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.     

Effects of pasteurization of colostrum on subsequent serum lactoferrin concentration and neutrophil superoxide production in calves

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 X 10(6) 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.     

Passive transfer of colostral immunoglobulins in calves

Passive transfer of colostral immunoglobulins has long been accepted as imperative to optimal calf health. Many factors, including timing of colostrum ingestion, the method and volume of colostrum administration, the immunoglobulin concentration of the colostrum ingested, and the age of the dam have been implicated in affecting the optimization of absorption. The practice of colostrum pooling, the breed and presence of the dam, and the presence of respiratory acidosis in the calf also may affect passive transfer. Various tests have been reported to accurately measure passive transfer status in neonatal calves. The radial immunodiffusion and the enzyme-linked immunosorbent assay (ELISA) are the only tests that directly measure serum IgG concentration. All other available tests including serum total solids by refractometry, sodium sulfite turbidity test, zinc sulfate turbidity test, serum gamma-glutamyl transferase activity, and whole blood glutaraldehyde gelation estimate serum IgG concentration based on concentration of total globulins or other proteins whose passive transfer is statistically associated with that of IgG. This paper presents a comprehensive review of the literature of passive transfer in calves including factors that affect passive transfer status, testing modalities, effects of failure of passive transfer on baseline mortality, consequences of failure of passive transfer, and some treatment options. Many previously accepted truisms regarding passive transfer in calves should be rejected based on the results of recent research.     

Chloramphenicol 3. Clinical pharmacology of systemic use in the horse

The use of chloramphenicol in the horse is now prohibited as horses are classified as food-producing animals. However, chloramphenicol has until recently been widely available for oral, intramuscular or intravenous administration. A critical appraisal of the published literature on the use of chloramphenicol in the horse clearly demonstrates that there are sound pharmacokinetic and microbiological reasons for concluding that chloramphenicol is not an appropriate antibiotic for systemic use. The short half-life of chloramphenicol in the horse, together with the broad range of minimum inhibitory concentrations of target pathogens, preclude the use of practical dosage regimens. It can be concluded that the withdrawal of chloramphenicol will have no adverse effects on chemotherapy in the horse.     

New methods and strategies for monitoring susceptibility of fleas to current flea control products

A flea larval bioassay was developed by an international team of scientists to monitor the susceptibility of fleas (Ctenocephalides felis) to imidacloprid (Advantage, Bayer HealthCare). The assay was validated using laboratory and field isolates of C. felis. Flea eggs representing different field isolates of C. felis were collected by veterinarians in the United States, United Kingdom, and Germany. Of the 972 flea isolates obtained during the 5-year study, 768 contained sufficient numbers of eggs to conduct the larval bioassay. Greater than 5% survival occurred for only six of the field isolates evaluated. Further evaluation and analysis of these isolates demonstrated that they did not differ significantly in their susceptibility to imidacloprid from the reference strains used to develop the assay. Collections of field flea isolates will continue in an attempt to detect and document any change in the susceptibility of field flea populations to imidacloprid.     

Colostral immunoglobulin concentrations in Holstein and Guernsey cows.

OBJECTIVE: To compare the concentration of IgG in colostrum between Holstein and Guernsey cows and among cows of various lactations. DESIGN: Cross-sectional cohort study. SAMPLE POPULATION: Colostrum samples from 77 Holstein and 24 Guernsey cows. PROCEDURE: Colostrum samples were obtained from 101 cows. Colostral IgG concentration was determined, using a radial immunodiffusion assay. Regression analysis was used to determine the effect of breed and lactation number on colostral IgG concentration. Survival analysis and t-tests were used to compare the proportion of colostrum samples that would provide 100 g of IgG for various volumes of colostral intake. RESULTS: Guernsey cows produced 36.4 g of IgG/L of colostrum more than that of Holstein cows. Cows in the third or greater lactation produced 19.5 g of IgG/L of colostrum more than that of first-lactation cows. The IgG concentration of colostrum produced by second-lactation cows did not differ significantly from that produced by first-lactation cows. The colostral IgG concentration of these Holstein and Guernsey cows was higher than values that have been reported elsewhere. CONCLUSIONS AND CLINICAL RELEVANCE: Volume of colostrum needed to meet IgG intake goals is probably lower for Guernsey cows than Holstein cows. Colostrum from first-lactation cows was adequate in IgG content. The practice of discarding colostrum from first-lactation cows on the basis of inadequate IgG content was not justified in this study.     

Endogenous enzymes, heat, and pH affect flavone profiles in parsley (Petroselinum crispum var. neapolitanum) and celery (Apium graveolens) during juice processing

Flavones are abundant in parsley and celery and possess unique anti-inflammatory properties in vitro and in animal models. However, their bioavailability and bioactivity depend in part on the conjugation of sugars and other functional groups to the flavone core. The effects of juice extraction, acidification, thermal processing, and endogenous enzymes on flavone glycoside profile and concentration in both parsley and celery were investigated. Parsley yielded 72% juice with 64% of the total flavones extracted, whereas celery yielded 79% juice with 56% of flavones extracted. Fresh parsley juice averaged 281 mg flavones/100 g and fresh celery juice, 28.5 mg/100 g. Flavones in steamed parsley and celery were predominantly malonyl apiosylglucoside conjugates, whereas those in fresh samples were primarily apiosylglucoside conjugates; this was apparently the result of endogenous malonyl esterases. Acidification and thermal processing of celery converted flavone apiosylglucosides to flavone glucosides, which may affect the intestinal absorption and metabolism of these compounds.     

The role of essential trace elements in embryonic and fetal development in livestock

This review addresses the concept that essential trace minerals play a vital role in many enzymatic and metabolic pathways that are critical for conceptus development during pregnancy in livestock species. The conceptus relies entirely on the maternal system for a sufficient supply of trace minerals and other nutrients needed for normal development. If this supply is inadequate, growth and/or health of the conceptus can be affected adversely, and many of these effects carry over into the neonatal period. Information, accumulated in our laboratory and presented herein, indicates that zinc, copper and manganese are among the trace minerals that have the greatest impact on reproduction. For example, levels of zinc, copper and manganese were several fold greater in the conceptus than in other reproductive tissues, indicating that the conceptus preferentially accumulates these minerals, an action that may be important for conceptus development, growth and survival. Moreover, some recent results indicate that increasing the biological availability of zinc, copper and manganese, by attachment to short peptide chains (i.e., proteinated trace minerals) can enhance reproductive performance of swine. Mineral concentrations in conceptuses from female pigs consuming proteinated trace minerals were greater than those from females that consumed only inorganic mineral salts. Elucidating the mechanisms whereby conceptus development and survival are enhanced by essential trace minerals may lead to development of specific feeding programs to increase the number and health of offspring at parturition, thereby allowing for further improvements in production efficiency in animal agriculture.     

Comparison of refractometers and test endpoints in the measurement of serum protein concentration to assess passive transfer status in calves

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.