Advanced weaning benefits

28 Oct, 2005 08:45 PM
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THE myth that it's easier to achieve the desired bodyweight of lambs by leaving them on the ewe rather than weaning was dispelled last week.

Speaking at Bruce Rock during a week of seminars for Elders Livestock Management Solutions, Animal Logic Group senior technical team member Rick White said producers could achieve the desired weights if lambs were weaned properly.

³If you manage the animal¹s stress and wean correctly you can get them to the desired weight,² Mr White said.

³If you don¹t they can lose weight and take a long time to put that weight back on and producers wish they had left them on their mothers.

³But conducted correctly they won¹t lose weight but will take off and be better lambs at the same age than lambs still on the ewe.²

Mr White said a client in Temora, NSW, facing drought conditions had to feed crossbred ewes with lambs at foot a 1.5kg ration of grain a day to maintain the ewes during lactation.

The producer was forced to wean the lambs at three weeks of age into a feedlot situation.

³By the time they were 14 weeks old they were 45kg liveweight and sold,² Mr White said.

³The point is if they are weaned properly and the stress of weaning is managed properly, there is no period of weight loss and they gain weight right from the start even at three weeks old.²

Mr White said they divided the lambs into four groups based on weight with the youngest lambs in weight ranges of 9-12kg.

³These lambs finished quicker and with less feed than the older/heavier group,² he said.

³The reason for this is the younger they are when weaned the more their rumens develop and the more efficient they are.²

Mr White said while he does not recommend weaning at such an early age in most instances he believes producers should be weaning a lot earlier than under present practices.

Lambs and calves are born without a functioning rumen, therefore the younger the animal when weaned the more scope available for developing the rumen.

³Once it is five months old the architecture of the rumen is set for life,² Mr White said.

³The diet the animal is exposed to affects the level of rumen development.

³Effective early weaning can only occur however when the animal has achieved a bodyweight that¹s needed to digest feed of high quality to sustain growth.

³Lambs should be 20kg and roughly 45-60 days of age while calves should be 140kg at 100-120 days.²

Mr White said producers had changed the game since the early evolutionary weaning through the selection of animals over many years for high early growth rates and high milk production levels to achieve a high bodyweight quickly.

³The thing that really switches off the development of the rumen is the bodyweights they get to, so in the process we¹ve pegged back the cut off point for rumen development,² he said.

³The rumen does not slowly develop over a couple of years anymore it develops very quickly and then stops developing so we¹ve changed the picture in an evolutionary sense.²

The American dairy industry has been conducting advanced weaning for years, weaning their calves at one day of age then putting them straight onto starter rations that are high in grain.

³Those calves develop massive rumens and are far more efficient than a late weaned calf,² Mr White said.

Animals that have a diet high in milk and low in starch during the pre-weaning period have less rumen development than those whose starch intake is higher.

Weaning is necessary as milk suppresses the development of the rumen and is a less efficient way of feeding both the ewe and lamb.

It takes 30-40pc less feed to maintain a dam and its progeny separately than it does to leave them together.

³By the time a lamb is 8-10 weeks old the ewe is producing a lot of milk but the actual benefit the lamb is getting is minimal,² Mr White said.

³At this age the lamb is starting to eat pasture so the contribution of milk to growth is around 10-20pc.

³It costs the ewe a hell of a lot of energy to make it but it¹s not actually doing the lamb much good as it¹s already switched over and deriving most of its intake from pasture.

³By the time a lamb is 12-14 weeks of age its energy and nutrient requirements being met by milk is down to 10pc so it¹s not getting much from milk, its just suppressing rumen development.²

Mr White said the example of advanced weaning was not a one-off with many producers forced to do this in the eastern states due to drought.

According to Mr White a number of sheep studs were also undertaking the practice due to obvious benefits to the reproductive ability of the ewe from taking the lamb off early.

³It¹s not just about the development of the rumen, fertility is one of the big benefits as the ewe is able to gain weight more quickly and get back into condition once the lamb is weaned,² he said.

³There¹s also the ability to run more ewes as you are reducing the food bill, creating food surplus.

³Once you have got a whole generation of animals early weaned the whole system becomes more efficient not just the lamb.²

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