26
Passage of Fluids through the Stomach of Sheep
the ruminal contents become fluid (Tests 9 and 10), but even then there is no
definite indication of this condition favouring the reflex. It has been found
therefore, that preliminary starvation is necessary for an effective stimulation
of the reflex and it is for the same reason that from observations made by
LeRoux [1932] and Ross [1934] in connection with the parasiticide action of
drugs on gastro-intestinal worms, it was claimed that the operations were
more successful in the case of sheep which had been starved for some hours.
Considering the ill effects caused by prolonged starvation, Monnig [1929],
however, does not favour this practice. It was also noticed by us that if sheep
are allowed free grazing after prolonged starvation, cases of digestive troubles,
such as tympany and impaction of the rumen, are not uncommon. An over-
night fast (15-18 hours), however, is usually a routine practice and this period
should not in any way produce any ill effects. There is, therefore, no harm
if the sheep are fasted for 15-18 hours, and this period according to LeRoux
[1932] is essential when maximum effect is to be obtained for the treatment of
haemonchosis in sheep. Experiments carried out by us show that 2 ounces of
a 2 per cent copper sulphate solution when dosed after this period of starvation
will pass in bulk to the abomasum (Test 2).
If starvation is prolonged for 38-42 hours, it is noted that the question of
the stimulation of the reflex closure of the oesophageal groove is negligible as
even simple water is able to pass, in part or as a whole (Test 5) into the abo-
masum. When the sheep are kept away from water only for this period, the
reflex fails even with a 2 per cent copper sulphate solution (Tests 7 and 8).
This result confirms the findings of Ross [1934] who claims that water or drugs
when given in solution, after withholding water for 40 hours, pass in bulk into
the omasum and abomasum, but it is necessary that food should also be withheld
for the same period. It appears that, for producing a favourable condition for
the reflex, a suitable equilibrium of food and water in the rumen is essential,
but further investigation must be carried out in this connection. When there
is deficiency of water in the rumen, most of the water or fluid drugs, even with
their ability to stimulate the reflex, are retained in the rumen (Tests 7 and 8).
This confirms the findings of Monnig and Quin [1935] who observe that dryness
of ruminal contents is an unfavourable condition for the stimulation of the
reflex. It can, therefore, be summarised that after routine dosing of sheep
for gastro-intestinal worms, the animals may be allowed to graze for some-
time after dosing and then given water in small quantity, as most of it will then
be retained in the rumen and there would be little possibility of the dilution of
the drug in the abomasum. Under these circumstances there appears to be
no necessity for starving the animal after dosing.
SUMMARY AND CONCLUSIONS
From the experimental data recorded during the year 1939-40 it has been
found that:—
1. Copper sulphate in solution is able to stimulate the reflex closure of
the oesophageal groove.
2. The intensity of the stimulation of the reflex with copper sulphate
solution is more marked with a stronger solution when adminis-
tered under identical conditions of preliminary starvation.