Water Measurement in Pig and Poultry Production

Our thanks to the author and Conference Organisers, a Committee consisting of both University and Industry colleagues.

The full paper will appear in the Conference Proceedings ('Recent Advances in Animal Nutrition - 2007', edited by Phil Garnsworthy and Julian Wiseman) published by Nottingham University Press in the autumn of 2007 www.nup.com

Water Measurement in Pig and Poultry Production - Image 1
Courtesy of the 41st Annual University of Nottingham Feed Conference www.nottingham.ac.uk/biosciences/ah/research/conferences.php

This paper outlines the key issues of water measurement in pig and poultry production in commercial and similar situations. Issues are illustrated using data measured from a range of production sites. Academic research of water intake is very limited, so the information presented is largely qualitative and interpretative.

Introduction

Life is water. It makes up the greater part of body tissues, and the greater part of dietary intake of farmed animals. Without water, animals quickly become ill and die. Despite that, water intake is relatively unexplored territory in commercial production. It tends to be assumed that if it of "adequate" quality with "adequate" availability, then everything will be "OK".

From a pollution and regulatory point of view, there is somewhat more interest in what comes out at one end, than goes in at the other.

This is partly because water is cheap and no one particularly makes money out of it. It matters to producers, plumbers and animals, say, but not to feed companies. At least, not on the face of it. If it has been measured at all, it is merely daily manual readings. This tends to miss most of the information - the signals - in the data.

The Hardware

Water Meters

In commercial scale production, water measurement using standard "utility" type meters, with "pulse" output is cost effective and adequate. Utility type meters cost £50 to £150. More specialist types such as turbine "flow meters" and ultrasonic detectors are also available for more specialist applications - such as measuring for small groups of animals in pens.

In practical terms, meters are "integrating" meters. That is, they measure total (accumulating) volume - a pulse per unit volume of water - not rate of flow. Typically, the unit of measurement (resolution) is 0.5 or 1 litre. Turbine flow meters can be down to 0.01 litres.

Water Meter Issues

minimum flow rate
pressure drop
accuracy
scaling and debris

Water meters have a limited dynamic range, and cause a pressure drop. The higher the flow rate, the greater the pressure drop. For that reason, they must be chosen carefully so that flow rates fall in the correct range and, in practical situations, must be at mains pressure.

Below their minimum flow rate, meters typically register "no flow". This is a significant issue since many water systems are worn (standard float valves are only rated for 200,000 operations) and this can lead to large reading errors. It's advisable to maintain systems and replace float valves if installing metering. Accuracy within the specified range is not generally an issue (around 2%).

Scaling and particulate matter (silting up) are a common cause of failure, since farm supplies are usually from a borehole, and farms are very reluctant to use filters or settling tanks.

Data Logging

Manual recording of water use is almost worthless, especially in pig production, and particularly from a diagnostic perspective, so electronic recording is essential.

This means that the "pulse" contacts on the meter are connected to a data logger, which counts up each unit of consumption. Recording every 15 minutes appears to be adequate for detection of data signals, without excessive volumes of data. Water data is of limited use without the relevant associated data such as temperature, number and of animals, etc.

Therefore logging systems should include recording of the other related data.

"On-screen" displays of current readings are of little benefit other than to check that sensors (for water, temperature, etc) are functioning. A data logger suitable for long term use in agricultural surroundings costs from around £1000 for 8 input channels, plus £200 per additional 8 inputs. In practice, cost is dominated by installation cost - due to the long wiring runs.

Due to the distances and wide range of farm layouts, effective wireless data networks have yet to emerge for agricultural situations, but may be expected within the next 3 years/

In practice, on-site staff rarely have sufficiently developed data or interpretative skills and water intake data is generally used off-site. Therefore remote connection via modem (using landline modem, cellular, or broadband) and remote presentation of data are essential.

Modern control and regulation systems (such as Dicam®) have the facility for data logging (added to control functions) and this offers a very cost effective method.

However, data logging capability varies considerably from manufacturer to manufacturer.

Data Signals

Data signals are information or factors within the data that affect the measured value - that is, a change in the measured value indicates a changed parameter or circumstance.
Signals have varying frequencies. The main signals are:

Feed intake
Growth
Body clock and lighting
Temperature
Feed type and taste
Health
Feed availability
Socialisation, behaviour and habit
Water quality
Water availability
Leakage and dribbling

For example, larger pigs drink more, so increased consumption is an indication of growth. However, this takes place over a long period of time (low frequency data).

The body clock means that water intake varies considerably over each day. This higher frequency is superimposed on the lower frequency growth data. The measured data is therefore a waveform of greater or lesser complexity.

Water Measurement in Pig and Poultry Production - Image 2
Typical intake pattern for poultry and pigs (2 days)

Uses of Water Intake Data