Equine ingestion of haylage harvested at different plant maturity stages

The influence of plant maturity at harvest of haylage on equine ingestion times and ingestive behaviour was studied. Haylage was harvested at three different occasions: June, July and August, from the primary growth of the same grass-dominated sward. Twelve adult horses of European warmblood type were divided into three groups and used in a change-over experiment with three periods, so that all horses had been fed each of the three haylages at the end of the experiment. Measurements of eating time (min/kg dry matter (DM)), chewing rate (chews/min), swallowing rate (swallowing/min) and the number of chews/swallowing were made for five consecutive days in each period for each horse. Haylages were analysed for chemical composition and nutritive value. Results showed that horses ingested haylage harvested in June (29 min/kg DM) faster (P < 0.0001) than haylages harvested in July and August (37 and 36 min/kg DM, respectively). Pearson's correlation coefficients were calculated between eating time and ingestive data and between eating time/ingestive data and composition of haylages. The highest correlation coefficient (0.94***) was found between eating time and number of chews/kg DM. The highest correlation coefficient related to fibre composition of haylage and ingestive behaviour was 0.66 (***), and was found between eating time and content of neutral detergent fibre in the haylage. Similar correlation coefficients were present for eating time and other variables describing fibre content (content of acid detergent fibre and lignin) in the haylage. In conclusion, a late harvest date of haylage may prolong total eating times for adult horses, partly due to a longer eating time per kg dry matter for such haylage, but also due to the generally higher feeding level needed to cover the energy and nutrient requirements of the horse when late harvested forages are used in forage-only diets.