WATER TREATMENT AND ANIMAL WELFARE ARE CLOSELY LINKED
Luis Ángel Hidalgo
Cuhigen Technical Team
Translated from Spanish by Michelle Doherty
One of the most important undertakings in daily veterinary practice is knowing how to treat water and, accordingly, choosing the correct, most suitable treatment depending on the species and in the light of each circumstance.
In recent years, water has gone from being the great mystery that we have to hand but don't think important, to being "responsible for all ills". It is also true that the way in which water treatment systems have been implemented is completely different across species, as is usually the case with livestock.
The poultry sector was the first to set up water treatment systems, followed by the white pig and then the Iberian pig farming sectors. It is only in the last few years that such systems have started to be used in ruminant production.
A Vital Nutrient
A few years ago, we analysed the water on a dairy farm and found it to be highly contaminated. Nonetheless, the farmer stood by the fact that he had been drinking the water for 20 years and he was fine. This example demonstrates the degree of importance that we give to water, even though it is the "number one food" for animals by quantity consumed. Often a lot of time and effort is invested in analysing mycotoxins, fungi, algae, etc. in feed but the most important ingredient by volume, water, is not taken into account.
We won't detail the properties of water fit for human consumption, specified in the Royal Decree 140/2003, but at the present time there are no distinct regulations for livestock.
In this article we discuss the different treatment systems available, to make sure that they fit the parameters in the regulations.
What is the ideal treatment system?
The big question on all of the farms that we provide services to is, "Which water treatment system is best?” As a good Galician, the answer would be, "It depends". And the answer to the question, "Depends on what?" would be, "It depends on many factors".
The key variable factor at the time of treatment is the type of water, which can be totally different from one farm to another, even supposing they are neighbours. Not only that, but it can also vary considerably throughout the year.
When the physical and chemical properties of water are analysed, it can be seen that the main problems, quantitatively speaking, are hardness and nitrates. Sulphates are next in order of importance, especially on the Northern plateau where the soil is predominantly loam. Other properties to consider are chlorides in coastal areas, especially in the East due to over-use of aquifers, and iron and manganese in Galicia, Extremadura and parts of Castilla la Mancha.
Chlorides, iron, manganese and sulphates
Chlorides, iron and manganese are generally quite easily controlled using ion exchange resins, a method which is not overly expensive.
Controlling sulphates is more difficult, due to the fact that their maximum level in water considered safe for drinking is high. It is therefore impossible to eliminate them using chloride ion exchange, as the latter tends to have a much lower concentration in water.
In such cases the only solution is reverse osmosis, which has the major drawback of requiring large quantities of water. Only 50% of the total water used is useful, and the waste water becomes an extra problem. This solution is more suitable for eliminating chlorides in coastal areas, since waste water is returned to the sea.
Dissolved solids and oxygen demand
In wet springs, a new problem can often arise. The amount of dissolved solids, the biological oxygen demand after 5 days (BOD5) and the chemical oxygen demand (COD) all increase due to the transport of organic matter. This phenomenon is common after periods of heavy rain and is worse in water originating from marshes, rivers or shallow wells.
Increased turbidity, permanganate oxidability and very high levels of dissolved solids, BOD5 and COD are observed.
The solution to this problem lies in the correct sizing of both mesh or ring filters that retain suspended solids and anthracite/sand filters used for water clarification.
Chlorine dioxide generator
A variety of treatments can be used to control microbiological contamination.
In terms of treating microbiological contamination, chlorine dioxide is an extremely effective disinfectant but it has been used only relatively recently.
The limitations of this treatment are the poor stability of the product in previously prepared solutions and the high cost of machines that prepare the product on demand.
Another solution is hydrogen peroxide, which has been used a lot during the last decade, due to its ability to eliminate biofilms and the fact that it leaves no extra taste in the treated water. It also performs well in hard water.
Chlorine is still the most widely used product for treating water on our livestock farms, due to its low cost.
It is particularly effective in water with low pH, either naturally occurring or due to previous acidification. This acidification can occur due to organic acids (formic, propionic, lactic, citric and their salts1), which are mainly used in poultry farming, or inorganic acids that are usually used on pig farms (based on hydrochloric acid due to price or phosphoric acid for its ease of handling).
Chlorine tablets are sometimes the only solution. However, the desired result is not always obtained, since free chlorine is highly variable. As such, at times there are very high chlorine levels and animals decrease their water intake, at other times low or zero levels and thus the water isn't really treated.
Control and dosing panel for chlorine and pH
Another treatment system is electroperoxidation, which is particularly useful for water with high electrical conductivity2 and without problems of lime precipitation. Furthermore, it has the advantage that no additional chemicals are needed.
Ozone is useful for water with large amounts of organic matter, but should be combined with chlorine or peroxide after disinfection, as the ozone disappears quite rapidly.
Ultraviolet light can be a good complementary method of water treatment. It is particularly useful alongside vaccine treatments, such as Gumboro in poultry farming, as in that case residual disinfectants cannot be used and if the water is not treated at all it might cause serious problems.
Having outlined the major and most common water treatments for livestock farms, it must be noted that to determine which one is most effective a preliminary analysis must be carried out and each case assessed independently, in the light of the external factors affectingit.
Farmers should always bear in mind for production that water is an essential element of nutrition, as should technicians during testing and analysis.