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).
