VISUAL-ACUITY OF CATTLE DETERMINED BY THE METHOD OF DISCRIMINATION-LEARNING

Behavioral tests using the method of discrimination learning were conducted to determine the visual acuity of Japanese Black cattle. Three heifers were trained to discriminate visually a correct target from two options presented simultaneously. A Landolt ring and an ordinary ring were used for the visual targets, where the Landolt ring was a negative target with a non-reward trough and the ordinary ring was a positive target with a reward trough. Left and right positions of the two targets were shifted at random. After the cattle were fully trained, their visual acuity was determined by reducing the sizes of the targets (Test 1) or by increasing the distance from the target (Test 2). The best scores of visual acuity obtained in Test 1 and Test 2 were 0.045, 0.045 for Heifer 1, 0.083, 0.083 for Heifer 2 and 0.063, 0.064 for Heifer 3.