It is common knowledge that every case of clinical milk fever is costly. Lesser-known are all the negative effects of invisible milk fever i.e. cows developing a lack of calcium around calving but not having any clinical symptoms.
Approx. 50 % of all other cows are suffering from invisible milk fever (Reinholdt et al., 2011), whereas only a smaller part are developing clinical milk fever. Because of this high percentage of invisible milk fever, this disease involves larger costs than clinical milk fever at herd level.
Since the negative effects of invisible milk fever have been thoroughly examined, recent research has changed the limit for when a cow is identified as sick. Earlier a cow with a calcium level lower than 2.0 mmol/L was considered as a cow with invisible milk fever. Now the value 2.1 and 2.2 mmol/L is used more often and thus far more cows are considered sick.
In a more recent Canadian test with 55 herds it was found that cows with a level below 2.1 mmol Ca/L (i.e. invisible milk fever) in average were lacking 2.6 L/milk/cow/ day (Chapinal et al., 2012). Moreover, the cows with a calcium level below 2.2 mmol/L in the blood at calving are more likely to develop metritis and to have 15 extra empty days.
The product X-Zelit can remedy the problem with invisible milk fever and clinical milk fever. The product has a positive effect on milk yield, somatic cell count, reproductive diseases and durability.