SCIENTISTS as well as industry representatives are excited by findings from a new lamb breakthrough feeding study that has uncovered that lambs fed under identical conditions can vary in feed efficiency by as much as 10 kilograms of feed for every one kilogram of live weight gained.
What started as an experiment to monitor the feed intake of lambs has now finished approximately 500 group housed lambs.
The lambs represent a range in genotypes and eating from automated feeders, enabling the project to determine what makes some lambs more feed efficient than others.
The study – administered jointly by Victorian Department of Primary Industries and Meat and Livestock Australia - began in 2007, with the aim of improving the feed efficiency of lambs by identifying how management and genetics impact weight gain and feed conversion efficiency.
Each lamb is scanned for body composition at weaning, and at entry and exit from the finishing system.
During the seven weeks that the lambs spend in the finishing system feed intake is recorded on a daily basis and lamb weights recorded weekly.
Scientists learned that for the most efficient lambs to gain 15 kilograms in liveweight during a finishing phase, they consumed 37.5 kilograms to put on the weight.
The poor performing lambs consumed up to 180 kilograms of feed for the same liveweight gain, representing a difference in feed conversion ratio of 2.5:1 versus 12:1.
"Even at grain prices of $400 a tonne, the better lambs have a feed cost of approximately $10 (as opposed to $70 for the poor converters)," said program head Nick Linden at a Bestwool Bestlamb forum in Bending last week.
"Overwhelmingly, the point of interest is how much the efficiency of apparently similar lambs can vary."
Mr Linden said his research also indicated the age lambs are finished has a big impact on the efficiency of the lambs during finishing.
"While we looked at finishing lambs at 21, 29 and 39 weeks of age, our work shows mid (29 weeks) aged lambs as being most efficient during finishing," he said.
"Furthermore, weight at weaning also seems to play a part in lamb performance.
"Lambs that are light at weaning can still have reasonable feed efficiency, although there is strong evidence that these lighter lambs will infact always be lighter and do not recover from their lower liveweights.
"In our work, these lambs should have been sold off earlier at lighter carcass weights, rather than fed for longer targeting an export market."
Figures from Meat and Livestock Australia suggest that feed efficiency is connected with genetics, where in test cases crossbred ewe progeny of some maternal sires were found to consume up to 15 per cent less feed for maintenance than similar weight ewes by other sires.
According to Mr Linden, the study has real impacts for people commercially finishing lambs.
The results highlight that selection for growth remains a key area – although muscle should not be overlooked – to make a more cost efficient finishing system.
"Looking at the inputs rather than outputs is a new way of thinking," he said.
"There are things we can do which are not beyond our control to improve the efficiency of our sheep – it is not pie in the sky and not hard.
"It's about getting good weaning weights, feeding the right feed at the right time and getting the conditions right."
Hannah Marriott, co-owner of Yarallah lamb, in Benalla, Vic – which turns out 500 lambs a week – said the feed efficiency variability reported in the study was exactly what the industry needed to be focusing on.
"This study is very relevant to the industry," Ms Marriott said.
"At the moment we take out shy feeders but as yet you cannot identify which lambs are actually growing slowly or staying the same.
"Yes you could do that with electronic ear tags and we will be going down that path….but it still does not tell you how much they are eating."
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