Mineral supplements for stockers grazing small grains pasture
Gazing out across a field of green wheat or rye or triticale forage, one might assume the nutritional needs of stocker cattle are being adequately supplied by the forage. However, concentrations of macro- and trace minerals can range from deficient to adequate in these forages.
Relative to calf requirements, the calcium concentration in small grains forages ranges from adequate to marginal to very deficient in some instances, while phosphorus can be slightly deficient to adequate. Magnesium concentrations can be low relative to requirements of a lactating cow but marginal to adequate for stocker calves. Copper and zinc, two trace minerals of concern, also range from very deficient to adequate. Mineral deficiencies can retard growth and impair immune function. Calcium is involved in smooth muscle contraction and a calcium deficiency may play a role in the incidence and severity of bloat.
Research has demonstrated that stocker cattle grazing small grains pastures will respond efficiently to a complete mineral supplement. “Complete” meaning a supplement containing salt, macro-minerals and trace minerals in appropriate concentrations. On wheat pasture in northwestern Oklahoma, providing a complete mineral supplement to stocker cattle increased daily gain 0.50-0.57 lb compared to no supplement (no salt or other feeds). In another 4 year trial in Oklahoma, daily gain was 0.24 lb higher when stockers on wheat consumed a complete mineral supplement versus grazing with no supplements. The responses in these two studies occurred with average mineral supplement intakes ranging from 0.16 to 0.46 lb/day. Based on these responses, providing a mineral supplement would have improved 120 day gains by 29 to 60 lb/head with mineral consumption ranging from 19 to 55 lb/head. If the value of added gain on a stocker calf is $1.00/lb, in the worst case scenario of 29 lb added gain and 55 lb mineral consumption, the breakeven cost for the mineral supplement would be about $1050/ton.
In addition to supplying necessary mineral elements to stockers, mineral supplements are a means of delivering ionophores that can further enhance weight gain. The 4 year Oklahoma study mentioned previously also compared a mineral+ionophore (Rumensin @ 1600 gm/ton mineral) to no supplement or mineral supplement without ionophore. Including an ionophore in the mineral supplement increased daily gains another 0.23 lb/day compared to mineral only while the ionophore+mineral combination increased daily gain 0.46 lb/day compared to no supplement. Average consumption of the ionophore+mineral supplement was 0.15 lb/day. So, across a 120 day grazing period, including the ionophore in the mineral would have added another 28 lb compared to mineral alone and 55 lb compared to no supplement. Assuming a daily intake of 0.20 lb/day of the ionophore+mineral, the 120 day consumption would be 24 lbs/head. Compared to no supplement, the breakeven cost of the ionophore+mineral supplement would be over $4000/ton if value of added weight on the stocker calf is $1.00/lb.
Bottomline, forage analyses has shown that mineral concentrations in small grains pasture can be marginal to deficient and research has demonstrated that stocker cattle grazing small grains forages will respond efficiently and economically to mineral supplements.
Information written by Dr. Ted McCollum, Texas A&M AgriLife Extension, Beef Cattle Specialist.
