Dr Jeff Cave
District Veterinary Officer
It is important to remember, even if the current dry seasonal conditions wane, many farmers will still be feeding-out to livestock due to the lack of nutritious pastures.
It is essential to provide stock with the minimum nutritional requirements to prevent deficiencies, sub-optimal production, disease and death.
As feeding-out to livestock continues, deficiencies in fat-soluble vitamins, particularly vitamins A and E are possible, although it is worth remembering that vitamin A and E deficiency only occurs if green feed has been absent for many months.
Treatment for both vitamin A and E deficiencies are by supplementation via injection or drench but should only be considered if lambs and cattle have been lacking green feed for three to four months, or if adult sheep have been lacking green feed for more than nine months.
Calcium, phosphorous and sodium deficiency are three mineral deficiencies that may also be seen during longer periods of feeding-out.
Calcium deficiency most commonly occurs in diets containing a high proportion of cereal grain. The addition of agricultural limestone mixed with the ration can be an effective form of prevention.
Phosphorus deficiencies occur when diets consist mainly of low-quality roughage for an extended period. The main signs of phosphorus deficiency are shifting lameness, an arched back and difficulty walking.
With extended deficiencies, stock may chew sticks, stones or bones from carcasses in paddocks to gain their phosphorus requirements. This then leads to a significant risk of botulism from the ingestion of bacterial spores in the decomposing tissues attached to bones.
Sodium is a major component of salt. Salt is important for the regulation of many processes in the animal’s body.
Most grains are deficient in sodium, so an addition of salt to diets containing a large proportion of grain, where stock drinking water has a low salt content, is recommended to prevent deficiencies.
The addition of salt to grain diets fed to wethers and rams may also assist in the prevention of bladder stones and urinary blockages by increasing water intake.