At the beginning of the present century active interest was being
shown in the agronomic characteristics of various herbage plants. The
need for establishing uniformity in the seed trade also had its impact on
the testing of seed samples , at first for cleanliness as regards weed
seeds , and later for yield , habit of growth and , especially , date of
flowering. The main improvement sought ( Stapledon , 1957 ) was greater
persistence and leafiness , a pasture rather than a hay typo of grass.
Work led to the differentiating of three distinct types ( Stapledon , 1933);
namely (1) the early , erect , lax , low tillering hay tape , (2) the
multi-tillered , more spreading medium -early , relatively dense , intermediate hay pasture type , and (3) the high tillering , late
flowering , dense and prostrate growing pasture type. This work came to
fruition in the synthesis of herbages of the desired pasture and hay types.
Through breeding and selection fcr leafiness and later for seed
production , the Aberystwyth bred types have become known in the trade as
" S " varieties , all of which have certain features in common. The other
types , which have developed over the years primarily on the basis of seed
production characters , have become known as " Commercial " varieties.
Differences in yield of commercial and pedigree herbage as single
plants ( Stapledon , 1920 -3 , Green , 1948.51 ) and as swards (Prendergast
and Brady , 1955a , Hunt and Thomson , 1955 , Hughes , 1956 ) have
been shown under cutting managements , but such differences are commonly
not reflected in animal experiments when using such swards. The reasons
2. are many , but at times are due to the fact that sampling methods have
failed to mea sure adequately the total herbage on offer to the animal
which may well graze below the height of cut ( Raymond. , 1943 , Wliliams , 1949 ) : the animal then consumes more herbage than has been estimated by
sampling. Evidence exists ( Roberts , 1931 , 1932 , Roberts and Williams , 1940 ) which indicates differences in yield between commercial and pedigree
swards under animal grazing conditions , though not on a closed farm
system , where , in practical farming terms , there is no direct
application. There exists no literature of a similar comparison elsewhere.
Surveying the present sampling techniques gross insufficiencies and
lack of precision have been observed . Using existing techniques a critical attitude was maintained throughout with the hope of finding a way
of either improving existing methods or formulating new ones with a view
to creating greater statistical and practical precision.
The comparative simplicity of managing a simple grass or a one grass - one clover sward makes necessary the study of the total herbage production
and of animal output from such swards under practical grazing conditions.
It also allows a comparison between the yield of commercial and pedigree
varieties , sown singly or in such mixtures as advocated by Percival
(1923 -4) , Gilchrist (1911) and others. The main problem in complex
mixtures is the inability of many species to stand up to competition with
other species either through lack of , or delay in , seed germination , or as Davies (1928) showed , because of inter -species competition due
to time of starting active growth. Italian ryegrass for instance often
dominates the sward early in the season , and consequently suppresses
the other constituents.
The present investigation thus seeks to measure the productivity of
commercial and pedigree swards under two different types of management , ( grazing and no- grazing ) to see whether similar differences obtain; under
both systems , and whether such yields bear any relationship to the animal
returns from them. A new technique , discussed later , is employed in
sampling herbage at 3- weekly intervals without the grazing animal , using
a Wolseley sheep shear modified for herbage sampling. The technique is
varied for sampling under the second management regime . This shear cuts
down to ground level and is powered by direct drive from an Allen mower. The total amount of herbage available may be estimated by this technique.
The investigation concerned was carried out on two existing experiment:
at the Grassland Research Institute , Hurley, H138 ( List of Experiments , 1957 ) , H15 ( List of Experiments , 1958 ) , on swards established
respectively in 1956 and from 1950 onwards , sown for direct comparison of
both commercial and pedigree swards maintained on a closed farm system.
Previous comparisons were made only of animal live- weight and wool returns,
sheep alone were used on H138 : sheep and cattle were used on H15 either
grazing together or singly. The techniques described have been used in
measuring herbage differences , and they are checked by intake observations.
A cursory attempt was made to study the root mass under grazed sward
conditions to see if there were varietal differences and to what extent
clover influenced this. The root mass has been considered in terms of total
organic matter accumulated in the top three inches of soil as measured by
An evaluation of varieties that takes all these aspects into account
under practical conditions is necessary on scientific and economic grounds , and refined techniques should be used for such evaluations .