ISSUE FOCUS FEED & ADDITIVE MAGAZINE November 2025 57 HoloRuminant unites scientists, industry and farmers to uncover how ruminantassociated microbiomes interact with their host across early life, weaning, diet shifts and lactation. By combining genomics, metabolomics and other multiomics tools, the project links microbial connectivity and heritability to animal health, welfare, productivity and environmental efficiency. One of its key insights concerns early-life health: Calf scour remains one of the most persistent and costly diseases in dairy production. By understanding and supporting the calf gut microbiome during this critical stage, we can strengthen immune responses, reduce disease risk and build the foundation for healthier, more resilient herds. SUPPORTING CALF GUT HEALTH TO PREVENT SCOUR THE CHALLENGE OF CALF SCOUR Diarrhoea, commonly known as scour, is one of the most frequent and costly diseases in young calves. It can affect up to half of all dairy calves, often leading to dehydration, loss of appetite, and stunted growth. In severe cases, scour is the leading cause of death during the first month of life. Even when calves recover, the long-term impact can be substantial, including lower growth rates, delayed fertility, and reduced milk yields later in life. The complexity of the disease makes treatment difficult. Scour is often caused by multiple pathogens at once—such as rotavirus, coronavirus, and Cryptosporidium—and not by bacteria, meaning that antibiotics are ineffective. Prevention, rather than treatment, is therefore the key to controlling scour. Early-Life Immunity: A Vulnerable Window Newborn calves enter the world with an under developed immune system. They rely entirely on antibodies from colostrum to protect them against infection in the first weeks of life. However, this passive immunity declines sharply after two weeks, while the calf’s own immune system only begins to function effectively around three to four weeks of age (Image 1). This creates a vulnerable gap where the calf’s defenses are at their lowest—just when exposure to By Sabine Scully, Teagasc Walsh & Geena Cartick, European Forum of Farm Animal Breeders Geena Cartick Sabine Scully
RkJQdWJsaXNoZXIy MTUxNjkxNQ==