Pigs identify the human voice as part of a human being present. The animals responded differently to human presence when no voice was broadcasted.

That was the result of a research carried out by scientists of the French National Research Institute for Agriculture, Food and the Environment (INRAE), which was published recently in the peer-reviewed journal Applied Animal Behaviour Science.

Human voice facilitates human-pig relationship

The researchers hypothesised that the human voice facilitates the development of the human-pig relationship. In order to do so, they studied the behaviour of 90 weaned female piglets divided into 3 treatments:

  • A. Human presence with voice. In this treatment, an idle experimenter was present in the pen for 5 minutes per day, for 3 weeks and a female voice was broadcast from a speaker.
  • B. Human presence without voice. In this treatment, an idle experimenter was present in the pen for 5 minutes per day, for 3 weeks, but instead of a voice, a recorded background noise was broadcast.
  • C. Control group. For these piglets, only routine husbandry care was provided.

Test 1: human voice is used with piglets

The scientists then carried out 2 tests. In test 1, the scientists broadcasted the voice for the piglets in group A and background noise was broadcasted for the others. In this test, piglets from group A and B investigated the experimenter earlier and more often than in group C. The piglets in group A moved sooner in the pen than in group C.

Test 2: no human voice is used with piglets

For test 2, only the background noise was broadcast – that includes the piglets in group A. In this 2, the piglets expressed more stress reactions; their latency to move was longer compared to the others. The piglets in group A also had more physical and vocal interactions: they stayed in the experiment area longer than piglets in group B and group C, and grunted more.

Necessary properties

The researchers concluded that broadcasting a human voice did not modify the pig response to human presence and handling in auditory conditions similar to the interaction sessions. However, not broadcasting a human voice induced stress responses and increased interactive behaviour, which suggests that piglets identify the human voice as part of the experimenter’s necessary properties.

Pig Progress | Vincent ter Beek |

Image Source – Canva.com