Body traits and chemical composition of muscle in the common carp ( Cyprinus carpio L.) as influenced by age and rearing environment

Abstract

To investigate body traits and muscle chemical composition in common carp as influenced by age and rearing environment, 2000 fry were stocked in two earthen ponds (300 m 2): warm (W), with warm water (refluent from a thermal power station) at about 10 °C above natural temperature, and natural (N), with water from Lake Trasimeno. Because of the different growth rate, W subjects were sampled 3 times (at 12, 15 and 18 months of age) while N-subjects were sampled only once (at 15 months of age). The W 12-month-old fish weighed on average 102 g while N-fish did not reach this weight even at 15 months. At this age, the W subjects showed, in comparison with N-subjects, higher body weight (143 vs. 85 g), component weights, linear measurements (20.94 vs. 17.8 cm), fins (1.80 vs. 1.63g) and filleting remnants (12.80 vs. 11.25%) and lower incidence of skin and head index; no differences resulted in proximate analysis, but muscles of W-fish were richer in saturated fatty acid and in n − 3 PUFA content and showed a higher n-3 n-6 PUFA ratio. By comparison with the 15-month-old subjects collected in October 1992, the 12-month-old W-subjects, collected in July 1992, showed lower fin (0.59 vs. 1.8%), viscera (7.6 vs. 10.2 %) and head (20.36 vs. 22.92%) percentages but higher gill (4.27 vs. 3.24%), filleting remnant (14.99 vs. 12.80%), skin (3.92 vs. 3.37%) and dressing (92.4 vs. 89.79%) percentages. The 18-month-old W-subjects, collected in January 1993, did not differ significantly from the 15-month-old subjects either in body weight (154 vs. 143 g) or in the other traits studied, excluding the incidence of viscera (12.01 vs. 10.21%) and gills (2.69 vs. 3.34%), respectively, in the older subjects. Intramuscular lipid content decreased from July according to a seasonal trend. Allometric coefficient showed tachyauxesis for viscera, pectoral and pelvic fins, skin and total muscle and bradyauxesis for filleting remnants and head.