Measuring and monitoring flock mortality

If you would like to reduce flock mortality pre and post lambing, then start to measure and monitor flock performance. With lamb losses from scanning to sale running at an estimated 15% to 20%, there’s plenty of scope to reduce to 10% or less, says ADAS’s Kate Phillips.

Spending a little time measuring and monitoring flock performance to identify key weaknesses in the system can have a huge impact on the flock’s long term physical and financial performance.

Getting started

Measuring and monitoring can vary from basic recording of lambs reared and ewe and lamb losses, to more detailed records of date, age, weight and cause of death. This data enables farmers to benchmark farm performance year on year and carry out detailed analysis for every ewe in the flock, for example to work out the kilograms of lambs reared per ewe. Discussing these records with your vet or livestock consultant can help to identify issues and any remedial action necessary to help improve flock productivity and performance.

With the majority of ewes now electronically tagged, EID can facilitate records for measuring and monitoring flock performance more accurately. Particularly recording the daily live weight gain (DLWG) of growing lambs, monitoring performance of the progeny of different rams, assessing the effect of different treatments and selecting specific maternal and neonatal lamb traits (e.g. lambing ease, mothering ability). EID can also be effectively used to record medicines or treatments given to individual animals. More specific animal details (e.g. weight, condition score, health status) can be used to help select high performing animals for replacements and also to identify underperforming animals and other health issues.

Setting targets

All flocks should aim for less than 15% lamb losses and the top performing flocks are achieving closer to 10%.

Targets for reducing lamb losses: 

• <5% scanning to lambing 
• <5% lambing and week 1
• <2% week 1 to weaning 
• <2% weaning to sale/retention

Further investigation is required if:

• Ewe losses are over 3%
• Lamb losses are over 15%
• Barren ewes are more than 2% at scanning

It is essential that all health issues and losses are recorded in detail to help identify the cause.

Ewe and ram losses

Ewe and ram losses at more than 2-3% may suggest an underlying health problem and further investigation would be worthwhile. High numbers of ewe deaths could suggest significant health issues, sub-optimal nutrition, or that ewes are being retained on the farm for too long.

If more than 2% of the ewes are barren at scanning, consider blood testing for abortion (particularly Toxoplasmosis). A number of other factors could be responsible for high barren rates, such as ram fertility, trace element imbalances, lack of good quality grazing for flushing, parasitism and/or lameness. Poor scanning results and low body condition of barren ewes may suggest sub-optimal nutrition and specific health issues such as fluke.

If more than 2% of ewes lose their lambs between scanning and lambing, a number of lambs are born dead, or a number of weakly lambs are born, you could consider testing for abortion.

Prolapse and hypocalcaemia can be responsible for a large number of ewe and lamb losses pre lambing. Monitoring condition score and formulating a correct ration can reduce the incidence.