References
Bovine neonatal enteric immunity: a key consideration in the prevention of calf diarrhoea
Abstract
The mucosa is the largest component of the immune system, providing a first line of defence against most pathogens encountered. Although the mucosa is located in all areas where there are mucosal surfaces (such as the respiratory and urogenital tracts), the clinical importance of diarrhoea in calf veterinary practice means the gastrointestinal mucosa is of particular interest. Taking steps to promote good health of the gastrointestinal mucosa can enhance gastrointestinal mucosal immunity and aid prevention of calf diarrhoea, the leading cause of mortality and morbidity in calves under 1 month old.
The clinical importance of diarrhoea in calves means that the gastrointestinal mucosa is of particular interest to veterinarians. This article looks at the structure and function of the gastrointestinal mucosa and the development of the gastrointestinal microbiota, followed by strategies for optimising gastrointestinal mucosal immunity, including the use of colostrum, enhancing enteropathogen-specific antibodies and supporting the microbiota.
The mucosa is the largest component of the immune system, providing a first line of defence against encountered pathogens. The gastrointestinal mucosa is highly specialised and, uniquely, needs to balance immune and digestive functions. It comprises three primary layers: a mucus barrier, an epithelial cell layer and the lamina propria (Figure 1). Together, these layers form an effective defence against enteropathogens termed the ‘mucosal firewall’ (Chase and Kaushik, 2019).
The inner layer of the mucus barrier is made up of a dense proteoglycan gel created by the combination of mucin and mucus produced by goblet cells (specialised epithelial cells). Antimicrobial peptides and antibodies, such as secretory IgA, are concentrated here, generating effective protection against pathogen incursion. Collectively this layer (comprising mucus and antimicrobial compounds) is termed the ‘kill zone’ (Chase and Kaushik, 2019).
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