Nutritional evaluation of vegetable and mixed crude glycerin in the diet of growing rabbits

Abstract

-The objectives of this study were to determine the chemical composition of vegetable and mixed crude glycerin and digestible energy to and evaluate different inclusion levels in rabbit feeding. A total of 108 rabbits were used in the digestibility assay, assigned in a completely randomized design into nine treatments, one reference diet plus eight test diets, where the glycerin types were included at levels of 4, 8, 12 and 16%, replacing the reference diet roughage. In the performance assay, 180 rabbits were assigned to a completely randomized design into a 2 × 4 factorial arrangement (two types of glycerin and four levels of inclusion: 3, 6, 9 and 12%) plus a reference diet and ten replications. The vegetable and mixed crude glycerin showed digestible energy of 5,099 and 4,953 kcal/kg of dry matter, respectively. Although feed intake decreased linearly with the growing inclusion of both kinds of glycerin during both evaluated periods (from 32 to 50 and 32 to 70 days), performance losses occurred only with the inclusion of vegetable crude glycerin. The inclusion of mixed crude glycerin up to 12% allowed similar animal performance to the reference diet up to 50 days, unlike vegetable crude glycerin, for which inclusions over 6% in the diet resulted in poorer performance compared with that obtained with the reference diet. In the total period, differences were not observed for live weight or weight gain of the animals fed both glycerin types. Carcass weight decreased linearly with the inclusion of both glycerin types, with lower values compared with the reference diet only for the two highest levels of glycerin inclusion. Mixed crude glycerin can be included up to the maximum level studied (12%), while vegetable glycerin can be added up to 6% in the diet of growing rabbits.

Growth and energy metabolism of Nile tilapia juveniles fed glycerol

“…Glycerol has been studied as a dietary energy source in several nonruminant animal cultures, such as poultry (Lima et al, 2012), swine (Shields et al, 2012), rabbit (Retore et al, 2012), and dogs (Lima et al, 2014). However, little is known about its inclusion in Nile tilapia (Oreochromis niloticus) diet.…”

Effect of dietary glycerin supplementation in the starter diet on broiler performance

“…However, these additional procedures increase the cost (Min et al 2010). Thus, several studies on the inclusion of glycerin in its raw form in animal diets have been carried out to reduce the cost of production without affecting the performance (Jung and Batal 2011;Retore et al 2012). Additional advantages deriving from the use of crude glycerin in animal diets have also been reported, such as the improvement of growth, economic performance, and feed conversion ratio (Sehu et al 2013).…”

“…In broilers, Dozier et al (2008) found that the efficiency of energy use was approximately 95% of gross energy, depending on methanol, fatty acid, and glycerol contents of the sample (Dozier et al 2011), and the efficiency might vary according to the manufacturing process adopted (Retore et al 2012).…”

Crude glycerol negatively affects rabbit spermatozoa motility in vitro

“…Pure glycerol contains low amount of chemical residues and has been extensively used as a permeating cryoprotectant since Polge et al (1949) discovered its protective effects on cryopreserved spermatozoa. Crude glycerol is rich in fatty acids and contains chemical impurities such as methanol, sodium and potassium salts (Retore et al, 2012). Biodiesel industry is constantly producing crude glycerol as a by-product from biofuel fabrication through the NaOH-or KOH-catalysed transesterification of triacylglycerols (Ma and Hanna, 1999;Van Gerpen, 2005;Thompson and He, 2006).…”

“…The ready availability of crude glycerol makes it a promising alternative to the energy-rich diet used in animal nutrition, which could cover the energy needs of livestock (Kijora et al, 1995;Rosebrough et al, 1996;Simon et al, 1996;Cerrate et al, 2006). Therefore, numerous studies have focused on assessing the nutritional value of crude glycerol and optimizing its use in animal feeding (Retore et al, 2012). In non-ruminants, including rabbits, glycerol is absorbed through the gastrointestinal tract (Tao et al, 1983) and subsequently utilized as an energy source (Cryer and Bartley, 1973).…”