Hydrolyzable and fermentable carbohydrates in North Italian pastures for horses

Digestive and metabolic disorders in the horse were previously associated with hydrolyzable and nonhydrolyzable but rapidly fermentable components of nonstructural carbohydrates, particularly fructans. Aim of the study was to assess the contribution of the carbohydrate fractions to the composition of pastures in specific areas of Italy ordinarily designed for horses feeding. Seventy-seven samples from 11 pastures differing for floristic composition were collected across two growing seasons from April 18th 2008 to May 10th 2009 in the foothills (380 m a.s.l.) of the province of Parma (Italy). All samples were collected during the vegetative growth phase. To identify the bioclimatologic conditions of the growth, the average fortnightly thermohygrometric index (THI) was used. Slow fermentable carbohydrates mean concentration (NDF: 510.6, ADF: 274.7, ADL: 31.5 g/kg DM) reflected the typical chemical composition of high-quality grass and grass-legume mixtures. Among the nonstructual carbohydrates (NSC: 199.9 g/kg DM), hydrlolyzable carbohydrates content accounted for about the 18%. Nonhydrolyzable but rapidly fermentable carbohydrates were constituted for about the 23% by fructans (37.7 g/kg DM, range 15.5 to 138.2). The environmental conditions significantly affected the carbohydrate concentration in forages. Among NSC, fructans concentration in pastures was affected by bioclimatologic conditions (P<0.05). The floristic composition influenced the fructans content at a lesser extent. These results indicate a high variability of fructans concentration and reflect what previously observed in other areas. In any case the high levels observed for fructans in some geographic areas are not been achieved. Further interdisciplinary studies in this area between veterinarians and forage researchers are clearly warranted.