Balanced Mineral Intake at Calving can Boost Dairy Income - Massey Scientist
Results of studies at the university and overseas indicated that the mineral intake of pregnant cows during the three weeks either side of calving significantly affected peak milk production, reproduction, health and ultimately farm profitability.
Efforts to balance mineral intake to pregnant cows on the university's dairy cattle research unit coincided with a 14% increase in milk protein produced in early lactation. Massey animal scientist Gavin Wilson said calcium deficiency, causing clinical and subclinical effects, was the most common animal health problem resulting from mineral imbalances in the cow. He said cows could become calcium deficient before calving through having pastures too high in potassium relative to sulphur and chlorine. "They can also be deficient after calving when pastures have low calcium and / or magnesium concentrations through cold soil conditions or excessive potash use - especially if combined with nitrogen applications".
Dr Wilson said cows with milk fever represented the tip of the iceberg and many animals in the herd would be suffering sub-clinical calcium deficiency that would prevent them from milking to their potential. If two to five percent of cows showed clinical signs of milk fever, 30 to 40 per cent were probably suffering sub-clinical effects, he said.
Sub-clinical effects included mastitis, ketosis and a lower chance of mating sucessfully. Farmers had several options for minimising calcium deficiency including reducing excessive use of potash fertilisers or, at least, restricting their application in the summer-autumn period. They could feed pasture and low potasium supplements such as maize silage, brewer's grains or hay prior to calving or supplement cows' diets with anionic salts prior to calving. They could also ensure limiting minerals such as magnesium, zinc, and copper were fed during the three weeks either side of calving.
Published in Waikato Times, March 4, 1998
Balancing cow's mineral intakes around calving time can boost farm income, dairy farmers were told at a field day at Massey University's seasonal supply property.
