The effects of L lysine in the diet of silver catfish (Rhamdia voulezi) female broodstocks

Abstract

ABSTRACT. The objective of this study was to assess the L-lysine effect in silver catfish, Rhamdia voulezi female reproduction. Four hundred fish were used distributed in a random in 16 net cages (25 fish each × 4 replicates = 100 fish per treatment). The treatments consisted in four diets, isoproteic and isoenergetic (30% crude protein and 3,500 kcal kg -1 digestible energy) with different L-lysine levels: T1: 1.30; T2: 1.40; T3: 1.60 and T4: 1.95%. After 185 days of experiment 18 females per treatment were weighed, measured, and submitted to hormonal induction (0.5 and 5.0 mg kg -1 Carp Pituitary Extract). The females were then sacrificed and had their ovaries, liver and fat removed and the respective organosomatic indices were estimated. With regard to the reproductive parameters, the released oocytes, absolute fecundity and remaining ovaries were influenced (P < 0.05) by the diet, and the highest mean values were observed in the treatment with 1.95% L-lysine. Among the organosomatic indices, only the visceral fat was influenced (P < 0.05). The estradiol levels and the composition of essential amino acid in oocytes were not affected (P > 0.05). We can conclude that L-lysine affects the reproductive parameters and accumulation of visceral fat in R. voulezi.

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes, Pimelodidae)

“…This result obtained because our histological identification revealed relatively high percentages (constant and always above 20%) of CA in maturing and mature females that presented, unusually for the former pattern, three batches of oocytes: complete VI, CA and PV. The occurrence of migratory species with a reproductive cycle similar to that of total spawners (with a demarcated spawning season and a long resting period) but presenting characteristics of asynchronous oocyte development has already been described, especially for small-to medium-sized species, such as Astyanax altiparanae (Cassel et al, 2017), Rhamdia quelen (Reidel, Boscolo, Feiden, & Romagosa, 2010) and Rhamdia voulezi (Bittencourt et al, 2018).…”