Restriction of free access to feed and resting area after last milking before dry-off associated with lower blood calcium levels in dairy cows

A recent publication has emphasized the fact that subclinical hypocalcaemia can be found in dairy cows immediately following dry-off (Krogh et al., 2018) and the condition of atypical milk fever (clinical hypocalcaemia in late gestation) has been described before (Radostitis et al., 2007). Despite considerable research into dry cow management and the increasing level of milk production at dry-off in the modern cow, there is limited information available on the prevalence of hypocalcaemia at dry-off and potential associated risk factors. This study aims to assess the prevalence of subclinical hypocalcaemia after the last milking before dry-off in dairy cows in United Kingdom. Additionally, to evaluate the effect of the restriction of access to feed and lying area on the mean serum total calcium value at this stage of the lactation cycle.

Overall, 67% (132/197) of cows were without access to feed or lying for ≥ 1 hour after their last milking before dry-off. Analysis of serum total calcium demonstrated that 2% of cows had hypocalcaemia (5/197) 8-12 hours after their last milking before dry-off. Statistical analysis demonstrated that cows with ≥ 1h without access to feed and lying area had a significantly lower mean serum calcium value (mmol/L) 8-12 hours after their last milking before dry-off compared to those that were without access to feed and lying area for < 1hr (2.400 vs. 2.441, P=0.018).