Nutritive value of pasture. III. The influence of the intensity of grazing on the composition and nutritive value of pasture herbage (Part I)

Abstract

The present investigation was undertaken with the object of ascertaining the effect of cutting at fortnightly instead of weekly intervals on the yield of pastures, and on the composition, digestibility and nutritive value of the herbage.The main trial was carried out on the 1925 light-land pasture. The plot was divided into 14 sub-plots, and one sub-plot was mown per day. The whole plot, therefore, was cut over once per fortnight during the season. The results in respect of yield, composition and nutritive value were compared with corresponding results obtained on the same pasture plot under a system of weekly cuts during 1925.A second trial was carried out on sub-plots 2 and 3 of the 1926 heavy-land pasture, one sub-plot being cut weekly and the other fort-nightly. The work in this case was restricted to securing comparative data in respect of yield and composition of herbage.The results from both trials lead to the conclusion that the differences in chemical composition, both organic and inorganic, between pasture grass cut at weekly and fortnightly intervals are inconsiderable. The dry matter of the fortnightly-cut grass is extremely rich in crude protein and contains, in comparison with grass cut at the hay stage of maturity, a low percentage of crude fibre. Moreover, these characteristics are retained, by systematic cutting at fortnightly intervals, over the entire season.The results of the digestion trials justify the conclusion that the dry matter of the pasture herbage grown under a system of fortnightly cutting is a protein concentrate equal in digestibility and nutritive value to that obtained by weekly cutting. There is no significant running off in respect of composition and feeding value during the second week of growth. At the end of a fortnight the herbage still consists of the same immature, non-lignified. tissue as it was at the end of a week's growth.