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Abstract

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.

Design—Prospective study.

Animals—90 calves.

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)

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in Journal of the American Veterinary Medical Association

Abstract

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 15.7 days.

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)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether serum IgG concentrations in neonatal calves are adversely affected by short-term frozen storage of colostrum.

Design—Prospective study.

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) colostrum.

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 group.

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)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate several practice-adapted assays for determination of passive transfer status in crias.

Animals—24 llama and 9 alpaca crias.

Design—Prospective study.

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 endpoint selected.

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 2000;216:559–563)

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in Journal of the American Veterinary Medical Association

Abstract

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 Res 2000;61:1019–1025)

Full access
in American Journal of Veterinary Research