Daily infusions with a chemical commonly associated with feelings of happiness were shown to increase calcium levels in the blood of Holstein cows and the milk of Jersey cows that had just given birth. The results, published in the Journal of Endocrinology, could lead to a better understanding of how to prevent milk fever (hypocalcaemia) in cows.
Hypocalcaemia is considered a major health problem for cows. It is associated with immunological and digestive problems, decreased pregnancy rates and longer intervals between pregnancies.
Whilst there has been research into the treatment of hypocalcaemia, little research has focused on prevention.
In rodents it has been shown that serotonin (a naturally occurring chemical commonly associated with feelings of happiness) plays a role in maintaining calcium levels.
Based on this, a team from the University of Wisconsin-Madison, led by Dr Laura Hernandez, investigated the potential for serotonin to increase calcium levels in both the milk and blood of dairy cows.
The team infused a chemical that converts to serotonin into 24 dairy cows in the lead up to them giving birth. Half the cows were Jersey and half were Holstein.
Calcium levels in both the milk and circulating blood were measured throughout the experiment.
Whilst serotonin improved the overall calcium status in both breeds, this was brought about in opposite ways.
Treated Holstein cows had higher levels of calcium in their blood, but lower calcium in their milk (compared with controls). The reverse was true in treated Jersey cows and the higher milk calcium levels were particularly obvious in Jerseys at day 30 of lactation – suggesting a role for serotonin in maintaining levels throughout lactation.
“By studying two breeds we were able to see that regulation of calcium levels is different between the two,” Ms Hernandez said.
“Serotonin raised blood calcium in the Holsteins, and milk calcium in the Jerseys. We should also note that serotonin treatment had no effect on milk yield, feed intake or on levels of hormones required for lactation.”
The next steps are to investigate the molecular mechanism by which serotonin regulates calcium levels, and how this varies between breeds.
“We would also like to work on the possibility of using serotonin as a preventative measure for hypocalcaemia in dairy cows,” Ms Hernandez said.