Nutritional characteristics of almond hulls treated with sodium hydroxide and urea or supplemented with polyethylene glycol as an alternative feed resource for ruminant nutrition in Mediterranean area: in vitro study

Abstract

This study aimed to evaluate the effect of chemical treatments of almond hulls (AH) issued from two mediterranean countries (Tunisia and Palestine) on chemical composition, gas production (GP), methane (CH4), and in vitro ruminal fermentation. Treatments included AH untreated, AH supplemented with PEG, treated with NaOH, and with urea for 40 d. Significant (P <0.01) region × treatment interactions were observed for all nutrients, lag in GP and gas yield (GY24), degradability of dry matter (dDM) and acid detergent fiber (dADF), total volatile fatty acids (VFA), acetate, and butyrate. NaOH treatment lowered crude protein (CP) and structural and nonstructural carbohydrates. However, urea treatment decreased the fiber fraction and increased CP. Compared with the untreated AH and urea chemical procedures, NaOH treatment of AH from Tunisia increased the CH4 production. NaOH and urea chemical procedures of AH from Tunisia increased (P <0.05) the dDM, total VFA, and MCP. However, urea treatment increased (P <0.05) the degradability of the fiber fractions and butyrate. It is concluded that the AH from Palestine had fewer fibers than that from Tunisia and that the treatment of AH with NaOH increased CH4 production in Tunisia, whereas urea treatment decreased it. Moreover, treatments of AH from Tunisia with NaOH and urea increased fiber degradability and enhanced ruminal fermentation.

Keywords

• Almond hulls
• chemical composition
• chemical treatment
• secondary metabolites
• degradability
• in vitro fermentation