You are here
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
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
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.
Cooling Water to Combat Heat Stress
Most of the recent research
effort with water has centered around heat stress problems. Adding sodium
chloride, potassium chloride, potassium sulfate or carbon dioxide to broiler
drinking water has been shown to increase gain slightly and lower body
temperature (Teeter, 1988). Most of this effect is probably attributable to the
resulting increased water intake. One report of broiler work also shows a
benefit in daily gain from providing cool drinking water (55 degrees F). Work
at the University of Florida with cooling hens' drinking water to 50 or 70
degrees during hot daylight hours did not improve performance other than the
shell and interior quality of eggs. Artificially refrigerating water for
poultry during the summer is probably not economically feasible, but there are
some adjustments that can be made. Those include insulating water pipes or
installing them underground rather than near the roof as is often done.
Lowering the temperature just a few degrees could make a critical difference.
Hardness is primarily a
measure of calcium and magnesium content, so Atteh and Leeson (1983) examined
the effect of adding these to broiler drinking water. They found that up to 100
ppm magnesium significantly improved feed efficiency but increased the
incidence of swollen hocks and shortened tibia. Up to 100 ppm of calcium had no
effect. Work at the University of Florida sponsored by the Southeastern Poultry
and Egg Association found significant decreases of water consumption and egg
production when 2000 ppm calcium was provided in lactate form through the drinking
water. These drops were probably due to the taste factor; however, egg shell
quality was significantly improved even when the diet contained 3.75% calcium.
When hard water is a problem in proper equipment operation, it can easily be
“softened” with commercial water treatment equipment. Most of the processes
exchange the sodium ion from sodium chloride for other minerals present. Roush
and Mylet (1986) studied the influence of softening on hens over a 308-day
period. The process was concluded to improve performance of birds consuming
diets with no added salt. No benefit was shown when diets were supplemented
with .35 or .70% salt. It is recommended that the sodium of softened water be
monitored because it may influence the amounts of fish meal, defluorinated
phosphate, bakery products or salt used by your nutritionist.
Chlorinating to Eliminate Bacterial Contamination
Bacterial contamination can
be a pesky problem for both the humans and chickens that drink the water.
Again, there is little research with animals, but most everyone agrees that
there should be no fecal coliform contamination. The first step towards
eliminating contamination is to determine if the source is the well or the
distribution system. For a properly sealed and located well, treatment of the
well cavity with a chlorine source such as sodium hypochlorite may remedy the
problems. If continuous chlorination seems necessary, it should be applied
gradually. Most people tend to be very cautious, and wisely so, about starting
this procedure for fear of the strong odor or taste causing reduced
performance. Between two and five ppm of residual chlorine is recommended.
Start at the lower concentration and increase it until control is satisfactory.
Since water intake is the most sensitive criteria, it should be monitored
during this process for signs of intolerance. We have completed trials with
sodium hypochlorite to help answer the question “How much is too much?” Body
weight of broiler chicks was not significantly reduced by 150 ppm chloride from
sodium hypochlorite, while daily water intake dropped at between 10 and 100 ppm
chloride. Egg production of White Leghorns was not significantly affected by 50
and 100 ppm chloride, but water consumption was affected adversely at 50 ppm.
We think this demonstrates a good safety margin above the upper recommendation
of five ppm.
Contamination from Pesticides and Organic Chemicals
What about pesticide and
organic chemical contamination? Since the Safe Drinking Water Act was passed,
the improved sophistication of detection methods has allowed the discovery of
organic chemicals in drinking water faster than their health significance could
be assessed. By 1980 more than 700 volatile organic compounds had been
identified. Pesticide contamination would not appear to be a widespread problem
according to a 1983 publication by the Dow Chemical Company. They reported the
results of a $5 million study by Cornell University in which virtually no
pesticide residues could be found in water wells representing 63% of the U.S.
rural population. The study did show that 29% of the homes had excess levels of
coliforms and 25%, too much mercury. Almost 64% of those with problems (14
million) had high concentrations of two or more contaminants. In Michigan, a
study of groundwater contamination causes showed that only three of 441
occurrences were due to pesticides. Improper storage and handling of gasoline
accounted for 110, or 25%, of the total. Certainly these problems with
agricultural chemicals and fuels do occur and, unfortunately, regulatory
decisions are often more political than scientific, as the data above
emphasize. Florida is leading in this area with new tank registration,
containment and inspection laws.
The results of two rather
extensive water quality surveys in Georgia (French et al., 1988) and Arkansas
(Barton et al., 1987) offer some reassurance concerning poultry performance.
Georgia's sampling was over 10 locations in each of five broiler companies with
the conclusion that “with few exceptions, water in north Georgia is of
excellent quality and is ideal for poultry and livestock production.” The
Arkansas study examined the water of 300 producers and looked for correlation
between quality and bird performance. Twenty-five of the top and bottom
producers were selected at each location by each company. Performance data from
the previous year was the basis of selection and comparison. The conclusion was
that water quality did not significantly contribute to top or bottom producer
status, except in the case of nitrate.
Well, what usable
information can we draw from this? It does not appear that water mineral load
poses a serious problem to bird performance. It is much more likely to affect
watering and washing equipment operation. Existing treatment technology can
help with these aspects. In the future we may even find an advantage in adding
sodium or potassium to drinking water before times of heat stress to increase
water intake and help cool the bird.
Bacterial contamination can
be a more persistent problem requiring some sleuthing to pin-point the source,
but the standard treatment is chlorination with sodium hypochlorite or chlorine
coupled with clean troughs and drinkers. Long-term correction may require well
sealing or re-siting. The installation of septic tanks, spray fields and
disposal pits also needs to include consideration of well location and the
direction of underground water flow. When using water as a carrier of nutrients
or medication, weather can be an important factor to affect calculations. Most
drug dosages are formulated for an environmental temperature of 70 degrees F
which may mean that we overmedicate by a factor of 50% in the summer and
undertreat somewhat in winter. Young birds also drink more in relation to their
body weight than older birds.
We can take heart from the
on-farm surveys of our colleagues that say the water supply in the southeast
U.S. is still in good condition overall.
By B. L. Damron, University
of Florida IFAS Extension