Weaning and Cobalt Supplementation of Lambs
Trace element deficiency can be an issue in some sheep producing areas and it is known that the concentration of trace elements vary significantly during the grazing season. The main trace elements of concern in sheep production are cobalt copper, iodine and selenium.
Weaning
Weaning should take place when lambs are 14 weeks of age (100 days). This will involve good grassland management. Ewes will need sufficient grass after drying off to reach the correct body condition score at mating. Weaned lambs will need quality grass to continue to thrive. Leaving the lambs suckling the ewes for longer than 14 weeks will have a negative effect as ewes will be competing with lambs for grass. If ewes are thin, grass height is below 4cm or lambs are growing less than 150 grams/day, early weaning is beneficial.
Target weight
The target weaning weight for lambs sired by terminal sire breeds is 34kgs. The reasons for producer inability to reach the target weaning weight from grazed grass are likely to include:
- ewe genotype
- grassland management practices
- parasite control
- mineral deficiency.
Ewes and lambs should be prepared several days prior to the planned weaning date by allowing lambs use creep gates to access leafy grass, while keeping ewes on poorer quality grass to reduce milk production.
Lamb health
Vaccinations should be carried out prior to weaning, along with stressful jobs such as castration and tagging. Once lambs are weaned, implement an effective parasite control programme and focus on trace element supplementation as an option to improve lamb performance. The main trace elements of concern in sheep production are cobalt copper, iodine and selenium. Mineral imbalance can have detrimental effects on performance, fertility, health and profitability of livestock. Results from a recent survey undertaken on 56 lowland sheep farms throughout Ireland showed that, herbage on 73% of farms had deficient cobalt concentrations whilst herbage on 89% of farms had marginal selenium concentrations.
Cobalt
Cobalt is an essential mineral for sheep as it is a component of vitamin B12 which is essential for the metabolism of a rumen volatile fatty acid. Symptoms of cobalt deficiency include:
- loss of condition
- poor fleece quality
- ears become dry and scaly
- loss of appetite
- runny eyes with tear staining on the face
- raised worm count.
Cobalt is not stored in the lamb’s body and is needed in the rumen at a rate of 0.5mg/day, for vitamin B12 production.
Selenium
Selenium deficiency is associated with poor lamb performance and white muscle disease. It is important to consider the pros and cons of the various mineral supplementation options which include bolus, mineral bucket, oral drench or minerals mixed in concentrate feed. If you are unsure that there is a mineral deficiency issue in your flock, treat a percentage of the flock and monitor performance or if a trace element deficiency is suspected on symptoms present, it needs to be identified by blood and tissue samples.
Teagasc Research in Athenry concludes that cobalt supplementation had no beneficial effect on ewe productivity but did increase post weaning lamb performance. As grass growth slows down it is a good time to cull ewes after weaning and select replacements for the next breeding season.