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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Objective

To determine the relationship between serum ɣ-glutamyltransferase (GGT) activity and serum IgG concentration in neonatal crias.

Design

Prospective observational study.

Animals

21 llama and 4 alpaca crias from 0 to 5 days old.

Procedure

Serum GGT activity was measured, using a commercially available kit. Serum IgG concentration was determined by use of radial immunodiffusion. With a serum IgG concentration of 1,000 mg/dl (considered adequate passive transfer), specificity and sensitivity of serum GGT activity in the detection of failure of passive transfer were determined. Regression models were developed to determine the relationship between serum GGT activity and serum IgG concentration.

Results

Sensitivity ranged from 0.56 to 0.89, and specificity ranged from 0.88 to 0.31, depending on the value of serum GGT activity chosen as a threshold. Proportion of crias correctly classified ranged from 0.76 to 0.52. Regression models failed to demonstrate a significant relationship between serum GGT activity and serum IgG concentration.

Clinical Implications

Passive transfer status in crias cannot be accurately predicted on the basis of serum GGT activity. (J Am Vet Med Assoc 1997;211:1165–1166)

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in Journal of the American Veterinary Medical Association

Objective

To develop an algorithm for predicting passive transfer status of lambs of various ages, using the lamb's age and serum ɣ-glutamyltransferase (GGT) activity.

Design

Prospective study.

Animals

51 Suffolk, Columbia, and crossbred lambs from 1 to 16 days old.

Procedure

Serum was obtained from all lambs. Serum GGT activity was measured, using a commercially available kit. Serum IgG concentration was determined by use of radial immunodiffusion. Day-1 serum IgG concentration was estimated from sample IgG concentration, lamb age, and the published 14-day half-life of IgG in lambs. Stepwise multivariate regression models were developed to estimate day-1 serum IgG concentration as a function of the natural logarithm of serum GGT activity (In[GGT]) and natural logarithm of lamb age (In[age]) at the time of sampling. These regression models were then used to calculate serum GGT activities that were equivalent to various day-1 IgG concentrations in lambs of various ages.

Results

In(GGT) and In(age) were significantly associated with estimated day-1 IgG concentration. Day-1 serum IgG concentration could be predicted using the formula: IgG = −7,686 + 1,366(In[GGT]) + 1,199(In[age]). The model was moderately accurate in predicting serum IgG concentration (R 2 = 0.52).

Clinical Implications

Serum GGT activity can be used to assess passive transfer status of lambs. (J Am Vet Med Assoc 1997;211:1163–1164)

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in Journal of the American Veterinary Medical Association

Abstract

Objectives

To examine stability of -glutamyltransferase (GGT) activity in stored serum from neonatal calves.

Animals

10 commercial beef calves between 36 and 60 hours old.

Procedure

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.

Conclusion

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. (Am J Vet Res 1997;58:354-355)

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in American Journal of Veterinary Research