Danos reprodutivos causados pela alimentação de machos de tilápia do Nilo com rações contendo glicerina bruta

Abstract

The objective of this work was to evaluate the effects of the inclusion of crude glycerin in feeds of Nile tilapia (Oreochromis niloticus) broodstock on growth, seminal and sperm characteristics, some blood parameters and histological features of liver and testicular tissue. The animals were distributed in a complete randomized experimental design, composed by five treatments and four replications. The treatments were constituted by lipoprotein and isocaloric feeds containing 32% of digestible protein (DP) and 3200 kcal of digestible energy (DE).kg of feed-1 and, five levels of inclusion of crude glycerin in the proportions of 0, 4, 8, 12, and 16%. Ten months after the beginning of the experiment, males reproductive parameters were evaluated. Eight males from each experimental unit were submitted to blood collection for quantification of plasmatic calcium, triglycerides and glucose levels. Subsequently, all the males were subjected to euthanasia for dissection and individual measurement of liver, gonads and viscera weights for evaluation of zootechnical and somatic parameters. Gonads and liver histology was also evaluated. There were reduction of the semen volume released by the males, of the fecundity and effective fecundity in a directly proportional manner (p<0,05) to the increase of this food in the feeds. The other seminal and spermatic parameters were not influenced. Among the blood parameters, only the glucose levels were influenced (p<0,05), reduced proportionally to the increase of crude glycerin in the diets. The zoothecnical performance was not influenced. The hepatosomatic index showed a directly proportional increase (p<0,05) at the level of inclusion of crude glycerin in the feeds. The medium, maximum and minimum areas of the hepatocytes were not influenced. In the testicular histology, it was verified the presence of all the differentiation cysts in all the treatments, but there was a greater presence of spermatozoids in the treatment with 0% of glycerin than in the treatments with higher inclusion of glycerin in the feeds. Thus, the use of this by-product in the feeding of Nile tilapia broodstock males is not recommended, since it can affect their reproductive performance.