Early rumen development in calves: Biological processes and nutritional strategies-A mini-review

Abstract

The transformation of the reticulo-rumen (hereafter rumen) from a monogastric state to a functional rumen during early calf development is driven by complex transcriptional reprogramming and changes in metabolic pathways. This transformation involves coordinated morphogenesis, gene regulation, and microbial colonization. These processes promote muscle growth, epithelial differentiation, and efficient nutrient absorption and fermentation. Microbial succession begins at birth and is characterized by interaction with the host and the early introduction of solid feed. This succession establishes anaerobic, fibrolytic, and amylolytic bacterial species that are critical for nutrient absorption and productivity. In addition, optimizing grain processing in calf diets along with ensuring adequate forage intake is critical to promoting effective papilla development while maintaining stable fermentation and supporting a stable ruminal pH. Together, these factors are essential for implementing targeted nutrition and management strategies to improve calf health and productivity.

Summary: The transition of dairy calves from a milk-based diet to solid feed is essential for the development of a fully functional rumen and requires coordinated changes in rumen structure, microbial colonization, and gene expression. During this period, rapid growth of the papillae and maturation of the epithelium are crucial for effective nutrient absorption. Early dietary interventions, especially starter diets rich in starch and balanced forage, play a critical role in optimizing rumen growth and functionality. Starter diets promote microbial fermentation and papillae development, although excessive starch content can increase the risk of ruminal acidosis. Forage supplementation, in contrast, supports rumen pH stability and reduces non-nutritive behaviors by stimulating saliva production, although it may limit energy intake due to gut filling. By modulating transcriptional reprogramming and microbial composition, these nutritional strategies promote optimal rumen development, laying the foundation for improved health, growth, and productivity in dairy calves.