Milverton-Wellesley Veterinary Services
We know that calcium in the fresh period plays such a big role in determining the outcome of a dairy cow’s lactation. Low blood calcium has been shown repeatedly to be linked to increased risk for adverse events in the transition period, including likelihood to get a Displaced Abomasum (DA). We know from experience that not all cows bounce back the same way after surgery, for a variety of reasons; how quickly a diagnosis was made, how ketotic the cow is, level of rumen fill, quality of follow-up care, and any complications during surgery (like fatty liver, adhesions or peritonitis) or concurrent health conditions (mastitis, metritis, pneumonia, etc.). But sometimes we can’t really explain why certain cows seem to do better than others after surgery. Researchers out of New York wanted to determine if blood calcium levels were correlated to prognosis for recovery from DA surgery.
The field study included 152 American dairy cows with LDAs that went through surgery, and had their blood taken at the time of LDA diagnosis to check their blood calcium levels. Because this study drew on regular dairy practitioners to participate by drawing blood from their everyday DAs, it was difficult to control for farm and veterinarian factors, compared to a more controlled clinical trial run at a university dairy, for example. However, this makes it fairly applicable to “real life.”
The researchers compared blood calcium levels and categorized cows into “low” and “high” level groups, then compared those numbers with milk production and herd removal rates in the first 60 DIM. So what were the findings?
The median (or most common) calcium level of all the cows in the study was 2.1 mmol/L which falls into the “low” category.
Several cows also had low enough calcium levels that they would be expected to be down.
They did not find any significant effect of calcium levels on milk production and cull rate.
So what can be taken away from this study? Many cows with DAs have low blood calcium. We have learned before that off-feed fresh cows are often hypocalcemic, due to the increased calcium demand and reduced intake from feed. It is interesting to find out just how low many of them are hypocalcemic, which explains the weakness sometimes seen in cows with LDAs, or why some even go down during surgery! This study doesn’t seem to indicate that we need to be running blood work on every DA in order to tell us how well they will do after surgery, nor do we need to run a bottle of calcium into every cow we do surgery on. However, it does point to the probable merit of supplementing calcium in these cows - which is most commonly already done at our clinic by pumping with a milkshake which contains calcium propionate. If the cow isn’t pumped, then a bolus or SQ calcium could be given if deemed necessary.
Remember, this study was not controlled for various differences in veterinary protocols, including after-care, so some of these cows received calcium supplementation, or other treatments like pain killers or different antibiotics that could have influenced the results. The data shows that LDA cows are often low in calcium, and this should be considered when deciding how to treat one of your surgery cows, especially those cows that just aren’t bouncing back as expected.
Bach, KA., McArt, JAA. March 2021. “Blood calcium as a prognostic indicator of success after surgical correction of left displaced abomasum.” Journal of Dairy Science Communications, volume 2.