Serum IgG antibody concentrations against environmental microbes in mares and foals during different seasons and effect of stabling practices.

This research investigates the serum IgG antibody concentrations in mares and foals against various environmental microbes during different seasons and changing stabling practices. The study revealed that antibody concentrations varied significantly between seasons and stabling practices, affecting the horses’ immune response.

Methods of the Study

• Over the course of 22 months for mares and 14 months for foals, monthly serum samples were taken for analysis.
• The samples were measured using ELISA against antigens from several environmental microbes including Aspergillus umbrosus, Penicillium brevicompactum, Rhodotorula glutinis, Absidia corymbifera, Aspergillus fumigatus, Humicola grisea, Micropolyspora faeni, and Thermoactinomyces vulgaris.
• The horses were kept on pasture from early June to early October and then stabled during the winter season until the following June.

Key Findings

• In mares, antibody concentrations against most microbes were typically higher in midwinter and late spring when the horses were stabled. However, the peak for antibodies against Rhodotorula glutinis was in August.
• Antibody concentrations differed significantly between the summer and winter seasons and, in most instances, between two consecutive years.
• There appeared to be a correlation between antibody concentrations and the amount of rainfall during the previous harvest season.
• Passively acquired antibodies in foals disappeared within 3 to 4 months after birth, and during their first year of life, foals showed significantly increased autogenous antibody concentrations only against Rhodotorula glutinis.
• Antibody concentrations against the other microbes increased gradually towards the end of the indoor season.
• A subgroup of foals kept outdoor 6 weeks longer than the others had lower antibody concentrations when measured in December.

Conclusions annd Implications

• The results suggested that to minimize exposure to microbial spores during the winter season, horses should ideally be kept outdoors as long as possible.
• Ventilation in stables and the quality of feeds and beddings should receive increased attention as they can influence antibody concentration and by extension, the horses’ immune response.
• The study provides valuable insights into how environmental factors and care practices can impact the immune response in horses, particularly how different seasons and stabling conditions can influence the concentrations of antibodies against specific microbes.