Assessment of gametes in tilapia Oreochromis niloticus: effects of body weight in a new lineage

Abstract

The objective of this study was to obtain information about the reproductive performance of tilapia gametes GIFT and compare the influence of the weight of these animals on quality of gametes. We used thirty healthy breeding females and males weighing between 250 and 500 g (light animals) and thirty breeding females and males ranging in weight from 600 to 1000 g (heavy animals). The animals were placed in tanks and after twenty days, the gametes were collected for further analysis. Were evaluated sperm morphology, sperm motility, and sperm concentration in males. In females, we evaluated the diameter of oocytes and morphology of the micropyle. The weight of the animals did not affect (P>0.05) sperm motility, whose values for heavy and light animals were 86 ± 6% and 96 ± 1% respectively, and influence the sperm concentration (P<0.05) whose values were 2.44 ± 0.41 × 109 sperm/mL in weighed animals and 1.66 ± 0.14 × 109 sperm/mL light animal. The animal weight did not change size of oocytes (P>0.05) with 1.31 ± 0.04 μm for light animals and 1.27 ± 0.02 for heavy animals. The animal weight influenced (P<0.05) the sperm morphology. The heavier animals had higher rates of abnormalities tail tucked, head and isolated part degenerated intermediate in relation to light animals whose highest level of abnormality in relation to the sperm head was heavy degenerate. The micropyle GIFT tilapia showed a funnel-shaped depression, with vocal arrangements around the micropylar region and after thirty minutes from the entrance of the sperm, a lump was found in the micropylar channel, giving birth to its closure. Taking into account the parameters studied, tilapia breeding GIFT between 250 and 1.000 g can be used in commercial breeding herds and comparable to the traditional lineages.