Genetic characteristics of colostrum refractive index and its use as a proxy for the concentration of immunoglobulins in Holstein cattle

Abstract

Background Colostral concentration of immunoglobulins (Ig) is crucial for the passive transfer of antibodies from the cow to the new-born calf. Direct determination of Ig by the gold standard radial immunodiffusion method is demanding in terms of time and costs. For this reason, a refractometer is commonly used at the farm level for an indirect estimation of colostrum quality, which is given as the Ig concentration. In this study, colostrum samples were collected from 548 Italian Holstein cows within 6 h of calving. The refractive index (BRIX, %) of these samples was assessed using a portable optical refractometer, as well as the concentration of total protein, IgG, IgA, and IgM by radial immunodiffusion. A four-trait animal model was used to estimate genetic parameters for BRIX and the different immunoglobulin isotypes. A receiver operating characteristic analysis was carried out to evaluate the BRIX diagnostic accuracy. Results Colostral BRIX was moderately heritable (0.26) and its genetic and phenotypic correlations with IgG (0.91, 0.78), IgA (0.57, 0.57), and IgM (0.71, 0.61) were all positive and of similar order, although the genetic correlations were generally higher than the phenotypic correlations. Low-quality colostrum samples, defined as those with an IgG concentration lower than 50 g/L, were accurately identified by the refractive index on the BRIX scale, with an area under the curve of 0.90. Conclusions The use of a refractometer is recommended on dairy farms to produce a proxy for colostral Ig concentration. BRIX is a useful phenotyping tool that can be used in cattle to improve the quality of colostrum for first feeding of calves through both traditional genetic and genomic strategies. Improving colostrum quality will reduce the incidence of failure of passive transfer of immunity in young stock.

A Review: The Effect of Bovine Colostrum on Immunity in People of All Ages

“…Feeding management may also lead to changes in the quality of BC, and it has been found that dairy cows vaccinated at 28 days of expected farrowing and started on an acidproducing diet 21 days before farrowing can increase the concentration of IgG in BC [75]. In addition, genetic traits also have a role in the quality of BC, but this is controversial and has had opposed results in different studies [62,[76][77][78]. Again, this reflects the complex diversity of factors influencing BC quality.…”

The Role of Colostural Indicators in Prevention Coronavirus and Rotaviral Diarrhea in Calves

“…In order to reduce infection rates for both diseases, it is considered more appropriate to prioritize preventive measures in the management system along with immunization. This includes protocols such as cleanliness in the maternity ward, immediate weaning of the calf at birth, placing the calf in individual pens, placing a newly hatched calf in a clean pen, feeding the calf with a personal teat, and not handling the calves with dirty tools (Costa, 2022).…”