Does the pig see the world as we see it ?

No, it does not. Even if the pig's eye was built similar to the human eye, it would not see the same world. Vision involves more than just the eye. It includes the brain which interprets the signals of the optic nerves. Whatever picture we gain from a pig's eye, it is our brain which makes the final interpretation. Nevertheless, we can measure the nerve impulses coming from the eye and the brain of the pig. This allows us to create a model of the pig's vision.

Fig. 1

The ISE Ultramicroelectrode measures the nerve impulses between eye and brain. The information is processed by an array of NACs (Neural Accelerator Chip) into an image which can be seen on the computerscreen.

Is the pig's world colourful ?

Yes, it is! The human eye is able to see contrasts because of the inhibiting effects of stimulated receptors in the retina on their neighbouring nerve cells. This inhibitory effect in a pig's eye is much weaker so that boundaries between light and dark areas blurr into each other. The same phenomenon affects colour sensitivity. Where human beings see a sharp boundary between two contrasting colour fields the pig perceives the whole spectrum of hues leading from one field into the other. The pig has what we call a spectralvision.

Fig.2

Unlike the human vision, the pig's vision does not perceive sharp lines. Between two colourfields additional hues of the lightspectrum appear.

How does the pig recognize objects ?

The recognition of patterns and objects is a function of the brain. The human brain "draws" contours along contrasting fields of light. The pig's brain recognizes boundaries in a similar way by tracing bands of spectral gradation. The more hues occur in a boundary the more prominent an object becomes. On the other hand, if spectral gradation occurs in reality, the pig is not able to recognize it as a boundary, since there is no contrast between succeeding hues. Pigs cannot see the rainbows in the sky !

Fig.3

The pig tends to see solid objects merely as flat planes of single colours. Unless two colourfields form a sharp borderline, the pig cannot perceive a difference. The soft blurring and gradation of the colours in a rainbow makes it invisible for the pig's vision.

What are the innovations for the pigsty ?

The fact that the pig draws most attention to areas showing a broad spectrum of colours can be used in the daily work in the pig industry. Staff's working clothes and the architecture of the pigsty can be adjusted so that stress with the pig can be avoided more easily. A colour spectrum applied to the legs of a worker's overalls will lead the pig's attention to the worker's feet. An additional colour contrast between boots and background colour of the floor increases the downwards thrust. The pig's attention is drawn by something which comes from the lower part of its visual field, and so causes less anxiety.

Fig. 4

Pigs are easily scared when a large object approaches them. PIGVISION's working overall disguises the size of the working staff and makes them appear like harmless "walking boots" to pigs.

What increases the pig's appetite ?

Pigfood does not only require the correct balance of nutrients but also needs to be appreciated by the animals. Wild pigs spend a lot of time searching for food. Vision, smell and taste are the primary sensual experiences which constitute the feeding habit. With the introduction of coloured food in the pig industry the feeding habit of pigs can be improved. A rich colour spectacle in the pig's menu improves daily food intake and digestion.

Fig. 5

The pig's spectral sensivity is characterized by three major wavelength areas: blue, green and red. The juxtaposition of these three colours will invoke the strongest visual response. Recognizing the positive correlation between visual response and appetite, PIGVISION developed its tricoloured pigfood. A mixture of blue, green and red pellets increases feed efficiency in comparison with single coloured or twocoloured food.