Cross-sectional study investigating the components and quality of colostrum and colostrum replacement products fed to Ontario dairy goat kids.

Colostrum replacement products for use in goat kids are sourced from bovine colostrum and often used by producers to supplement or replace maternal colostrum to prevent infections. To compare the colostrum replacement products fed on-farm to caprine colostrum a cross-sectional study was undertaken. Ontario dairy goat producers were asked to collect first milking colostrum from their goats and samples of the reconstituted commercial replacement product currently in use. The frozen samples were thawed and submitted for testing of fat, protein and lactose content, IgG1 concentration and aerobic bacterial culture. Compared with caprine colostrum, the reconstituted replacement products were lower in protein (11.7%; P = 0.0007), and fat (4.6%; P < 0.0001) and higher in lactose (5.4%; P < 0.0001) on average. The average IgG1 concentration in goat colostrum (53.5 g/L; range: 16.6-1985.8) was significantly higher than in colostrum replacement products (33.7 g/L; range: 10.7-55.3) (P < 0.0001). The Brix cut-point for good quality goat colostrum (50 g/L) was calculated at 23% (sensitivity = 69.6%, specificity = 88.0%) for goat colostrum and 26% for the colostrum replacement product (sensitivity = 87.5%, specificity = 100%). The average aerobic count for goat colostrum was lower (2.95 log10 cfu/mL) than the colostrum replacement product samples that were cultured (3.85 log10 cfu/mL; P < 0.0001). Further investigation into colostrum replacement products, including on-farm storage of opened powdered product and mixing and storage of reconstituted product, is warranted. Variability in the levels of IgG1, aerobic bacterial growth and fat, protein and lactose content in colostrum replacement products also requires further exploration to determine their effects on kid health.

Genetic and Epigenetic Regulation of Immune Response and Resistance to Infectious Diseases in Domestic Ruminants.

Infectious diseases are the outcome of complex interactions between the host, pathogen, and environment. After exposure to a pathogen, the host immune system uses various mechanisms to remove the pathogen. However, environmental factors and characteristics of pathogens can compromise the host immune responses and subsequently alter the outcome of infection. In this article, genetic and epigenetic factors that shape the individual variation in mounting protective responses are reviewed. Different approaches that have been used by researchers to investigate the genetic regulation of immunity in ruminants and various sources of genetic information are discussed.

Genetic selection of cattle for improved immunity and health.

The immune system is a sensing structure composed of tissues and molecules that are well integrated with the neuroendocrine system. This integrate system ensures non-self from self-discrimination. In this capacity the immune system provides detection and protection from a wide range of pathogens. In mammals, the immune system is regulated by several thousand genes (8-9% of the genome) which indicate its high genetic priority as a critical fitness trait providing survival of the species. Identifying and selectively breeding livestock with the inherent ability to make superior immune responses can reduce disease occurrence, improve milk quality and increase farm profitability. Healthier animals also may be expected to demonstrate improvements in other traits, including reproductive fitness. Using the University of Guelph's patented High Immune Response technology it is possible to classify animals as high, average, or low responders based on their genetic estimated breeding value for immune responsiveness. High responders have the inherent ability to produce more balanced and robust immune responses compared with average or low responders. High responders dairy cattle essentially have about one-half the disease occurrence of low responders, and can pass their superior immune response genes on to future generations thereby accumulating health benefits within the dairy herd.

Effects of parturition and dexamethasone on DNA methylation patterns of IFN-γ and IL-4 promoters in CD4+ T-lymphocytes of Holstein dairy cows.

This study investigated epigenetic mechanisms by which DNA methylation affects the function of bovine adaptive immune system cells, particularly during the peripartum period, when shifts in type 1 and type 2 immune response (IR) biases are thought to occur. Stimulation of CD4+ T-lymphocytes isolated from 5 Holstein dairy cows before and after parturition with concanavalin A (ConA) and stimulation of CD4+ T-lymphocytes isolated from 3 Holstein dairy cows in mid-lactation with ConA alone or ConA plus dexamethasone (Dex) had significant effects on production of the cytokines interferon gamma (IFN-γ, type 1) and interleukin 4 (IL-4, type 2) that were consistent with DNA methylation profiles of the IFN-γ gene promoter region but not consistent for the IL-4 promoter region. ConA stimulation increased the production of both cytokines before and after parturition. It decreased DNA methylation in the IFN-γ promoter region but increased for IL-4 promoter region. Parturition was associated with an increase in IFN-γ production in ConA-stimulated cells that approached significance. Overall, DNA methylation in both promoter regions increased between the prepartum and postpartum periods, although this did not correlate with secreted cytokine concentrations. Dexamethasone treated cells acted in a manner consistent with the glucocorticoid's immunosuppressive activity, which mimicked the change at the IFN-γ promoter region observed during parturition. These results support pregnancy as type 2 IR biased, with increases of IFN-γ occurring after parturition and an increase in IL-4 production before calving. It is likely that these changes may be epigenetically controlled.

Cette étude avait pour objectif d'investiguer les mécanismes par lesquels la méthylation de l'ADN affecte la fonction des cellules du système immunitaire adaptatif bovin, en particulier durant la période péri-partum, lorsque les changements des biais des réponses immunes (IR) de type 1 et type 2 sont sensés se produire. La stimulation de lymphocytes T CD4+ isolés de cinq vaches laitières de race Holstein avant et après la parturition avec de la concanavaline A (ConA) et la stimulation de lymphocytes T CD4+ isolés de trois vaches laitières de race Holstein en milieu de période de lactation avec de la ConA seule ou de la ConA plus de la dexaméthasone (Dex) a eu des effets significatifs sur la production des cytokines interféron gamma (IFN-γ, type 1) et interleukine 4 (IL-4, type 2) qui étaient conformes avec les profils de méthylation de l'ADN de la région du gène promoteur IFN-γ mais pas pour la région du promoteur IL-4. La stimulation par la ConA augmenta la production des deux cytokines avant et après la parturition. Elle diminua la méthylation de l'ADN dans la région du promoteur IFN-γ mais augmenta celle dans la région du promoteur IL-4. La parturition était associée avec une augmentation presque significative de production d'IFN-γ par les cellules stimulées par la ConA. De manière générale, on nota une augmentation de la méthylation de l'ADN dans les régions des deux promoteurs entre la période pré-partum et la période post-partum, sans que cela ne soit corrélée avec les concentrations des cytokines sécrétées. Les cellules traitées avec de la dexaméthasone se sont comportées d'une manière conforme à l'activité immunosuppressive des glucocorticoïdes, qui simulait les changements observés dans la région du promoteur IFN-γ durant la parturition. Ces résultats soutiennent le fait que la gestation amène un biais de type 2 de la réponse immunitaire, avec une augmentation d'IFN-γ se produisant après la parturition et une augmentation de production d'IL-4 avant le vêlage. Il est probable que ces changements peuvent être contrôlés de manière épigénétique.(Traduit par Docteur Serge Messier).