Abstracts.
257
Group II animals were then given the test substance for seven weeks, Group I now serving as controls. Iodinated
casein was fed during both the test period at the rate of 15 gm. daily per animal. Protamine feeding consistently
caused increased fat excretion in milk as well as higher daily milk yield, but the animals lost weight heavily. Pulse
rate of protamine-fed animals was always 10-13 beats higher than the control cows. Their body temperature was
also higher and more sensitive to atmospheric changes than that of the control cows.
In the second experiment, long-term feeding with iodinated casein was studied. Twelve animals were divided
into two groups of six each. The cows in the experimental group received iodinated casein, usually at the rate of
1.5 gm. daily per 100 lb body weight, but the rates were changed in some cases after the first four weeks in an effort
to effect increased production without causing large losses in body weight. The total feeding period lasted from 10
to 13 weeks. In contrast to the previous experiment, iodinated casein feeding showed higher fat excretion for the
first six weeks only and increased milk yield for the first five weeks, but following this the control cows averaged higher
production. The average weight loss was 32 lb whereas control animals showed an increase of 36 lb during the
same period. Pulse rate and body temperature increases in the iodinated casein-fed group were similar to those
seen in the first experiment.
It is doubtful whether the increased production secured by feeding iodinated casein would be great enough
or would continue over a long enough period to justify possible injury to milch cows through losses in body weight,
increases in pulse rates and higher body temperature. [S. N. R.]
The use made by the chick of dietary sources of carotene and vitamin A during the first
month of life. H. TEMPERTON, F. J. DUDLEY and M. B. THORN (1945). Harper Adams Utility
Poul. J. 30, 57—84
T HE authors studied the effect of (a) fortifying a vitamin A poor breeder diet on the vitamin A and carotene con-
tent of the eggs, as well as of the livers and yolk sacs of day-old chicks hatched from them, and (b) similar supple-
mentation of the starter ration on the liver reserve of vitamin A when these chicks are a. month-old. For this purpose,
the breeding stock was divided into four identical groups. The birds in group 1 (controls) received the unsupple-
mented breeder ration, while those in groups 2, 3 and 4 were given the same ration supplemented with ß-carotene,
shark liver oil and shark liver oil plus ß-carotene respectively. A uniform quantity of vitamin D3 was available
to the birds in all the groups. Out of the chicks obtained from each breeder group, those remaining after taking
samples of livers and yolk sacs were distributed into four rearing groups. The basal ration and vitamin D3 allowance
were common to all the groups (5-8), but the diets for groups 6, 7 and 8 were supplemented in the same way as for
groups 2, 3 and 4.
The vitamin A content of the eggs was the lowest in the control breeding group. The livers and yolk sacs of
day-old chicks originating from the latter had a lower vitamin A value than those from other breeding groups.
When the chicks of the control breeding group were reared on the control starter ration for one month, their livers
had less vitamin A than those of month-old chicks from any other rearing group. In all cases, the livers of month-
old chicks contained less vitamin A and carotene than the livers and yolk sacs combined of day-old chicks. Unlike
other groups, the mortality among chicks in the control rearing group was heavy, irrespective of the breeding group
from which they originated. During the first month of life, the chickens utilized dietary ß-carotene and vitamin
A (the latter being more effective) and could not depend entirely upon reserves carried over from the hatching egg.
[R. M.]
Evaluating the efficiency of dairy cattle and estimating profitableness of dairy cows.
S. BRODY and A. C. RAGSDALE (1935-1936). Bull. Mo. agric. Exp. Sta., 351 and 368
B ULLETIN 351 describes a method for estimating energetic efficiency of milk production, which is the ratio of
energy in milk produced to energy in digestible feed consumed. Whether large or small cows are more efficient
milk producers and how the percentage of fat in milk affects efficiency are also explained. A Table has been provided
by means of which milk of a given fat percentage can be converted into a 4 per cent fat milk which is standard and
is called fat-corrected milk (F. C. M.). If the weights of cows and the fat content of the milk are the same, the
cow that produces more milk will make a larger return for the feed. But if the fat percentages and body weights
differ, it is essential to equalize the energy content of the two milks into 4 per cent fat to determine the influence
of body weight on efficiency of milk production. By charts and Tables the method of working out the efficiency of
cows of varying weights and fat percentages in milk is described. If efficiency is the same in large and small cows
and if the milk is sold at the same rate, then a large cow would be more profitable.
However, under present feeding practices small cows seem to be slightly more efficient than large cows. If
the object of the dairyman is to produce more butter and cream, small cows may be preferable regardless of effi-
ciency, as the fat content is higher in small cowsmilk.
In order to produce a given amount of milk more, small animals are required than large ones; this involves
investment and overhead charges. Thus the apparent higher energetic efficiency of small cows is balanced by the re-
duced cost of management of large cows. Udder capacity and stimuli to high milk production are more important
than live weight in profitable milk production. Selection of breeding animals should be on the basis of efficiency
of individual cows. [M. K. S.]
K