ABSTRACTS
255
The semen may also be collected from the vagina of females after actual mating.
It is, however, not necessary in most species to have females in heat for the purpose,
as most males may be easily trained to mount a female out of heat. The semen is re-
covered from the vagina by a suitable syringe or a spoon, but the quantity collected is
usually small and mixed with vaginal secretion which is deterimental to the storage of
sperm.
A Breeder's bag can only be used for stallions and jacks. It permits the collection
of a whole ejaculate in practically uncontaminated condition. The method of ejacu-
lation by manipulation has been successfully used in cattle, dogs and fowls. In bulls,
an arm is inserted in the rectum. The seminal vesicle and the ampullae of the vas de-
ferens are located and massaged by backward strokes and the semen is expelled. It
requires great experience and technique for such collection. Similarly in dogs the base
of the penis is gently massaged, inducing erection and ejaculation. In poultry, the
copulatory organ is made to protrude by rapid massaging of the soft part of the abdomen.
It is then held by the thumb and the forefinger, and the semen is gently squeezed out.
In Australia, a laboratory method of collection of semen by electrical stimulation
has been devised and used successfully in rams. This process, however, is not suitable
for all species.
Before insemination is carried out, the examination of semen is essential, as it deter¬
mines the volume, colour, cloudiness, consistency, motility, the number of sperms per
cubic millimeter, freedom from contamination, hydrogen ion concentration and the rate
of respiration of the sperm. The volume of semen, which is generally measured in a
graduated bottle, is of great importance, as the number of inseminations depends on the
quantity and the percentage of active sperms per cubic millimeter. Generally the cal-
culation of volume is made on the total ejaculate produced in a given interval of time on
several occasions. The colour and consistency indicate the quality of sperm. A sample
of sperm of the whole ejaculate is taken and the motility, the number of sperms per
cubic centimeter and other abnormalities, if any, are examined under a microscope,
keeping the same at a constant temperature between 38°C. and 40°C. on a hollow ground
slide. Three types of motility have been observed, such as (1) progressive motion in
straight line, (2) rotary motion in a circle and (3) convulsive and oscillatory motion with-
out change of place. As the motility determines the vitality of the sperm, many arbi-
trary gradings have been suggested by various workers, based upon a discrimination
between various types of motility and the proportion of sperms exhibiting the respective
types. However, the best grade sample of semen is one which contains the largest num-
ber of sperms showing progressive motility. Physiological, anatomical and pathological
abnormalities of spermatozoa having a direct bearing on low fertility are also observed.
Abnormal sperms in bulls and rams should not exceed 17 per cent. However, the per-
centage of abnormal sperms is said to depend on the breeding season, previous sexual
activity and methods employed for semen collection. The state of breeding activity
of a ram tends to influence the abnormal sperm content as, according to certain authors,
the first ejaculate after a prolonged sexual rest contains a larger percentage of abnormal
sperms. This is said to be due to the sperms undergoing slow degeneration in the epi-
didymis and vas deferens. Examination of sperm for abnormalities is made by making
a smear of well-mixed material, with a coverslip, and then staining when dry with 0.5
per cent alcohol solution of Gentian violet, for three minutes. The other methods of
staining are as follows:—
(1) The smear is air-dried and put into a saturated solution of chlorazene for 5 to
10 minutes and rinsed in distilled water. It is then fixed in 10 per cent formalin for three
to five minutes, rinsed in distilled water, stained with Ziehl's Carbotfuchsin for two
minutes, washed gently in running water and dried. (2) Two drops of freshly collected
semen are placed on a slide and mixed with 3 drops of opal blue (Brasslau) which has
been heated till it steams, filtered and cooled to room temperature immediately before
staining. After staining it is spread and allowed to dry. The number of sperms per
cubic millimeter is calculated by means of a haemocytometer. The semen is diluted 100
or more times with 0.9 per cent saline solution by a special pipette and well shaken before
a drop is placed in the counting chamber. The presence of pathogenic organisms and
protozoan parasites indicates a diseased condition of the spermatozoa or the reproductory