Methane emission and performance indicators of sheep fed Super Napier grass, sodium hydroxide-treated rice straw and leaves of two browse species (Leucaena leucocephala and Albizia lebbek)

Methane produced during enteric fermentation in ruminants is influenced by dietary factors. To lower enteric methane emissions without lowering overall production performance, appropriate diets are needed. Thus, the performance and methane emission of sheep fed Super Napier grass (SN), sodium hydroxide treated rice straw (NaOHRS) and leaves of browse species (Albizia lebbek (AL) and Leucaena leucocephala (LL)) were assessed. Twenty-four lambs (12 ewes, 12 rams) (10.32 ± 0.51 kg average weight) were used. The diets fed for twelve weeks were: SN, SN+NaOHRS, SN+NaOHRS + AL and SN+NaOHRS + LL. Methane was measured using a methane gas detector. Sheep fed SN+NaOHRS + AL, SN+NaOHRS + LL and SN+NaOHRS had higher (p < 0.05) average daily feed intake than those fed SN. Sheep fed SN+NaOHRS + AL and SN+NaOHRS + LL had a higher average daily weight gain (p < 0.05) and feed conversion efficiency than those fed non-browse leaves diets. Nitrogen digestibilities were higher (p < 0.05) in sheep fed SN+NaOHRS + AL and SN+NaOHRS + LL than those without the browse component. Dietary treatments did not significantly (p > 0.05) affect methane emission. It is concluded that diets with LL and AL can enhance sheep performance without reducing methane emission.