26. Conventional (enclosed) housing systems often involve large numbers of birds being housed together. The risk of birds suffering heat stress is greater in these situations. However, we did not find any evidence of heat stress mortality during our investigation. This might be expected as the major production peaks are limited to the Christmas and Easter markets i.e. during the cooler months. However, many companies produce turkeys throughout the year and we witnessed some birds panting in hot and humid house environments during visits to producers on very hot days. We believe that these birds were suffering heat stress. Prolonged periods of severe panting are stressful and must be avoided.
27. Shallow panting is a normal response to increased environmental temperature and should be expected for short periods of time amongst a proportion of birds during the summer months. In these situations turkeys pant to prevent their body temperature from rising. Turkeys encounter heat stress when they are in a hot environment and are unable to prevent body temperature from rising. The efficiency with which birds can lose heat by panting is greatly influenced by the relative humidity of the environment. Panting will not be effective when the relative humidity is high. It is for this reason that the risk of heat stress is greatest when both the temperature and the relative humidity are elevated.
28. The wide variations in building design and ambient conditions make it difficult to prescribe a formula which would minimise heat stress. However, information about the avoidance of heat stress is contained in a MAFF publication "Heat Stress in Poultry - Solving the Problem" which is available free from MAFF Publications, London SE99 7TP (tel: 0645 556000) - quote reference PB 1515. All producers should familiarise themselves with this booklet. Examples of some of the steps which may need to be taken are: increase the air speed at bird level using re-circulation fans; ensure that the insulation of the house is satisfactory; allow the house to cool at night; and reduce stocking density. Sufficient drinking water must be provided and it may be necessary to increase the density of the diet during prolonged periods of hot weather when the birds will eat less.
29. It is essential that the automatic equipment and alarms are in good working order. During our visits we found that producers were well aware of this requirement but we would like to use this report to remind all farmers raising birds in intensive units that automatic equipment must be thoroughly inspected at least once a day. The Welfare of Livestock Regulations 1994 require it. The Regulations also require automatic ventilation systems to be fitted with alarms and a fail safe device in the event of failure. These must be tested every week.
30. The MAFF publication "Heat Stress in Poultry - Solving the Problem" should be amended specifically to include turkeys as a species and night cooling in periods of high temperature.
31. Those responsible for the keeping of turkeys should familiarise themselves with the amended version of the MAFF publication "Heat Stress in Poultry - Solving the Problem" and the The Welfare of Livestock Regulations 1994.
32. To help to ensure that heat stress, as shown by excessive panting for long periods, is avoided as far as is practicably possible for the time of year,
the person responsible for turkeys kept in conventional (enclosed) houses must ensure that the stocking density used for each flock in each building is within the maximum recommended in paragraph 75 of this report.
33. If heat stress mortality occurs, the onus must rest on the person responsible for the flock to demonstrate that the house had been stocked at a pre-calculated density which was appropriate for the design of the building, its locality and the predictable maximum temperature at the time of mortality.
34. Temperature and humidity levels should be such that the birds do not pant continuously for long periods.