“In the Netherlands we monitor what is happening and communicate our findings to the government and the producer organisations and interbranch organisations”, De Bruijn explains. The increase in old poultry diseases was not found by GD Animal Health alone. Also international publications mention a growing number of reports about bacterial diseases that accompany loss. “Within the Netherlands it may only concern a limited number of farms, but the companies that have to deal with these diseases suffer great damage. The phenomena reaches beyond the borders of the Netherlands, with its high poultry density. It also occurs in countries such as Denmark, where poultry is kept in alternative housing systems, at large distances from each other.”
The increased occurrence can be largely explained by the changing housing styles. “We know the concerning pathogens from the past, when poultry was kept in colonies.” After a period in which one focused on safety in food production for the consumer, we went back to alternative, more animal friendly systems. This is accompanied by a rise in the occurrence of old diseases. After the switch, apart from colony housing, laying hens are no longer kept in cages. In modern housing styles birds have more contact with other birds, but also with manure, dust and pathogens. The latter, such as bacteria, viruses and parasites, will quickly spread through the house. Pathogens can be found everywhere in the birds’ environment. It is in the animals themselves, and is excreted via the gastrointestinal tract. “Particularly ill birds excrete vast amounts of pathogens with the manure. Chickens tend to examine everything, including each other’s excretions. Eating each other’s manure brings them into contact with high levels of pathogens. The disadvantage of free-range systems is that pathogens are difficult to eliminate. After all, excavating a meter of soil is not a realistic solution. As pathogens remain in the environment animals can be infected again and again.”