As the dry seasonal conditions lingers, the risk of vitamin and mineral deficiencies in sheep and cattle increase.
It is very important to provide stock with their minimum nutritional requirements to prevent deficiencies, sub optimal production, disease and death.
If dry conditions continue, deficiencies in fat-soluble vitamins, particularly vitamins A and E are possible.
Vitamin A is obtained from carotene, a substance found only in green feeds. Vitamin A deficiency only occurs after green feed has been absent for many months. Deficiencies in lambs occur when they have been without green feed for a minimum of six months.
Older sheep will become deficient only after 12 months with no green feed. As cattle have smaller stores of Vitamin A, it takes about three months without any green feed before they become deficient.
Signs of Vitamin A deficiency include night blindness and ill thrift.
Vitamin E deficiency is also attributed to a long-term lack of green feed. Affected lambs and calves exhibit a stilted gait, shifting lameness and arched back. Wool and body growth rates are also affected.
Treatment for both Vitamin A and Vitamin E deficiencies are by supplementation via injection or drench. This 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 be seen during dry seasonal conditions.
Calcium deficiency most commonly occurs in diets containing a high proportion of cereal grain. The addition of agricultural limestone mixed with the ration is 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 in an attempt 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.
For further information please contact your local veterinarian or Agriculture Victoria Veterinary or Animal Health Officer, or in NSW your Local Land Services.