A. J. MACDONALD AND S. BOSE 155
pen. The average egg size of 2.05 oz. in Groups
2 and 5 was also satisfactory. As the total per-
centages of protein in both the separated milk
ration and the meat offal ration were slightly below
14 per cent, which is generally regarded as the
minimum requirements for satisfactory egg pro-
duction, it appears that both separated milk and
meat offal are satisfactory sources of proteins.
The average egg production in Group 1 of 95.0
cannot be considered satisfactory as it is equiva-
lent only to a calculated annual production of
123.8 eggs. The average egg size of 2.00 oz. was
also appreciably lower than that of Groups 2 and 5.
The egg production record from Group 1 on a total
protein intake of only 10.4 per cent, however,
suggests the necessity of further investigation into
the protein requirements for maintenance and egg
production. Halnan [1938] gives the daily re-
quirements for a 4 pound bird as 7.8 gm. digestible
protein for maintenance and 10 gm. protein for
each 2 oz. egg produced. The actual consumption
of total protein per bird per day in Group 1 was
only 10.2 gm. Calculated on the results of various
digestibility trials [Jull, 1930], it can be safely
assumed that the protein digestibility coefficient of
the combined mash and grain ration used did not
exceed 80 per cent. On a digestibility basis of 80
per cent, the average daily intake of digestible
protein was only 8.2 gm. It is, therefore, obvious
that the egg production of 95.0 eggs during a period
of 280 days could not be maintained on Halnan's
standards for maintenance or production, unless
the birds were able to pick up considerable quanti-
ties of protein from the run. However, even after
making allowance for the consumption of green
food fed to the birds and for the limited amounts
picked up from the runs, it is extremely doubtful
whether the birds consumed the necessary stipu-
lated requirements for maintenance and egg-pro-
duction. The results add further confirmatory
evidence to the conclusion [Macdonald, 1937] that
maintenance and egg production can be supplied
by rations containing considerably less protein
than the present accepted standards. The rations
containing supplements of soya bean meal and
earthnut meal gave no better egg production than
the cereal plus salt ration. The poor results with
both of these vegetable proteins is rather surprising
in view of the beneficial results obtained from them
in chikenegrations [Macdonald, 1941, 1942]. The
avecra egg size recorded from the two vegetable
protein supplemented groups was similar to that
obtained from Group 1.
The average egg size in all groups decreased with
the rise in temperature, which occurred during
periods 9 and 10. In countries where the tempera-
ture does not exceed 70-80°F., the size of eggs
from pullets rises steadily for five to six months
and thereafter remains fairly constant during the
remaining portion of the first laying year. The
drop in egg size recorded during this experiment
is similar to that experienced in former years and
supports the findings of Warren [1939], who de-
monstrated that temperatures of over 70°F. have
an adverse influence on egg size in pullets. Though
the data presented is somewhat limited, it is in-
teresting to note that the egg size in Groups 2 and
5 did not decrease until the 10th period, whereas
in the other groups on rations giving poorer egg
production and egg size, the drop in egg size com-
menced earlier. As the average food consumption
per bird decreased with the onset of the hot weath-
er, it is probable that such reductions in egg size
are due to lack of essential nutrients and to loss of
appetite. The lower food consumption figures in
Groups 1, 3 and 4 cannot be attributed solely to
unpalatability, since Group 2 consumed more food,
excluding the milk, than Group 1 which received
similar mash and grain rations. Group 5, however,
had to be fed on a wet mash which probably result-
ed in increased palatability, and further work is
necessary to throw more light on this aspect of the
problem. Groups 2 and 5 consumed significantly
less food per pound of egg produced than Groups
1, 3 and 4. The lower food utilization by Group 1
was probably due to the low percentage of protein
in the food consumed. The rations of Groups 3 and
4, however, had similar protein contents to Groups
2 and 5, and their poorer utilization of food must,
therefore, have been due to the poorer quality of
the protein supplements.
The general health of the birds, excluding a con-
siderable amount of moulting in Groups 1, 3 and 4
during the middle part of the experiment, was good.
The moulting which occurred in these three groups,
however, suggests that the rations fed to them were
deficient in some factor necessary for good egg
production. Though Group 2 had the highest
mortality (16.7 per cent), there was no significant
difference in the mortality rate in the five groups.
Deaths were mainly due to ovarian and other
miscellaneous causes, and there was no indication
that any of the rations were directly concerned.
Despite the better egg production which must have
thrown a greater strain on the stamina of the birds,
Group 2 had a higher average body weight at the
end of the experiment than any of the other
groups.
As good egg production alone may be very mis-
leading in estimating the value of a ration for
breeding fowls, incubation trials were carried out
to throw more light on this important point.
Group 1 on the low protein diet gave the highest
fertility and almost as good hatchability as Group
2 which gave the best hatchability results. The
good fertility and hatchability obtained from group 1