Biofortification of milk with different selenium sources: Analysis of the immune system and integrative metabolome of ruminal fluid, blood serum, and milk of lactating cows

• Grant number: 24/21017-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Arlindo Saran Netto
• Grantee: Iuli Caetano da Silva Brandão Guimarães
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 21/07131-0 - Biofortification of milk with selenium: effect on nutritional bioavailability and action on human health, AP.TEM

Abstract

Once selenium (Se) is introduced into an organism through diet, it begins to interact with various biological components, depending on its specific form. This interaction results in the distribution of Se throughout organs, within cellular structures, and its transformation into various metabolites during metabolic processes. In the biofortification process, nutrients are provided to lactating cows (fortifying dairy cow diets), resulting in milk with greater nutritional value, which is being tested for its potential benefits to human nutrition and health. However, fortifying lactating cow diets may also benefit the animals. Selenium's antioxidant action, which is involved in cellular protection against the attack of reactive oxygen species, is highly important for animal health. Simultaneously, metabolomics becomes crucial for understanding Se behavior within a biological system. Much is known about the role of supplementation with different Se sources on metabolism, bioavailability, and phenotypic outcomes in dairy cows; however, until now, no studies in the literature have shown the impact of such supplementation on the metabolome of different biological systems in dairy cows. This project aims to advance the current understanding of the impact of Se supra-supplementation for the production of biofortified milk in dairy cows by evaluating the innate immune system and the metabolome of ruminal fluid, blood serum, and milk in an integrative manner. Thirty-two lactating dairy cows will be used over 12 weeks (2 weeks of dietary adaptation and 10 weeks of biological sample collection and experimental data collection). The animals will be housed in a free-stall facility with sand bedding and will be assigned to the following treatments: Control diet (C); Control diet + selenium amino acid (SeAa, Selisseo® 2% selenium); Control diet + selenium yeast (SeLv; Sel-Plex® 0.1% Se); Control diet + inorganic selenium (SeIn; Sodium Selenite (Se+4) 45.6% Se). Supplemented diets will receive 2.5 mg Se/kg of dry matter. Milking will be performed twice daily. Milk and blood will be collected in week 0 (covariate) and the 12th experimental week. Ruminal fluid will be collected only in the 12th experimental week. Phagocytosis, oxidative burst, and L-selectin expression of peripheral blood polymorphonuclear cells will be evaluated with in vitro challenges of Staphylococcus aureus and Escherichia coli. Metabolomics analyses using Nuclear Magnetic Resonance (NMR) spectroscopy will be performed on ruminal fluid, blood serum, and milk samples, which will be analyzed integratively. This study is expected to advance knowledge in Se supplementation for dairy cows by exploring potential changes in innate immune activity and systemic metabolic pathways that may explain commonly reported phenotypic outcomes.