ABSTRACTS 287
Three experiments of 72 weeks duration each were carried out on Single Comb
White Leghorns ; the progeny of the first year's experimental birds were studied in the
second year, the various groups being fed the same rations as in the first year. A fresh
stock of birds was used in the final year. The birds in each experiment were equally
distributed among eight groups and fed all mash rations in which the percentage of skim
milk ranged from 0 to 8.75. The other constituents in the feed were suitably altered,
within narrow limits, to maintain an average content of 16.9 per cent protein, 1.7
per cent calcium and 1 per cent phosphorus during the first 12 weeks of growth,
and 14.4 per cent protein, 2.4 per cent calcium and 1.7 per cent phosphorus there-
after. Males were separated at 4 and 6 weeks of age and used for studying the shrinkage
of live weight in shipping broilers.
The chicks were weighed at bi-weekly intervals till 24 weeks of age, and the mean
weight in pounds per bird for each group has been presented. According to the authors,
the beneficial effects of skim milk feeding were most pronounced in the first two weeks,
and persisted till 10 weeks, during which period the gain in body-weight increased in
proportion to the amount of milk fed; the differences in all cases, however, were relatively
small. The efficiency of food utilisation appeared to be slightly better in the higher
milk level groups in the early phase of growth, but this was counteracted in later weeks.
When both efficiency of food utilisation and early rapid growth are considered, the best
response was obtained from the groups fed 1.25 and 2.5 per cent milk.
Although the figures cited show no advantage in feeding skim milk beyond 10 weeks
from the standpoint of body-weight alone, it is doubtful if its discontinuance would be
beneficial in the long run. No data are included on the effects of such a procedure on
subsequent egg production. The fact that among the laying hens in the second genera-
tion, age-at-first-egg decreased, and weight-at-first-egg increased with increasing levels
of milk, and that mortality was significantly higher in the groups receiving 5 per cent
and less of skim milk indicates the favourable effect of a liberal supply of milk.
Egg production of the birds in the first generation (1st and 3rd years of experiment)
was more or less similar in all the groups, but in the second generation (2nd year of ex-
periment) production was rather poor in the no milk and 1.25 per cent milk groups.
There was no corresponding increase beyond the 5 per cent level in any of the years.
Highest egg weights were obtained from the 3.75 and 5 per cent groups. Eggs from
the 2.5 per cent and 3.75 per cent groups hatched as well as those laid by birds receiv-
ing higher amounts of milk. Taken together, these observations indicate that the opti-
mum supplement of dry skim milk for laying hens is between 2.5 and 5 per cent, when
the ration is otherwise well balanced.
The internal quality of the eggs was also tested in the first year on a random selection
of 10 eggs from each group from one day's production. The factors studied were per-
centage of egg shell of total egg weight, percentage of ash in egg shell, percentage of yolk
and firm albumin of total egg weight, albumin and yolk scores, and yolk index; but there
were no significant differences in any of these factors in any of the groups.
In two experiments on the shrinkage of live weight in shipping broilers, the greates
shrinkage occurred in the no milk group, while the most satisfactory results were obtained
in the 2.5 and 3.75 per cent milk groups.
[Y. V. N.]