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Tools for better management of water and effluent

In France, dairy and beef farms consume about 38% of water used by agriculture, excluding irrigation. About 75% of this water is used for drinking by the animals. The objective of this work was to propose equations to predict water requirements and urinary and fecal water excretions, at the scale of a dairy cow, from parameters linked to the animal, its diet and the meteorological conditions. These equations were built with the objective to be relevant in large conditions of diets and climate.

Prediction equations of the main flow of water in dairy cow

The first step of this work consisted in constituting databases of measurements of water balance obtained in dairy cows, either at the experimental farm of Méjusseaume or by using literature data, to establish empirical equations.
Given that the main part of the collected data were obtained in thermoneutral condition, new measurements of the water balance in dairy cows under controlled thermic conditions were also realized to establish the effects of an increase in ambient temperature on all the flows of the water balance.
Our experiments showed that when all water flows were reported to ingestion, water consumption systematically increased with ambient temperature when the latter exceeded 15°C and that this increase was systematically equivalent to that of evaporated water. These results allowed adopting a mechanistic approach to include the effect of ambient temperature in the prediction equations of water flows at the scale of the animal through the use of published models of latent heat loss by animal in relation to meteorological conditions. The use of our equations to predict water consumption in dairy cows for the experimental farms of Trinottières and Derval showed that our predictions were to be increased by 15% when constant level drinking trough are used instead of individual water bowls.

Tools to assess impact of farming practices on environment

The models published from this work will be used for life cycle assessment at the scale of the dairy systems in our context of temperate climate where livestock watering can represent a substantial proportion of blue water necessary for milk or beef production. Further, these equations will contribute to establishing new diagnostic methods to measure the efficiency of water use in farms by a better detection of the water leaks or by detecting and quantifying situations of a deficient water supply to the animal that are currently reported in farms. Our predictive equations of excreted water volume could contribute to the simulation models of effluent management for dairy production system, necessary to evaluate the effect of the practices on environmental problems at the scale of a territory.

These studies were conducted during the PhD project of Hajer Khelil-Arfa (2009-2012) and in collaboration with the ‘Institut de l’Elevage’, and the ‘Chambres d’Agriculture’ of ‘Loire Atlantique’ and ‘Maine et Loire’ within the CASDAR project « management of water consumption by livestock farming ».

For further information

Khelil-Arfa, H., Faverdin, P., Boudon, A. (2014). Effect of ambient temperature and sodium bicarbonate supplementation on water and electrolyte balances in dry and lactating Holstein cows. Journal of dairy science, 97 (4), 2305-2318. (DOI)

Khelil-Arfa, H., Boudon, A., Maxin, G., Faverdin, P., 2011. Prediction of water intake and excretion flows in Holstein dairy cows under thermoneutral conditions. Animal 6 : 1662-1676. (DOI)

Khelil-Arfa, H., 2012. Étude des principaux déterminants du bilan eau chez la vache laitière : modélisation des principaux flux journaliers. Thèse de doctorat de VAS. Soutenue le 30 mai 2012.

Boudon, A., Khelil-Arfa, H., Thomas-Morel, M., Banville, M., Pham, T. H. V., Ménard, J.-L., Brunschwig, P., Huneau, T., Coutant, S., Lamy, J.-M., Faverdin, P. 2012. Construction et validation d'un modèle de prédiction des besoins en eau des vaches laitières incluant l'effet de la température ambiante. 19èmes Rencontres Recherche Ruminants Rencontres autour des Recherches sur les Ruminants, Paris. pp 177-180 (online)

Contact

Anne Boudon, Alimentation and nutrition team (anne.boudon[at]rennes.inra.fr)