Water for poultry
Most of the standards that we are attempting to apply to animal drinking water are taken from those set for humans, and even they have a rather short history. The Public Health Service Act of 1962 was some of the first human water quality legislation and dealt only with sanitary surveys of water involved in interstate commerce. It was the Safe Drinking Water Act of 1974 that made the Environmental Protection Agency responsible for establishing national drinking water regulations, overseeing the safety of public water systems and protecting underground water sources against contamination.
Problems with Measurement Standards for Poultry-Quality Water
Some of the measurement characteristics commonly used to define human potable water quality, such as pH, hardness and electrical conductivity, are not very useful in predicting poultry performance. Hydrogen ion concentration (pH) tells nothing about the solution's buffering capacity or the identity and amount of individual ions. Hardness indicates the tendency to precipitate soap or to form scale on heated surfaces. What one really needs to know is the individual concentrations of calcium and/or magnesium, the principal contributors to this measurement. Electrical conductivity provides a measure of total mineral load and no individual ion analysis.
A number of popular articles have been written about water quality for poultry, yet very few research papers dealing with the subject could be found in the scientific journals during the past ten years. Clearly, we have much work ahead to develop an accurate specialized tolerance profile for poultry. The first step towards this goal was made by a National Academy of Sciences subcommittee in 1974 with their review booklet entitled “Nutrients and Toxic Substances in Water for Livestock and Poultry.” That publication summarized the literature before 1974 and indicated that a total soluble salt level of 1000 ppm or less would present no problem to livestock or poultry. It also provides recommended limits for several other potentially toxic substances (As, Cd, Cr, Co, Cu, F, Pb, Hg, Ni, N02, N03, V and Zn). Many of these are heavy metals and would not be a problem except in special situations. Several of the popular articles carry compilations of “good, maximum, tolerable or threshold” values for poultry water supplies. Most of these hinge on human standards, the NRC publication or a combination of other tables and are, overall, quite variable. For instance, iron tolerances ranged from 0 to 50 ppm, nitrates from 20 to 200 ppm, sulfates from 200 to 1000 ppm and sodium from 50 to 1000 ppm. Some of this variation is due to the standard pitfall of trying to consider each element individually when there are many interactions that influence their tolerance, but a paucity of research data is the biggest culprit.