Objective—To evaluate 3 refractometers for detection
of failure of passive transfer (FPT) of immunity in calves,
and assess the effect of refractometric test endpoints
on sensitivity, specificity, and proportion of calves classified
correctly with regard to passive transfer status.
Procedure—Blood samples were obtained from calves
that were < 10 days old. Serum IgG concentration was
determined by use of a radial immunodiffusion assay.
Accuracy of 3 refractometers in the prediction of serum
IgG concentration was determined by use of standard
epidemiologic methods and a linear regression model.
Results—At a serum protein concentration test endpoint
of 5.2 g/dL, sensitivity of each refractometer
was 0.89 or 0.93, and specificity ranged from 0.80 to
0.91. For all refractometers, serum protein concentration
test endpoints of 5.0 or 5.2 g/dL resulted in sensitivity
> 0.80, specificity > 0.80, and proportion of
calves classified correctly > 0.85. Serum protein concentrations
equivalent to 1,000 mg of IgG/dL of serum
were 4.9, 4.8, and 5.1 g/dL for the 3 refractometers.
Conclusions and Clinical Relevance—The refractometers,
including a nontemperature-compensating
instrument, performed similarly in detection of FPT.
Serum protein concentration test endpoints of 5.0
and 5.2 g/dL yielded accurate results in the assessment
of adequacy of passive transfer; lower or higher
test endpoints misclassified larger numbers of
calves. (J Am Vet Med Assoc 2002;221:1605–1608)
Objective—To evaluate precolostral hypogammaglobulinemia
in neonatal llamas and alpacas, to determine
when postcolostral peak serum IgG concentrations
develop, to determine whether differences in
postcolostral serum IgG concentrations between llamas
and alpacas exist, and to determine postcolostral
half-life of serum IgG in llamas and alpacas.
Design—Prospective observational study.
Animals—29 llama and 10 alpaca crias.
Procedure—Blood samples were collected prior to
suckling and on days 1, 2, and 3 after parturition and
analyzed for serum IgG concentration by use of a
commercial radial immunodiffusion assay. Additional
samples were collected on days 8, 13, and 18 from 8
crias to determine mean half-life of IgG.
Results—Llamas and alpacas are born severely
hypogammaglobulinemic. Mean serum IgG concentrations
for day-1, -2, and -3 samples for llamas were
1,578 mg/dl, 1,579 mg/dl, and 1,401 mg/dl, respectively,
and for alpacas were 2,024 mg/dl, 1,806 mg/dl,
and 1,669 mg/dl, respectively. Peak serum
immunoglobulin concentration developed between
days 1 and 2. Mean half-life of IgG for all crias was
Conclusions and Clinical Relevance—Although
increased mortality has been linked to failure of passive
transfer, it is clearly possible to raise crias that
have low serum immunoglobulin concentrations.
Llamas and alpacas do not differ significantly with
respect to immunoglobulin absorption or IgG concentration
in neonates. The optimal sampling time for
passive transfer status is between 1 and 2 days.
(Am J Vet Res 2000;61:738–741)
Objective—To determine whether serum IgG concentrations
in neonatal calves are adversely affected
by short-term frozen storage of colostrum.
Sample Population—Experiment 1 consisted of 10
pairs of Holstein calves (n = 20) fed matched aliquots
of either fresh (n = 10) or frozen and thawed (10)
colostrum. In experiment 2, 26 Holstein calves were
fed either fresh (n = 13) or frozen and thawed (n = 13)
Procedure—Experiment 1 consisted of calves resulting
from observed parturitions; calves were randomly
assigned to treatment groups (fresh or frozen and
thawed colostrum) in pairs. Calves were fed 4 L
aliquots of colostrum via oroesophageal intubation at
3 hours of age. Serum IgG concentrations at 2 days of
age were compared between the 2 groups by use of
a paired t-test. Experiment 2 consisted of calves
resulting from observed parturitions; calves were randomly
assigned to treatment groups (fresh or frozen
and thawed colostrum). Calves were fed 4 L aliquots
of colostrum via oroesophageal intubation at 3 hours
of age. Regression analysis was used to determine
whether calf serum IgG concentration was a function
of colostral IgG concentration and colostrum storage
Results—Significant differences were not observed
between the 2 groups in experiment 1. No significant
relationship was observed between colostrum storage
group and serum IgG concentration in experiment
2. The model that best predicted serum IgG concentrations
accounted for 20% of the variability in
serum IgG concentration.
Conclusion and Clinical Relevance—Frozen
colostrum is an adequate source of IgG for calves. (J
Am Vet Med Assoc 2001;219:357–359)
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 the effects of pasteurization
of colostrum on serum lactoferrin concentration and
neutrophil oxidative function by comparing values
from calves given pasteurized (76 C, 15 minutes)
colostrum versus calves given fresh frozen colostrum.
Animals—8 Holstein bull calves were used to study
the effects of pasteurization of colostrum on the
absorption of lactoferrin and neutrophil oxidative burst.
Three additional calves were used to study the effect
of exogenous lactoferrin on neutrophil oxidative burst.
Methods—Calves were fed fresh frozen or heat pasteurized
colostrum (76 C for 15 minutes) via
esophageal feeder within 4 hours of birth. Neutrophils
were isolated from whole blood samples. Neutrophil
oxidative burst was induced by phorbol ester (300
ng/ml) stimulation of cells (1 × 106 cells) at 37 C.
Serum lactoferrin concentrations were compared,
using immunoblot analysis. Serum IgG concentrations
were determined by radial immunoassay.
Comparisons were made between the use of the 2
types of colostrum in calves by measuring subsequent
serum IgG and lactoferrin concentrations and
neutrophil superoxide production.
Results—Serum IgG and lactoferrin concentrations
increased more in calves receiving fresh frozen
colostrum. Neutrophil superoxide production was higher
in neutrophils prepared from calves receiving fresh
frozen colostrum. Colostral lactoferrin addition to neutrophil
incubations resulted in increased oxidative burst.
Conclusions and Clinical Relevance—Compared
with calves given fresh frozen colostrum, calves given
pasteurized colostrum had decreased serum IgG and
lactoferrin concentrations and neutrophil superoxide
production 24 hours after administration. These
results suggest that pasteurizing bovine colostrum at
76 C for 15 minutes has substantial effects on passive
transfer of proteins and neutrophil function. (Am J Vet