Autumn is an ideal opportunity to evaluate your animals’ trace element status in preparation for winter and calving.
Hitting target body condition scores and ensuring adequate trace elements and nutrients will help set up the herd and young stock for a productive season ahead.
What trace elements does my herd need?
Trace elements are needed for normal function, growth and production and for the animal’s cells to work properly. If trace element levels are only borderline, reduced production occurs including less milk produced and pregnancy losses. When trace elements are too low animals are at risk of disease.
As we head towards the calving period trace element levels should be assessed to keep cows healthy and set them up for optimised milk production and reproductive performance. Young stock are most severely impacted by trace element deficiency as they have higher demands for growth.
Supplements can be given in a number of ways: injectable, on pasture, and in drench, feed and water, so we have to remember additive effects. Animals can also be over-supplemented, which can cause toxicity.
By comparison macro elements are required in larger quantities. These include: calcium, chlorine, magnesium, phosphorus, potassium, sodium and sulphur. Inadequate levels of macro elements have massive impacts too – one clinical case of milk fever is associated with 10-15 sub-clinical cases silently reducing production and animal performance in your herd.
Trace elements are stored differently in the body. Some are water soluble (urinated out), meaning they need to be supplemented daily, while others are stored in the liver, so can be supplemented up to safe levels with infrequent dosing. The diet animals intake differs in trace elements levels. This must be considered when assessing trace element status and how animals should be supplemented.
Optimal trace and macro element status makes life easier for farm staff, with reduced transitional disease including calvings, retained foetal membranes and down cows.
Trace elements and what they do
Copper (Cu): Used by nerves, bone, immunity and growth. Deficiencies cause “swayback” in young stock, disease outbreaks (low immunity), poor growth, decreased reproductive performance, poor coats.
Selenium (Se): Maintains cell membranes, thyroid metabolism and immune responses. Deficiencies result in reduced milk production, and reduced conception rates (embryonic loss).
Iodine (I): Critical for thyroid hormones that control metabolism in all cells. Severe deficiency cause goitre, increased new born deaths, and foetal membrane retention.
Zinc (Zn): In enzymes needed for metabolism, gene expression and immune system. When deficient, many body systems are affected.
Cobalt: Needed to make B12 in the rumen for glucose metabolism. Deficiency causes poor growth.
Preparing for the calving season ahead
During April
- Use body condition score and anticipated calving date to calculate dry off date. We can generally only put on half a body condition score each month a cow is dry, excluding the last month of pregnancy where she will not gain any body condition.
- Assess trace element status (iodine, copper, selenium, cobalt) pre-calving (pasture, soil, herbage and bloods/liver sampling) to identify if levels are adequate and give enough time to elevate levels if they are not.
- Remember young stock too. Due to New Zealand soil types, most youngstock need supplementation. The positive changes can be amazing and quick. Growth rates, coat colour and vigour can all improve in just weeks.
Talk to your vet about how best to test, and number of tests needed for each age group. For cows, if levels are deficient your vet will likely recommend supplementing over winter and/or in the colostrum mob e.g. inject iodine, copper, selenium, B12. Discuss with your vet how you will assess macro-element status (calcium and magnesium especially) closer to calving.
For farmers feeding supplements including palm kernel extract and fodder beet, it is vital you talk to your vet about this. Trace elements and macro element testing, and supplement as requirements change.