Magnesium status in Canarian and Holstein Cows in early lactation: correlation between serum and urine testing

Abstract

High-producing dairy cows often experience various metabolic disorders, particularly during stressful periods or times of increased production, such as pre- and post- partum stages. These disturbances can lead to health problems for the animals and economic losses for farmers. One of the most important disorders is hypomagnesemia, also known as grass tetany, which is important in cattle worldwide. The main way for the control of this pathology is prevention, as well as continuous monitoring and early detection of those cases that do not show clinical signs (subclinical). The methods for its evaluation are diverse, being mainly used the measurement of magnesium in serum and urine samples through multiple clinical and laboratory procedures. The aim of this study is to assess the usefulness of paired serum and urine magnesium determination, and its comparison between cattle breed with potentially different feeding strategies (Holstein versus Canarian breed), in addition to evaluate the potential use of an alternative (non-validated) urine magnesium methodology using the IDEXX ‘Catalyst One’ system. This study included a total of 15 cows (n=15), of which 10 belonged to Holstein Friesian cows and 5 to Canaria breed cows, selecting animals that were between 0-60 days of lactation (DIM). Blood and urine samples were collected from each animal. Urine samples were analysed using two different methods: one by a reference laboratory procedure, and the other by the ‘Catalyst One’ biochemical analyser, which has not yet been validated for this purpose. The results demonstrated a strong correlation between both methods, stating that ‘Catalyst One’ can be used for the analysis of magnesium in bovine urine samples with a certain degree of reliability. However, definitive validation requires a study with a larger sample size. Also, it was proved an agreement between the results from blood and urine samples, so both samples are very useful for assessing magnesium levels in cattle. Future studies should focus on collecting more data and information through the selection of a larger number of animals.