Effect of maturity on the potential nutritive value of burr medic (Medicago polymorpha) hay

Abstract

The aim of this experiment was to determine the potential nutritive value of Medicago polymorpha hays harvested at vegetative, flowering and seeding stages using the chemical composition, in vitro gas production kinetics, Organic Matter Digestibility (OMD) and Metabolizable Energy (ME) content. Harvesting stage had a significant (p<0.001) effect on the chemical composition except for ash content, in vitro gas production kinetics, OMD and ME content of Medicago polymorpha hay. The cell wall contents of Medicago polymorpha hay were significantly increased with increasing maturity whereas crude protein content was decreased. The Acid Detergent Fibre (ADF) and Neutral Detergent Fibre (NDF) contents ranged from 31.16 to 43.69% and 41.66 to 66.23%, respectively. The CP content of Medicago polymorpha hays ranged from 13.67 to 22.05%. The OMD and ME content of Medicago polymorpha hays ranged from 40.66 to 79.76% and 10.42 to 11.78 MJ kg-61 DM. The most of the gas production kinetics, ME and OMD were negatively correlated with ADF and NDF content of Medicago polymorpha hay whereas the same parameters were positively correlated with CP content of Medicago polymorpha hay. Due to low level of cell wall contents and higher CP, OMD and ME Medicago polymorpha plant should be harvested or grazed at vegetative stage to obtain hay with higher nutritive value. © 2007 Asian Network for Scientific Information.