ABSTRACTS

The value of artificially dried grass, silage made with added molasses and
A. I. V. fodder in the diet of the dairy cows and their effect on the quality of the
milk, with special reference to the value of the non-protein nitrogen. WATSON,
S. J. and FERGUSON W. S. (J. Agric. Sci., 26, 337-367,1936).

AN experiment was carried out to study the nutritive value of artificially dried
grass and of silages prepared by two distinct processes, one with the addition of molas-
ses which entails a fair degree of protein breakdown and the other A. I. V. silage where
the protein breakdown is limited, in relation to the yield and quality of milk of dairy
cows, with special reference to non-protein nitrogen whose feeding value has long been
debated upon.

Four lots of four cows each were fed for a continuous period of 17 weeks, one lot
on the control ration (ordinary winter ration) consisting of hay, roots and concentrates
and the other three on artificially dried grass, molassed silage and A. I. V. fodder respec-
tively which replaced a considerable part of the concentrates. The rations had been so
adjusted that each supplied equal amounts of starch equivalent and digestible crude
protein for maintenance and milk production. The experimental foodstuffs were all
of good quality, high digestibility, with a high proportion of crude protein ranging
from 17 to 21 per cent of the dry matter and supplying half of the total digestible crude
protein in the ration. Artificially dried grass was fed at the rate of approximately
8 lb. and molassed silage and A. I. V. fodder at 30 lb. per head daily and these supplied
5.9 per cent, 31.4 per cent and 25 per cent of the total digestible crude protein intake
in the form of non-protein nitrogenous compounds, besides the 10 per cent of the diges-
tible crude protein in the form of non-protein nitrogen compounds supplied by the basal
ration. The control ration was low in carotene whilst the experimental ones raised the
carotene intake appreciably.

A statistical analysis of milk and butter-fat yields, butter-fat percentage and live-
weight changes of the cows showed no significant differences between the four rations.
The artificially dried grass diet had been the most efficient as regards its effects on solids-
not-fat content of milk and the A. I. V. fodder the least. The other two rations showed no
significant difference. The mean of all the cows showed a value just below that of the legal
standard of 8.5 per cent solids-not-fat in milk and all the rations, except the artificially
dried grass, were below the standard. The artificially dried grass, molassed silage and
A. I. V. fodder had also increased the carotene content in milk and thus the vitamin A
potency to a level equal to that of the grazing season for cows on pasture. Artificially
dried grass; at the level fed, had replaced an equal weight of nutrients in the form of
concentrated foodstuffs.

Thus for milk production the digestible crude protein of the foodstuffs, whether
present in the form of non-protein compounds to the extent of 30-40 per cent of the ni-
trogen intake as in this experiment or as true protein, had all been utilized.

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