The development of water quality guidelines for poultry production in southern Africa

Abstract

The objective of this study was to develop water quality guidelines for poultry reared under South African conditions and production systems. This was achieved by a modeling approach that was based on a survey of water used by poultry producers throughout the country. Potentially hazardous constituents identified were – Sodium, Magnesium, Chloride, Sulphate, Nitrate, Calcium and Phosphorus. Three experiments were conducted to test these constituents’ effects on poultry production. Experiment 1 examined the influence of different levels of magnesium, sodium, sulphate and chloride in the drinking water of layers and the effect thereof on their production. The study showed that 12 different combinations of Mg, Na, Cl and SO4 had no significant effect on growth, food and water intake, and egg production or egg quality. Poultry producers in areas with naturally high levels of these minerals in their ground water can therefore continue to function successfully if the concentrations present are up to 250 mg/l of Mg, 500 mg/l of Cl, 500 mg/l of SO4 and 250 mg/l of Na. Experiment 2 examined the effect of elevated levels of NaNO3 in the drinking water of layers and broilers. No negative effects on broiler production and growth were observed. The only mineral ion to show a significant effect on performance was nitrate, with lower nitrate concentrations in well water being associated with better performance. Experiment 3 examined the effects of Ca and P in the drinking water on egg production, egg quality, bone integrity and shell strength. The results showed that water can be a valuable asset to increase eggshell integrity, but waterline maintenance may be increased because of the tendency of calcium to precipitate. Water should be seen as a dietary source of minerals (Ca + P) and should be taken into consideration when nutrient specifications are set for feed formulations to be used in the various poultry production systems. The preceding results served as basis for developing a modeling approach to water quality guidelines for poultry.