The effect of fertilisation on the nutritive value of forage from permanent Karst meadow. 1 botanical and chemical composition, in vitro digestibility and concentration of net energy for lactation

Abstract

Nutritive value of forage from a long term fertilisation experiment was estimated on the basis of concentration of net energy for lactation (NEL) and digestibility of organic matter that were calculated on the basis of chemical composition and gas which was produced during the incubation of samples with rumen liquor in vitro. Unfertilised treatment (0), treatment which was fertilised with phosphorous and potassium (PK) and treatment fertilised with phosphorous, potassium and nitrogen (NPK) were compared. The total yield was separated into grasses, legumes and forbs and analysed separately. Nutritive value of grasses, legumes and forbs was affected by fertilisation only slightly. The concentration of net energy for lactation was considerably higher in legumes than in grasses and forbs: 5.95, 5.24 and 5.36 MJ per kg dry matter respectively. However, due to relatively small differences in proportion of legumes higher concentration of NEL in legumes was not manifested in differences between treatments. Yield of NEL was markedly increased by fertilisation: 12000, 19500 and 34500 MJ per ha in 0, PK and NPK respectively. Differences between variants were due mainly to differences in dry matter yields. Differences in NEL concentration contributed relatively little to differences in NEL yields.