Dose Effect of Drinking Water Nitrate on Health, Feed Intake, Rumen Fermentation and Microbiota, and Nitrogen Excretion in Holstein Heifers for a Sustainable Water Use

The present study aimed to evaluate the potential hazardous effects of NO3− concentration in drinking water on health, feed intake, rumen fermentation and microbiota, and nitrogen excretion of Holstein heifers fed a high-concentrate diet for a sustainable water use. Twenty-four Holstein heifers were individually allocated and assigned to one of four treatments with increasing drinking water NO3− concentration: CTR, without NO3−; LOW, with 44 mg NO3−/L; MOD, with 110 mg NO3−/L; and HIGH, with 220 mg NO3−/L. The entire study lasted 168 days. Fortnightly water NO3− concentration and daily feed and water intake were recorded. Blood parameters, rumen pH, volatile fatty acids, NO3− and NO2− concentration, microbiota, and apparent total tract digestibility were determined at the beginning and at the end of the study. Most of the analyzed parameters were similar among treatments. Denitrifying bacteria population, estimated as nosZ gene copies, were greater in HIGH animals than in CTR animals at the end of the study. In conclusion, drinking water NO3− concentration up to 220 mg/L has no detrimental effect on health, feed intake, rumen fermentation, nor N excretion in dairy beef cattle for periods up to 168 days; moreover, denitrifying bacteria population increased, which are related with the neutralization of the greenhouse gas N2O.

This research was funded by DARP (Generalitat de Catalunya) and by FEADER (European Union)—Operational Group “Guia per a la optimització de l’ús i el tractament de l’aigua de beguda en vedells d’engreix”, grant number 56 21 026 2017 5A. The authors M. Devant, S. Marti, and L. Llonch belong to the Consolidated Research Group of Sustainable Animal Husbandry, funded by the AGAUR (Generalitat de Catalunya); ref. 2021 SGR 01552) and the authors M. Viñas and M. Guivernau belong to the Consolidated Research Group of Sustainability in Biosystems, funded by the AGAUR (Generalitat de Catalunya); ref. 2021 SGR 01568). IRTA also thanks the support of the Generalitat de Catalunya through the CERCA Programme.

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