Effect of calcium supplementation on milk production and hypocalcaemia

Abstract

A dairy farmlet trial carried out in Central Taranaki in 1999/2000 and 2000/2001 examined the effects of calcium (Ca) supplementation (110-180 g/cow of fine limeflour drenched daily between calving in August and mid-mating in December) on serum Ca, incidence of milk fever and milksolids (MS) production at stocking rates of 2.5, 3.2, 3.7 and 4.2 Jersey cows/ha. Pasture Ca contents in spring were around 0.4% in both years and in the marginal to adequate range for dairy cow requirements. However, average blood serum Ca concentrations of 2.4 mmol/l were moderate and only 5% of non-Ca-treated cows occasionally had serum Ca less than 2 mmol/l, within the range for sub-clinical hypocalcaemia. Incidence of clinical milk fever was negligible (0-1%) in milking cows, with no treatment differences. There was no significant effect of Ca supplementation on MS production, although there was a consistent trend (all farmlets in both years) for a small response (3-4%) at the first herd testing. Keywords: calcium supplementation, dairy cow reproduction, dairy cows, hypocalcaemia, milksolids production