Physiological and biochemical parameters for egg quality determination in lake trout, Salmo trutta lacustris

摘要

Ovarian fluid pH, protein concentrations and activities of aspartate aminotransferase and beta-D-glucuronidase of lake trout were significantly (P<0.001) correlated with viability of ova, measured in terms of the number of eyed-stage embryos. Batches of ova with high viabilities (>=80%) had ovarian fluid pH values between 8.44 and 8.57, protein concentrations below 235.56 mg/100 ml ovarian fluid, aspartate aminotransferase activities below 31.65μm/min/litre ovarian fluid and beta-glucuronidase activities below 8.62μm/min/litre ovarian fluid. The increase in wet weight of ova during water hardening was significantly (P<0.001) correlated with the number of eyed-stage embryos; batches with high viability (>=80%) increased in wet weight by >=13% duringwater hardening. The number of eyed-stage embryos was significantly (P<0.01) correlated with the activities of NADP-dependent isocitrate dehydrogenase (viability >=80% at >=2.07 nM/min/mg protein) and NAD-dependent malate dehydrogenase (viability >=80% at>=47.25 nM/min/mg protein), respiration rate (viability >=80% at >=8.71 nM/min/mg protein), the ratio of NADH to NAD levels (viability >=80% at >=0.872), the levels of free, non-esterified fatty acids (viability >=80% at >=72.34μg/mg protein), and the ratio ofnon-esterified to esterified fatty acids (viability >=80% at >=0.749). Subjective and visual methods for distinguishing batches with viable and non-viable ova are described.