A comparison of serum harvesting methods and type of refractometer for determining total solids to estimate failure of passive transfer in calves

Monitoring the passive transfer of immunoglobulins from colostrums particularly in noncentrifuged samples can be useful for calf health management programs. The results of total solids refractometry from centrifuge and noncentrifuge harvested sources of serum were highly correlated (R2 = 0.95). Results from a digital and a hand-held refractometer were highly correlated (R2 = 0.96).     

Septicemic colibacillosis and failure of passive transfer of colostral immunoglobulin in calves

Septicemic colibacillosis is a highly fatal disease that occurs in calves less than 2 weeks of age. The disease occurs when a calf that fails to absorb protective levels of immunoglobulin from colostrum is exposed to an invasive serotype of E. coli. Management to ensure good passive transfer of colostral immunoglobulin will prevent this disease and reduce calf mortality caused by other infectious diseases as well.     

Seasonal variation in passive transfer of immunoglobulin G1 to newborn calves

Forty-eight-hour serum concentrations of immunoglobulin G1 (IgG1) were determined for 123 female calves born on 1 farm during a 12-month period and fed 2.8 L of colostrum by esophageal feeder within 2 hours of birth. Mean monthly serum IgG1 concentrations were lowest in the winter, and increased during the spring and early summer to reach their peak in September, after which they decreased. Eight of 64 calves (12.5%) born from June through October had failure of passive transer of IgG1 (serum IgG1 less than 8 mg/ml), whereas 27 of 58 (46.5%) born from November through May had failure of passive transfer.     

Evaluation of a commercially available immunoassay for assessing adequacy of passive transfer in calves

OBJECTIVE: To evaluate diagnostic utility of a commercially available immunoassay for assessing adequacy of passive transfer of immunity in neonatal calves. DESIGN: Prospective study. ANIMALS: 123 calves. PROCEDURE: Blood and serum samples were obtained from the calves prior to 2 weeks of age. The immunoassay was performed, along with refractometry and an 18% sodium sulfite turbidity test. Serum IgG concentration was determined with a radial immunodiffusion assay. Sensitivity and specificity of the immunoassay, refractometry, and the sodium sulfite test were calculated by comparing results with results of the radial immunodiffusion assay. RESULTS: Sensitivity and specificity of the blood IgG immunoassay were 0.93 and 0.88, respectively, compared with 1.00 and 0.53 for the sodium sulfite test. For refractometry, sensitivity and specificity were 0.71 and 0.83, respectively, when a serum total solids concentration of 5.2 g/dl was used as the cutoff between positive and negative test results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the immunoassay performs well in detecting calves with inadequate passive transfer of immunity.     

Evaluation of a lateral-flow immunoassay for use in monitoring passive transfer of immunoglobulins in calves

OBJECTIVE: To determine the predictive ability of a commercially available lateral-flow immunoassay used for determining passive transfer of immunoglobulins in calves. ANIMALS: 204 male Holstein calves ranging from 4 to 8 days old. PROCEDURE: Serum samples were obtained from each calf. Results of refractometry, zinc sulfate turbidity technique, and the lateral-flow immunoassay were determined. Sensitivity, specificity, accuracy, and predictive ability were calculated on the basis of IgG concentrations determined by turbidimetric immunoassay (TIA). RESULTS: Mean IgG concentration in the study was 10.9 mg/ml as determined by TIA. Rate of failure of passive transfer in this study population was 56%. Associations between the values for the refractometry and zinc sulfate turbidity techniques were established by regression analysis. Accuracy for the lateral-flow immunoassay, refractometry, and zinc sulfate turbidity methods was 95, 80, and 73%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The lateral-flow immunoassay was better at determining the status of passive transfer of immunoglobulins, compared with the refractometry or zinc sulfate turbidity methods. The ability of the lateral-flow immunoassay to provide accurate results should enable clinicians to make immediate management or intervention decisions.     

Enzyme-linked immunosorbent assay, single radial immunodiffusion, and indirect methods for the detection of failure of transfer of passive immunity in dairy calves

BACKGROUND: Confirmatory tests for failure of transfer of passive immunity (FTPI) in dairy calves require direct measurements of the serum immunoglobulin G concentration. Enzyme-linked immunosorbent assay (ELISA) has advantages over single radial immunodiffusion (SRID) in terms of cost and time. OBJECTIVES: To evaluate the agreement between ELISA and SRID, and to compare the diagnostic performance of ELISA with indirect methods, in the detection of FTPI in calves. ANIMALS: One hundred and fifteen dairy calves (aged 0-10 days) from 23 calf-rearing facilities. METHODS: Prospective, observational study. The agreement between SRID and ELISA was determined by the Bland-Altman method. Fixed bias (SRID - ELISA) was calculated. For comparison of the diagnostic performance of ELISA with indirect methods, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated at cut-off values of 500 and 1,000 mg/dL. RESULTS: The agreement between SRID and ELISA was 94%. Fixed bias (SRID - ELISA) was 140 +/- 364 mg/dL. The AUC and sensitivity of ELISA at the cut-off value of 1,000 mg/dL were higher than those of indirect methods (P<.004). The specificity of ELISA at the cut-off value of 1,000 mg/dL was not higher than that of indirect methods, except for serum total protein concentration assay. CONCLUSION AND CLINICAL IMPORTANCE: ELISA exhibited good diagnostic performance and good agreement with SRID. ELISA is an adequate method for both screening and confirmatory tests for FTPI in dairy calves at the cut-off value of 500 mg/dL.     

Failure of passive transfer in foals: incidence and outcome on four studs in New South Wales

Objective To determine the regional incidence and effectiveness of treatment of failure of passive transfer (FPT) in foals. Design A study of disease incidence. Animals Eighty-eight foals and 57 mares from four studs in the practice area of the Rural Veterinary Centre were tested. Procedure Foals were tested for their serum IgG and total serum protein (TSP) concentration within the first 72 hours of life. Colostrum was collected from mares and specific gravity determined. FPT and partial failure of passive transfer (PFPT) of immunoglobulins was diagnosed when serum IgG concentrations were < 4 g/L and 4 to 8 g/L respectively. Owners of foals diagnosed with FPT were offered treatment with 1 to 2 L plasma (TSP > 70 g/L); 9 (64%) of the affected foals were treated. Results Fourteen foals (16%) had FPT whereas 15 (17%) had PFPT. There were significant differences between the mean TSP concentration in foals with FPT (42.6 ± 4.2 g/L), PFPT (48.1 ± 3.9 g/L) and those acquiring adequate passive immunity (58.9 ± 5.5 g/L) (P < 0.01). Sixteen (29%) mares had pre-suck colostral specific gravity < 1.060 and 12 (71%) foals raised by these mares had FPT or PFPT. The incidence of severe disease (categorised by a sepsis score > 11, positive culture of bacteria from blood or disease requiring hospitalisation) in all foals in the first 2 months of life was 10%. However, none of the nine foals with FPT that received plasma experienced severe disease. In contrast, foals with PFPT had an increased susceptibility to severe disease (P < 0.001) when compared with normal foals. Conclusion Treatment of foals with FPT may reduce the subsequent incidence of severe disease. Pre-suck colostral specific gravity and foal TSP may be used to predict the likelihood of FPT and PFPT. Even though the number of foals studied is small the results highlight the importance of optimal management practices in reducing the incidence of FPT and disease associated with this process.     

Failure of passive immunoglobulin transfer: a major determinant of mortality in newborn alpacas (Lama pacos)

Failure of passive transfer (FPT) of immunoglobulin from colostrum was demonstrated as a major determinant of mortality in newborn alpacas (Lama pacos; crias). Serum IgG concentrations of dying crias were significantly (P less than 0.0001) lower than were serum IgG concentrations of crias that lived. Of 82 crias, 10 (12%) died within 1 month of age, and 7 of these had 0 to 9 mg of IgG/ml of serum at 48 hours after birth; 5 of the 7 had evidence of infectious diseases. The serum IgG concentrations of the remaining dead crias were 12, 13, and 20 mg/ml. On the basis of serum IgG concentrations of crias that died in the first month, FPT was defined as a 48-hour serum IgG concentration less than 9 mg/ml, which was greater than 2 SD below the 48-hour mean of clinically normal crias. Using this definition, the prevalence of FPT in the 82 crias studied was 9%. Corroborative evidence of the relationship between FPT and mortality was obtained from a retrospective study of 21 dead crias. The postmortem serum IgG concentration of 5 crias that died 2 to 10 days after birth ranged from less than 1 to 3 mg/ml; all were greater than 2 SD below the mean of age matched clinically normal crias. The range of serum IgG concentration was 2.2 to 21 mg/ml in 8 crias that died 11 to 20 days after birth; serum IgG concentration in 1 cria was greater than 2 SD below the normal mean, and 6 were greater than 1 SD below the normal mean.(ABSTRACT TRUNCATED AT 250 WORDS)     

A review of diagnostic tests for diagnosing failure of transfer of passive immunity in dairy calves in New Zealand

ABSTRACT

The aim of this review is to critically assess the test characteristics and practicality of published data on direct and indirect tests for diagnosing failure of transfer of passive immunity (FPT) in dairy calves in New Zealand, to provide recommendations for veterinary practitioners, and to examine the recommended sample size for assessing herd-level prevalence of FPT and the confidence in the results obtained. The definition of FPT is based on measurement of concentrations of IgG in serum of neonatal calves after colostrum intake. The gold standard method for measurement of concentrations of IgG is radial immunodiffusion. However its cost, requirements for laboratory equipment, and the time taken to obtain results have meant that alternative tests have been developed. The turbidimetric immunoassay and ELISA also directly measure concentrations of IgG. Indirect tests include measurement of concentrations of total proteins (TP) in the laboratory or using a refractometer, γ-glutamyl transferase (GGT) activity, and the zinc sulfate turbidity (ZST) test. Of the indirect tests, measurement of concentrations of TP in the laboratory or using a refractometer combine high specificity and sensitivity with a consistent association with concentrations of IgG in calves between 1–7 days of age. Using a refractometer is less accurate than direct measurement in a laboratory, but is still a suitable test if low cost and speed are important. Although GGT activity is strongly associated with concentrations of IgG in serum, the relationship varies with time after birth. Therefore the target thresholds change with time, increasing error compared to the measurement of concentrations of TP in serum. Similarly, factors other than total concentrations of IgG have a significant effect on the association with ZST test, complicating interpretation. Thus, when direct measurement of concentrations of IgG is not feasible, the recommendation is that concentrations of TP in serum should be used as the diagnostic test for diagnosis of FPT, providing calves are not dehydrated. Using a sample size of 12 calves is suitable for estimating whether the herd-level prevalence of FPT is <20% or >20%, if there are no calves or >5 calves diagnosed with FPT, respectively, but is limited in diagnostic confidence when 1–4 calves test positive. Diagnostic interpretation can be significantly improved if tests of FPT are used alongside information on the likely risk of FPT on the tested farm.     

Insulin-like growth factor-I, passive immunity transfer, and stereological characteristics of small intestine of newborn calves

This study evaluated the concentration of insulin‐like growth factor (IGF)‐I present in the mammary secretions, its relation with changes in serum IGF‐I and immunoglobulin (Ig)G, and intestinal mucosa alterations of 42 calves during the first week of life. Cows were randomly assigned to two groups, treated and control, with 21 animals in each. The treated group was injected with 500 mg recombinant bovine somatotropin (rbST) at day ?35 relative to predicted calving date. Newborn calves were randomly assigned to a 2 × 3 factorial scheme: dams group and slaughter date (at birth, 2 and 7 days of life). IGF‐I concentration was higher in the colostrum of treated cows (P < 0.05), but did not differ in the subsequent mammary secretions. Immunoglobulin G concentration in colostrum and subsequent mammary secretions did not differ between groups (P > 0.05). No differences were found in calf serum IGF‐I levels from birth to the seventh day or serum immunoglobulin G concentration after 24 h of life (P > 0.05). IGF‐I colostrum levels observed in this study did not affect the small intestine morphometry. The segment from the middle jejunum showed higher mucosa partial volume (Vv) at birth and 7 days old compared to other segments, and at just 2 days of age this segment reduced its Vv, not differing from other segments of the same date.