Effect of dietary supplementation of glycerin on growth performance, meat quality, and blood biochemistry of growing Japanese quails (Coturnix coturnix japonica)

Crude glycerin (CG), a by-product of biodiesel production, has demonstrated potential as an energy source and could serve as a novel ingredient in poultry diets. This study aimed to evaluate the impact of CG supplementation on growth performance, carcass traits, meat quality, and blood parameters in Japanese quails. A total of 375 one-day-old quails were randomly assigned to five dietary treatments in a completely randomized design (CRD). Each treatment was replicated five times, with 15 birds per replicate. The experimental diets included varying levels of CG (0%, 3%, 6%, 9%, and 12%). Glycerin was incorporated into the basal diet. Parameters such as feed intake, weight gain, and feed conversion ratio were assessed to gauge the impact of CG on growth performance. Additionally, carcass traits (e.g., carcass yield, breast yield, thigh yield, liver weight, gizzard weight, and heart weight) and meat quality indicators (e.g., thawing loss and drip loss) were analyzed to determine the influence of CG on meat production and quality. The potential effect of CG on the serum biochemical parameters (e.g., serum total protein, albumin, globulin, glucose, cholesterol, triglycerides, and uric acid) was also measured to assess the health and metabolic status of the birds. Data were statistically evaluated using one-way ANOVA under CRD, and treatment means were compared using Duncan's multiple range test at a 5% significance level. The results of this study demonstrated that the dietary inclusion of 12% CG significantly enhanced growth performance, as evidenced by increased feed intake, weight gain, and improved feed conversion ratio compared to the lower glycerin levels and control group. Birds fed 12% CG also had higher carcass yield (P < 0.05), though other carcass traits, such as breast yield, thigh yield, liver weight, gizzard weight, or heart weight, remained unaffected. Meat quality analysis revealed that the inclusion of 12% CG reduced thawing loss without significantly affecting drip loss. Blood profile analysis showed that the control group had significantly higher serum total protein levels than the 9% glycerin group, while serum glucose levels were higher in the control group compared to the 12% CG group. Other parameters, including serum albumin, globulin, cholesterol, triglycerides, and uric acid, were not significantly affected by dietary treatments. In conclusion, 12% CG supplementation enhanced growth performance, carcass yield, and some meat quality traits without adversely affecting blood profile indicators.