Why Do Sow Bite Their Piglets? Methods to Protect Piglets
Sows sometimes (more commonly right after farrowing) tear at and bite piglets, injuring or killing them. In extreme cases, cannibalism occurs and they eat their own piglets. This behavior often cannot be stopped and causes considerable losses. Biting attacks on piglets occur most easily with the piglets of first-litter sows, and this is the biggest problem when all farrowing sows in a new first-litter herd are reared using farrowing crates.
1. The factors that cause attacks include the following:
(1) On indoor rearing farms in the UK, when nulliparous (first-litter) sows enter the farrowing crate for the first time before farrowing and the pig has no time to settle. For example, the effect is greater when they farrow on the day they enter the crate (extreme restlessness). Likewise, sows that have no time to build a nest outside also tend to attack.
(2) From mating to farrowing preparation, general husbandry and management of nulliparous sows may also affect the pigs' behavior. Having more contact with people during pregnancy eases their wariness when entering the farrowing crate.
(3) The sudden reduction in feed supply that is necessary to avoid milk secretion or physiological problems before farrowing increases the sow's restlessness.
(4) The behavior of the worker in the farrowing house also affects the sow's behavior. A restless, impatient worker puts the pigs in a state of tension, while a person who works quietly and calmly can keep the pigs calm.
(5) For first-litter sows that produce fewer but larger piglets, the discomfort during farrowing (dystocia) may become the trigger for their attacks. When there are more piglets and each piglet is smaller, there is less pain during farrowing.
(6) Contagion effect (a chain reaction that spreads from one link to the next): when pigs are reared in the same room in the same way, if one sow calls her piglets to nurse, the other pigs all take the same action. That is, if an aggressive sow attacks piglets, the other sows all take the same action.
(7) Cross-fostering. Once piglets are placed in the farrowing crate at birth, it is difficult to place them with the sow again. If piglets are exchanged within 12-24 hours after the sow has nursed her own piglets, she will react to the foster piglets and harm them.
2. Transition period
Sometimes some piglets are found dead, or parts of a piglet's body are found. Occasionally, a single piglet may be attacked. Countermeasures should be taken according to the degree of damage. If it is very severe, euthanasia may also be carried out.
3. Prevention of attacks
(1) Handle nulliparous sows gently.
(2) Carry out quiet management in the farrowing room.
(3) Place the sow in the farrowing crate at least 3 days before her expected farrowing date.
(4) Before farrowing, replace the high-nutrient compound feed with wheat bran.
(5) Carefully monitor the farrowing process and place the piglets in the farrowing crate.
(6) Cull sows that have attacked more than one litter of piglets.
(7) Do not carry out cross-fostering with first-litter sows.
(8) Use sedatives to calm pigs that show signs of aggression during or just after farrowing.
(9) Administer analgesics when a sow attacks during farrowing.
(10) Attach a marker to the nose of an aggressive sow.
(11) Place a rabbit near the sow's head within 4-8 hours before farrowing (note: the rabbit may sometimes be bitten) (translator's note: this method is not recommended from the standpoint of biosecurity and animal protection).
4. Economic impact
The economic impact of attacks is determined by the number of affected piglets. On one farm, the mortality rate increased by 1%, which is equivalent to a loss of 120 piglets per year on a farm with 500 sows.
On a farm where attacks were relatively severe, at a scale of 300 sows, 50% of the piglets of first-litter sows were attacked, and the total number of piglets killed reached 426 over 6 months.