Crude glycerol in diets for Nile tilapia in the fattening stage

Abstract

The objective of this work was to evaluate the use of crude glycerol as an energy source to replace corn, in diets for Nile tilapia (Oreochromis niloticus) in the fattening stage. Two hundred Nile tilapia (190±4.5 g) were distributed in 20 tanks, in a completely randomized design. The treatments consisted of crude glycerol at 0, 60, 120, 180, and 240 g kg-1, to replace the dietary levels of corn, in order to maintain a constant digestible energy. Fish productive performance and the chemical composition of the fillet were evaluated. Histological analyses of the hepatopancreas, intestine, and visceral fat were also carried out. Crude glycerol had no effect on the performance parameters; however, it caused a quadratic reduction of visceral fat. There was an increase in the moisture and a decrease in the ether extract of the fillet. A linear effect on the blood glucose levels was verified in fish fed the diet without glycerol, and the peak occurred at 90 min. There were no differences for measurements of intestinal villi height and hepatocyte area. Crude glycerol can replace corn in diets for Nile tilapia in the fattening stage, without adversely affecting fish metabolism, productive performance, or survival.

Use of glycerol in fish nutrition: a review

“…In most surveys, the formulation of diets for fish containing the inclusion of glycerol is based on the replacement of corn (Li et al, 2010; Meurer et al, 2016; Moesch et al, 2016; Balen et al, 2017; Santos et al, 2019; Theisen et al, 2020). However, some authors choose to formulate fish diets differently.…”

“…The processing may be done by extrusion or pelleting, taking into account the food habit of the target species. The matrix sizes used to obtain the pellets vary according to the species and age of the fish (Neu et al, 2013; Moesch et al, 2016; Balen et al, 2017; Santos et al, 2019).…”

“…The use of glycerol as an energy source in fish varies according to fish species and size (Neu et al, 2013), possibly due to the gastrointestinal tract formation and the composition of the product (Fernandes et al, 2016). It is a potential source of energy for Nile tilapia (Meurer et al, 2012; Neu et al, 2012b; Costa et al, 2015; Gonçalves et al, 2015; Meurer et al, 2016; Moesch et al, 2016; Santos et al, 2019), common carp (Fernandes et al, 2016), channel catfish (Li et al, 2010), jundiá, pacu (Balen et al, 2014) and curimbatá (Balen et al, 2017) (Table 3).…”

“…A similar effect was observed by Santos et al . (2019) for Nile tilapia in the fattening phase, where blood glucose levels in fish fed a control diet containing no glycerol, only corn starch, took longer to restore to baseline levels. This proves that the ingestion of high starch levels results in high blood glucose levels and that return to baseline levels is much slower than when fish are fed other food items (Santos et al, 2019).…”

Effect of dietary crude glycerin on the productive performance of Nile tilapia fingerlings

“…Dietary glycerol is metabolized to lipids or carbohydrates and used as an energy source by tilapia Oreochromis mossambicus (Peters, 1852) juveniles (Costa et al 2017). In O. niloticus, dietary crude glycerol completely replaced maize for individuals ranging from 10 to 30 g (Moesch et al 2016) and from 190 to 355 g (Santos et al 2019). In individuals weighing over 35 g, inclusion levels greater than 10% characterize it as a lipogenic nutrient (Costa et al 2015).…”