Does selection for growth rate in broilers affect their resistance and tolerance to Eimeria maxima?

L.S.,

In your introduction you mentioned:
Such an emphasis on productive traits may have compromised the ability of modern broilers to cope with metabolic and skeletal disorders (Dawkins and Layton, 2012; Julian, 1998) and infectious pathogens (Cheema et al., 2003; Yunis et al., 2000). This raises concerns amongst the general public and have led, for example, the Dutch Organisation of Retailers to take the strategic decision that they will only sell chicken meat from slow-growing animals.

The reasons, however, why Dutch retailers chose for slow growing birds are very diverse. It was not so much the general public but more the pressure of action groups with different agendas that forced the retailers to take actions. These actions were partly based on false accusations.

Different parameters of disease and welfare in regular broilers were and are very good in the Netherlands. The average mortality rates and the amount of antibiotics used are very low in both the regular and the slower growing birds.

To our surprise, however, we are seeing more severe outbreaks of Coccidiosis (mainly E. tenella) in slower growing birds than in the regular broilers.

I would be curious to hear about your ideas about this observation.

Regards.