Effect of oak acorn (Quercus persica) on ruminal fermentation of sheep

The objectives of this study were to evaluate the effect of oak fruit (Quercus persica) in the diet of sheep with and without polyethylene glycol (PEG) on nutrients digestibility, rumen fermentation parameters, protozoal count and microbial protein supply. In Exp. 1, five fistulated mature male sheep were used in a 5 × 5 Latin square design, with 5 dietary treatments arranged in a 2 × 2 + 1 factorial: (1) control as a basal diet; (2) control plus 10% oak acorn (OA); (3) control plus 30% OA; (4) control plus 10% OA with 100 g PEG; and (5) control plus 30% OA with 100 g PEG. Incorporation of OA decreased digestible organic matter (DOM), digestible crude protein (DCP) and digestible neutral detergent fiber (DNDF) and the lowest values were observed at the level of 30% OA. However, administration of PEG to the diets overcame deleterious effect of acorn on these parameters, significantly (P < 0.01). With the addition of OA a noticeable decrease in ammonia and TVFA concentration was observed and adding PEG to the diets increased these values even higher than those of control (P < 0.01). Incorporation of acorn to the diets lowered urinary purine derivatives (PD) and urinary, retained and absorbed nitrogen and increased fecal and endogenous nitrogen (P < 0.01). Meanwhile, addition of PEG increased PD and urinary, retained and absorbed nitrogen and decreased fecal and endogenous nitrogen. Total protozoa content was affected in somewhat by OA and PEG supplementation. Isotricha, dasytricha and, diplodinium contents did not differ due to inclusion of OA, however, the trend for entodinium and ophryoscolex was to be decreased (P < 0.05). There was a significant effect on individual genera of protozoa following addition of PEG to the diets. Cellulolytic and proteolytic bacteria were not influenced by incorporation of OA but the trend was in decreasing manor. In Exp. 2, in vitro gas production was conducted to evaluate kinetics of gas produced by diets. The parameter “A” did not differ among experimental treatments. Half-time of gas production in control group was higher than that of other treatments. Methane production from diets containing OA and PEG were lower than that of control group. In conclusion, supplementation of OA with PEG may be a practical approach to overcome detrimental effects of tannins in this feedstuff.