July 14th, 2016 Animal Welfare, Ethical Pork

Talking Pigs


There are infinite sensory differences between a high-welfare pig farm and a factory pig farm. At a factory farm, smell is the most shocking. The pungent smell of biodegrading faeces is hard to appreciate until it actually invades your nostrils. The sight of a factory farm is a more obvious sensory experience, with the light-deprived flesh of pigs contrasted with shit as they are forced to lie in their own excrement in barren and crowded cages.

But this article is about sound, with the key difference between high-welfare farms and factory pig farms being the noises the pigs make. The screeching squeal of pigs is a particularly noticeable element of the factory, as conditions are so bad they are often driven to cannibalising their fellow prisoners. There is a reason that a pig’s squeal is so jarring… it is an expression of an emotion. We instinctively recognise the distress, the same way we would if we heard a disturbing scream from a human. And pigs are naturally expressive, the extent to which is the subject of a recent study published by the Royal Society, which studies their noise signalling.

‘Acoustic signals’, as Friel et al. refer to them, “convey a wide range of information about the signaller, including their emotional, motivational and physiological state” (1: 1-2). High-frequency noises – typically squeals and screams – have, rather obviously, already been identified as expressions of fear and distress (2,3,4). However, whilst these noises are more typical in a low-welfare environment, low-frequency noises like grunts, which are normal communication among pigs, are less common (1). This suggests that maltreatment makes pigs less expressive.

Friel et al. compared pigs from ‘barren’ and ‘enriched’ environments on their response to social isolation and to being presented with novelty objects. The ‘barren’ environment was a small space (3.4 x 2.2m) with a partially slatted concrete floor, no straw and two wooden blocks for enrichment. The ‘enriched’ environment was a larger space (5.2 x 2.2m) with a solid floor, straw bedding and three wooden blocks for enrichment.

It should be mentioned here that whilst the barren environment is clearly a low-welfare environment, the ‘enriched’ cannot be considered ‘high’-welfare. Both groups had spent their whole lives indoors with limited space.

Nonetheless, a clear difference was found between the two groups when compared in social isolation for 3 minutes, and after when entering a space with a large white bucket and an orange traffic cone suspended from the ceiling (1). Friel et al. studied the movements and noise signalling of the pigs and found not only that grunt frequency was a clear indicator of the personality of the pig but also, crucially, that those from the enriched environment were far more expressive.

Environmental quality influenced personality score, with individuals from the enriched environment being more proactive than individuals from the barren environment (1: 7).

This aligns itself with past research showing that animals from low-welfare environments develop a ‘learned helplessness’ (5), and become less vocal than counterparts from more enriched environments. Pigs that are treated right develop more expressive personalities and talk more. Fascinating! But also kind of obvious.

[T]he question is not, Can they reason? nor, Can they talk? but, Can they suffer?

Jeremy Bentham

If the question wascan they reason?’, the answer would be ‘probably’. If the question was ‘can they talk?’, it would be ‘definitely’. But ultimately, Jeremy’s right – all that really matters is whether they suffer, and pigs certainly do suffer in factory pig farms. But we can all help bring an end to factory pig farming buy only buying high-welfare pork, so that pigs can be happy before we take their lives.


  1. Friel, M., H. P. Kunc, K. Griffin, L. Asher and L. M. Collins (2016), Acoustic signalling reflects personality in a social mammal, Royal Society open science, 3: 160178
  2. Kiley, M. (1972), the vocalizations of ungulates, their causation and function, Tierpsychol. 31, 171-222 (doi:10.1111/j.1439-0310.1972.tb01764.x)
  3. Tallet, C., P. Linhart, R. Policht, K. Hammerschmidt, P. Simecek, P. Kratinova, M. Spinka (2013), Encoding of situations in the vocal repertoire of piglets (Sus scrofa): a comparison of discrete and graded classifications. PLoS ONE, 8, e71841 (doi:10.1371/journal.pone.0071841)
  4. Morton, E.S. (1977), On the occurrence and significance of motivational-structural rules in some bird and mammal sounds, Am Nat. 111, 855-69 (doi:10.1086/283219)
  5. Sufka, K. J., M. W. Feltenstein, J. E. Warnick, E. O. Acevedo, H. E. Webb, C. M. Cartwright (2006), Modeling the anxiety-depression continuum hypothesis in domestic fowl chicks, Pharmacol, 17, 681-689 (doi:10.1097/FBP.0b013e3280115fac)


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