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The developing microbiome and calf health
A recent review article (Du et al., 2023) focusing on the colonisation and development of the gut microbiome in calves has highlighted it’s importance for calves’ growth and health, emphasizing its role in nutrition, immune function, and gut barrier integrity.
The gut microbiome evolves from the foetal stage through various factors such as diet, probiotics, age, environment, and genotype.
Microbial communities dynamically change during different growth stages, which can impact calf health, including the prevention of digestive diseases like diarrhoea and intestinal inflammation.
Dietary changes before weaning have lasting effects on the gastrointestinal microbiome. Therefore, it is vital to have a suitable milk-feeding plan in place with complementary fresh concentrates and clean water to ensure the calf smoothly transitions from milk to solid feed at the time of weaning.

French research by INRA (Zened et al., 2024) was carried out to determine whether once-a-day versus twice-a-day milk feeding had any effect on dairy calves’ ruminal microbiota and metabolomic profile. Feeding milk replacer once daily (Shine Original Milk Replacer, manufactured by Bonanza Calf Nutrition, Ireland) did not compromise the establishment and function of the ruminal microbiota.
Once-a-day milk (OAD) feeding was also found to be more economical, reducing labour expenses by 39% compared to feeding them twice daily. This reduction in labour costs made the OAD feeding program a more economical option for dairy farmers without compromising the growth, health, or ruminal development of the calves. As these results reflect, feeding calves OAD can be a practical and cost-effective strategy without detrimental effects on calf development.
Findings from this study showed a progressive development of the ruminal microbiota with age, with the most significant changes occurring between 7 and 35 days of age.
The gut microbiome significantly impacts calf health in several ways:
1. Nutritional Support: Gut microbiota aids in the fermentation of feed, producing short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate, which are crucial energy sources for the calf. These SCFAs also support the growth and health of gut epithelial cells.
2. Immune Function: The gut microbiome interacts with the calf’s immune system, helping to develop and regulate it. For instance, certain gut bacteria can stimulate the production of immunoglobulin A (IgA), which plays a role in neutralizing pathogens and maintaining gut homeostasis.
3. Gut Barrier Integrity: A healthy gut microbiome contributes to the integrity of the gut barrier, preventing the colonization of harmful bacteria and reducing the risk of infections and inflammation. It also helps produce antibacterial peptides and mucus glycoproteins that protect the gut lining.
4. Disease Prevention: A balanced gut microbiome can prevent digestive diseases such as diarrhoea and intestinal inflammation by maintaining microbial homeostasis and inhibiting the growth of pathogenic bacteria.
5. Metabolism of Nutrients: The microbiome is involved in the metabolism of amino acids and other nutrients, which are essential for the calf’s growth and development. It also helps in the degradation of plant fibres, enhancing feed efficiency.
6. Probiotic Effects: Supplementing calves with probiotics can promote the establishment of beneficial gut microbiota, improve feed conversion, reduce diarrhoea incidence, and enhance overall growth performance.
Overall, the gut microbiome plays a critical role in the nutritional, immune, and overall health of calves, influencing their growth and development from birth through weaning and beyond.
References
Du, Y., Gao, Y., Hu, M., Hou, J., Yang, L., Wang, X., Du, W., Liu, J. and Xu, Q., 2023. Colonization and development of the gut microbiome in calves. Journal of Animal Science and Biotechnology, 14(1), p.46.
Zened, A., Julien, C., Cauquil, L., Pascal, G., Canlet, C., Tremblay-Franco, M., Ali-Haimoud-Lekhal, D., Enjalbert, F., Bayourthe, C. and Combes, S., 2024. Milk replacer feeding once or twice a day did not change the ruminal metabolomic profile and the microbial diversity of dairy calves from birth to weaning. Journal of Dairy Science.
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