M.A. Hanafy1; Mervat S.H. Youssef2; Azza M. Badr2; Wafaa M.A. Ghoneem1 and M.R. Rashid2
1Animal Production Department, Faculty of Agriculture, Cairo University, Giza, Egypt.
2Regional Center for Food and Feed, Agricultural Research Center, Giza, Egypt.
In vitro studies were carried out to investigate the effect of using crude glycerol (biodiesel co-product) as a substitute for yellow corn with some feed additives. Corn comprising 30% of the whole diet was substituted by crude glycerol at four levels (0, 25, 50 and 75%) with three types of additives; buffer (NaHCO3& MgO), dry yeast (Saccharomyces cerevisiea) and fibrolytic enzymes. In vitro dry matter disappearance (IVDMD), organic matter disappearance (IVOMD) and total gas production (GP) were studied. Crude glycerol substitution at 25% significantly increased (P<0.05) IVDMD, IVOMD and GP values, while 50 and 75% glycerol significantly decreased (P<0.05) IVOMD and GP values compared with control. No significant difference was observed for IVDMD value when crude glycerol was included at 50% of yellow corn. Addition of 4 g/kg DM of either fibrolytic enzymes or dry yeast significantly increased (P<0.05) IVDMD by 6.5 and 6%, IVOMD by 6 and 4% and GP by 15.8 and 11.5%, respectively. On the other hand, buffer addition had no effect on measured parameters. Using high level of fibrolytic enzymes or dry yeast (6 g/kg DM) significantly increased (P<0.05) IVDMD, IVOMD and GP values for 25 and 50% glycerol compared with the lower level (4 g/kg DM). In conclusion, crude glycerol in combination either with 6g/kg DM fibrolytic enzyme (ALLZYME™) or dry yeast (Saccharomyces cerevisiea) could replace up to 50% of the yellow corn equivalent to 15% of the whole dietary DM.