Effects of extracts derived from pistachio by-products on ruminal fermentation and methane production

The objective of this study was to evaluate the effects of different doses of pistachio by-product (PBP) extracts supplemented with alfalfa hay (AH) or barley grain (BG) on microbial fermentation in an in vitro fermentation system. The total extracted phenolic compounds were 36.96, 65.78, 67.02 and 8.85% and total extracted tannin contents were 37.11, 59.64, 56.87 and 7.55% when PBP was extracted with water, ethanol 70%, methanol 80% and a mixture of chloroform and methanol, respectively. Adding the mixture of chloroform and methanol extracts to both substrates reduced the gas production (P<0.01). Most of PBP extracts caused a significant reduction (P<0.01) in ruminal ammonia compared to controls with both substrates while, the effects of PBP extracts on ammonia production were greater for BG than AH based substrate. The concentrations of volatile fatty acids (VFAs) were higher (P<0.01) in all solvent extracts compared to control (except the low level of methanol PBP extract) with both substrates. Furthermore, in both substrates there was no decrease in methane productions with the addition of all extracts compared to controls. In conclusion, some of PBP extracts may have a favourable effect on rumen fermentation parameters such as gas production, ruminal ammonia and VFAs concentrations and they can also assist in developing novel feed additives for decreasing the nitrogen excretion in the ruminants.