Tuesday, July 7, 2009

Sow Cannibalism

Bad sow.

Sow cannibalism, aka "savaging" is a problem with pigs and other animals. Here's some references:
Pig Progress: savaging, puerperal psychosis
The Pig Site: savaging of piglets
Google Books: Domestic Animal Behaviour and Welfare

The Pig Site lays out the common case clearly:
This is a condition mainly in first litter gilts that may account for up to 3% increase in piglet mortality.
  • Offending gilts can often be identified by their nervous apprehension at the onset of farrowing.
  • They have a "wild eyed" look.
That's fairly excusable: they haven't been through birth before and are very stressed. When stressed, pigs attack things.

Some Mangalitsa sows engage in cannibalism. I first encountered this in Austria. We saw an old sow that only had 3 pigs and asked why there were so few.

Christoph Wiesner explained that she'd eaten some of her piglets. He explained further that when the sows get older (this one was about 5 years old), some of them don't like the little pigs anymore, so they attack them. It doesn't take much for a sow to kill a little pig; she's got a mouth full of very sharp teeth.

As described in "Domestic Animal and Behaviour", the cannibalism Christophe described is an extreme variety of cannibalism - the sow purposefully maims the piglets. Other forms of cannibalism can be benign: she kills them accidentally and nibbles on them.

Lucky to be alive: the bad sow's three surviving piglets

This came up today because one of our star sows savaged one of the first pigs that she farrowed. She typically weans 8 to 9 pigs, substantially more than the breed average of 5.5. The herdsman was really looking forward to her farrowing today, because he had justifiably high expectations.

This morning, he heard a pig screaming. It kept on screaming and screaming, which is unusual.

The herdsman finally discovered that sow #22 had attacked her litter's first newborn piglet, minutes after birth. She'd bitten off one foot, one leg and ripped open its belly such that its guts were coming out. Yet it wasn't dead, so it was screaming. The herdsman euthanized the piglet by knocking its head on the ground.

Later on, he saw a pig drop out of her vulva (smacking the floor) while she was standing and eating. That's unusual; normally sows lie down to give birth, and the pig just slides out. It looked like maybe the whole litter was going down the tubes. Yet a bit later, she was lying down, letting 4 pigs suck. She wasn't done farrowing when we talked, so maybe she'll have more than four piglets.

A number of points came up in our conversation:

1) She can still be worth keeping. If she weans more than 5.5 pigs, she's doing better than average, savaging or no.

2) Because the breed is known for savaging, taking drastic action isn't indicated. E.g. if she's produced otherwise good gilts, keeping them would be fine. The same for her boars. We won't cull her offspring just because of her bad behavior.

3) Maybe she just had a bad day. Maybe if she'd woken up on the right side of the pen, she wouldn't have savaged that pig.

4) Although we really despise this sow's savaging, she's just a sow. She isn't a human. She doesn't have the impulse control that humans have. If pigs were conscientious creatures, able to delay gratification and resist the urge to lash out, they wouldn't be pigs.

5) We'll probably give her another chance. Hopefully she won't savage the pigs next time. of course, the problem will probably get worse over time. But until we've got replacements expected to be better than 22, she's worth keeping around.

If humans behaved like pigs, we'd take measures to protect the pigs, at the expense of the mother's freedom. E.g. we'd restrain the mother, preventing her from attacking her newborn baby. As mentioned in this book, farrowing crates, can help to protect the pigs from sows: unless the pig walks right in front of the sow, she can't bite him.

Some people attack farrowing crates, because they restrict a sow's freedom (even if only temporarily). Those people have probably never had to euthanize a savaged pig. People who work to prevent (directly or indirectly) farmers from taking care of their animals (with things like crates) are causing unnecessary death and suffering.

1 comment:

Helge said...

Very interesting post. I've heard of sows doing this and often wondered when the line was drawn and the sow was put down.