Influence of rainbow trout planting material feeding technology on variability of its linear-weight parameters

The objective of this study is to conduct a comparative analysis of the impact of feed distribution method on the linear-weight parameters of juvenile rainbow trout, taking into account their variability. The study subjects were rainbow trout fry reared in tanks at Fedorenko N.V., LLC. Before the study, fish from both tanks were sorted, their size and weight parameters were determined, and then re-mixed and placed in the same tanks. Feeding, both manually and automatically, was performed every hour around the clock for 33 days. Upon completion of the study, the fish were again sorted, their linear-weight parameters were measured, and their variability (Cv) was determined. The null hypothesis that the compared populations were identically distributed was tested using the nonparametric Mann-Whitney U-test. When comparing rainbow trout by weight and zoological length before the experiment, the samples (44 and 43 in size, res-pectively) had the same distribution with a reliability of 95 %. However, when comparing fish by the same parameters after the experiment (45 and 33 in size, respectively), the value of the T statistic (3.515 and 6.245, respectively) is greater than the tabulated value of the Student's t-test for the degree of freedom df = 76 and the significance level α = 0.05 (T(0.05,df) = 1.992). Therefore, the differences between the studied samples were significant; feeding method (manual vs. automatic feeder) significantly impacted fish body weight and length (with a 95 % confidence level). Automatic feeding had the greatest impact.