ABSTRACTS
337
through R. bursa adults and Ornithodorus lahorensis. (4) Rickettsiosis including
(a) Heart water in ruminants through A. lebraeum ; (b) Rickettsia bovis infection
in cattle through species of Hyalomma; (c) Rickettsia canis infection in dogs
through R. sanguineus. Mention has also been made about the tick-transmitted
rickettsiosis of man and dog including (a) Fievre boutonneuse ; (b) Sao paulo typhus ; (c)
Tick bite fever ; and (d) Rocky mountain spotted fever of man. (5) virus diseases, viz„
(a) Louping ill through the agency of I, ricinus ; (b) Nairobi sheep disease through
R. appendiculatus ; (c) Rabbit papillomatosis through H. leporis palustris. (6) Pasteure¬
llosis (Pasteurella tularense infection) through the different species of Dermacentor.
In the end the authors have given charts explaining in tabular form the tick-borne
diseases, localities, vectors, hosts, and incubation period in each case. [H. R. K.].
Carotene requirements of dairy cows: I. The carotene requirements for
normal reproduction. H. T. CONVERSE and E. B. MEIGS. (1938). (Jour. Dairy Sci.
21, 114.) II. Carotene requirements of dairy calves. R. E. WARD, S. I. BECHDEL
and N. B. GUERRANT (1938). (Jour. Dairy Sci. 21, 168.) III. Vitamin A content
of the colostrum of dairy cows. J. STEWART and J. W. MCCALLUM (1938).
(Jour. Agric. Sci. 28, 428).
I. THIS is a continuation of the author's previous work on the effect of various rations
on the reproduction of cows. The animals were fed on diets of grain and hay where the
roughages, which furnished the carotene, constituted approximately half the ration. It
was found that with U. S. No. 1 alfalfahay, there was a normal number of healthy calvings
With U. S. No. 3 alfalfa or timothy hay, all calvings were abnormal and with U. S. No. 1.
timothy hay or U. S. No. 1 clover hay less than 50 per cent of the calves were normal at
birth. Quantitative estimation of the carotene intake during the last three months of
gestation showed that when the amount of carotene ingested was from 80—130 mg.
daily or from 178—260 micrograms per kilogram of body-weight, all calvings were ap-
parently normal. One heifer calf which received 42 mg. of carotene daily at calving
(114 microgram daily per kilogram of body-weight) gave birth to a still-born calf. Two
other cows receiving daily 30 mgs. of carotene (60 to 70 micrograms per kg. of body-
weight) gave birth to very weak calves, of which only one survived. It is concluded that
for normal calving, cows should receive 80—100 mg. daily during the last months of
gestation. If the intake is below 60 mg. per cow daily, there will be a considerable propr¬
tion of dead calves.
II. Twenty-seven animals (twenty Hoslteins and seven Guernseys) have been fed
varying amounts of carotene from the following sources : Alfalfa hay, timothy hay corn
silage, alfal fasilage, yellow corn and a commercial carotene preparation (Puratene).
When alfalfahay or Puratene was used as the source of carotene, 12—14 micro-grams per
pound of body-weight per day was sufficient to prevent the symptoms of vitamin A defi-
ciency. With timothy hay or corn silage, the requirements were about 25 per cent higher
than the values mentioned above. With alfalfa molasses silage, the requirements may be
even higher than the latter value. Increased growth or improved well-being did not occur
on feeding more than 20—30 micrograms per day per pound of body-weight. The data
indicate that the Guernsey calves require the same amount of carotene as Holstein calves.