A Detailed Explanation of Comprehensive Prevention and Control Methods for Tail Biting in Pigs

Tail biting in pigs is a type of pica, a stress syndrome caused by disorders of nutritional and metabolic function, abnormal taste perception, and improper feeding management. The incidence rate is particularly high from August to December and from January to March, generally occurring in pigs weighing 18-80 kg, with a higher incidence rate in pigs weighing 24-40 kg (12-14 weeks of age). More sows are affected than boars; it is estimated that approximately 4.6% of boars and approximately 3.4% of sows are bitten.

I. Causes of the Disease

(I) Improper feeding management: High stocking density and too many pigs per pen, disorderly social hierarchy, narrow trough space, restricted feeding and insufficient drinking water, poor hygiene conditions or mixing pigs from different pens, poor uniformity of the pig herd, less than 1 sq m of rearing area per pig, and large disparities in size and strength among pigs in the same pen can all induce tail biting.

(II) Environmental factors: Poor environmental conditions in the pig house, such as indoor temperatures that are too high or too low, poor ventilation and accumulation of harmful gases, abnormal weather changes, and dampness in the pig pen causing itchy skin, can cause discomfort or poor rest in pigs and trigger biting. Excessive lighting in the pig house causes pigs to be in an excited and restless state. A monotonous living environment, fright, and pigs running chaotically between groups and other stressors can all trigger tail biting.

(III) Nutritional imbalance: When the nutritional level of the feed is below the feeding standard and cannot meet the nutritional needs of pig growth and development, tail biting can occur, such as deficiency of protein or excessively low crude fiber in the feed, both of which can lead to the occurrence of tail biting. In addition, imbalances in various nutrients in the diet, such as insufficient iron, calcium, phosphorus, etc. in the diet, deficiency or poor quality of vitamins and protein, and deficiency or imbalance of iron, copper, calcium, phosphorus, magnesium and other elements, can also cause the condition. Some speculate that long-term addition of olaquindox and furazolidone to feed can also cause this condition. It has been reported that sodium salt deficiency can lead to large-scale tail biting in pigs.

(IV) Breed and individual differences: If different breeds or pigs of the same breed with excessively large body weight differences are raised in the same pen, mutual biting often occurs. Due to differences in breed and behavioral characteristics, conflicts and competition for dominance lead to biting. When there are large differences between individuals, the phenomenon of the strong bullying the weak often occurs when competing for sleeping space and food.

(V) Disease: When pigs suffer from external parasites such as lice and mange, it can cause skin irritation and restlessness in pigs. Rubbing against pen fixtures leads to exudates behind the ears, on the flanks and other areas, which attract other pigs and induce tail biting. Internal parasitic diseases in pigs, especially Ascaris suum, stimulate affected pigs to attack other pigs, resulting in tail biting.

(VI) The playful nature of piglets: Piglets that are comfortable in their environment and content with their living conditions bite other pigs' tails for play.

II. Clinical Symptoms

Affected pigs are initially restless in behavior, sensitive to external stimuli, have reduced appetite, and have a fierce gaze. At first, only a few pigs bite each other, then gradually more pigs join in, mainly biting tails, and a few also bite ears. It is common to see hair loss and bleeding at the bitten tail. The biting pigs then develop a pica for blood, causing tail-biting vice, and the harm gradually expands. Bitten pigs often show skin and hair loss at the tail, affecting body weight gain. In severe cases, secondary infection can occur, causing osteomyelitis and abscesses. If not treated promptly, it can be complicated by septicemia and other conditions leading to death.

III. Prevention and Control Measures

(I) Strengthen feeding management: (1) Individual differences among pigs in the same pen should not be too large; they should be as similar as possible. (2) Applying tar to pig tails can prevent tail biting. (3) Stocking density should not be too high; ensure a rearing area of 0.8-1 sq m per finishing pig, 0.6-0.7 sq m per growing pig, and 0.3-0.5 sq m per piglet. (4) Strengthen ventilation in the pig house, reasonably divide groups, limit lighting, feed at fixed times and in fixed amounts, do not feed moldy or spoiled feed, ensure clean drinking water, provide sufficient trough and water trough facilities, pay attention to hygiene, and avoid fighting over food and uneven feed intake. (5) Try to create a relatively suitable microclimate environment for pig growth to avoid stress caused by extreme heat and cold, draft invasion, manure contamination, poor air quality, dampness and other factors.

(II) Piglet tail docking: At birth, cut off the tail approximately 1 cm from the tail base using tail-docking pliers and apply iodine tincture. Alternatively, when ear-notching piglets at 1-2 days of age, use wire pliers to clamp twice consecutively at the lower 1/3 of the tail, with the two clamps about 0.4 cm apart, crushing the tail bone and tail muscle, flattening blood vessels and nerves, and pressing the skin into a groove. After 7-10 days, the lower 1/3 of the tail will fall off. This method is simple, causes no bleeding or inflammation, and is effective. Tail docking of piglets is an effective measure for controlling tail biting.

(III) Distract the pigs' attention: Place toys such as chains, rubber balls, old tires, and green forage in weaner pens. These toys become the focus of the pigs' attention, thereby reducing the occurrence of tail biting. According to research, placing a 2 m long soft hose in the pig pen is more effective. This soft hose should be able to be bitten by pigs but not be damaged by them.

(IV) Meet the nutritional needs of pigs: Pay attention to the completeness of the compound feed, appropriately increase the amount of salt used, raise the calcium and lysine levels in the diet, strengthen vitamins in the diet, and select high-quality protein feed. Salt licks can also be used. Salt licks contain calcium, sodium, manganese, zinc, iron, magnesium, copper and other elements, and should be placed on one side of the pig pen at a height level with the pigs' heads.

(V) Drug control: Inject chlorpromazine hydrochloride at 50 mg per pig per treatment. Alternatively, spray the pig's whole body and nose area with white liquor above 50 degrees, 3-5 times per day; generally, tail biting can be controlled within two days.