The impact of diet on the slaughter yield, proximate composition and fatty acids profile of fillets of tench (Tinca tinca (L.))

Abstract

The aim of the study was to determine the impact of diet (natural or formulated feed) on the biometric parameters, slaughter yield, proximate composition, and fatty acids profile of tench, Tinca tinca (L.). The study material was comprised of fish from earthen ponds that had fed on natural food (age 5+, mean body weight 420 g) and specimens obtained from intensive fattening on formulated feed in a recirculating system (age 3+, mean body weight 354 g). The tench fed formulated feed were characterized by a lower carcass and fillet yield, which resulted from higher viscera weight (P < 0.01). The meat of these fish contained less water (73.57 vs. 80.23%) and protein (16.52 vs. 18.19%), and more fat (8.85 vs. 0.58%) (P < 0.01). The qualitative fatty acid composition of the meat, similarly to the relative content of saturated fatty acids (SFA) and unsaturated fatty acids (USFA) was not dependent on the diet (P > 0.01). However, it was determined that the meat of the tench reared on formulated feed contained more monounsaturated fatty acids (MUFA) (42.15 vs. 27.90%) and less polyunsaturated fatty acids (PUFA) (33.62 vs. 46.92%) (P < 0.01). The higher MUFA content in the meat of the fish reared on formulated feed in comparison with that from the pond-reared tench stemmed primarily from the various contents of 16:1 (palmitoleic), 18:1cis9 (oleic), 20:1n-9 (gadoleic) and 22:1n-11 (cetoleic). The lower content of PUFA was primarily the result of differences in the amount of n-6PUFA, and to a lesser degree to that of n-3PUFA. The n-3/n-6 ratio in tench reared in recirculating systems and fed formulated feed was nearly two-fold higher than that noted in the pond-reared fish (3.60 vs. 1.93; P < 0.01). The meat of the fish fed intensively with formulated feed contained many-fold less 20:4n-6 (arachidonic, AA; 0.58 vs. 8.92%; P < 0.01), while the content of 20:5n-3 (eicosapentaenoic, EPA; 7.38 vs. 7.97%) and 22:6n-3 (docosahexaenoic, DHA; 12.91 vs. 13.87%) did not differ significantly statistically (P > 0.01).

CORRESPONDING AUTHOR:

Dr Barbara Jankowska, Uniwersytet Warmińsko-Mazurski, Katedra Technologii i Chemii Mięsa, pl. Cieszyński 1, 10-718 Olsztyn; Tel./Fax:+48 89 5233694;
e-mail: barbara.jankowska@uwm.edu.pl