There is evidence to suggest that exposing lambs to a feedlot diet prior to feedlot entry and ensuring sufficient intake of that diet could increase feed intake and lamb growth.
That was the conclusion that Charles Sturt University PhD student Thomas Keogh came to after researching whether creep feeding pre-weaning and providing access to a feedlot diet post-weaning would allow lambs to better transition to the feedlot environment and improve their growth rates.
Mr Keogh conducted this experiment on his family's southern NSW property because there was evidence suggesting post-weaning lamb growth weights were consistently less than potential.
"Single-born lambs were exposed to one of four pre-weaning treatments for six weeks prior to weaning," he said.
"The treatments included creep access to grain (barley and lupin mix), lucerne hay, both grain and hay, and a control that received no supplementation.
"At weaning, lambs were randomly assigned to one of three post-weaning treatments - grazing irrigated lucerne with or without access to grain, or weaned directly into a feedlot."
After the 30-day post-weaning period, all lambs entered the feedlot for the 39-day finishing period.
"The feedlot diet of 70 per cent whole barley, 25pc whole lupins and 5pc commercial mineral pellet and rumen buffer, contained 12.9 megajoules of metabolisable energy and had a crude protein percentage of 17.2pc," he said.
"Lambs were provided with lucerne hay during the 16-day induction to the grain diet and had unrestricted access to barley straw for the remainder of the finishing period."
Mr Keogh said when it came to analysing the results, lamb growth rates pre-weaning did not differ between creep fed treatments, with daily liveweight gain from marking to weaning averaging 373 grams a day.
There were no differences between treatments in grain intake (93g a day) or lucerne hay intake (119g a day) throughout the 42-day pre-weaning period.
"These results suggest no benefit in liveweight gain pre-weaning from creep feeding lambs, most likely because of the high quality and quantity of feed available to ewes and lambs," he said.
During the post-weaning period, growth rates were lower for lambs weaned directly into the feedlot than lambs grazing lucerne or lucerne supplemented with grain.
He said supplementing lucerne with grain did not increase growth rates during this period.
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During the finishing period, Mr Keogh said feed intake and lamb growth rates were greater for lambs that were weaned into the feedlot and lambs with access to grain on the lucerne compared to lambs that only grazed lucerne post-weaning.
He said there were no differences in grain intake in the feedlot in the finishing period as a result of pre-weaning treatment.
"Prior exposure to grain pre-weaning has previously been shown to improve acceptance by lambs in a feedlot, but in the current study prior exposure only increased intake for lambs that were supplemented with grain during the post-weaning phase," he said.
"This could suggest there is a certain level of intake required to familiarise lambs to increase subsequent intake or that providing grain when there is sufficient supply of high quality feed available is not an effective way to familiarise lambs to the novel feed source."
He said what was interesting was that when lambs grew, they deposited energy as both fat and protein and the peak of protein deposition happened earlier in their maturity, whereas for fat, the peak happened later on.
"As you increase a lamb's intake, its first priority is to meet its maintenance requirements, then it begins to deposit protein, but only when a lamb's intake gets to higher levels it does start to deposit fat," he said..
"If I was to restrict a lamb to meet maintenance and deposit the majority of the protein it needed to at that particular stage of maturity, there would be very little fat deposition, shifting the peak of a fat deposition later into maturity.
"Following this period of restriction and provided the supply of high quality feed, the lamb would compensate and deposit a far greater proportion of fat than protein.
"As the proportion of the gain shifts from 100pc protein to 100pc fat, ruminants become more efficient at utilising energy.
"This is one reason that following a feed restriction, compensatory gain has shown to be faster and more efficient.
"I'm not advising you to restrict your lambs' growth but if you plan on feedlotting, there is potential that moderate growth prior to entry could result in better feed conversion."
The project was funded by the Meat & Livestock Australia Donor Company and the Graham Centre.
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The story How to get your lambs to best adapt to a feedlot situation first appeared on Farm Online.