Diets containing crude glycerin damage the sperm characteristics and modify the testis histology of Nile tilapia broodstock

The effects of crude glycerin in the diets of male Nile tilapia (Oreochromis niloticus) on growth, seminal and spermatic characteristics, blood parameters, histological aspects of the hepatic and testicular tissue, and on the chemical composition of different organs/tissues were evaluated. For 10months, the animals were fed diets containing 32% digestible protein (DP), 3200kcal digestible energy (DE)·kg ration−1 and five inclusion levels of crude glycerin (0, 4, 8, 12 and 16%). Growth, seminal and spermatic parameters were evaluated, and the plasmatic levels of calcium, triglycerides and glucose were measured. Gonadosomatic, viscerosomatic and hepatosomatic indexes were evaluated and combined with the histological parameters of the testicles and liver. Finally, the centesimal composition of the muscles, testis, liver and viscera were evaluated. The volume of semen released, fecundity, effective fecundity and plasmatic levels of glucose decreased proportionally (p