title: Hydrogen and oxygen stable isotope fractionation in body fluid compartments of dairy cattle according to season, farm, breed, and reproductive stage.
abstract: Environmental temperature affects water turnover and isotope fractionation by causing water evaporation from the body in mammals. This may lead to rearrangement of the water stable isotope equilibrium in body fluids. We propose an approach to detect possible variations in the isotope ratio in different body fluids on the basis of different homoeothermic adaptations in varying reproductive stages. Three different reproductive stages (pregnant heifer, primiparous lactating cow, and pluriparous lactating cow) of two dairy cattle breeds (Italian Friesian and Modenese) were studied in winter and summer. Blood plasma, urine, faecal water, and milk were sampled and the isotope ratios of H (2H/1H) and O (18O/16O) were determined. Deuterium excess and isotope-fractionation factors were calculated for each passage from plasma to faeces, urine and milk. The effects of the season, reproductive stages and breed on δ2H and δ18O were significant in all the fluids, with few exceptions. Deuterium excess was affected by season in all the analysed fluids. The correlations between water isotope measurements in bovine body fluids ranged between 0.6936 (urine-milk) and 0.7848 (urine-plasma) for δ2H, and between 0.8705 (urine-milk) and 0.9602 (plasma-milk) for δ18O. The increase in both isotopic δ values in all body fluids during summer is representative of a condition in which fractionation took place as a consequence of a different ratio between ingested and excreted water, which leads to an increased presence of the heavy isotopes. The different body water turnover between adult lactating cattle and non-lactating heifers was confirmed by the higher isotopic δ for the latter, with a shift in the isotopic equilibrium towards values more distant from those of drinking water.
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per Produzioni Foraggere e Lattiero-casearie, via Porcellasco 7, 26100 Cremona, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Abeni
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per Produzioni Foraggere e Lattiero-casearie, via Porcellasco 7, 26100 Cremona, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Petrera
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per Produzioni Foraggere e Lattiero-casearie, via Porcellasco 7, 26100 Cremona, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Capelletti
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per Produzioni Foraggere e Lattiero-casearie, via Porcellasco 7, 26100 Cremona, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Dal Prà
authors.affiliation: Fondazione Edmund Mach-Centro di Ricerca Istituto Agrario San Michele all'Adige-Dipartimento Qualità Alimentare e Nutrizione, via E. Mach 1, 38010 San Michele all'Adige (TN), Italy.
authors.forename: Luana
authors.initials: L
authors.lastname: Bontempo
authors.affiliation: Fondazione Edmund Mach-Centro di Ricerca Istituto Agrario San Michele all'Adige-Dipartimento Qualità Alimentare e Nutrizione, via E. Mach 1, 38010 San Michele all'Adige (TN), Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Tonon
authors.affiliation: Fondazione Edmund Mach-Centro di Ricerca Istituto Agrario San Michele all'Adige-Dipartimento Qualità Alimentare e Nutrizione, via E. Mach 1, 38010 San Michele all'Adige (TN), Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Camin
mesh_terms: D000383:Agriculture; D000818:Animals; D001825:Body Fluid Compartments / Q000737:chemistry*; D001947:Breeding; D002417:Cattle; D005260:Female; D006859:Hydrogen / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010103:Oxygen Isotopes; D012098:Reproduction; D012621:Seasons
chemical_list: D010103:Oxygen Isotopes; D006859:Hydrogen; D010100:Oxygen