ABSTRACTS
67
Rams on rations not supplemented with vitamin A showed impaired body
growth, low levels of plasma vitamins A and C, high percentage of cystic pituitary
glands, degeneration of the germinal epithelium of the testees except in one, and
production of semen of low quality. Deficiency symptoms characterised by mus-
cular and nervous in co-ordination, partial loss of appetite, general weakness, night
blindness, mild convulsions and general unthriftiness developed after periods varying
from 7 to 21 weeks. Supplementation of vitamin A caused normal growth, normal
level of vitamins A and C in blood plasma and normal semen production. None of
the rams receiving vitamin A had cystic pituitary gland. The effects of the supple-
mentation with testosterone propionate or pregnant mare serum were negligible and
these products exerted no beneficial effect on semen quality of rams on vitamin A
deficient ration. Rams getting ten B-complex vitamins in addition to vitamin A
and those supplemented with vitamin A alone did not show any marked difference
in the characters studied except that the initial motility and methylene blue reduc-
tion time of semen showed a statistically significant difference in favour of the former
but because of the small number of animals, it cannot be judged whether the
differences are due to change individuality of the rams or to the addition of
B-complex vitamins. Blood haemoglobin content remained at normal level in all
the experimental animals.
Eight rams out of both the vitamin A deficient and supplemented lots died of
urinary calculi during the experiment. (S.G.)
Breeding Cattle for Increased Adaptability to Tropical and Sub-tropical Environments.
BONSMA, J. C. (1949). J. Agric. Sci. B39, 204-221. (Union of South Africa)
T HE knowledge of the various attributes which promote adaptability in cattle
will be of great help to the animal breeder as successful adaptation of animals
to the climatic conditions is accurately reflected in their ability to grow, to reproduce
regularly, and in the production of milk, meat or fat. Animals to be economically
productive in the tropics should be endowed with resistance against intense radia-
tion, high temperatures and parasites; furthermore, they should be able to thrive
on coarse fodder. The observations recorded in this paper on climatological
influence on bovines relate to the Messina Experimental Farm and Mare Agricultural
Research Station in the Northern Transvaal.
The indigenous cattle are endowed with hair and hide colour and other attri-
butes (hair characteristics) to protect themselves against excessive radiation. Black
cattle are best adapted for high altitudes where mist frequently occurs. In warm
relatively dry regions black colour is unfavourable.
The Indian and Afrikaner cattle maintain thermostability even when there is
high atmospheric temperature by alteration in their body metabolism, dispersion of
superfluous heat from the lungs or evaporation from the hide's surface and to act as
radiators of heat they have in addition a well developed dewlap, umbilical fold.
They are relatively deep and are of the respiratory types. The coat is smooth and
the hair do not have any felting quality. Furry coated animals with woolly hair
type coat react drastically in hot weather. Animals with higher H.T.C. (heat
tolerance coefficient) at one year are likely to be better suited for use in the tropics.