With April 2021 the frostiest on record for 60 years there are potentially a few challenges for this year’s lamb crop. Most worryingly the lack of grass growth. Five consecutive days of soil temperature of 5◦C+ is required for grass growth so it’s easy to see why the grass is a little late to flourish this year.
Growth rates of more than 250g per day should be achieved in lambs up to eight weeks old (AHDB). Up to this age the main energy source for lambs is milk. However, if the grass growth is poor, ewes may produce less milk and drop condition quicker than expected. Lambs may need to start eating more grass from a younger age to meet their energy requirements for growth. This means directly competing with their mothers for the limited grazing, leading to a vicious cycle of poor grass availability and associated problems.
Body condition of ewes, lamb growth rates and height of the grass (sward height) can all help make decisions about when additional action is required. Ways to overcome these include creep feeding, pasture rotation, reduced stocking density, supplementary feeding or a combination of these. It’s important not to forget some grazing will be required for finishing lambs and putting condition back on ewes pre-tupping.
From a disease perspective, if grass growth is poor there’s potential for more soil ingestion from grazing at the base of the grass which can cause problems for lambs especially in terms of increasing parasite burden and higher risk of clostridial diseases from bacteria and toxins in the soil.
Again, these can be managed by good husbandry practices. Worms and cocci are the biggest parasites to worry about as a higher density of infectious larvae are found closer to the ground. Worm and cocci burden in lambs can be monitored using drops in daily live weight gain and worm egg counts at approx. four-weekly intervals throughout the grazing season. Regular monitoring allows problems to be identified sooner than waiting for clinical signs i.e. dirty bottoms when a large amount of damage to the guts may have occurred.
Clostridial diseases can be vaccinated against. Vaccinating ewes with Heptavac P Plus (or equivalent) pre-lambing and ensuring adequate colostrum intakes as neonates ensure lambs are protected from clostridial diseases for the first few weeks of life.
A variety of clostridial vaccines are available and should be given from approx. four weeks old to continue immunity against clostridial disease. Your lambs’ requirements may vary depending on the system so best to chat to one of the vets or SQPs for more information.