Replacement of alfalfa hay (Medicago sativa L.) with subabul (Leucaena leucocephala) leaf meal in diets of Najdi goats: effect on digestion activity of rumen microorganisms.

This study investigated the effect of replacing alfalfa hay by subabul leaf meal (SLM) on digestion, fermentation parameters and rumen bacteria and fungi activity of Najdi goats. Six Najdi goats (150 ± 15 days of age and initial body weight of 35 ± 1.1 kg) were randomly assigned to one of two dietary treatments in a balanced completely randomized design (three goats per treatment) for 56 days. Experimental treatments included alfalfa hay as control group and diet containing SLM (SLM replacing alfalfa hay at 50% level). Bacterial and fungi activity and rumen fermentation parameters of animals fed experimental diets were determined. Dry matter disappearance (DMD) was unaffected by replacing SLM with alfalfa hay for both rumen bacteria and fungi in different incubation times, except for 48 h of incubation in specific culture medium of mixed rumen bacteria, which decreased for SLM group (P > 0.05). NDF disappearance (NDFD) and ADF disappearance (ADFD) after 24 and 48 h of incubation in specific culture medium of mixed rumen bacteria was not affected by experimental diets (P > 0.05). However, 72 h after incubation, NDFD in SLM treatment decreased (P > 0.05). Gas production parameters of rumen bacteria were similar for both experimental diets, but partitioning factor (PF), efficiency microbial biomass production (EMBP), microbial protein production (MP), and organic matter truly digested (OMTD) decreased (p < 0.05) in specific culture medium of mixed rumen fungi for SLM diet. There was significant decrease in total protozoa population for diet containing SLM (p < 0.05). Results indicated that replacement of alfalfa hay by SLM had no major effect on rumen microorganisms' activity of Najdi goats, so it may be used as an alternative for alfalfa (at 50% level) in susceptible areas.