Focus on Growth Rates

Growth rate is a key driver influencing the productivity and hence the profitability of commercial sheep flocks.

High growth rates can:

  • Increase the weight of lambs being sold
  • Increase production efficiency by reducing days to slaughter 
  • Improve the timing of lamb sales to target high priced markets 
  • Increase the proportion of lambs sold off grass
Which EBVs are important?

Eight Week Weight EBV (kg)

Estimates breeding potential for growth from birth to 8 weeks old.

Interpretation:

A ram with an EBV of +3 is expected to produce lambs that are 1.5kg heavier at 8 weeks than a ram with an EBV 0. (figures derived from 50% genetic potential of ram)


Scan Weight EBV (kg) (Weight at 5 months old)

Estimates breeding potential for growth from birth to 5 months old.

Interpretation:

A ram with an EBV of +4 is expected to produce lambs that are 2kg heavier at 5months than a ram with an EBV of 0. (figures derived from 50% genetic potential of ram)


Growth rate is important under any system, including extensive management and store lamb production.

Remember:
  • High growth rates will only be realized under good management with adequate feed and good flock health.
  • Increasing lamb growth rates can result in an increase in ewe mature size; this may not always e desirable.
Rams with high EBVs for growth rate will increase lamb weights and reduce days to slaughter.