Stability of some serum enzymes in sheep, cattle, and swine during storage at different temperatures.

Owing to the increased use of serum enzyme determinations in veterinary diagnostic work, greater knowledge about the keeping qualities of different animal sera under various storing conditions seems desirable. The present paper deals with the stability of serum aspartate aminotransferase (AspAT = GOT), alanine aminotransferase (A1AT = GPT), lactate dehydrogenase (LDH), and a-hydroxybutyrate dehydrogenase (HBD) in cattle, sheep, and swine. Sera from 14—16 animals of each species were analysed daily for 5 days after storage at room temperature (22°C) and in the refrigerator (4°C). Samples kept in the deep-freezer (—20°C) were reanalysed once after 32—38 days. Significant differences of serum activity were found between individuals for all enzymes in the three species. Great variations were found in the stability of enzyme activities of different species. To summarize, it may be said that the changes of transferase activities were less pronounced under the different storing conditions than those of the dehydrogenases investigated. Pig serum in particular showed heavy losses of the latter enzymes already after 1 day, more pronounced at refrigerator than at room temperature. As a consequence of the results obtained, practical recommendations for analytical work on these enzymes are suggested.