Friday, 23 August 2019 11:44

Small things make a big difference

Written by  Julie Roberts, Ravensdown animal health area manager
Julie Roberts. Julie Roberts.

Lamb daily growth rates on sheep farms in New Zealand are in a huge range — from as low as 80g to 350g or more per lamb per day. 

Getting to the top of this range requires attention to detail.

Ewe condition score and milking ability, pasture quality and quantity, weather, trace elements and genetics are just some of the variables farmers need to manage.  If just one of these ingredients is missing, or is in short supply, lambs will struggle to reach target weights. 

Trace elements, although only required in small amounts, are a key part of this big picture. Adequate dietary levels are essential for healthy lamb growth and production.  Selenium and cobalt (used to make Vitamin B12) are of particular importance in NZ farming systems. 

 Providing the ewe’s selenium and B12 levels are adequate, her suckling lambs should receive enough of these minerals through to weaning.  If the ewe mineral levels are not adequate, then extra supplementation may be necessary to ensure good lamb growth rates.  

The trick is to know if you need extra supplementation and whether to give this to the ewe or the lamb.  If targeting the ewe, then a pre-lamb mineral boost is ideal. If targeting the lamb, then docking/tailing is the first ideal opportunity. 

Test before supplementing

Herbage samples in the spring, when the grass is actively growing, can give you an idea as to whether the pasture will supply adequate amounts of key minerals. 

Herbage trace element information should be supported with liver or blood samples, to confirm actual levels for animals and the level for supplementation required.   

All stock have different needs for each trace element. However, an animal health professional can help you decide where there may be shortfalls and interpret the results.

There are different options available for boosting animal trace elements, including mineral amended fertilisers, mineralised drenches, injections, pour-ons, etc.  

Your regional animal health technical advisor can advise you on mineral requirements for stock this spring.

Ideal selenium and B12 levels for lambs



(mg/kg DM)



Serum Blood (nmol/L)







Vitamin B12

– >375



• Julie Roberts is Ravensdown animal health area manager


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