High concentrations of Total Dissolved Solids (TDS) and salts in drinking water, often exacerbated by drought conditions, have been reported to have a detrimental impact on cattle health and performance. This research investigated water quality parameters including TDS and salts (sodium, calcium, magnesium, potassium, aluminium, zinc, iron, manganese, carbonate, bicarbonate, sulphate, nitrate and nitrite). The project summarised the range of TDS and salts in feedlot drinking water across Australia, thus determining potential impacts on cattle health and production. Additionally, feedlots using surface water sources for drinking water had the cyanobacteria species present identified and quantified. Such a study has not previously occurred in Australia.

The study was split into four parts with this report including over 100 historical water samples taken prior to 2018; 68 feedlot managers/owners completed the survey regarding water use delivered in paper and online format; 82 water samples from April to June 2019 from 58 feedlots were analysed for a suite of parameters. Where multiple water sources were used, the source water was analysed, this occurred for 24 samples. Additionally, water samples that included surface water were analysed for cyanobacteria (27 samples). Feedlots participating in the project were equivalent to over 50% of the licenced cattle feedlots.

Of the 68 feedlots completing the paper based and online survey, the majority (64%) source their cattle drinking water from groundwater. On a per-head basis, the use of groundwater as a drinking water source became even more important, covering two thirds of surveyed feedlot cattle. Surface water from dams and rivers were also a common source of water, and less common sources included reverse osmosis treated water from coal seam gas operations, tank roof water, and irrigation water.

The majority of feedlots (75%) were not aware of any issues with their drinking water quality. Of those that indicated that they had concerns about their water quality, seven feedlots identified cyanobacteria (Blue green algae) and Escherichia coli as an issue; four identified turbidity and scale (likely from calcium build up) clogging floats; and four feedlots reported that they now treat water for use in their boiler, but do not treat for cattle, while one feedlot identified high iron as an issue for boiler water.

Among trough water samples analysed for TDS, the majority (86 %) were considered satisfactory for cattle consumption and would not be expected to limit animal performance (≤ 3,000 mg/L). There were, however, cases of poor water quality identified. The highest TDS reported was 11,600 mg/L in groundwater. This water was shandied with surface water and was the maximum in the mixed trough water (5,400 mg/L), which would be expected to limit cattle performance (NASEM, 2016). Chloride was present in the highest concentration of all anions analysed. Nitrate concentrations were highest in the groundwater samples with only one trough sample exceeding the nitrate concentration threshold of 20 mg/L (NASEM, 2016). Sulphate ranged from undetected (<0.3 mg/L sulphur as sulphate) to 575 mg/L, with the highest values in groundwater samples, all samples were below the 1,000 mg/L guideline (ANZEC, 2000). Only 3% of trough samples exceeded the ANZEC (2000) limit of 5 mg aluminium/L. Manganese concentration was highest in surface water samples with 57% to 90% of trough water samples sourced from surface water exceeding the 0.05 mg/L upper-limit guideline (NASEM, 2016). The biological significance of high manganese waters remains to be elucidated, although water concentrations are well below the Maximum tolerable limit reported for dietary Manganese of 1000 mg/kg dry matter (NASEM, 2016). Two surface water samples were in excess of the trigger value for Microcystis aeruginosa (11,500 cells/mL) and were reanalysed and tested for toxins. Only one sample was below a pH 5.1 and one sample above pH of 9.

Several water treatment scenarios were investigated with distributors and installers in Australia with reverse osmosis being the most suitable treatment option. As there are no Australian references for the effect of water quality on the performance of the cattle, Patterson et al. (2004), a publication from the USA, was used for the analysis of benefit and cost of water treatment with reverse osmosis. Treatment with reverse osmosis lead to increased, and more cost-effective, cattle productivity. However, the water used in the article by Patterson et al. (2004) had high sulphate concentrations, so the same responses are unlikely with Australian water. Future research testing water quality in the range of variation experienced by Australian feedlots, in a controlled manner, would allow the industry to determine the most relevant animal production gains and thus the benefits of reverse osmosis.

In conclusion, water quality was determined to be of suitable quality for the majority of feedlots surveyed. Isolated cases of poor water quality were identified. This project is beneficial to the industry as it has yielded a comprehensive understanding of the current sources and quality of feedlot drinking water for a single point in time. Overall, this project will improve feedlot decision-making regarding the conditions when water quality parameters may impact animal health and production in beef cattle feedlots.