Seminal plasma composition, sperm motility, and milt dilution in the Asian catfish Clarias macrocephalus (Gunther)
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Ionic composition of the seminal plasma and factors that initiate sperm motility in the freshwater Asian catfish Clarias macrocephalus, were examined to develop an artificial seminal plasma (ASP) that can be used to dilute milt. The optimum ratio of milt:ASP that can reversibly activate the sperm and milt–ASP:ovulated eggs that will result in high fertilization rates were further determined to minimize the number of males to be sacrificed during artificial insemination. Seminal plasma of C. macrocephalus contained 17.8±0.1 mM/l potassium, 164.4±0.6 mM/l sodium, 8.4±0.0 mM/l calcium and 1.6±0.0 mM/l magnesium, and had an osmolality of 269.0±6.4 mOsm/kg, and pH of 7.8±0.2. Sperm motility was highest and longest in all electrolyte (NaCl, CaCl2, KCl) and non-electrolyte (mannitol) solutions of 200 mOsm/kg. Catfish sperm were motile in all isotonic NaCl–KCl solutions, and were reversibly activated in the ASP (143 mM NaCl, 30 mM KCl, 8 mM CaCl2, 2 mM MgCl2, 10 mM HEPES) solutions of pH 6.4–9.4. Altogether, these results suggest that sperm motility in C. macrocephalus was mainly initiated by a decrease in osmotic pressure, rather than ions and pH. High fertilization rates (89–94%) were observed when 10 μl milt, diluted with 1000 μl ASP, was activated with 5 ml of 0.6% NaCl (198.24 mOsm/kg) to fertilize 5 or 10 g of ovulated eggs. Results obtained from the present study provide information on sperm physiology that will lead to more efficient gamete management, and hopefully, an increase in the yield of catfish fry in the hatchery.
CitationTan-Fermin, J. D., Miura, T., Adachi, S., & Yamauchi, K. (1999). Seminal plasma composition, sperm motility, and milt dilution in the Asian catfish Clarias macrocephalus (Gunther).
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Effects of human chorionic gonadotropin (hCG) and handling stress on spermiation of silver perch Leiopotherapon plumbeus (Kner, 1864) PJT Denusta, EGT de Jesus-Ayson, MA Laron & LMB Garcia -
Journal of Applied Ichthyology, 2014 - WileyThis study determined the effect of human chorionic gonadotropin (hCG) and handling stress on the spermiation and milt response of silver perch Leiopotherapon plumbeus based on the measurement of spermatocrit, sperm density, and milt production. Compared to saline-injected fish, the mean spermatocrit (or packed sperm) of hCG-treated fish was significantly lower at 18 h (47.9%) and 30 h (40.2%) post-injection while mean sperm density was significantly lower at 30 h post-injection (3.6 × 106 cells μl−1) but not at 18 h. At 18 h (1.8 μl g-BW−1) and 30 h (2.5 μl g-BW−1) post-injection, mean milt production of hCG-treated fish was significantly higher than in the saline group. Milt consistency was also thinner in the hCG-treated group. Mean sperm density of handled fish (18.0 × 106 cells μl−1) was significantly lower than control fish (23.4 × 106 cells μl−1). However, mean sperm density of handled plus saline-injected (16.2 × 106 cells μl−1) and handled plus hCG-treated fish (8.4 × 106 cells μl−1) was significantly lower than in the control goup. Having thicker milt consistency, mean spermatocrit and milt production of handled (77.5%; 1.1 μl g-BW−1, respectively) and handled plus saline-injected fish (75.4%; 1.1 μl g-BW−1, respectively) were not significantly different from the control fish (76.2%; 1.3 μl g-BW−1, respectively). Handled plus hCG-treated fish had the lowest mean sperm density (8.4 × 106 cells μl−1) and spermatocrit (54.7%), but had the highest mean milt production (5.5 μl g-BW−1) among the treatment groups. These results demonstrate that the hCG injection effectively induces spermiation and milt expression and that handling-related stress negatively affects such responses. The spermatocrit method may be used to assess the spermiation and milt response of silver perch.
Conference paperMN Duray - In F Lacanilao, RM Coloso & GF Quinitio (Eds.), Seminar-Workshop on Aquaculture Development in Southeast Asia and Prospects for Seafarming and Searanching; 19-23 August 1991; Iloilo City, Philippines., 1994 - SEAFDEC Aquaculture DepartmentStudies on sea bass (Lates calcarifer) broodstock were directed at techniques to maximize egg production. Now known are the: optimum luteinizing hormone releasing hormone analogue (LHRHa) dose range to induce spawning, optimum egg size responsive to LHRHa induction, appropriate time for induction, proper storage conditions for LHRHa, and induction of spermiation in males. Gonadal maturation and spawning are successfully induced by LHRHa and/or 17 alphamethyltestosterone. An experiment on photoperiodic induction of sexual maturation is being conducted to produce seed year round. Increased information on larval morphology and physiology of sea bass led to improvements in feeding strategies and transport techniques. Studies on nutrient requirements and practical diets are currently being undertaken for different stages/sizes of sea bass. An economic assessment found an integrated sea bass production system viable. Studies on groupers (Epinephelus spp.) have been geared towards broodstock development including induction of sex inversion by hormonal control, intraspecific interaction, and sex control using synthetic anabolic steroids. Spontaneous maturation and successive spawnings of captive Epinephelus suillus were achieved in 1990. Larval rearing techniques used for other marine fish species were tried but with limited success. Culture techniques in ponds and floating cages using SEAFDEC-formulated diets or commercial pellets are being developed. Studies on snappers (Lutjanus spp.) have been started with the identification of species common in Panay Island.
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