Pilot Monitoring of Shipboard Environmental Conditions and Animal Performance

Summary

Temperature and humidity data loggers have been used successfully to establish linkages between environmental conditions and animal performance. This pilot project evaluated equipment, data collection, downloading and collation procedures and made recommendations about future data collection.

The information arising from the pilot project should be analysed to see if it could be used to re-calibrate (or validate) assumptions contained within the industry heat stress risk assessment (HS) model.

This report notes the many contributing factors affecting the heat tolerance of livestock. Because these factors are likely to vary from voyage to voyage and from time to time during a voyage, a large amount of information may be required before estimates of heat tolerance can be validated using onboard monitoring.

Despite these limitations, onboard monitoring using data loggers could be used:

• To provide a record of environmental conditions onboard ship.

• To provide more detailed information if a heat-stress incident occurs.

• To help establish direct linkages between environmental conditions and animal performance.

• To develop a better understanding of onboard ventilation systems.

Animal performance with regard to heat tolerance was measured using a panting score. This score proved to be a reliable and repeatable measure despite its subjectivity. It is therefore recommended that panting score be utilised as the primary indicator of heat stress. The industry HSRA model utilises a definition of heat stress threshold that relates to a shift in core body temperature (Stacey, 2003). The linkage between this and the panting score has been established (John Gaughan, pers. comm.) although this linkage needs to be strengthened.

Information was collected on nine voyages during the period April to October 2004. These voyages generated 79 discrete data sets for subsequent analysis. Analysis of this data was outside the scope of the current project and needs to be completed.

Provided statistically significant findings are made, it is recommended that onboard monitoring be continued. It is not envisaged that monitoring be conducted on all long-haul voyages to the Middle East, rather it is suggested that monitoring be conducted on an opportunistic basis, when lines of livestock are identified as being of particular interest. This will require the monitoring to be actively managed (see 7.1 Recommendation 3).

Because of the many contributing factors to heat tolerance, it was necessary to collect a considerable amount of information to ensure that the data collected could be interpreted. The most challenging of these factors was site selection. To establish heat stress thresholds, it was imperative that the information measured by the data loggers was representative of the air surrounding the animals in the pen. It should be noted that the wet bulb temperature will vary considerably within a hold (up to 3-4 °C wet bulb, depending on the wet bulb rise within the deck). Site selection was therefore crucial to ensure a proper linkage to animal performance.

Livestock description was relatively straightforward, with breed-type being the most important consideration. Coat-length, fatness, age, sex and weight were also recorded. The preparation history of the livestock in question was more difficult to obtain. It is difficult to obtain this information once the vessel has sailed. Even onshore, the origins of livestock are often obscured when mobs are mixed when they pass through assembly centres.

Pen and deck information was collected. Pen area was used to calculate stocking densities. In most cases the actual weights of animals were not available and had to be estimated on the basis of known weights within the consignments. The stated pen air-turnover was utilised as the preferred measure of airflow through the deck. The presence or absence of significant airflow above the animals was also noted, as was the proximity to supply and/or exhaust vents.

The ship’s crew measure bridge temperatures every four hours. This information was used to represent the ambient challenge.

Information relating to wind speed and direction (relative to the ship) was also collected from information held on the bridge. This was important to allow proper interpretation of data collected from open decks. Information about feeding times, clock retard times and deck washing procedures was also collected to assist in the interpretation of the collected data.

Because panting score is a relatively recent measure within the live export industry, it was supported by measures of respiratory rate, respiratory character and heat stress score. These measures were useful to the inexperienced participants and helped to make the assessment of a panting score more consistent among the monitoring participants. With practice participants found these supporting measurements less relevant and were able to rely solely on the panting score.

Most of the voyages that were monitored were relatively uneventful and rarely recorded anything other than mild levels of heat stress in the livestock. However, on three of the voyages, significant heat stress incidents occurred. It is recommended that these incidents be subjected to more thorough investigation.

It was initially envisaged that stockmen would collect most of the project information. However the requirement for all long voyages to the Middle East to be accompanied by a veterinarian resulted in it being better to utilise veterinarians for the monitoring work in some cases. Stockmen were also utilised to undertake the required work.

The full benefits of this project will not be evident until the collected data is statistically analysed. The information has been collated and is presented in a form that should facilitate easy analyses. Animal performance was monitored twice daily. Temperature and humidity information is presented as two-hourly averages. Thus data collection procedures can be matched to onboard management procedures.​