Exploring the use of tertiary reclaimed water in dairy cattle production

Abstract

The objective of this study was to explore through both in vitro and in vivo experiments the use of reclaimed urban wastewater in dairy cattle production systems with the aim of improving water efficiency and sustainability. Firstly, the use of different tertiary treatments (ultrafiltration (UF), ultraviolet disinfection (UV), chlorination process, and their combination) to improve the quality of an urban secondary effluent was studied in intestinal primary cell cultures evaluating the expression of genes related to apoptosis, cell damage, and inflammation. The results revealed that secondary treated wastewater and waters that were treated with a chlorination process (even tap water) caused an increase in apoptosis, intestinal primary cell damage, and inflammation. The in vivo experiment evaluated the short-term effects on health and performance of using UF- and UV-treated secondary effluent compared with the use of tap water for drinking and preparing milk replacer in young calves from 5 to 47 days of age. Calves previously fed with UF + UV treated secondary effluent clearly preferred tap water when they were exposed to a double water choice at the end of the study. This reduction of the palatability and acceptability was probably due to a greater level of water salinity of the treated reclaimed water (570 vs 1437 ± 76.5 μS/cm of conductivity for tap water and UF-UV treated secondary effluent, respectively), which potentially entailed a reduction of calf concentrate intake (466 vs 351 ± 32.2 g/d for calves fed with tap water and UF-UV treated water, respectively). The use of reclaimed water did not pose an acute risk to animal health. It is concluded that improvements on the tertiary treatment to reduce water salinity should be considered when using reclaimed water for drinking purposes in livestock production systems. This study is a first approach to a more sustainable and efficient use of water in animal husbandry for countries with water scarcity. However, more studies are required before its implementation to further study long-term effects and the presence of new-contaminants not defined in the current legislation.