Content of nutrients and energy in pasture vegetation and their apparent digestibility in Old Kladruber horses

This study focuses on the determination of apparent digestibility of pasture vegetation nutrients in horses of the Old Kladruber breed through a balance indicator method (determination of acid insoluble ash). When evaluating the nitrogenous substances, their determination was based on the content of pure protein (sum of amino acids) which is more accurate than crude protein. There were differences in the chemical composition of dry matter from pasture vegetation and horse excrements. Regarding crude fat, crude fibre, acid detergent fibre, neutral detergent fibre, acid detergent lignin, ash, P and Mg, the average values in dry matter of horse excrements were significantly (P <= 0.01) higher; on the contrary, we found significantly (P <= 0.01) lower mean values of nitrogen-free extract, organic matter and Ca in the dry mass of pasture grass. The highest coefficient of apparent digestibility for organic nutrients was determined in the nitrogen-free extract (73%) followed with organic matter (71%), pure protein (68%), crude protein (65%) and crude fat (61%). In case of fibre and its fractions, the apparent digestibility coefficients decreased as follows: crude fibre (66%), neutral detergent fibre (66%), acid detergent fibre (63%) and acid detergent lignin (42%). Significantly lower values were determined for coefficients of apparent digestibility for minerals P (16%) and Mg (50%), which highlights the need for their regular supplementation in horses on pasture. This study extends the current state of knowledge regarding the apparent digestibility of pasture vegetation which is a prerequisite for optimal nutrition of horses.