Abstract The cooling of Litopenaeus vannamei shrimp spermatophores for assisted insemination can enable the transfer of gametes between reproduction laboratories. This study aimed to assess three extenders for cooling L. vannamei spermatophores for assisted insemination. Spermatophores were chilled at 15 °C for 24 or 48 hours using powdered coconut water ACP® (PCW), mineral oil (MO), and sterilized seawater (SSW) as extenders. All treatments demonstrated consistent responses over time. Apparent viability and morphological integrity percentages remained above 60% and 70%, respectively, across treatments and storage durations. Focusing on diluents, normal cell percentages for MO, SSW, and PCW treatments were 74.9±9.20%, 77.3±9.40%, and 78.1±6.35%, respectively, irrespective of storage time. The highest hatching rate was observed in the SSW treatment (80.67±12.01%), which was significantly superior to the PCW treatment (50.15±20.75%). The hatching rates observed in the MO treatment (71.47±18.83%) did not statistically differ from either PCW or SSW treatments. The cooling protocol successfully preserved the spermatophores' ability to maintain favorable levels of apparent viability, normal morphology, and hatching rates after 48 hours of storage at 15 °C using mineral oil, seawater, or ACP® as extenders. Sterilized seawater emerged as the most efficient diluent, delivering superior hatching rates following artificial insemination.

Abstract To assist the reproductive management of tambaqui (Colossoma macropomum) males in laboratory and commercial fish farming, a linear regression model was obtained from concentration curves using the spectrophotometric method. Twenty-two tambaqui males with an average age of three years old were selected and divided into two groups containing 11 animals each. Both groups alternately received a single dose of carp pituitary extract (CPE; 2.0 mg/kg body weight, intracoelomic). Sperm was collected 14 h after hormonal treatment and diluted (1:4000; sperm:formaldehyde saline). The concentration was estimated by counting spermatozoa in a Neubauer chamber and by using a spectrophotometer (λ=540 nm). Individual sperm concentration ranged from 11.40 to 71.13 × 109 sperm/mL. The degree of transmittance ranged from 62.1% to 95.0%. There was a significant correlation (r2 = 0.966; p < 0.0001) between sperm concentration analyzed in a Neubauer chamber and transmittance at 540 nm. Analysis by spectrophotometry and the prediction provided by the equation Y=100.293 - 0.509X proved to be an efficient and fast method for estimating sperm concentration in tambaqui and can be used in routine procedures in artificial fish reproduction laboratories.

Resumo Visando auxiliar o manejo reprodutivo de machos de tambaqui (Colossoma macropomum) em piscicultura de laboratório e comercial, obteve-se um modelo de regressão linear a partir de curvas de concentração por método espectrofotométrico. Foram selecionados 22 machos de tambaqui com idade média de três anos. Eles foram divididos em dois grupos contendo 11 animais cada. Ambos os grupos receberam alternadamente uma única dose de extrato de hipófise de carpa (EHC; 2,0 mg/kg de peso corporal, intracelomático). O esperma foi coletado 14 horas após o tratamento hormonal e diluído (1:4000; esperma: solução salina formaldeído). A concentração foi estimada por contagem de espermatozoides em câmara de Neubauer e por espectrofotômetro (λ=540 nm). A concentração espermática individual variou de 11,40 a 71,13 × 109 espermatozoides/mL. O grau de transmitância variou de 62,1 a 95,0%. Houve correlação significativa (r2 = 0,966; p < 0,0001) entre a concentração espermática analisada em câmara de Neubauer e a transmitância em 540 nm. A análise por espectrofotometria e a predição pela equação Y=100,293 - 0,509X mostrou ser um método eficiente e rápido para estimar a concentração espermática de tambaqui, podendo ser utilizado em procedimentos de rotina em laboratórios de reprodução artificial de peixes.