Milt cryopreservation for rheophilic fish threatened by extinction in the Rio Grande, Brazil.

BACKGROUND: Specific protocols for milt cryopreservation have been established for some freshwater fish species. However, cryopreservation reduces sperm quality, giving unsatisfactory results in reproduction. OBJECTIVE: The objective of this work was to evaluate the effect of different cryoprotectants on the quality of Prochilodus lineatus, Brycon orbignyanus and Piaractus mesopotamicus milt after cryopreservation. METHODS: The milt was diluted in different cryoprotectant solutions containing 10% methanol, dimethyl sulfoxide, glycerol, propylene glycol or ethylene glycol combined with the Beltsville Thawing Solution extender (5%), then placed in the vapour of a liquid nitrogen (LN) storage tank for 24 h, after which they were immersed in LN. After rewarming, the rate (%) and duration (s) of milt motility and abnormal morphology were evaluated. RESULTS: All of cryoprotectant solutions tested used maintained the viability of P. lineatus and P. mesopotamicus milt. However, in P. lineatus, glycerol ensured a lower percentage of abnormal morphology. In case of P. mesopotamicus, all of the cryoprotectant solutions tested may be used in the cryopreservation process, with the exception of those containing glycerol. CONCLUSION: For B. orbignyanus, cryoprotectant solutions containing methanol and ethylene glycol are recommended for use in the cryopreservation process, although they reduced the quality of sperm post-rewarming.

Effect of three feeding management systems on some reproductive parameters of Scorpion mud turtles (Kinosternon scorpioides) in Brazil.

Chelonians have been exploited since ancient times for their meat, eggs, fat, and offal, among other things. Among these animals, there is Scorpion mud turtle (Kinosternon scorpioides) which is an omnivorous turtle with semiaquatic habits and is widely consumed in Brazil. The aim of this study was to evaluate the influence of different feeding management systems on the reproductive performance of captive-bred Scorpion mud turtles, including egg quality and chemical composition. Study animals included 15 males and 48 females, divided into three groups. Animals were fed with either a commercial diet or a commercial diet supplemented with one of two different mixes (wet diet). All animals were fed at 1 % BW/day divided on Mondays, Wednesdays, and Fridays. Treatments were as follows: TR = 100 % fish food (22 % CP); TRM1 = 70 % fish food + 30 % mix 1 (bovine offal and fish); TRM2 = 70 % fish food + 30 % mix 2 (bovine offal, fish, and shrimp). Samples were collected during 7 months, and eggs were identified, weighed, measured, and frozen for later analysis. Statistical analyses, including ANOVA, were performed using the program SAEG 9.0. Measurements taken from the nests were compared using the Tukey's test (P < 0.05). The different diets were associated with differential egg-laying performance and eggshell thickness. Animals fed with wet diets containing protein of animal origin displayed the best performance. Furthermore, nests with fewer eggs contained eggs of better external quality (e.g., greater length, width, and eggshell thickness). Finally, animals fed with only commercial feed produced eggs with lower saturated fatty acid content.

Aceite de clavo como anestésico para el pez Pacu (piaractus mesopotamicus) / Clove oil as an anesthetic for pacu fish (piaractus mesopotamicus)

Con el propósito de minimizar el daño causado a los peces por el uso de sustancias anestésicas, se ha evaluado, en este trabajo, la concentración más adecuada de aceite de clavo como anestésico para el pez pacu (Piaractus mesopotamicus). Fueron utilizados 40 peces, con peso promedio de 716,18 g. Los tratamientos fueron compuestos de soluciones con diferentes concentraciones de aceite de clavo, 30, 60, 90, 120 y 150 mg/L. Fueron utilizados dos acuarios de vidrio: uno con 20 litros de agua con la solución anestésica para cada tratamiento y otro con 20 litros de agua limpia, para el regreso de los animales de la condición de sedación. Se observaron de forma individual: el tiempo hasta llegar a la anestesia profunda y el tiempo de recuperación de la anestesia profunda. El diseño experimental fue completamente aleatorizado con cinco tratamientos (concentraciones de aceite de clavo) y ocho repeticiones (peces). Los tiempos hasta anestesia profunda e hasta la recuperación total de los peces fueron evaluados por regresión, con 5% de significancia. Se observó un comportamiento linear de los tiempos hasta la anestesia profunda y hasta la recuperación total de los peces a concentraciones crecientes de aceite de clavo. La concentración de 30 mg/L es suficiente para la inducción anestésica de los animales, por otra parte, las concentraciones más elevadas, hasta 150 mg/L, causaron inducciones aún más rápidas, sin pérdida en las condiciones para la recuperación de los peces(AU)

In order to minimize damage to fish caused by the use of anesthetic substances, this study was to evaluate the concentration of clove oil as an anesthetic most appropriate for pacu (Piaractus mesopotamicus). A total of 40 fishes, with average weight of 716.18 g. The treatments were: anesthetic procedures with solutions of different concentrations of clove oil, 30, 60, 90, 120 and 150 mg.L-1. We used two glass aquariums: one with 20 liters of water containing the anesthetic solution for each treatment and the other with 20 liters of clean water, the animals return to the condition of sedation. Were observed individually: the time to reach deep anesthesia and recovery time of deep anesthesia. The experimental design was completely randomized design with five treatments (concentrations of clove oil) and eight replicates (individuals). The data were submitted to regression, with 5% significance level. There was a linear time of anesthesia and return of fish to increasing concentrations of clove oil, and 30 mg.L-1 is sufficient for the induction of the animals, but higher concentrations of up to 150 mg.L-1, still show inductions faster, without loss in time and conditions for the recovery of fish(AU)