The aim of the current experiment was to evaluate the chemical composition, metabolizable energy (ME), organic matter digestibility (OMD), gas and methane production of some legume plants estimated by in vitro gas production technique, and to determine the relationship among chemical composition, ME, OMD, gas and methane production of some legume plants. Although species has a significant effect on the chemical composition, gas production, ME and OMD species has no effect on methane emission of legume hays. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) ranged from 22.86% to 42.93% and 20.24% to 37.16% respectively. Crude protein (CP) contents of legume hays ranged from 13.61% to 20.55%. Neutral detergent fibre and ADF contents of legume plants are negatively correlated with gas production, ME and OMD. It can be concluded that legume plant studied in the current experiment showed a wide nutritional diversity and will provide not only protein but also fibre for livestocks. They may exhibit complementary role for ruminant animals grazing on poor quality forages. Legume species studied in the current experiment had a no anti-methanogenic properties.

This research was undertaken with the aim of determining the effect of sodium hydroxide (NaOH) treatment on the chemical composition, in vitro gas production, neutral detergent fiber digestibility (NDFD) and true dry matter digestibility (TDMD), dry matter intake (DMI), and relative feed value (RFV) of common reed (Phragmites australis) straw. Reed straw was treated with 0% (control), 1%, 2%, and 3% NaOH and stored in 1.5-L glass jars in triplicate for 21 days. NaOH treatment had a significant effect on the chemical composition, in vitro gas production, NDFD and TDMD, DMI, and RFV of the reed straw. While it decreased the cell wall content of the reed straw, it significantly increased the NDFD, TDMD, DMI, and RFV. The neutral detergent fiber content of the reed straw decreased with NaOH treatment in a dose-dependent manner and ranged from 56.03% to 65.05%, whereas the NDFD increased and ranged from 53.10% to 59.99%. Metabolizable energy, organic matter digestibility, and TDMD values were improved, ranging from 9.15 to 10.19 MJ/kg DM, 58.46% to 65.05%, and 55.29% to 62.33%, respectively. The estimated RFV and DMI also improved, ranging from 84.70% to 95.58% and from 1.87% to 2.14% of body weight, respectively. The most effective treatment dose of NaOH was 3%. Therefore, it can be suggested that NaOH treatment has the potential to improve the nutritive value of reed straw. However, before large applications, further in vivo investigations are required to determine the effects of NaOH treatment on the feed intake and production of ruminant animals.