332
ABSTRACTS
of low fertility (due to low concentrations of spermatozoa in the semen). The diagnosis
of pregnancy by the blood serum and the urine tests are described.
In cattle, fertility is influenced to a far greater extent by disease such as infection by
Brucellus and Trichomonas and other causes and it is difficult to define physiological
infertility. The fertility (breeding efficiency) of a herd can best be measured by calculat-
ing the ' service record ' or the number of services to produce one pregnancy. This
averages 1.7 for normal herds. Temporary sterility may be due to failure of ovarian
functioning ; this can usually be overcome by pinching the corpus luteum or punchuring
the ovarian cysts. Low fertility in bulls can be overcome by feeding of animal protein or
injection of anterior pituitary hormones. Artificial insemination has contributed greatly
to the raising of fertility and productivity of farm animals. Semen from bulls collected
in an artificial vagina is sufficient for 15 cows and the service records are 1.6-1.7.
Deficiency in sperm production has been observed in rams ; the ewe is anoestrus
(in temperate zones) from March to July. Too frequent a service by boars reduces the
vitality of the sperm, but in the sow, prenatal mortality due to as yet unknown causes is
the main factor in defining fertility. [W. L. D.].
The phosphatase test for control of efficiency of rasteurization. H. D.
KAY, R. ASCHAFFENBURG AND F. K. NEAVE. Technical Communication No. 1
of the Imperial Bureau of Dairy Science, Shinfield, Reading. October 1939,
pp. 53.
T HE original phosphatase test of Kay and Graham is now six years old and the
modified test, four years old. Some later modifications of the test originating from
the "United States of America have also been introduced. This monograph describes
the progress made with the test during this period.
It may be said that the test is by far the most satisfactory test yet devised for control-
ling milk pasteurization and this is accepted by health authorities and dairy scientists.
The test depends on the destruction by heat of the enzyme, phosphatase, in milk at time-
temperature combinations somewhat similar to those recognised in official commercial
pasteurization (30 minutes at 145°F); the test is linked up with the aims of pasteuriza-
tion in that a 96 per cent destruction of phosphatase takes slightly longer heat treatment
than the complete destruction of a pathogene such as Myco. tuberculosis.
The test depends on the measurement of phosphatase activity. The enzyme is
allowed to react in a buffered solution for a definite length of time on di-sodium pheny
phosphate (sodium p—glycerophosphate in the original test). The phenol which is libera-
ted is determined coloumetrically either by the blue colour formed by Folin's reagent
or the red colour formed by reaction with 2 : 6 ditromoquinone chlorimide (BQC) (The
colour is a blue-red-yellow mixture when measured in a tintometer).
By carrying out the test by a strictly standard technique properly pasteurized milk
shows 2.5 units or less of blue colour (2.5 cm. layer), improperly pasteurized, 2.3-6.0
units, and gross errors in pasteurization over six units. An outfit with standard blue discs
(Lovibond-B. D. H.) has been made to simplify the test. Two tests, a short ½ hour test
useful as a sorting test to determine whether milk has been heated or not, and a more
accurate 24 hours test which detects small as well as gross errors in pasteurization, are
used, the latter more commonly. A large number of modifications, especially to suit the
United States of America holder pasteurization temperature of 143°F, have been intro-
duced and are described. The field and the laboratory tests of Scharer, using BQC, are
important modifications. The techniques of the various tests are given in a very infor-
mative appendix.
The test has been investigated mostly on holder pasteurized milk. Many cases of
inefficient pasteurization of commercial milk are quoted. The test is also applicable to
milk pasteurized by the high temperature-short time method, a method which incidentally
will suit Indian conditions better. The test has also been applied for controlling the
manufacture of dairy products from pasteurized milk and cream, and for determining
whether such products have been manufactured from pasteurized liquids. [W. L, D.]