Heaviest lambs at weaning are leanest
Scientists looked at the feasibility of using a lamb’s weight early in life to predict carcass quality at target weight.
They found that lambs heavier at weaning, typically at 13 weeks of age, were significantly more likely to have leaner and more muscular carcasses. And these carcasses were significantly more valuable at slaughter, even after accounting for seasonal variation in lamb prices.
The study was carried out at Rothamsted’s farm lab at North Wyke Farm Platform, Devon, with data collected from 2 963 sheep.
The team concluded that a stronger focus on ewe nutrition before and during lactation is key to increasing profitability.
PhD student Andy Jones said they have shown that the leanness of lamb meat is determined very early in an animal’s life. Given that the majority of lambs’ pre-weaning nutrition comes in the form of ewe milk, it is now likely that carcass quality is also affected by management of ewes during pregnancy and lactation. On the other hand, how to manage lambs once weaned may not be as important as those early life experiences.”
Other benefits of improving growth
As most heavier-weaned lambs leave the flock before lighter-weaned ones, an increase in average weaning weight could also free up more pasture for ewes in the latter stages of the current season, and enhance ewe condition and fertility for the following season.
The findings could also have implications for the climate change effects of livestock farming because if these lambs spend a shorter time on the farm and this can trim down emissions of both methane and nitrous oxide as well.