Abstract
This study aimed to evaluate the effects of the inclusion of crude glycerin in silver catfish (Rhamdia quelen) broodstock diets on their growth, characteristics of fresh and cryopreserved sperm, blood biochemical parameters, and tissue centesimal composition. A total of 150 males (52.8 ± 2.93 g) and 225 females (53.4 ± 3.38 g), reared in 15 excavated 16 m2 nursery tanks, were included in the study. The fish were fed rations containing 300 g digestible protein (DP) kg−1 and 12.55 MJ digestible energy (DE) kg−1 diet, and five different crude glycerin levels (0, 40, 80, 120, and 160 g kg−1). Male growth and reproductive parameters, the DNA integrity in fresh sperm, as well as the characteristics of cryopreserved sperm were evaluated 12 months after the start of the experiment. Blood samples were also obtained to quantify the calcium, triglyceride, glucose, total protein, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total cholesterol, and high-density lipoprotein (HDL) cholesterol plasma levels, and to evaluate the erythrocyte DNA integrity. Fish were euthanized and dissected to evaluate the hepatosomatic (HSI), viscerosomatic (VSI), and gonadosomatic (GSI) indices, and to evaluate the centesimal composition of the organs and tissues. There was an increase (p < .05) in the sperm concentration of animals fed the highest level of crude glycerin. The other seminal and spermatic parameters from fresh or cryopreserved sperm remained unchanged (p > .05). Among blood parameters, the total cholesterol and total protein levels were augmented (p < .05) in fish fed rations containing 80 g glycerin kg−1, while the calcium level decreased (p < .05) in fish fed 160 g crude glycerin kg−1. The growth was not altered (p > .05). Increases were observed in the muscle dry matter and ash and testicular raw protein contents (p < .05) in the group fed the ration with the highest crude glycerin level; in contrast, the muscle protein levels were decreased (p < .05). The preliminary results showed that Rhamdia quelen males fed the highest crude glycerin dietary levels led to metabolic alterations which increased protein deposition in the testis and increased sperm concentration, without damages on growth or survival. The higher sperm concentration will allow to producing more doses of cryopreserved sperm.
Published Version
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