Summary. Shade-type preferences by
Holstein–Friesian cows were investigated under natural climatic
conditions. The trial was conducted in south-east Queensland, Australia, over
88 days in summer. Forty-two cows were placed in a dirt-floored yard (zero
grazing) provided with different shade types. Shade types provided were a 3 m
high galvanised iron roof, Sechium edule (choko) vines
on a 3 m high trellis, 70% shade cloth on a 3 m high frame and natural
shade trees. The floor area under the shade structures was concrete. An
unshaded area (the remainder of the yard) was also provided. Each cow was
scored for coat colour based on the proportion of black and white. Number of
cows using a particular shade type and their respiration rates were recorded
daily at 1300 hours. Ambient temperature, relative humidity, solar radiation
and wind speed were also measured. Cows selected the galvanised iron roof most
frequently when temperatures rose above 30°C, with no significant
differences between the other shade types. At temperatures below 30°C,
animals did not seek shade. As ambient temperature, solar radiation and
relative humidity rose, respiration rate rose. Cows with a high percentage of
black coat preferred shade, while those with a high percentage of white coat
did not seek shade.
DEPENDENCIES BETWEEN PRL GENE POLYMORPHISM AND PRODUCTION PROGRESS IN POLISH HOLSTEIN-FRIESIAN BLACK-AND-WHITE COWS