Mussel meal in poultry diets - with focus on organic production

Summary

The first limiting nutrients for poultry are the sulphur containing amino acids, particularly methionine. To fulfil the recommended requirement, conventional diets are supplemented with synthetic methionine. Since this is not allowed in organic production it becomes important to have access to alternative high quality protein feed ingredients. The aim of this thesis was to investigate whether blue mussels (Mytilis edulis) could be used as a protein source in diets for organic poultry and determine whether the amount of fish meal commonly used today in organic diets could be replaced with mussel meal. Four experiments during both short time periods and during whole production cycles were conducted to evaluate production performance, egg quality and animal health when using mussel meal in the diets. Additionally, the effects of the mussel toxin okadaic acid (oa) were evaluated. oa is a toxin that unpredictably appears in mussels some years. The experiments were performed both in laying hens and in broiler chickens and for laying hens, both in furnished cages and floor systems. Inclusion levels of mussel meal in the diets of up to 12% for broiler chickens and 15% for laying hens were used. Mussel meal in the diets did not affect production performance for laying hens or broiler chickens in any of the experiments. oa at moderate level used in diets for laying hens did not negatively affect the birds and no oa was detected in the egg yolk. When extremely toxic mussels were included in the diet, broiler chickens got diarrhoea, lower growth rate and feed intake than birds fed the control diet. Egg yolk pigmentation differed significantly between diets in all experiments with laying hens. The egg yolk was more darkly coloured when the hens were fed a diet containing mussel meal. Off flavour and off odour did not differ in any eggs. In one experiment plumage conditions was evaluated and an improved total score was observed when mussel meal was included in the diet. These results indicate that mussels may be a good and high quality protein source for poultry and may replace fish meal in organic diets for laying hens and broiler chickens.