Abstract

LENIS, Gustavo A; RESTREPO, Luis F  and  CRUZ-CASALLAS, Pablo E. Evaluation of three protocols hormone treatment on the size of the oocytes of sabaleta Brycon henni. Rev Colom Cienc Pecua [online]. 2009, vol.22, n.2, pp.131-142. ISSN 0120-0690.

The evaluation of three hormone treatments on the diameter size of ovocytes in Sabaleta was conducted during the breeding season from May to July 2008. Twelve Brycon henni females and 24 males, 100 g and a standard length of 24 cm, were selected according to their sexual maturity and external features such as bulging belly, red genital papilla and semen expulsion after softly pressing its coelomic cavity. The fish were selected from a 320 brood fish batch caught in the wild in August 2007 and kept in captivity in a 200 m² earth pond. The presence of an anal fin with or without spines of a maximum length of 50% was considered as sexual dimorphism in females. Internal characteristics were also considered; e.g., an ovarian aspiration biopsy was performed in females in order to observe its nuclei position and diameter. Ovocytes from selected females were at least 900 µm in diameter. Animals were distributed into three treatment groups for four sampling dates: T1 carp pituitary extract (CPE) (Argent Chemical Laboratories Inc., USA), n = 4; T2 Ovopel (Sigma Co. USA), n = 4; and T3 Ovaprim (Syndel Laboratories Ltd., Canada), n = 4. Each female was fertilized with the semen of two males previously injected with CPE. 11 out of 12 females had a treatment response, and resulting ovocyte average diameters were 1428.8 and 1679.8 (T1), 1531.2 and 1879.2 (T2), and 1712.8 to 1803.3 (T3), before and after hormone treatment, respectively. Significant differences were found within T1 and T2 (p <0.05); however, this was not the case for T3. For T1, frequency distribution of the diameter of ovocytes before the hormonal treatment was bimodal. T2 had two modes before and one after the treatment (bimodal and unimodal), and T3 had two before and two after (bimodal). Fertilization rates were low in T1; nevertheless, T2 and T3 had high rates until 12 h eggs incubation.

Keywords : Fish; ovocyte diameter; pituitary extract; reproduction.