Download Concentration of Chlorine in Drinking Water of Broiler

Concentration of Chlorine in Drinking Water of Broiler Chickens in New Zealand.
N.S. Boxall1*, N.R. Perkins2, D. Marks3, B. Jones4, S.G. Fenwick5, P.R. Davies6
1
ESR, Kenepuru Science Centre, P.O. Box 50-348, Porirua, New Zealand
2
The EpiCentre, IVABS, Massey University, Palmerston North, New Zealand
3
Tegel Foods (NZ) Ltd., Bruce McLaren Drive, Henderson, Auckland, New Zealand
4
Inghams Enterprises (NZ) Pty. Ltd., Ngarua, Waitoa, New Zealand
5
School of Clinical Sciences, Division of Health Sciences Murdoch University, Perth,
Western Australia, 6 Department of Clinical and Population Sciences, University of
Minnesota, St Paul MN 55108, USA.
Summary
Different sites within a grow-out house were examined for free available chlorine
(FAC) concentration at different times of the day to determine spatial and temporal
differences in FAC concentrations. There were no significant differences between the
concentrations of FAC taken from various drinkers around the grow-out house. There
were differences in the variation of measurements taken from the same drinker within a
grow-out house at different times of the day, with variation increasing in the afternoon.
Three grow-out houses consistently met the chlorine concentration suggested by the
New Zealand Drinking Water Standards of 0.2ppm.
Introduction
Contaminated drinking water has been associated with large outbreaks of human
Campylobacteriosis (1), and is considered an important route of transmission among
broiler chickens (2). Chlorine is an effective disinfectant against Campylobacter (3) and
both chlorination and acidification of drinking water have been recommended as
potential control measures in broiler production (4,5) and processing (6). The amount of
HOCl and OCl- in water is referred to as free available chlorine (FAC). In New
Zealand, chlorination policies differ between major poultry companies, one company
aims to provide growing broilers with chlorinated water at a target FAC concentration
of 2ppm (mg/L), ten times higher than the concentration allowed in potable water for
human consumption (7).
Materials and Methods
Over three weeks, eleven grow-out houses were tested in a similar fashion with birds of
different ages (5-35 days), six grow-out houses from one company A and five from
another company B. One grow-out house from company A that did not chlorinate
drinking water was included in the study as a negative control (grow-out house F) (8).
The 10 grow-out houses with chlorinated drinking water were sampled to detect a 50%
reduction of FAC concentration to be statistically significant from the targeted 2ppm
(80% power, alpha of 0.05, standard deviations of 0.5 and 0.75 ppm).
Water samples were collected at 10.30 am, 1:00 pm and 3:00 pm from multiple
locations of different water lines to investigate the effect of sampling time and location
on FAC. Seven to 10 different locations were included with at least one sample taken
from every drinker line and five samples taken from one drinker line. Where possible, a
Proceedings of the 10th International Symposium on Veterinary Epidemiology and Economics, 2003
Available at www.sciquest.org.nz
water sample was also taken from a tap at the end of a drinker line, within 5m of the
header tank.
A calibrated Palintest 1000 Chlorometer™, cuvettes and N,N-diethyl-pphenylenediamine (DPD) tablets were used within the grow-out house to perform the
DPDFT (9). Fifty millilitres of water was collected from each drinker and allowed to
settle for 2 min. The concentration of FAC was determined by measuring the amount of
light absorbed by a 10ml sample at 510nm.
Results
The average chlorine concentration in the water of the negative control shed was
0.01ppm. In the 10 grow-out houses with chlorinated drinking water, there was no
significant difference between different sites within grow-out house (p=0.75). Chlorine
concentration did not significantly increase with time but the variability differed
between sampling times. In the morning reading, the coefficient of variation was
13.8%, whereas at 1:00 pm it was 101.3% and at 3:00 pm it was 90.1%. All samples in
the remaining ten grow-out houses were collected as close to 10:30 am as possible.
Mean grow-out house FAC concentrations in drinking water were consistently below
the 2ppm target. FAC concentrations were different between grow-out houses
(p<0.001), FAC concentration was below 1ppm in all samples tested from drinkers, and
mean FAC concentrations exceeding 0.2ppm were found in only three of the grow-out
houses tested. The tap concentrations were consistently more than 2.8 standard
deviations higher than the mean of those seen in the drinkers; they were therefore
excluded from further analyses.
Discussion
The increase in variation between the FAC concentrations in the afternoon compared to
the morning may be due to an increased usage of drinkers in the afternoon. The increase
in drinker use may ‘pull down’ more water from the header tank, resulting in
fluctuations of FAC concentrations in drinkers.
The inability to achieve the targeted FAC may be explained by the incoming water
quality (presence of inorganic and organic solids), drinker type, delivery system (metal
or plastic) and whether sufficient chlorine solids were added to the water.
Drinker lines had higher concentrations of FAC than did the drinkers. There may have
been a build up of water within the 1m space between the tap and the main water
supply. Decreased water demand may have affected the FAC concentration. Biofilms
may also have been present in the drinker lines which would reduce the FAC present in
the broilers drinking water (10). The FAC concentrations measured from taps are an
overestimate and may not represent that being delivered to the birds.
Two American studies in 1986 (11) and 2001 (12) indicated that adequately chlorinated
drinking water did not influence the incidence and degree of Salmonella or
Campylobacter infection in birds in a contaminated environment. However, these
experiments were conducted in the USA where broiler husbandry utilises sheds with
dirt floors, and does not include mechanical removal of litter, high-pressure washing,
Proceedings of the 10th International Symposium on Veterinary Epidemiology and Economics, 2003
Available at www.sciquest.org.nz
disinfection or fumigation of sheds between flocks. In NZ and in Norway, such
practices are followed and sheds have concrete floors. In Norway, studies indicate that
the disinfection of drinking water is the preventive measure most likely to have the
greatest impact on the prevalence of Campylobacter among broiler chicken flocks
(population attributable fraction = 0.53) (5).
This study has shown that broiler chickens on commercial farms in New Zealand are
rarely supplied with similar FAC concentrations as targeted, which may enable C.
jejuni to spread easily amongst a flock, such that the flock enters the human food chain
contaminated with C. jejuni. It also demonstrates the differences seen when taps were
used to measure FAC concentration instead of the drinkers. This information should
prove useful to the managers of broiler farms, and will encourage more accurate
measurement of the FAC concentration in water available to commercial broiler
chickens.
References
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Proceedings of the 10th International Symposium on Veterinary Epidemiology and Economics, 2003
Available at www.sciquest.org.nz