262
ABSTRACTS
any marked effect on the speed of separation, but the
amount of curd deposited in separator bowls was much
reduced. Increase in the amount of serum solids re-
tained by the final fat between 0.1 to 0.2 per cent was
generally associated with improved flavour of the fat.
Decantation of a part of the serum did not reduce the
curd deposition in the separator. Dilution by condense
water in direct steam melting was found to be about 17
per cent. Coefficients of heat transfer from fat to metal
were given. The bacterial count of the fat per ml. was
below 10. The contamination of copper and iron and the
need to avoid them are dealt with. The analytical
methods for the determination of water (Karl Fisher
method) copper and iron (McDowell's modification of
Moir's method) are described. Cooling to about 70°F.
in tins was necessary to get a desirable texture for the
butter fat. About 14 tons 4 cwts. of butter was hand¬
led. [C. P. A.]
Yield, chemical composition, and feeding value
for milk production of alfalfa hay cut at three
Stages of maturity. Tech Bull. U. S. Dep.
Agric. No. 739, 1940, 1-51
THE effect of cutting alfalfa at defferent stages of
maturity on its yield, chemical composition, colour,
leafiness and relative nutritive value as determined by
feeding experiments and digestion trials on sheep and
Holstein cows is given. Cutting alfalfa at 3 stages of
maturity, namely (a) initial bloom stage when not more
than 10 per cent of the plants are in bloom, (b) at half
bloom stage when about 50 per cent of the plants are in
bloom and (c) at full bloom stage when 90 to 100 per cent
of the plants are in bloom appears to have significant
effect on the quality. Alfalfa cut at the initial or half
bloom stage was markedly superior in the yield of hay;
(8938 lb. and 8888 lb. as against 6940 lb. per acre) and
yield of digestible nutrients per acre (4660 lb. and 4413
lb. as against 3269 lb. per acre per year) to the alfalfa
cut at the full bloom stage. The line of demarcation
between the first and second stage is not very signifi-
cant.
With sheep as experimental animals, the average
digestion coefficients obtained for crude protein were
77.7 per cent for the initial bloom hay, 77.1 for the
half-bloom hay and 75.4 for the full-bloom hay. The
corresponding digestible coefficients for crude fibre were
47.7, 41.4 and 38.3 per cent respectively. Experiments
on 3 Holstein cows fed exclusively on initial bloom of
alfalfa hay showed an average production of 11,099 lb.
of milk and 404 lb. of butter fat (calculated on mature
age basis). The cows on half bloom hay produced on
an average 9763 lb. of milk and 345 lb. of butter fat
(mature age basis) The 4 cows on full-bloom hay
produced an average of 8981 lb. of milk and 331 lb. of
butter fat on mature age basis. The rate of consumption
of initial bloom-hay per pound of milk and butter fat
produced was less than that of half and full bloom hay.
The calculated amount of milk produced per acre was
6330 lb. for initial bloom plot, 5234 lb. for the half bloom
plot and 3970 lb. for the full bloom plot after the actual
quantity of milk produced was corrected to 4 per cent
butter fac. [M. C. R.
The feeding of dairy cows for intensive milk pro-
duction in practice. E. MEIGS (1939). U.S.
Dep. Agric. Yearbook Agric., 566-91
THE importance of roughage and concentrates in the
feeding of dairy cows, the proper way of feeding and the
determination of the amount of food required are given.
The vital importance of good roughage, concentrates
and pasture for maintaining the high producing dairy
cow is stressed. Half and half of legume hay (alfalfa)
and grass hay (timothy) are recommended for high milk
yielders. A good concentrate mixture can be made
up of 4 parts of corn meal, 3 parts of wheat bran land
parts of one or more of the oil cake meals plus 1 per cent of
salt. Feeding cows according to the Savage Standard
which is very liberal standard, appears to be the best.
To maintain uniform body weight, heavy milking cows,
in the early part of the lactation, should be fed ad libitum
hay and as much concentrates in addition as they would
clear up in half an hour twice a day. For successful,
reproduction, cows need about 10 p. m. carotene in the
dry matter of the ration. Tender grasses or legumes
high quality alfalfa meal and cod liver oil are good vita-
min A concentrates. Cod liver oil in large quantities
appears to be harmful to cows. It reduces the fat
content of the milk. Mature cows can be fed two ounces
of cod liver oil per day. Heavy milking cows require
about 0.25 per cent each of calcium and phosphorus
in the dry matter of the ration. Iodine deficiency is
not frequent in dairy cows. The author discourages the
practice of administering mineral preparations and
vitamins to make up for poor rations. [M. C. R.]
Studies on the nutritive requirements of Bacteria.
WOLLEY (1941). J. Bact. 42, 155
THE author describes some of his interesting researches
regarding growth-factor and amino-acid requirements of
certain bacteria.
He found that the addition of riboflavin, pantothenic
acid and a suitable reducing agent to a tryptone and liver
extract medium, inactivated with alkali, could restore the
original effectiveness of the medium for the growth of
haemolytic streptococci.
He then attempted to grow
a member of group D of haemolytic streptococci on a
synthetic basal medium containing hydrolysate of puri-
fied casein, glucose, inorganic salts, riboflavin, panto-
thenic acid and reduced iron and observed that the
addition of vitamin to this medium was essential
for the growth. Then the only unknown constituents
of this basal medium were the amino-acids of casein
hydrolysate. He also discovered that substitution of a
mixture of 19 pure amino-acids in place of the casein
hydrolysate gave good growth. Glutaminic acid, trypto-
phane, isoleucine, lysine, arginine, systine and tyrosine
were, on the other hand, found, to be essential for
growth; mixture of these 7 amino-acids produced a good
growth of bacteria. But some closely related strains
failed to grow on this simplified mixture of amino-acids
and required a larger variety of amino-acids and
nicotinic acid.
Only the members of groups B and D of haemolytic
streptococci would grow on this purified medium. For
the growth of a member of group A, further addition
of an unknown water soluble factor of liver extract was
necessary.
The attention of the author was then drawn to the
fat soluble growth-factors and he found that many such
compounds possessing vitamin K activity were active for
the growth of Johne's bacillus.
He finally points out that the same compounds are
concerned in the growth of all living cells, and the use of
bacteria, rather than rats and other animals, for the
tssay of vitamins would materially reduce the cost
of the labour involved in the analysis of these substan-
ces. He also mentions how the studies on microbial
nutrition helped in the discovery of the chemical
structure of pantothenic acid. [N.B.D.]