1. During summer 1955 four farm silages were
made from wilted grass and clover, silage 1 from
bruised material and silages 2, 3 and 4 from long
material, all of medium - to low - crude protein
2. The season was exceptionally warm and dry.
The crops were stetmay and when cut contained the
low average moisture content of 76.6 per cent.
Based on a classification of weather, devised from
earlier investigations, meteorological, information
showed that weather conditions during ensilage of
silo 1 was very good; silo 2, ver oor - ver' :oo
silo 3, poor - very poor and silo 4, good - very
good. A proportion of silage was, therefore,
made under conditions highly favourable towards
overheating in the silo.
3. It was proposed always to cut one day in
advance of filling and to wilt each area for about
24 hours. Due to inexperience with harvesting
wilted material more herbage was sometimes cut
than could be collected and ensiled in one day
so that some of the material was severely wilted.
The primary cause of overwilting, however, was
faulty machinery which delayed work in the field.
4. Results of moisture determinations tended
to confirm previous field trials which showed
that (a) marked moisture drops occurred in all but
very poor weather (b) no advantage was gained by
postponing cutting until surface moisture had
evaporated and (c) wilted material still lying
in the field was not much affected by rain showers.
5. Tilted silage made from long herbage, containing: a minimum of overheated and mouldy material
can.be produced by making sure that (a) filling is
continuous, except during bad weather (b) as much
herbage as possible is wilted for periods of up to
24 hours only (c) consolidation is performed continuously, starting with the first layer (d) fillin
is carried out rapidly and commenced at the beginning
and not at the end of the week (e) no waiting period
are allowed for temperature to rise, and a layer of
unwilted material ensiled if temperature reaches
120 °11. (48.9 °C.), (f) unwilted herbage is used
during the final day's filling and (g) sealing is
performed immediately to give a soil depth of at
least 9 inches after compression by the tractor.
6. Results showed that overheating and moulding
is much less likely to occur in wilted material
.which has been bruised than in wilted long herbage;
It is concluded that for best results some form
of mechanical treatment is advisable.
7. Chemical analyses of the edible products
showed silages 1, 2, 3 and 4 to contain average
percentage moisture contents of 70.4, 70.3, 75.2
and 63.7, average percentage crude protein
digestibilities of 72.5, 62.0, 73.4 and 68.9,
average percentage butyric acid contents in the
fresh material of 0.13, 0.01, 0.21 and 0.14,
average percentage lactic acid contents of 0.93,
1.31, 1.64 and 0.85, average percentage acetic
acid contents of 0.52, 0.23, 0.34 and 0.26 and
average pH values of 4.2, 4.2, 4.3 and 4.8.
8. Excluding waste and mouldy material preservation was satisfactory in all four silages
o but temperatures of up to 130 P. (54.4
o C.) in
o silage 2 and 136
o 2. (57.8 C.) in silage 4 caused
depressions of crude protein digestibility amounting. to 5 per cent. and 15 per cent. respectively.
The depressions were small considering the
stemminess of the crop and frequency of overwilting
but much greater depressions of protein digestibility would probably have occurred had less
consolidation been given.
9. Visual inspection showed silages 2 and 4
to,be slightly brown and to possess a slightly
sweat odour; characteristics which were not present
in silages 1 and 3. The amount of top waste and
mouldy material was by far the greater in silage
4 containing the lowest moisture content of 63.7 per
cent. The degree of side waste was controlled by
type of silo, not by dryness of herbage.
10. The silages were fed to Galloway cows, and
also to 20 month old heifers and 7 to 9 month old.
calves out of blue-grey cows. Silage 3 of highest
moisture content, 75.2 per cent., was the least
palatable, it being consumed less greedily than
the other three silages.
11. Finally, while wilted stemmy grass and
clover herbage of medium - to low - crude protein
content can give a satisfactory silage with a moisture content of 70 per cent., and with
relatively small amounts of waste and mouldy
m` aerial, it is clear that a depression of about
10 per cent of crude protein digestibility is
inevitable unless the crop has been bruised to
aid consolidation. Provided all the conditions
under point 5 above are adhered to then satisfactory silage can be made from partially wilted
herbage in all weather conditions except that
classed as 'very poor'. Faced with such an
exacting list of rules it is doubtful whether
many farmers would seriously consider partial
wilting of crops for silage a worth while method.
No results are available for farm silages
made from wilted leafy herbage but it is thought
that the danger of producing overheated and mouldy
silage would be less with leafy grass and clover
than with stennny material such as that used during
the present investigation.