Objective—To evaluate several practice-adapted
assays for determination of passive transfer status in
Animals—24 llama and 9 alpaca crias.
Procedure—Serum IgG concentration was measured
by use of a radial immunodiffusion assay when crias
were 45 to 51 hours old. Results were compared with
serum γ-glutamyltransferase (GGT) activity, serum
total protein, albumin, globulin, and total solids concentrations,
and results of commercially available and
traditional sodium sulfite turbidity (SST) tests.
Results—Mean (± SD) serum IgG concentration was
1,762 ± 1,153 mg/dl. On the basis of a threshold value
of 1,000 mg of IgG/dl at 48 hours of age, 5 of 33
(15.15%) crias had failure of passive transfer. Serum
total solids, protein, and globulin concentrations were
significantly associated with serum IgG concentration,
whereas serum GGT activity and serum albumin
concentration were not. Serum IgG concentrations
were significantly different among crias with negative,
2+, and 3+ scores on the traditional SST test.
Serum IgG concentrations were not significantly different
between crias with negative and 100 mg/dl
scores or 100 and 300 mg/dl scores on the commercially
available SST test. However, all other comparisons
between crias with different scores revealed
significant differences. Sensitivity and specificity
ranged between 0 and 1, depending on the test and
Conclusion and Clinical Relevance—The commercially
available SST test and determination of serum
total protein and globulin concentrations are suitable
methods for assessing passive transfer status in
llama and alpaca crias. (J Am Vet Med Assoc
Objective—To determine sensitivity and specificity of
a cow-side immunoassay kit for assessing IgG concentration
Animals—76 dairy and 11 beef cows of various parities.
Procedure—Colostrum from first, second, and third
milkings and milk samples were collected, and IgG
concentration was determined by means of radial
immunodiffusion. The immunoassay was performed
according to the manufacturer’s instructions, and
sensitivity and specificity were calculated by comparing
results of the immunoassay (positive vs negative)
with results of immunodiffusion (< 50 g/L vs
≥ 50 g/L).
Results—135 colostrum or milk samples were collected.
Mean ± SD colostral IgG concentrations,
determined by means of radial immunodiffusion for
dairy and beef cows were 65.4 ± 51.4 g/L and 114.8
± 42.7 g/L, respectively. Mean IgG concentrations
for first-, second-, and third-milking colostrum samples
and for milk samples were 92 ± 49.0 g/L, 74.6
± 45.1 g/L, 47.5 ± 32 g/L, and 6.8 ± 3.8 g/L, respectively.
Sensitivity of the immunoassay (ie, percentage
of samples with IgG concentration < 50 g/L
with a positive immunoassay result) was 93%, and
specificity (ie, percentage of samples with IgG concentration
± 50 g/L with a negative immunoassay
result) was 76%.
Conclusions and Clinical Relevance—Results
suggested that the immunoassay kit was an
acceptable cow-side test to identify colostrum
samples with IgG concentrations < 50 g/L. The
immunoassay kit should be useful in screening
colostrum for adequate IgG concentration before
feeding to calves or storage. (J Am Vet Med Assoc 2005;227:129–131)