Farmers need specific programmes for supplementing trace elements. These programmes should optimise trace elements – especially those that are important in major events like calving (or lambing), mating, rapid growth and stress adaptation.
Farmers often think fertility is highly heritable and can be quickly improved by using the right bull or ram, or the so-called fertile breeds. But feeding and management play a more important role in fertility.
The two most important nutrition-linked factors for fertility are body condition at mating and trace element status. Selecting fertile, well-adapted animals should always be part of a long-term strategy but a good supplementation programme that ensures optimal condition and trace element status at lambing or calving is critical.
Functions of the most important trace elements:
■ Zinc is essential for sexual maturity, the onset of oestrus and optimal fertility.
■ Zinc is also essential for complete testicular development, the quantity and quality of semen and for libido.
■ Manganese is essential for oestrogen production, oestrus and ovulation, and for normal testicular development.
■ Manganese-deficient cows produce more bull calves than heifers.
■ Marginal selenium levels lead to a compromised immune system, abortions, retained afterbirths and weak calves.
■ Optimal copper levels are essential for normal oestrus, conception, embryo survival and the viability of young calves.
■ Along with phosphorus, copper is viewed as the most essential mineral for beef cattle production.
South Africa has world-class livestock experts (ruminant nutrition experts), and South African livestock farmers routinely supplement their veld with macro nutrients, protein, energy and phosphorus. But farmers should focus their attention more seriously on the trace element content of licks and on trace element supplementation.
Supplementing trace elements should not be based solely on licks because variations in the content of licks bind minerals – particularly calcium, sulphur, molybdenum and iron – in the digestive tract, and reduce their absorption significantly. This often leads to suboptimal trace element levels before calving or lambing, before mating, in vigorous young growth and with stress.
In Southern Africa, drinking water (especially borehole water) for cattle often contains a lot of calcium and/or iron, which greatly impedes the absorption of essential trace elements.
Programmes for supplementing trace elements in ruminants should always be based on two aspects: oral supplementation (licks) and injections. Inject trace elements four to six weeks before calving or lambing to ensure the trace element function will be optimal when needed.
Good quality injectable trace element preparations have the advantage that the trace elements are not bound in the digestive tract and the animals can use them very efficiently.
Note the following regarding injectable trace element preparations:
■ Use an injectable trace element preparation with a proven practical test result, as well as proven results for its bioavailability to provide what ruminants need before economically critical periods.
■ Trace element injections for cattle should contain zinc, manganese, selenium, copper and chrome. Iodine should also be injected in the areas where there is a real deficiency, such as in the Pietermaritzburg region.
■ Cobalt offers no benefits in an injectable product. It must be taken orally, from where it goes to the rumen where microbes use it to produce vitamin B12. If there is a cobalt deficiency, vitamin B12 may be injected.
■ Animals should be injected four to six weeks before economically critical periods.
When it comes to licks, note the following:
■ Ensure that phosphate and protein licks, and those for energy or production, provide at least 50% of the total trace element requirement.
■ Licks should contain zinc, manganese, selenium, copper, chrome, cobalt and iodine.
■ Cattle have a greater need for copper than sheep, and cattle licks should contain more copper than sheep licks. Consult your vet about assessing the status of copper in the livers of your sheep before adding copper to licks.
■ Supplement iron only if you are certain there is a deficiency. Basic feeds and drinking water usually contain more iron than ruminants need.
■ Make sure that licks do not contain too much calcium, sulphur, iron, molybdenum or other elements known to impede trace element absorption. There is often too much calcium and iron, which has detrimental results as it binds trace elements and reduces absorption.
■ Always have trace element licks available for animals, particularly from eight weeks before calving.
