Health status of the birds
Healthy birds will be more capable to endure the stress of transport and arrive at the slaughter house in good condition. Birds with some kind of health condition, but still fit enough for travel, are more likely to die during transport. To increase the chance for survival additional measures can be taken. For instance, vitamin c provision through the drinking water prior to transport can reduce the effects of stress and may increase survival rate.
Removing litter from the aisles will enable the use of carts in the house or smoothen the path catchers need to walk. This will lead to less damaged birds.
In general it is advised to withdraw food several hours before catching the birds so that the intestines are empty and no soiling of the birds with manure occur, in the crates as well as on the slaughter line. Common practice is to have the feeders empty in the morning of the day the birds will be transported. However, there is a lot of variation. There is discussion about the legally allowed duration of this feed deprivation. For laying hens no legal requirements are in force, but there are several codes of Practice (see more details here).
Birds collected in 1 section of the house
To reduce walking distances for the catchers sometimes birds from the far compartments are moved to the front compartments on the afternoon prior to depopulation. Although this moving of birds was done in a calm way, Van Niekerk et al. (2014) found more damaged birds at the slaughter house for this practice compared to flocks that had not been moved.
Hens are removed from cages either individually or in groups of 2 or 3 by pulling them out by one leg despite recommendations to handle poultry by two legs (e.g. UK Codes of Recommendation). In non-cage systems birds are taken from the perches at night. In aviary systems usually groups of 3 birds are held by one leg and brought outside to the crates. If the hen house is suitable, the crates may be brought in on carts, reducing the distance catchers have to walk with the birds. Experienced catching crews work calmly and with groups in each aisle, working in line from one end to the other end of the house. This causes a minimum of disturbance of the birds, reducing the number of birds that start running around. Birds that are moving away are collected at a later stage, when they have sat down elsewhere.
A direct comparison of different catching and carrying methods for end-of-lay hens showed that plasma corticosterone (stress hormone) concentrations were significantly higher when they were removed from their cages three at a time and carried in an inverted position from the house, than when they were removed singly and crated before removal from the house (Knowles and Broom, 1993).
Further reading (by language)
- Knowles, T.G. and Broom, B.M. (1993) Effect of catching method on the concentration of plasma corticosterone in end-of-lay battery hens. Veterinary Record 133, 527-528.
Hennen die verzameld worden in 1 sectie van de stal
- Van Niekerk, T. G. C. M., H. Gunnink, and B. F. J. Reuvekamp. (2014). Welzijn van uitgelegde hennen tijdens vangen en vervoer in de winterperiode. Wageningen UR Livestock Research; Report 758.