DEPENDENCE OF NUTRITIVE-VALUE OF LUCERNE ON THE STAGE OF MATURITY

The nutritive value (crude protein /CP/ and organic matter /OM/ degrad ability estimated in situ in 3 steers, protein digestible in the intes tine /PDI/ and net energy of lactation /NEL/), and the stage of maturi ty (Mean Stage by Weight: MSW) were determined in lucerne planes cut i n five-day intervals in the spring and summer cuts in two consecutive years. The rate of a decrease in CP degradability, OM degradability an d NEL in dependence on MSW did not differ (P > 0.05) between both year s either in the spring cut or in the summer cut. Rate of a decrease in PDI differed between both years both in the spring and in the summer cut. On the other hand, PDI decreased at the same rate in the spring c ut as in the summer cut both in the first and in the second year. The changes in CP degradability, OM degradability, and NEL (calculated ove r both years) were more influenced by the MSW in the spring cut than i n the summer cut: the slope of regression was -2.45 and -1.50, -5.51 a nd -4.26, -0.62 and -0.44, resp., P < 0.01. The changes in PDI were in fluenced equally in both cuts, the slope was -4.38 and -4.01, resp. (R (2) = 73% and 74%, resp.), P < 0.01. The temperature accounted for 35- 47%, the sunshine for 18-22%, and the precipitation for 5-7% of the va riability in the nutritive traits.