Effect of Heat-treatment on Accuracy of Infrared Spectroscopy and Digital and Optical Brix Refractometers for Measuring Immunoglobulin G Concentration in Bovine Colostrum

Survey on colostrum management by German dairy farmers focusing on frozen colostrum storage

Because calves are born with low levels of antibodies, effective colostrum management is one of the most critical factors for successful calf rearing. A timely and adequate supply of sufficiently high-quality colostrum immediately after birth is essential to ensure the passive immunization of calves. Frozen colostrum reserves are recommended to fulfill the immunological and nutrient requirements of newborn calves, even in exceptional situations; however, the implementation rates on German dairy farms and challenges of realization remain unclear. A 33-question online survey, focused on frozen colostrum reserves, was developed to obtain an overview of colostrum management practices on German dairy farms. The questionnaire was divided into 3 sections: (1) personal data; (2) farm characteristics; (3) colostrum management. Of the 155 responses we received, 63.9% were from female farmers, and 35.5% were from male farmers. Conventional farming was practiced on 89.0% of farms, and organic farming was practiced on 7.1% of farms. Of the respondents, 89.0% froze colostrum. The main reasons for freezing colostrum were (1) the dam does not produce enough colostrum; (2) the dam cannot be milked; or (3) the dam died during birth. Farmers primarily froze colostrum from cows during their third to fifth lactation. Before freezing, 33.1% of the respondents measured indicators in the colostrum to estimate Ig concentrations, whereas 2.3% determined the colostrum quality after freezing. Reusable and disposable polyethylene terephthalate deposits (23.1%, 22.3%) and colostrum bags (20.0%) were the primary containers used to freeze colostrum. The main reasons for not freezing colostrum were the high labor intensity and the availability of fresh colostrum from other cows. Thawing methods included buckets (47.7%) and professional water baths (13.8%). The survey identified areas in which improved knowledge transfer could enhance colostrum management. Furthermore, there appeared to be a lack of specific, feasible instructions for employees concerning the practical implementation of colostrum management. Most importantly, the regular determination and documentation of immunoglobulin concentrations should be emphasized. The added value of stored colostrum, relative to a greater workload, should also be promoted, particularly on smaller farms.

Comparison of turbidometric immunoassay and brix refractometry to radial immunodiffusion for assessment of colostral immunoglobulin concentration in beef cattle

BACKGROUND

Colostral immunoglobulin G (IgG) concentration is critical to the attainment of adequate transfer of passive immunity in cattle, however, studies comparing available tools for measurement of colostral IgG concentration in beef cattle are limited.

OBJECTIVES

To report the agreement between 3 commercially available tests for evaluating IgG concentration in beef colostrum.

ANIMALS

Two hundred six beef-breed cows hospitalized for calving management or dystocia.

METHODS

Retrospective study to assess IgG of whole colostrum measured stall-side via turbidimetric immunoassay (TI) and brix refractometry (BRIX), compared to fat separated (FS) analysis via single radial-immunodiffusion (RID; reference standard), TI-FS and BRIX-FS. Test performance was assessed using Passing Bablock regression, Bland-Altman analysis, and area under the curve to determine optimal thresholds.

RESULTS

Correlation between RID and TI-FS, BRIX-FS, or BRIX was similar (Spearman's ρ = 0.717, 0.715, 0.716, respectively) but correlation for TI was poor (ρ = 0.586). Regression analysis identified a substantial constant (-214.75 [CI: -272.03 to -178.07]) and proportional (13.24 [CI: 11.81-15.37]) bias between the RID and TI-FS which was similar for TI. TI-FS concentrations of 28.47, 38.75, and 50.62 g/L, BRIX-FS of ≤21.9%, ≤24.0%, and ≤27.4%, and BRIX of ≤21.3%, ≤23.8%, and ≤26.4% indicated IgG concentrations <50, <100, and <150 g/L, respectively; appropriate cutoffs for TI could not be generated.

CONCLUSIONS AND CLINICAL IMPORTANCE

Both TI and TI-FS demonstrated a large constant and proportional bias compared to RID; BRIX and BRIX-FS were well correlated with RID and remain a reliable method for estimation of colostral IgG concentration in beef cattle.

Bovine Colostrum for Veterinary and Human Health Applications: A Critical Review

Bovine colostrum harbors a diverse array of bioactive components suitable for the development of functional foods, nutraceuticals, and pharmaceuticals with veterinary and human health applications. Bovine colostrum has a strong safety profile with applications across all age groups for health promotion and the amelioration of a variety of disease states. Increased worldwide milk production and novel processing technologies have resulted in substantial growth of the market for colostrum-based products. This review provides a synopsis of the bioactive components in bovine colostrum, the processing techniques used to produce high-value colostrum-based products, and recent studies utilizing bovine colostrum for veterinary and human health.

Determining Immunoglobulin Content of Bovine Colostrum and Factors Affecting the Outcome: A Review

The immunoglobulin concentration in bovine colostrum should be measured to ensure feeding with sufficient immunoglobulins (≥50 mg immunoglobulin G mL-1). Adequate feeding prevents diseases, promotes development, and has a positive influence on the adult animal. Indirect and direct measurement methods are available for this purpose. Direct measurement methods cannot be easily used in practice; therefore, farmers use indirect methods such as a colostrometer and a refractometer. Many factors influence the immunoglobulin concentration of colostrum; some of them have already been intensively researched. In particular, lactation and temporal aspects play an essential role. Newer aspects such as dry period, seasonal influences, and genetics are gaining importance, but their impact on immunoglobulin content has not been sufficiently investigated. Developments are still needed, especially in data management. This review analyzes the outcome of different studies on the indirect and direct measurement methods and discusses different factors influencing the immunoglobulin concentration of bovine colostrum.

A Scoping Review of On-Farm Colostrum Management Practices for Optimal Transfer of Immunity in Dairy Calves

Newborn calves are agammaglobulinemic and rely for their first immune protection almost completely on the transfer of immune constituents via colostrum. Inadequate colostrum management practices such as on-farm colostrum storage practices and colostrum feeding methods could affect immune components in colostrum and subsequently immune status of the newborn calf. We conducted a scoping review to identify all literature on the interactions between several colostrum management factors and immunological colostrum quality and passive transfer of immunity. Three major stages were defined: milking methods, colostrum treatment and storage, and administration procedures. Separate CAB Abstracts searches were performed for each of the subjects of interest. The search process was completed on November 9, 2020. Colostrum should be milked as soon as possible, as IgG concentration diminishes over time, probably due to dilution. To minimize bacterial contamination, it is advised to pasteurize colostrum in small batches at maximal 60°C for 30 or 60 min. Freeze/thawing of colostrum does not or only slightly affect IgG concentrations, as long as thawing is done au bain-marie and temperature does not exceed 40°C. In on-farm situations, it is difficult to determine the volume that should be fed as the variables contributing to the absorption of IgG by the newborn calf are many and include the quality of the colostrum, the bacterial contamination, the time interval between birth and first moment of feeding and the weight of the calf. Despite all knowledge regarding optimal colostrum management strategies, it remains challenging to predict the effects of certain colostrum management choices in field conditions. Therefore, we recommend measuring the colostral quality, weighing the newborn calf, adjusting the feeding volume accordingly to ensure optimal colostrum intake for each calf.

Heat treatment of bovine colostrum: I. Effects on bacterial and somatic cell counts, immunoglobulin, insulin, and IGF-I concentrations, as well as the colostrum proteome

The objective of this study was to investigate the effects of heat treatment on colostral low-abundant proteins, IgG and IgA, insulin, and insulin-like growth factor I (IGF-I), as well as bacteria and somatic cells. First-milking colostrum samples >8 L and Brix % > 22.0 were harvested from 11 Holstein cows on a commercial dairy in New York State and split into 2 aliquots using single-use colostrum bags. One aliquot of each pair was cooled on ice immediately after harvest (raw, R; n = 11), and the other was heat-treated for 60 min at 60°C (heat, H; n = 11). All samples were analyzed for IgG and IgA via radial immunodiffusion assay and insulin and IGF-I concentrations by radioimmunoassay. Total bacterial counts and somatic cell counts (SCC) were determined using standard plate culture techniques and flow cytometry, respectively. Samples from a subset of 5 pairs (n = 10) were further analyzed by nano liquid chromatography-tandem mass spectroscopy, after ultracentrifugation at 100,000 × g for 60 min at 4°C to enrich the low-abundant protein whey fraction. Data were analyzed using either paired t-test or Wilcoxon signed-rank test or using an online software package to analyze proteomics data. Outcomes of proteomics analysis were fold change ≥1.5 between pairs, and paired t-tests with false discovery rate-adjusted P-value < 0.05. The median reduction of IgA concentrations was 8.5% (range: 0-38.0%) due to heat treatment, whereas IgG concentrations did not change due to treatment. Insulin concentrations decreased by a median of 22% (7-45%), and IGF-I decreased by 10% (0-18%) in H samples. Heat treatment was associated with a median reduction of SCC of 36% (0-90%) in paired samples, as well as a median reduction in total bacterial count of 93% (45-100%) in H versus R samples. Proteomics analysis identified a total of 328 unique proteins that were present in all 10 samples. Nine of the 25 proteins that decreased by at least 1.5-fold in H compared with R were identified as complement proteins. We conclude that heat treatment of colostrum is associated with a reduction in the concentration of bacterial counts and SCC, IgA, insulin, and IGF-I. In addition, proteomics analysis of colostral whey identified several complement components and other proteins that decreased in abundance due to heat treatment. Although IgG concentrations were unaffected and a reduction in bacterial counts was achieved, the change in several immunologically active proteins and growth factors may have biologically important effects on the developing immune system of the neonate fed heat-treated colostrum.

Quantitative assessment of German Holstein dairy cattle colostrum and impact of thermal treatment on quality of colostrum viscosity and immunoglobulins

OBJECTIVE

This study aimed to determine the color, fat, viscosity, IgG concentration, %Brix and refractive index of fresh postpartum colostrum of German Holstein dairy cattle and assess the impact of different thermal treatments on the visual and dynamic viscosity, in association to IgG concentration, of colostrum that can be used for pasteurization process.

RESULTS

Of the total 40 fresh postpartum colostrum, the color of colostrum (ranging from white-pale yellow to yellow and dark-yellowish), fat (1.4-8.2 100 g^-1), IgG (4-116 mg mL^-1), %Brix (8.5-35.4%), refractive index (1.3454-1.3905 nD), visual (ranging from watery to liquid and thick) and dynamic (4.9-219 cp) viscosity, were recorded. Statistical analysis between visual and dynamic viscosity of fresh colostrum showed significant correlation coefficients (r_s = 634). Moreover, a significant correlation between viscosity and three IgG concentrations was also observed. Heat-treated colostrum showed dynamic viscosity ranged from 25 to 3066 cP, where dynamic viscosity of colostrum before- and after heat-treatment showed no significant correlation. Treated colostrum at 60 °C/60 min and 63.5 °C/30 min containing IgG concentration ≤ 80 mg mL^-1 and ≤ 68 mg mL^-1 showed no significant change in the viscosity and can successfully be applied for pasteurization of first postpartum colostrum.