ANIMAL HEALTH Lamb growth
Ruminant animals source their B12 from the bacteria that digest feed in their rumen.
Pre-weaning treatments can be crucial BY: BEN ALLOTT
W
hen it comes to lamb performance at this time of year, I commonly get asked one of two questions; • Should I give my lambs a Vitamin B12 injection? • Should I drench my lambs before weaning? I’m addressing these not because I see them as the most important considerations for the season but because these are the two topics farmers question me about the most. The most important driver of lamb performance in the spring is high feed quality. This is possible with more legume and herb content in pastures. Also maintaining pastures in a vegetative growth phase.
Country-Wide
October 2021
Importance of vitamin B12 Vitamin B12 plays a very important role in energy metabolism in animals. Without sufficient B12 the liver stops being able to convert the products of food digestion into utilisable energy. Feed intake drops, energy levels decline, and growth rates suffer. Humans source their Vitamin B12 from eating animal products (meat, eggs, milk, fish) or from B12 supplements. Ruminant animals (sheep, cattle, deer), source their B12 from the bacteria that digest feed in their rumen. For these bacteria to make enough B12 they need a source of cobalt, a trace element found in soil and plants. There are regions of New Zealand where there is an absolute deficiency in soil cobalt. The most widely-known being the bushsickness band of volcanic country that extends north from the centre of the North
Island, through the King Country. Through other regions, while the soil may contain sufficient cobalt it can be ‘locked-up’ and therefore unavailable for plants to take up through their roots. The common soil factors that will reduce cobalt availability are: high manganese levels, high iron, high aluminium, acidic soil pH, low soil moisture content. Different plants will take up dramatically different amounts of cobalt when grown on the same soils. Legumes (clovers, lucerne) and the pasture herbs (plantain and chicory) will have far higher cobalt content than common pasture grass species. Given the large number of factors, how do I untangle this mess to reach a recommendation? • Look at the soil test data you already have. Soils with good cobalt levels, low manganese content and a solid liming history are less likely to result in B12deficient lambs. Soils with low cobalt levels, high manganese content, or an acidic soil test are more likely to result in deficiency. • Pastures dominated by grass with little clover and herb content are more likely to result in deficiency than clover rich pastures or herb stands. There are numerous reasons why a sheep breeding
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