Einfluss der täglichen Zunahme und des Körpergewichtes auf die Tiergesundheit von langsam wachsenden Masthühnern unter ökologischen Bedingungen – Eine Feldstudie

Summary

According to EU-Regulation 889/2008 slow growing strains shall be used in organic farming in order to ensure good broiler welfare. We examined effects of growth speed on broiler welfare in four different strains (33.01±5.8 to 44.02±8.0 g/day) in two batches on nine organic farms that kept two to four strains in parallel. The currently common slow growing strain (44.02±8.0 g/day) was a reference on all farms. In total 5593 broilers in 36 groups with 30 to 565 animals were kept. Live weight, lameness, skin and plumage condition and cleanliness of plumage were investigated on samples of 30 to 81 birds depending on group size. If possible, measures were taken repeat-edly (twice), at an average body weight of 1800 g to 2600 g. Individual data were analyzed using a logistic mixed model with daily weight gain, body weight and batch as fixed factors and farm as random factor. Percentages of birds without lameness, foot pad dermatitis, hock burn, plumage and skin damage on the breast, injuries and without dirty feathers decreased with higher daily weight gain (p<0.0001, breast skin damage p=0.004, n= 2260), and higher body weight (p<0.0001 to p<0.0429, except for hock burn). Thus, higher daily weight gain and body weight lead to more welfare problems also in broilers with relatively low daily weight gain under organic conditions.