The influence of pomegranate-peel extracts on in vitro gas production kinetics of rumen inoculum of sheep

Abstract

Different levels of pomegranate peel extracted by either water (PEH) or solvent mixture (PEM) were evaluated for their effect on in vitro gas production and ruminal fermentation patterns. Two levels of PEH or PEM (15 and 30 mg total phenolics (TP)/g DM of basal diet) were compared to a control (0) level. Ruminal fermentation parameters such as 24-h partitioning factor (PF_{24}), gas yield (GY_{24}), in vitro organic matter disappearance (IVOMD), metabolizable energy (ME), and microbial protein (MP) were calculated. The addition of PEH or PEM had no effect (P > 0.05) on asymptotic gas production, apparent degraded substrate (ADS), IVOMD, ME, PF_{24}, GY_{24}, MP, or total volatile fatty acids (VFAs). However, fermentation rate (P = 0.032) and the proportion of butyrate (P < 0.0001) decreased. The addition of either PEH or PEM with substrate resulted in lower acetate concentration (P = 0.002) and acetate to propionate ratio (P = 0.007) in comparison to the control. Inclusion of PEH or PEM led to a lower ammonia (NH_3-N) concentration (P = 0.0002) and protozoa counts in comparison to the control. In conclusion, the addition of PEH or PEM positively modified some rumen parameters such as acetate to propionate ratio, NH_3-N concentration, and protozoa population.