Lighting is an important part of dairy cattle management. Our convincing research has shown that an optimal light climate influences dairy cattle’s vision, behaviour, welfare and performances.
An optimal light climate can be realised by adjusting the different aspects of light to the vision and needs of the dairy cows.
Dairy cattle’s vision
Dairy cattle’s panoramic vision (i.e. total vision) is 340°. This means that dairy cows can see things in all directions except for what is right behind them. As you can imagine, they have a preference for their monocular vision, as this represents the majority of their total vision (figure 1). Due to their relatively small binocular vision, it’s more difficult for the cows to estimate distance, which limits their perception of depth.
Fig. 1: Dairy cattle’s panoramic vision
When it comes to spectral vision, dairy cattle have dichromatic vision. This means that dairy cows only have two types of functioning colour receptors or so-called cones in their eyes. Their receptors are mainly focused on the green and blue part of the light spectrum. Because of this, they can only perceive two pure spectral light colours. This in contrast to humans, who can perceive three.
Now, let’s have a look at the most important aspects of dairy cattle lighting and their influence on dairy cattle vision, behaviour, well-being and performances.
The light spectrum or visible spectrum is the part of the electromagnetic spectrum that can be seen. The different wavelengths are perceived by the eyes as different colours.
The visible spectrum of human beings and dairy cattle differs significantly, as you can see in figure 2. The visible spectrum of dairy cows reaches from about 400nm to 680nm with peak wavelengths at 451nm (blue) and 555nm (green).
By adapting the provided light to the dairy cattle’s visible spectrum, they are able to see better. This decreases stress and stimulates desired behaviour. Improved performances are the logical result of this.
Fig. 2. Spectral sensitivity of dairy cattle vs. human beings.
The light distribution – the spread of light throughout the house – is of key importance.
Since dairy cattle have poor depth perception, it’s very important to make sure there are no dark spots throughout the house. When dark spots appear on the floor or in front of the cows, it is likely they will startle and stop moving. This negatively impacts desired behaviour and induces stress.
By providing an optimal light distribution, dark spots can be prevented. This stimulates desired behaviour, makes the cows feel more at ease and reduces stress. The correct positioning of the lamps plays a major role here. This can easily be realised by creating a light plan prior to the purchase of the lighting equipment.
Light flicker – the rapid change in light output of a lamp (figure 3.) – may be perceived consciously and unconsciously.
Dairy cattle perceive light flicker similarly to human beings. This means that they notice flicker at a similar frequency (amount of fluctuations per second). For human beings, flicker can lead to headaches, eyestrain and loss of concentration. This may mean that the dairy cow’s health is affected by flicker as well.
As such, to improve the dairy cattle’s well-being, it is important to take light flicker and its frequency into account when purchasing lighting equipment.
Fig 3. Light flicker vs flicker-free lighting
Providing the right light intensity – the amount of light measured at one place – will help to improve dairy cattle’s performances.
Research has shown that the light intensity influences the creation of melatonin, which in turn influences milk production. By making use of a higher light intensity, milk yield can increase. Besides that, when providing a high light intensity and a correct distribution, dairy cattle’s vision will improve as well. This makes the cows feel more at ease and makes it easier for them to go to the milking robot or parlour.
Also important: a high light intensity makes life easier for the people working in the dairy cattle house. It becomes easier for them to see their stock and they are able to notice when the cows are on heat or when there’s something wrong earlier.