EFFECT OF DIETARY FISH-MEAL ON THE PALATABILITY AND FATTY-ACID COMPOSITION OF PORK

The effect of graded levels of dietary fish meal was studied with growing pigs in two trials. Test diets contained fish meal 0, 2.7, 6.5 and 13 % in trial 1 and 0, 2, 5 and 10 % in trial 2. In trial 2, diets containing 5 or 10 % of fish meal were divided into four different treatments, where fish meal was withdrawn from the diet 7, 5, 3 or 0 weeks before slaughter. There were no significant differences in performance results between the treatments in trial 1. The contents of long chain polyunsaturated fatty acids C22:5 and C22:6 in the pork fat were analyzed in both trials and they increased linearly with increasing level of fish meal in the diets (trial 1 and 2) (p<0.001) and with length of fish meal feeding period (trial 2) (p<0.001). In organoleptic analyses of fresh meat samples there were no statistical differences between the treatments in trial 1. No off-flavours could be found from the fresh meat samples in trial 2. After a freezing period of 7 - 8 months, the off-flavour of the meat increased linearly with increasing content of fish meal in the diet in trial 1 (p<0.001). In trial 2, distinctness of off-flavours increased also with the level of fish meal and with the length of fish meal feeding period.