Concentration and heritability of immunoglobulin G and natural antibody immunoglobulin M in dairy and beef colostrum along with serum total protein in their calves
Abstract Immunoglobulin (Ig) G and natural antibody (NAb) IgM are passively transferred to the neonatal calf through bovine colostrum. Maternal IgG provides pathogen- or vaccine-specific protection and comprises about 85 percent of colostral Ig. Natural antibody IgM is less abundant but provides broad and non-specific reactivity, potentially contributing to protection against the dissemination of pathogens in the blood (septicemia) in a calf’s first days of life. In the dairy and beef industries, failure of passive transfer (FPT) of colostral Ig (serum total protein (STP) <5.2 g/dL) is still a common concern. The objectives of this study were to, i) compare colostral IgG concentrations and NAb-IgM titers between dairy and beef cows; ii) assess the effect of beef breed on colostral IgG; iii) compare passive transfer of colostral Ig in dairy and beef calves; and iv) estimate the heritability of colostral IgG and NAb-IgM. Colostrum was collected from Holstein dairy (n=282) and crossbred beef (n=168) cows at the University of Guelph dairy and beef research centres. Colostral IgG was quantified by radial immunodiffusion and NAb-IgM was quantified by an enzyme-linked immunosorbent assay. In dairy (n=308) and beef (n=169) calves, STP was estimated by digital refractometry. Beef cows had significantly greater colostral IgG (146.5 ± 9.5 SEM g/L) than dairy cows (92.4 ± 5.2 g/L, p <0.01). Beef cows with a higher proportion of Angus ancestry had significantly lower colostral IgG (125.5 ± 5.8 g/L) than cows grouped as “Other” (142.5 ± 4.9 g/L, p= 0.02). Using the FPT cut-off, 13% of dairy and 16% of beef calves had FPT; still, beef calves had a significantly larger proportion with excellent passive transfer (STP ≥6.2 g/dL, p <0.01). The heritability of colostral IgG was 0.04 (± 0.14) in dairy and 0.14 (± 0.32) in beef. Colostral NAb-IgM titers in dairy (12.12 ± 0.22, log2 (reciprocal of titer)) and beef cows (12.03 ± 0.19) did not differ significantly (p=0.71). The range of NAb-IgM titers was 9.18 to 14.60, equivalent to a 42-fold range in antibody concentration. The heritability of colostral NAb was 0.24 (± 0.16) in dairy and 0.11 (± 0.19) in beef cows. This study is the first to compare colostral NAb-IgM between dairy and beef cows. Based on the range in NAb-IgM titers and the heritability, selective breeding may improve colostrum quality and protection for neonatal calves in the early days of life.