MVSc

Japanese quails, being the most recently introduced
species of poultry in India, are the least studied among the
different domestic species of birds. For economic rearing of
these valuable birds a thorough understanding of their basic
digestive processes is essential. Keeping this point in view
an attempt; was made to study the digestive physiology of adult
Japanese quails (Coturnix coturnix japonica) especially the
quantification of digestive enzymes like amylase, protease
(pepsin) and lipase of different regions of digestive tract,
the determination of pH of the contents of crop,
proventriculus, gizzard and small intestine and the feed
passage rate (FPR).
One hundred and ninety two, six-week old Japanese quails
of the same strain (egg type) were selected, at random, from
the Kerala Agricultural University Poultry Farm, Mannuthy and
maintained on standard, identical managemental and feeding
conditions in cage system for a period of two weeks in order
to stabilize the experimental conditions in the Department of
Physiology and Biochemistry, College of Veterinary and Animal
Sciences, Mannuthy. A batch of 24 birds (12 males and 12
females) of the same hatch were subjected for the
quantification of the specific digestive enzyme in a
particular region of the digestive system. Seven batches of

24 birds (a total number of 168 birds) were selected at weekly
interval from the poultry farm for quantifying the different
enzymes in specific regions. The eighth batch of 12 males and
12 females of the same hatch was utilized for studying the
feed passage rate (FPR). From this last batch, 12 birds were
randomly selected and utilized for estimation of pH of the
contents of different regions (crop, proventriculus, gizzard
and small intestine) of the digestive tract.
Each batch of 24 Japanese quails (12 males and 12
females) were sacrificed when they attained eight weeks of age
for the quantification of the digestive enzymes (amylase, acid
protease and lipase) in specific areas of the digestive system. The enzymes were quantified in the tissue homogenate
of the respective tissues. Amylase activity was estimated in
the mucous membrane of crop and small intestine, pancreas and
gall bladder bile. Quantification of acid protease (pepsin)
was conducted in the mucous membrane of proventriculus.
Lipase was quantified in the pancreas as well as small
intestinal mucous membrane. The data obtained were analysed
statistically.
From the results of the study it was observed that crop
mucosa of both sexes of quails showed an appreciable amount of
amylase activity and the activity in males was significantly



(P≤0.01) higher (47.98


± 10.49 S U/g of tissue) than in



females (13.26 ± 4.46 S u/g of tissue).


In adult Japanese


quails, when the values for both the sexes were pooled, the
activity was found to be 30.62 ± 6.65 S U/g of tissue. The
activity of amylase was independent of the presence of food in
the crop.
In pancreatic tissue also, amylase activity was

significantly (P≤0.01) higher in males (59.89 ± 3.36 S U./g of
tissue) than in females (38.72 ± 2.59 S U/g of tissue). When
both the sexes were taken together, the overall value of
pancreatic amylase was 49.30 ± 3.03 S U/g of tissue. The
(
value was higher than that of the crop. The bile from gall
bladder of ma Le Japanese quails exhibited, a higher P≤0.05)
mean amylase activity (156.23 ± 27.72 S U/g of tissue)
compared to that of female quails (87.65 ± 14.36 S.U/g of
tissue). The pooled mean value of both sexes was found to be
121.93 ± 16.86 SU/g of tissue, indicating an appreciably high
amylase activity in the bile of Japanese quail. The amylase
activity in the small intestinal mucous membrane of males
(234.38 ± 38.96 S U/g' of tissue) was significantly higher
(P≤0.01) than that of females (103.23 ± 8.08 S U/g of tissue).
The pooled mean value of amylase activity in small intestinal
mucous membrane of both the sexes of Japanese quails was
168.81 ± 23.78 S U/g of tissue.
When the amylase activity in different areas of digestive
system as crop, pancreas, bile and small intestine was
compared in both sexes of birds, it was observed that the
highest value was noticed in the male birds.
It was also
observed that when the birds (both males and females) were

maintained on identical ration and managemental conditions,
ma ;e birds preferred coarser particles of maize where as
females preferred finer particles of oil cakes. So the
increased amylase activity in different regions of male
quails, might be a normal response to the increased intake of
carbohydrates. In adult birds, intestinal mucous membrane
exhibited the highest amylase activity and the crop mucosa
exhibited 'the lowest activity indicating that digestion of
starch starts in the crop with salivary amylase and completion
of starch occurs in the small intestine with the help of
amylase derived from pancreas, bile and small intestine.
There was a negative correlation between the pancreatic weight
and amylase activity with the correlation in males as -0.975
and as -0.968 in females. This indicated that simple
homogenisation might not have liberated the intracellularly
accumulated enzyme completely and that the pancreatic weight
is mainly contributed by the intracellularly accumulated
enzyme.
The acid protease (pepsin) activity of proventricular
mucous membrane of male quails was found to be 185.67 ± 11.54
PU/g of tissue and that of female quails was 223.31 ± 38.91
P U/g of tissue. Though statistically nonsignificant, females
exhibited a slightly higher value than the males. It might be
a response to the increased intake of protein rich finer
particles of oil cakes of feed by the females. The pooled




mean value for pepsin activity when both the sexes taken
together was 204.48 ± 17.97 P u/g of tissue.
The lipase activity, of pancreas was quantified to 73.37
± 7.78 L u/g of tissue in males and 38.40 ± 3.39 L U/g of
tissue in females, the males had a significantly (P≤0.01)



higher value.


The intestinal mucous membrane exhibited a



significantly higher (P≤0.05) lipase activity in the males
(38.80 ± 10.93 L.U/g of tissue) than in the females (12.44 ±



4.15 L U/g of tissue).


In the present study, it was also



observed that the female birds preferred fat rich finer
particles of oil cakes than the males. Since fat is the high
energy yielding nutrient, the quantity in excess present in
the diet is prevented from hydrolysis by the reduced lipase



secretion in the females.


The overall lipase activity in



pancreas and small intestinal mucous membrane (when both the
sexes were taken together) were 55.88 ± 5.52 L U/g of tissue

and 25.62 ± 6.34 L U/g of tissue respectively, indicating that
pancreas was the major site of lipase origin in quails. There
was a negative correlation of pancreatic weight to lipase
activity in both sexes, with a correlation value of -0.882 in



males and -0.499 in females.


As in case of amylase,



homogenisation might not have liberated the intracellularly
accumulated lipase too.
The pH values recorded in the contents of crop,
proventiculus, gizzard and small intestine (duodenum) were

5.00 ± 0.26, 4.30± 0.11, 3.50 ± 0.17 and 6.50 ± o. 00



respectively.


The observed pH in crop is suggestive of the



amylolytic digestion in the crop. Though proventriculus is the
site of secretion of pepsin, the comparatively lower pH
(acidic pH) recorded in the gizzard suggested that acid
proteolytic digestion was undergoing in a better way in the
gizzard. The intestinal contents exhibited the highest pH than
.
the upper regions of the digestive tract indicating that the
enzymes of pancreas, bile and small intestine require a
comparatively higher pH for eliciting the optimum action in
the small intestine, thereby hydrolysis of starch, protein and
lipids are completed.
The feed passage rate (FPR) was recorded in the last
batch of 24 adult Japanese quails (12 males and 12 females) by
using carmine as the indicator dye and the time taken for the
first appearance of coloured excreta was taken as the index.
The recorded FPR values for males and females were 120.5 ±
10.88 min and 92.4 ± 10.65 min respectively. The difference
in FPR between male and female birds was not significant. The
overall FPR (when data from both the sexes were pooled) was



found to be 106.5 ± 8.00 min.


The time taken for complete



disappearance of the dye from the excreta was found to vary
from 249.min to even more than a day. Though nonsignificant,
the difference in FPR values observed between males and
females may be due to the difference in their body weight.

The results of the present study provide informations on
the relative functional importance of enzymes such as amylase,
protease and lipase at different regions of digestive tract of
Japanese quails. The study also throws light on the pH in
different regions of the digestive tract as well as transit
time of feed in Japanese quails. These informations may be of
use in understanding the physiology of digestion and
formulation of quail rations. The observation during the
course of this experiment of the preferential uptake of feed
particle by male and female quails is interesting warranting
further studies on feed intake behaviour in Japanese quails.