In vivo digestibility of two different forage species inoculated with arbuscular mycorrhiza in Mediterranean red goats

•We produced mycorrhized barley and berseem clover.•No external inputs were given to the forages.•In vivo digestibility was higher in mycorrhized barley as assessed in goats.•Minor effects were observed on mycorrhized berseem clover digestibility in goats.

The aim of this study was to evaluate the effect of field inoculation with arbuscular mycorrhiza spp. (AM) on the forage quality and in vivo digestibility of barley (Hordeum vulgare L.) and berseem clover (Trifolium alexandrinum L.) obtained using no external inputs. In November 2011 two plots were used for each species: one sown with seeds inoculated with AM and the other one with seeds not inoculated. For both forage species the following constituents were determined: crude protein (CP), crude fiber (CF), ether extract, neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), ash, Ca and P. In vivo digestibility of barley and berseem clover was evaluated in Mediterranean red dairy goats. Twenty-eight mature goats were randomly assigned to four groups, homogeneous for age (2.5 years) and body weight (43.3 kg), and received the fresh forages as follows: Mycorrhized barley group (MBG), Control barley group (CBG), Mycorrhized clover group (MCG) and Control clover group (CCG). Barley and berseem clover were given fresh ad libitum. The experimental period started after 15 days of adaptation and lasted 7 days. Coefficients of organic matter (OM), CP, CF, NDF and ADF in vivo digestibility were measured by using acid insoluble ash as internal indigestibility marker. Mycorrhized barley showed an increase in CP and a reduction in ADF and ADL concentrations. In addition, a significant effect of AM field inoculation on barley digestibility was observed. The MBG showed a significant increase of the following digestibility coefficients in comparison with CBG: CF (P < 0.01), CP, NDF and ADF (P < 0.001). Conversely, only OM and ADF digestibility coefficients of berseem clover were increased by mycorrhization (P < 0.05). Our results showed that the inoculation with AM was able to improve the quality and enhance the in vivo digestibility of barley grass offered to mature goats, whereas only minor effects were observed on berseem clover quality and digestibility.