The assessment of herbage legume varieties: III. Annual variation in chemical composition of eight varieties

Abstract

SUMMARYThe primary growth of eight varieties from three species—white clover (3), red clover (4) and lucerne (1)—was sampled at fortnightly intervals during 2 years and the percentage N, P, K, Ca, Mg, Na and in vitro dry-matter digestibility (IVD) were determined.Differences between species, date of sampling and years were highly significant for all constituents. Clover was significantly different from lucerne for all constituents except P, and white from red clover with the exception of Ca. There was a steady decrease in N, P, K, Na and IVD with advance of date of cutting but no marked trend in Ca and Mg. Some constituents changed considerably from first to second year, decreasingin the case of Ca, and increasing for N, P andNa; the remainder K, Mg, and IVD changed only 4–8%.The varieties did not give the same relative results in the 2 years for P, K and Ca content, but there was no interaction for N, Na, Mg, IVD content. Species differences accounted for mostof these interactions.Percentage composition is discussed in relation to the needs of cattle and it is concluded that these herbage legumes provided sufficient Ca, Mg, N, K, and Na (white clover, and the firsttwo cuts of S. 123 red clover and lucerne only) for milk production and growth. The level of P fell below the quoted needs of a 20 kg/day milking cow but was adequate for growth.