Stability of gamma-glutamyltransferase activity in calf sera after refrigerated or frozen storage.
OBJECTIVE
To examine stability of -glutamyltransferase (GGT) activity in stored serum from neonatal calves.


METHODS
10 commercial beef calves between 36 and 60 hours old.


METHODS
Serum samples were obtained from the calves, and each sample was divided into 8 aliquots. Serum GGT activity was measured on day 0 (fresh) and days 1, 2, 3, and 4 of refrigerated storage (4 C) and weeks 1, 2, and 3 of frozen storage (-20 C).


RESULTS
Serum GGT activities for each of the refrigerated aliquots did not significantly differ from day zero, with serum GGT activity (expressed as a percentage of initial activity) > 99% on all 4 days. Serum GGT activity in frozen aliquots decreased significantly after 1 and 2 weeks of frozen storage, 97 and 98%, respectively; however, this decrease in GGT activity was not biologically significant. The observed GGT activity did not decrease significantly in the samples stored frozen for 3 weeks; these samples retained 99% of initial activity.


CONCLUSIONS
The observed stability of serum GGT activity indicates that serum may be obtained, stored, and batch processed at a later time. This stability during storage is important to the success of a bovine passive transfer monitoring program based on GGT activity.
Muller
F
F
Department of Veterinary Clinical Sciences, Washington State University, Pullman 99164, USA.
Tyler
J W
JW
Parish
S M
SM
Johnson
K A
KA
Krytenberg
D S
DS
Wilson
L K
LK
D000818:Animals; D001793:Blood Preservation / Q000379:methods / Q000662:veterinary*; D002417:Cattle / Q000097:blood*; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D013997:Time Factors; D005723:gamma-Glutamyltransferase / Q000097:blood*
D005723:gamma-Glutamyltransferase