| Pigs
It ’ s not just a grunt : pigs really do have something to say
The grunts made by pigs vary depending on the pig ’ s personality and can convey important information about the welfare of this highly social species , new research has found .
S cientists specialising in animal behaviour and welfare devised an experiment to investigate the relationship between personality and the rate of grunting in pigs . They also examined the effect different quality living conditions had on these vocalisations .
Findings from the study , carried out by researchers from the University of Lincoln , UK , and Queens University Belfast , are published in the Royal Society journal Open Science ( 29th June 2016 ).
“ The sounds they make convey a wide range of information such as the emotional , motivational and physiological state of the animal ”
The study involved 72 male and female juvenile pigs . Half were housed in spacious ‘ enriched ’ pens with straw bedding , while the other half were kept in more compact ‘ barren ’ pens with partially slatted concrete floors , which adhered to UK welfare requirements .
To get a measure of the pigs ’ personalities , the researchers conducted two tests : a social isolation test and a novel object test . Each pig spent three minutes in social isolation , and five
www . farmingmonthly . co . uk minutes in a pen with a large white bucket or an orange traffic cone they had not previously encountered . Their behaviour , including vocalisations , were observed . These tests were repeated two weeks later , allowing the researchers to determine if the pigs ’ responses were repeatable – the defining characteristic of personality ( also known as ‘ coping style ’ in animals ).
They also recorded the frequency of grunts they made by counting the number of grunts produced per minute of the test , and investigated the effect different quality environments had on the sounds made .
The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals . The study also found that male pigs ( but not females ) kept in the lower-quality conditions made fewer grunts compared with those housed in the enriched environment , suggesting greater susceptibility among male pigs to environmental factors .
The results add to evidence that acoustic signalling indicates personality in pigs . This may have had far reaching consequences in shaping the evolution of social behaviours , the researchers believe . The findings also suggest personality needs to be kept in mind when using vocalisation as a measure of the animals ’ welfare status .
Principal investigator , Dr Lisa Collins , a specialist in animal health , behaviour and welfare epidemiology in the School of Life Sciences at the University of Lincoln , said : “ The domestic pig is a highly social and vocal species which uses acoustic signals in a variety of ways ; maintaining contact with other group members while foraging , parent – offspring communication , or to signal if they are distressed .
“ The sounds they make convey a wide range of information such as the emotional , motivational and physiological state of the animal . For example , squeals are produced when pigs feel fear , and may be either alerting others to their situation or offering assurance . Grunts occur in all contexts , but are typical of foraging to let other members of the group know where they are .”
Mary Friel , lead author of the study and PhD student at Queen ’ s University Belfast , added : “ The aim of this research was to investigate what factors affect vocalisations in pigs so that we can better understand what information they convey . Understanding how the vocalisations of pigs ’ relate to their personality will also help animal behaviourists and welfare experts have a clearer picture of the impact those personalities have on communication , and thus its role in the evolution of social behaviour and group dynamics in social species .”
July 2016 | Farming Monthly | 39