, Co Galway. For further information, see www.sheepnet.network

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