Cattle can perceive their surroundings at night even without light.
Light in the cowshed is therefore not necessary for cattle!
That makes sense, in nature no one stands near the animals with a light.
At best, moonlight is the only source of light in nature.
During a "cowshed check at night", it is more convenient for the farmer if there is some night lighting.
He sees less in the dark than his cows!
Cattle cannot perceive the color red.
A red light source with a light intensity of <5 Lux is sufficient for the farmer to see something in the stable environment.
Cows perceive this as dark.
Lux is the number of lumens per square meter (lx = lm / m²).