Spermatophore production and sperm quality of the river prawn Macrobrachium americanum Spence Bate, 1868 fed with different diets

Abstract

The effects of different diets on spermatophore production and sperm quality were investigated in the river prawn Macrobrachium americanum. River prawns were cultured and fed with three diets for 244 days: fresh food (50% squid meat, Dosidicus gigas and 50% sardine muscle, Sardinops sagax); commercial pellets (35 Purina®); and a 50:50 mixture of both diets. Spermatophore production was recorded every 24 days on average as the percentage of spermatophores produced per extraction per diet, weight and biochemical composition. Sperm quality was measured as the total number of sperm, the proportion of live/dead sperm and normal/abnormal sperm morphology. There were no significant differences in the mean biochemical composition of M. americanum spermatophores for any of the diets. Biochemical composition was 36.3% protein, 25.8% carbohydrate and 4.6% lipids for all data pooled. The weight of spermatophores and sperm counts was not significantly different among diets, nor were there any differences as a function of the male initial total length (p > .05). Male river prawn reproductive exhaustion was observed as a decline in spermatophore production, weight of the spermatophores and the number of sperm cells per spermatophore, with an increasing proportion of dead and abnormal sperm seen throughout the experiment. The recommended period of maintenance in captivity for male broodstock is less than 115 days. It is recommended to feed broodstock males of M. americanum with commercial pellets because no significant differences were detected with the diets tested; pellets are easier to use, ensuring the same spermatophore production and sperm quality that was obtained with fresh food.

Sperm viability in wild-caught males of Macrobrachium tenellum (Smith, 1871) (Decapoda: Caridea: Palaemonidae) fed with different diets

“…After 10 min, blue cells (dead sperm cells) were counted under light microscopy. Normal sperm cells appeared like an inverted-umbrella with a long spike projecting from its convex surface as was previously observed for M. rosenbergii (see Poljaroen et al, 2010) and M. americanum (see Pérez-Rodríguez et al, 2019). Abnormal sperm cells were distinguished from normal ones by malformed bodies or by a bent, short or missing spike (Leung-Trujillo and Lawrence, 1987).…”

“…Similarly, for example in Macrobrachium acanthurus (Wiegmann, 1836) the relationship between SW and body weight is low (p > 0.05) (Viana da Costa et al, 2016), verifying that large shrimp do not necessarily produce heavier spermatophores. Likewise, no differences in SW and AS in relation to the body weight of M. americanum were found (Pérez-Rodríguez et al, 2019). On the other hand, in the present work, the TS compared to the length and weight of the male were the indicators that presented a positive correlation, equal to what was mentioned for M. americanum (see Pérez-Rodríguez et al, 2019).…”

“…In general, the lowest values of sperm viability (less TS, higher DS and AS) were found in the group of wild specimens that were electrostimulated for the second time compared to the first electrostimulation. This suggests that repeated electrostimulation in M. tenellum is counterproductive in the long term, as has been reported in other species of the genus: M. americanum (see Pérez-Rodríguez et al, 2019), Macrobrachium malcolmsonii (Milne-Edwards, 1844) (see Samuel et al, 1999), M. rosenbergii (see Harris and Sandifer, 1986), as well as in marine shrimp (Rosas et al, 1993). In all cases a decrease in sperm viability is mentioned when comparing the first extraction with subsequent ejaculations.…”

“…Nauplius, 30: e2022007 hand, the work of Pérez-Rodríguez et al (2019) is the most important precedent for the present study, since they studied sperm viability and regeneration of the M. americanum spermatophore, a species native to basins of the Pacific region, with a similar distribution to M. tenellum (from Baja California, Mexico to northern Peru) (Holthuis, 1952). These authors did not find significant differences in the mean biochemical composition, weight and sperm count of the spermatophores of M. americanum among diets supplied (i.e., fresh feed, commercial feed and a mixture of both diets).…”

“…The number of sperm cells contained in each observed spermatophore (TS), as well as the percentage of abnormal sperm cells (AS) and percentage of dead sperm cells (DS) were estimated using the following formulas: 100 Where: Ds is the number of dead sperm cells counted and TS is the number of total sperm cells counted. Where: As is the number of abnormal sperm cells counted and TS the number of total sperm cells counted (Pérez-Rodríguez et al, 2019).…”