Necrosis and long tails do not go well together

16-05-2022 | Health | Article

Keeping long tails is only possible when SINS is not found at farm level.

Keeping long tails is only possible on farms that do not suffer from (ear or tail) necrosis, a phenomenon also known as SINS. This conclusion can be drawn with knowledge that is currently available.

Formally, tail docking is not allowed in the Netherlands – only under exceptional circumstances it can be performed. In practice, however, that results in routine docking being done on a relatively large scale. That practice, however, is very likely to end in 2030. As a result, the pig farming industry must find a way to be able to keep pigs with long tails. That is a challenge, as research shows that some form of necrosis is present on virtually all farms.

Blood flow problem

Necrosis is a form of tissue loss, that can result from a blood flow problem caused by a damaged, leaky gut that allows endotoxins to enter the bloodstream and cause excessive inflammatory responses and circulatory disorders.

“Various stress factors can be the cause of this leakage: heat stress, a nutritional transition, but also an infection by, for example, PIA [porcine intestinal adenomatosis – also known as ileitis]. Additional changes in the intestinal microbiome can also trigger (tail) biting by pen mates,” says Rutger Jansen of animal health company Boehringer Ingelheim. “All factors together can cause the bucket to overflow.”

It’s not only pigs that are sensitive to this; in horses, for example, intestinal problems can lead to laminitis. In cattle, claw problems can arise because of subclinical rumen acidosis, also known by the abbreviation SARA (sub acute ruminal acidosis), which releases endotoxins into the bloodstream.

German research

Veterinarian and geneticist Professor Dr Gerald Reiner, head of the pig department at the Justus Liebig University in Giessen, Germany, named the syndrome Swine Inflammation and Necrosis Syndrome (SINS) and is conducting research into its genetic cause. That research goes beyond just the character of the boar line. SINS is a combination of clinical inflammation from within and the presence of dead tissue or necrosis.

Attention to mycotoxins

Pigs are sensitive to mycotoxins. A number of mycotoxins can be reduced to acceptable amounts through a toxin binder, and piglet feeds contain higher quality raw materials and fewer mycotoxins. The most feared mycotoxin that is difficult to bind is deoxynivalenol (DON). It has been shown that DON is passed on in the womb and via the colostrum of the sow to newborn piglets that still have very vulnerable intestines. Although maximum values for mycotoxins apply in Europe for animal feed, Mirjam Lechner believes that these values are far too high for current genetics. For companies that purchase or grow raw materials themselves, it is wise to be critical of mycotoxins. Do not grow CCM year after year on the same plot, and watch out for fungal hot spots.
Research by Associate Professor Grazia Pastorelli of the University of Milan, Italy, has shown that SINS is a health problem. Due to the need to activate the immune system, the body loses not only feed intake but also feed efficiency, as it now has to “feed” the disease.

German research into SINS is a priority

Mirjam Lechner, consultant and animal signal trainer, works closely with Prof Reiner in SINS research and indicates that many factors are important in the approach to SINS. “First, attention to the genetic factor is needed to be able to keep commercial pigs with long tails,” Lechner says. The fact that a solution for SINS is high on the German agenda is shown by the fact that a lot of money is available in the federal states for research and keeping animals with long tails. Bavaria invests more than € 1 million in a breeding project to score animals on SINS using genetic testing.

In addition to paying attention to factors that trigger animals to bite out of discomfort – such as stress, a bad climate, overcrowding or nutrition – more attention is now being paid to SINS in the Netherlands. Breeding organisation Topigs Norsvin focuses much of its attention on behaviour and includes SINS in an ongoing study.

SINS in newborn piglets

A tail affected by necrosis in a newborn piglet. In the first three days after birth, SINS can be detected in piglets on the claws, teats and tail.

“With SINS, all factors come together, including genetics, pen design, climate, feed composition, mycotoxins, roughage, pen enrichment, but also water supply,” says Karien Koenders, veterinarian at the Lintjeshof practice, headquartered in Nederweert, in the south of the Netherlands. “For me, SINS provides a biological explanation for (intestinal) infections from within and also provides leads for the future to keep animals with long tails.” That starts with the gestation period and the newborn piglets.

Koenders now looks at the piglets differently and inspects, among other things, the ears and claws of newborn piglets. “To detect the syndrome, we use a thermal camera, which shows for example swollen warm blood vessels in the ears. Eventually, the small blood vessels in the ear tips can become blocked by the inflammation. Then the blood flow is disrupted, and we see a cooler image at the height of the ear and tail tips. I see the symptoms of SINS in newborn piglets on every farm, to a greater or lesser extent,” says Koenders. “A piglet born with SINS is already 1-0 behind in the context of ear or tail necrosis.”

The approach to the solution will be different on every farm. It might be lowering pen stocking, providing more roughage or more and better pen enrichment or giving clay minerals to bind mycotoxins. What applies to every company is that water intake must be increased. Especially for the weaned piglets, this is the number #1 priority to be able to dispose of waste.

Ear necrosis occurs in newborn piglets only when there is high SINS infection pressure, including a Streptococcus suis infection. — Ear necrosis in newborn piglets.

Ear necrosis in weaned piglets

Animal nutrition company Agrifirm is also active in monitoring weaned piglets in combination with thermal images. “At the moment we are less involved with SINS in newborn piglets and sows, which is something for the long-term focus,” says Tim van Sprang, veterinarian and sales manager at Agrifirm. “We focus on a good start after weaning, with which we want to prevent diarrhoea and promote good intestinal health. In addition, we strongly suspect that thermoregulation of the piglet also has a major influence on the development of ear necrosis in weaned piglets,” says Van Sprang.

“In the thermal camera images we take, we see that piglets in units where ear necrosis develops clearly have warmer ears than in units without ear necrosis. We strongly suspect that a piglet first develops a fever, and that ear necrosis develops after that.” Agrifirm also uses the Healthy Climate Monitor, which monitors the climate in the barn 24 hours a day in combination with camera images.

A solution for ear and tail biting is not only necessary for the animals’ well-being; there is also an economic aspect at play. A piglet with ear necrosis is more difficult to sell, especially in tough economic times. A finisher with a bitten tail also does not fit into a welfare concept with long tails as a requirement. In addition, a pig with an open wound is not allowed to be transported, not even to the slaughterhouse. At the same time, an immune and inflammatory response means an extra need for feed (amino acids and energy) for the body, reducing feed intake and efficiency.

Breeding research into pig behaviour

Monitoring the pigs’ behaviour is high on Topigs Norsvin’s research agenda, partly due to the development of new husbandry systems and legislation to stop docking. “We include SINS as part of the total behavioural research,” says researcher and consultant Roos Vogelzang. Also, SINS is a multifactorial problem – it’s not that a single gene is responsible. As with congenital defects, this makes selection more difficult.Vogelzang continues, “We are investigating whether there is a relationship between SINS and damage at a later age. To demonstrate a relationship, we score the newborn piglets on SINS and for damage in the final test on the scales. By doing this we try to contribute to a solution.“We already score damage in all breeding animals that are delivered. We speak of damage because it is not always clear whether the cause is necrosis or whether it is caused by aggressive behaviour. In newborn piglets, the symptoms of SINS are largely congenital, but some are mechanical. Think of cutting an ear tag that can cause damage, a rough concrete floor that causes teats to rub off or cutting too hot or carelessly. Necrosis therefore remains a difficult characteristic to assess.

“We do not want aggressive pigs (the perpetrators who will bite), but victims (the pigs that are bitten) are also undesirable. As a breeding organisation, we need reliable data; tracking down a perpetrator is simply more difficult than tracking down a victim. To track down perpetrators, we are using camera techniques to score automatic behaviours of individual animals.”

Different focus on genetics

“We need a different focus on genetics if we want to keep pigs with long tails. Take poultry farming with slow-growing broiler breeds as an example,” says consultant Mirjam Lechner, who co-developed the “Fit for pigs” app.“Especially with Piétrain boars, speed is needed to retain the genetics of the sire lines with little or no predisposition for SINS. Research has shown that currently only a few of the Piétrain sire lines score at the same level as Duroc or Yorkshire in terms of SINS and are therefore suitable for keeping animals with long tails. Due to the speed of breeding, it is important that we continue to maintain these genetics, so that we also have Piétrain as an option as a sire line in future pig farming. Genetic predisposition also plays a role in Yorkshire pigs, but we clearly see fewer SINS symptoms there.“If we stop docking with the current genetics, another welfare problem, tail biting, will take its place. Both are undesirable for the welfare of the pigs. The solution to keeping long tails lies in health and thus in optimising management factors on the farm. Building a new barn is not feasible for most pig farmers, but there are sufficient solutions for water, housing, pen enrichment, feed and climate. Pig farmers themselves have the tools for this.

“We are dependent on breeding organisations for genetic adaptations, and that is where the challenge lies. To solve SINS, genetics is not sacred, but without genetic correction it will certainly amount to nothing,” concludes Lechner. In Prof Gerald Reiner’s team at the University in Giessen, research has been going on for five years into the genetic predisposition of SINS.