ROTATIONAL GRAZING

Hawke's Bay Tribune, Volume XXI, Issue 279, 9 November 1931, Page 10

ROTATIONAL GRAZING

Thn underlying fundamental fact supporting the practice of rotational grazing, and at the same time explaining its results, is that young grass is more nutritious than grass that approaches maturity. On a dry-matter basis grass of three weeks’ growth, say, from five inches to eight inches high, will contain nearly three times the amount of protein that it possesses at the stage considered right for cutting for hay, i.e.„ when the seed has formed. To obtain grass of this age throughout the season it is necessary to divide grazing areas by fencing the pasture into a number of small fields, the size, and to some degree the number, of which will be determined by the size of the herd to be pastured, the object being so to rotate the feeding as to leave each field free of stock for a period of from two to three weeks for recovery. The stock is moved from .field to field as the growth of grass dictates, but if the number of stock is not sufficient to keep the grass eaten down in, say, from one to two weeks, then it must be mown to prevent it from maturing. The degree of success attending this plan of pasturage will, in the absence of irrigation, depend very largely on the rainfall, its amount and frequency, during the season, and more particularly towards the end of the season.

The nutritive value of a grass may be valued by the amount of its digestible protein. Experiments conducted at the Dominion Experimental Farms (Canada), during the last four years present the protein data, percentage, and yield, from plots rotationally grazed, and from those allowed to grow until seed was about to form. Thus in young grass (one to three weeks old) the percentage of digestible protein was 18.5 per cent., or 6901 b. an acre. In the case opmature grass (seed just formed) the percentage of digestible protein was 11 5 per cent., or 4201 b. an acre. These experiments furnish the scientific data which support the theory of rotational (or close) grazing, and further supply the chemical explanation of the increased milk and live weight production resulting from the adoption of this plan of pasturage.