Farm Table says:
Dr. Annette Litherland acknowledges that although it is well known that lambing percentage and lamb growth can substantially lift profitability, that many farmers are still having problems matching the end product with the farming system.
The New Zealand researcher explains the calculation of lamb survival.
- Lamb loss = scanning percentage (potential lambs) – marked lambs/ scanning percentage.
Average figures from lamb loss research for scanning percentages of 120%, 140%, 160% and 180% are 16%, 17%, 18% and 19% respectively. Dr. Litherland states that if your lamb losses are greater than these, then you should work through the following risks and understand your results:
- Inadequate vaccination program
- Poor mineral status
- Poor maternal traits in the ewe
- Steep slopes, poor shelter, and disturbance
- Poor ewe condition and nutrition
In New Zealand, average growth rates from birth to weaning are 270g/day for singles and 220g/day for twins. To affect the higher growth rates, the following have to be considered:
- Higher pasture cover
- Ewe condition at lambing
- Ewe genetics
- High pasture quality in late lactation
Post-weaning, 340g/day on very high-quality forages is the maximum growth rate for weaned lambs.