March, 1953]
ABSTRACTS
77
day for one to three days in a week, to selected atmospheres of known temperatures
and humidity. The temperature of the test atmospheres ranged from 30 to 45°C.
and the vapour pressure from 15 to 40 mm. Hg. Observations were made on the
rectal temperature, pulse rate, respiratory rate, respiratory volume, evaporative
water loss, food and water intake, body growth and general behaviour. It was
found that Camden Park Merino adapted fairly well to hot conditions, particularly
to hot, dry atmosphere. A high plane diet reduced the heat tolerance of these
animals and some of the heavy ewes actually lost weight during the period under
experimentation. Low diet on the other hand impaired heat regulating mechanism
and thus reduced animal's adaptability. Ewes on a medium-plane diet fared best.
[S.N.L.]
Water consumption of Hereford and Brahman cattle and the effect of cooled
drinking water in a hot climate. ITTNER, N. R., KELLY, C. F. and GUILBERT, H. R.
(1951). J. Anim. Sci. 10 :3, 742-751
W ITH a view to increase the productive efficiency of livestock in hot climates,
cooling of the outside of animals by shade and water sprinkling has been tried.
This paper describes the effect of cooling the inside of animals by giving refrigerated
drinking water. Eight Herefords for cooled and uncooled water, and four Brahmans
for uncooled water were used in the study.
Mean air temperature for the test period of June 14 to September 5, 1950 was
85.4°F. Mean of maximum temperatures was 100.5° F., mean of minimum 70.2°F.,
highest 118°F., and the lowest 54°F. Temperature fell below 70° F. on 29 days.
Average for relative humidity at noon was 38.4 per cent and 46.7 per cent for the
day. Humidity was highest (72.2 per cent) in early July and lowest (29.6 per cent)
in early August. Refrigerated water was supplied at 65°F. Uncooled water ranged
between 72° and 97° F. but averaged 88.2°F., for the day. Morning average of 83°F.
at six hours rose quickly to 90°. by 11, then gradually to the average maximum of
94.5° at 17 hours, and then cooled back to 83° at six.
Results showed significant benefit from the use of cooled water. Water was*
mostly consumed between 7 and 11 hours, and 16 and 20 hours. Feeding times
were 7.30 and 17 hours. Cooled water was consumed less than uncooled. Here-
fords on uncooled water took per head per hour, 0.3 gallons during night when water
was coolest, 1.1 gallons between 7 to 11 hours, 0.4 gallons between 11 to 14 hours
when heat was greatest, and 1.7 gallons from 16 to 20 hours. Brahmans behaved
similarly but drank less water per head and per 100 lb. body weight.
Effect of cooled and uncooled water intake was noticed on feed consumed per
100 lb. body weight and on gains made. Herefords on cooled water consumed more
food daily and were more efficient than those on uncooled water, but Brahmans on
uncooled water were the most efficient. Hay feed consumption per 100 lb. gain in
body weight was 1618, 2092, and 1255 lb. respectively. When the day's tempera-
ture ranged from 106 to 116°F., their respiration was 124, 137 and 77 and 14 to 16
hours, and 87, 96 and 51 at 9 to 11 hours. Brahmans respired much shallower
than Herefords and showed little discomfort from heat. [S.V.C.]