143. Award Talk: Nutrition as a Regulatory Signal in Dairy Management.

Abstract Through global research partnerships, our work in the last decade has sought to align nutrition decisions with a clear, mechanism-based understanding of cow physiology and metabolism. Central to this body of work is recognition that the transition period is the most biologically vulnerable and economically consequential phase of the lactation cycle, and that effective management requires prevention-oriented strategies grounded in coordinated metabolic and immune regulation rather than reactive intervention. Through pioneering application of nutrigenomics, this research demonstrated that nutrients function not merely as substrates, but as regulators of gene networks governing inflammation, oxidative balance, energy metabolism, and immune competence across multiple tissues. These discoveries provided mechanistic explanations for the development of metabolic disorders such as ketosis, fatty liver, and impaired immune function, thereby enabling refinement of transition cow diets to enhance resilience during early lactation. Work with rumen-protected methionine established its role in regulating antioxidant defenses, immune signaling, and epigenetic pathways, extending its relevance beyond milk protein synthesis to whole-animal health. Together, these findings have informed management strategies that are now implemented by the dairy industry, including optimized amino acid supply during the transition period, under heat stress, and throughout early lactation. Parallel contributions to understanding milk fat and milk protein synthesis addressed core objectives of dairy production systems worldwide by elucidating how specific fatty acids and amino acids regulate mammary metabolism and milk component yield. Research on mammary lipid metabolism clarified how dietary and rumen-derived fatty acids modulate lipogenic pathways and gene expression, providing a biological basis for managing milk fat depression and optimizing component efficiency across diverse feeding systems. Equally impactful were discoveries demonstrating that key amino acids serve dual roles as both substrates and signaling molecules, activating pathways such as mTOR signaling, enhancing translational efficiency, and supporting antioxidant capacity within mammary cells. These insights led to refined amino acid balancing strategies that can improve milk protein yield and nitrogen use efficiency while reducing environmental nitrogen losses. Beyond lactating cows, our collaborative work expanded prevailing management paradigms by demonstrating that nutritional decisions during late-gestation and early life exert long-lasting effects on offspring performance through developmental programming mechanisms. Studies revealed that enhanced maternal supply of methionine and related methyl donors, including choline, folic acid, and cobalt, programs hepatic, immune, and muscle metabolism in the neonatal calf by stimulating one-carbon metabolism, antioxidant defenses, and energy pathways. These changes accelerate hepatic maturation, improve insulin sensitivity, and confer metabolic resilience during early life, thereby redefining the dry cow–calf continuum as an integrated management unit. Such findings have substantial implications for replacement heifer development, calf morbidity, and long-term sustainability, particularly in systems challenged by environmental stressors and resource constraints. Collectively, these research themes have advanced dairy cattle management by bridging molecular discovery with practical application, ensuring that biological insight is translated into tangible improvements in animal health, productivity, and efficiency. The global relevance of this work is underscored by extensive international collaborations spanning grazing and confinement systems, temperate and tropical environments, and both established and emerging dairy industries across New Zealand, Europe, China, Southeast Asia, Latin America, Australia, and the Middle East. These partnerships have facilitated adaptation of nutritionally-driven management strategies to region-specific constraints, thereby contributing to global food security and sustainability. Equally important is the enduring impact of mentorship and leadership associated with this research program, which has trained a generation of scientists and industry leaders capable of integrating biological knowledge with real-world management decision-making. Former trainees now influence dairy cattle management through research, extension, and industry innovation in more than a dozen countries, amplifying the global reach of these contributions. Overall, our collaborative research program illustrates how integrating nutrition, physiology, and systems biology can fundamentally transform dairy cattle production management, shifting the discipline toward proactive, biologically informed strategies that enhance animal wellbeing, production efficiency, and sustainability across diverse production systems.