Research on animal health and welfare in organic farming—a literature review

A cross-sectional prevalence study of gastrointestinal helminths in Danish poultry production systems was conducted on 268 adult chickens selected at random from 16 farms in Denmark from October 1994 to October 1995. The trachea and the gastrointestinal tract of each bird was examined for the presence of helminths. In the free-range/organic systems the following helminths were found: Ascaridia galli (63.8%), Heterakis gallinarum (72.5%), Capillaria obsignata (53.6%), Capillaria anatis (31.9%) and Capillaria caudinflata (1.5%). In the deep-litter systems: A. galli (41.9%), H. gallinarum (19.4%) and C. obsignata (51.6%). In the battery cages: A. galli (5%) and Raillietina cesticillus or Choanotaenia infundibulum (3.3%). Exact identification of the cestodes was not possible because of missing scolexices. In the broiler/parent system: C. obsignata (1.6%), and finally for the backyard system: A. galli (37.5%) H. gallinarum (68.8%), C. obsignata (50.0%), C. anatis (56.3%) and C. caudinflata (6.3%). The results confirm the higher risk of helminth infections in free-range and backyard systems but prevalence may also be high in deep litter systems.