Effect of Cut Number and Heat Treatment on the Nutritive Value of Berseem Higazi Hay (Medicago Sativa)

Abstract

The effect of cut number, and heat treatment on chemical composition, in vitro gas production, organic matter digestibility (OMD), and metabolizable energy (ME) of Berseem Higazi were investigated. Berseem Higazi (Medicago sativa) samples were collected from two cuts (first and second cut) from the same field, in Hillat Kuku, at middle bloom stage on February 2. 2007, for the first cut, and on April 17. 2007, for the second cut. Hay were heated in a forced-air oven at different temperatures and heating intervals, to determine the effect of cut number, and heat treatment on chemical composition, in vitro gas production, organic matter digestibility (OMD), and metabolizable energy (ME) of Berseem Higazi. Gas production was measured at 3, 6, 9, 12, 24, 48, 72, and 96 hours, and gas production kinetics were estimated. Number of cut had a significant effect on chemical composition, in vitro gas production, OMD, and ME, second cut had the highest dry matter (DM), neutral detergent fiber (NDF), and acid detergent insoluble nitrogen (ADIN) content (95.59%, 53.05%, 7.59%, respectively), while the total nitrogen (TN) and crude protein (CP) contents were not affected by cutting number. Second cut had a significantly (P<0.05) higher gas production from quickly soluble fraction (a) (3.11), than the first cut (-2.73), while first cut had a higher gas production from slowly degradable fraction (b), gas VII production rate (c), OMD, and ME, (39.45, 0.11, 64.21%, and 8.49MJ/kgDM, respectively), than the second cut (33.43, 0.08, 59.46%, and 4.92MJ/kgDM, respectively). There were no significant differences among cuts in term of potential gas production (a+b). Heating the hay increased its DM, NDF, ADF, and ADIN, while TN and CP decreased with increased temperatures. Gas production rate (c), OMD, and ME, decreased with raised temperatures. Optimal heat treatments as indicated by the greatest increase in OMD and ME were140o C for 120 minutes (66.78%, 9.10MJ/kgDM) and130o C for 120 minutes (65.85%, 8.90MJ/kgDM).