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Although there is a general consensus that housing conditions affect the well-being of laboratory animals, the ideal cage size and density for housing laboratory rodents has not been established. The authors investigated the effects of cage size and cage density on growth, organ development, metabolic profile, and hemogram in juvenile Sprague-Dawley rats. Larger cages and increased cage density were associated with depressions in body weight and in the weights of several organs. In general, increasing group size and density correlated more strongly with detrimental effects on the growth of females than males, although hemogram values indicated that males are more prone to emotional stress and immune suppression than females in response to increasing group size and crowding.

Fish and other fishery products are among the foods recommended for the prevention and treatment of diseases with their high nutritional properties. The demand for fish caviar has increased in recent years due to the increase in fish consumption and their high nutritional and commercial value. In order to meet this increasing demand, caviar substitutes obtained from different fish species have been investigated, however in these limited studies, generally, information about products and markets are provided. In this study, caviar obtained from 30 female rainbow trout (Oncorhynchus mykiss, raised under farm conditions) were processed with different salt concentrations (2, 4 and 8%). Physicochemical [lipid peroxidation (with Thiobarbituric Acid Reactive Substance (TBARS), protein degradation (with Sodium Dodecyl Sulfate - PolyAcrylamide Gel Electrophoresis (SDS-PAGE), color (L*, a*, b*) and salt content of caviar formed by salting process)] and microbiological [total aerobic bacteria (TAB)] quality parameters on certain days of 21-day storage (4 °C) (0., 3., 6., 9., 12., 15., 18., and 21.) was investigated. As a result of the study, the changes in TAB, TBARS, L *, a *, b * values and salinity levels during storage were determined as important (p < 0.05). At the end of storage, it was detected in different profiles as well as phosphoprotein and glycoproteins as major protein groups in the SDS-PAGE analysis. In terms of microbiology, 8% salt concentration was found to be very low compared to control and other salt applications. Considering all the research findings, high salt concentrations were determined to have a positive effect on the preservation of quality.