Weaning will be on the horizon for many flocks now. There are several factors that can affect the success of weaning lambs; so it’s obviously a crucial period for lamb and ewe health. The ultimate aim is to wean without affecting growth rates – simple?
When to wean? There is no fixed answer for this question, as it is influenced by many factors such as ewe body condition score (BCS), feed availability and lamb growth rates. Continually assessing the ewe BCS and lamb growth rates can give a good indication of the ewes’ milk supply and group health status.
A sensible time to start thinking about weaning is eight weeks after the mid-point of lambing. At this point, you should consider these three things:
1. Assess the body condition of ewes
This is to judge how they are coping with the increasing demand that growing lambs put on their energy reserves. If ewes are looking a bit on the lean side two months after the midpoint of lambing it may be prudent to wean earlier. This gives the ewes sufficient time to regain the required condition for tupping.
It is generally accepted that it can take seven to eight weeks for a ewe to gain one body condition ‘score’ on unrestricted grazing. Ewes that are tupped at the correct BCS tend to have more lambs during the following lambing season.
2. Weigh the lambs to assess their growth rates.
In the first eight weeks of a lamb’s life the target growth rate should be greater than 250g/day. There are several factors which could have a negative impact on this growth rate including a parasitic burden and poor levels of milk production or forage quality. If you have a high percentage of lambs not reaching this target growth rate then further investigation is definitely warranted. We can examine faecal samples at our in-house lab to check for work eggs or coccidiosis.
Weaning should be triggered once lamb growth rates are less than 200g/day and lambs should be moved onto better forage.
3. Have a plan to reduce stress
Ideally weaned lambs should be moved onto a pasture type that they are familiar with. It is also beneficial for this land to be out of sight and sound of the ewes. Because of the immaturity of the digestive system at birth, it can take up to three weeks for the rumen to transition onto a new feed type. Evidence shows that lambs perform better on feed that they have experienced with their mothers. Weaning is a stressful time for any animal. Therefore any management tasks such as vaccination or worming should be performed a few weeks before or after weaning. The stress caused at weaning can impede the immune response, particularly to vaccines, thus increasing the lamb’s susceptibility to disease.
So all of these factors need to be considered when planning your flock’s weaning strategy. Speak to any of the sheep team to discuss what monitoring programmes may be helpful in planning for this period and to talk about how we can reduce the impact of other diseases or stresses on ewes and lambs at this time.