Digestibility of a forage-based diet in weanling horses during development and maturation

The efficiency of digestion could be limited in weanling and yearling horses if lower quality forage-rich rations are applied. In this study diet digestibility was examined in young Finnhorses (5 colts, 5 fillies) after weaning at 7 months of age (215 ± 8.0 days) up to the age of twelve months when a high-forage diet with long-stem medium or lower quality hay was fed. The experimental diet consisted of timothy-dominated dry hay (70% of the DM intake), oats (22%) and a protein concentrate. The experimental period consisted of six 4-wk periods, including an acclimation period of 23 d followed by a 5-day period of faeces sample collection. To follow and observe the development of the young horses, they were weighed and body measures were taken at 2-wk intervals. Digestibility data were observed using chromium-mordanted straw as an indigestible external marker. No gradual statistically significant improvement of digestion of nutrients could be detected from 7 to 12 months of age. However, the digestibilities of the nutrients numerically increased from the first (7 months of age) to the sixth period (12 months of age), except the CP digestibility. It appears that weanling and yearling horses can properly digest their forage-based diets. However, the ability to digest fibre may still be limited at the age of 12 months, and attention should be paid to the fibre content and nutritional quality of forage.