Elevated grids offer birds an opportunity to rest in a species-specific manner and can improve welfare, especially for medium growing chickens.
German research looked at whether environmental enrichments, which may improve welfare in broilers, could help dual purpose strains.
Increasingly, due to ethical reasons, there are attempts to fatten the male chickens of layer strains or to use dual purpose strains but until now there has been limited knowledge on the behaviour of these birds.
So, the aim of the study, carried out by scientists at three German research institutes, was to test the use of elevated grids and their effect on animal-based indicators, (eg physical condition).
In 2 successive trials, the researchers kept a total of 1,217 male chickens from 3 strains (Lohmann Dual, Lohmann Brown Plus and Ross 308) that show differences in growth performance in 24 pens (2 trials x 3 strains x 8 pens).
In half of the pens, grids were offered at 3 different heights (enriched groups); in the other half of the pens, no elevated structures were installed (control groups).
The scientists recorded the number of birds using the grids at different heights and also looked at:
Chickens with low and medium growth performance preferred the highest grids during both the light and dark periods.
In contrast, fast-growing chickens used the lowest grid more frequently. Fast growing chickens kept in the enriched pens tended to have a higher level of locomotor activity and reduced chest cleanliness.
Chickens from the medium growth performance strain showed better walking ability when kept in the enriched pens. Enrichment did not affect any of the welfare measures in the slow-growing chickens.
The findings suggest that elevated structures may improve chicken welfare, particularly for medium growing chickens. For fast-growing chickens, researchers found evidence for an improvement of animal-based indicators although they used the elevated structures less.
The article is published in the June 25 edition of Frontiers in Veterinary Science