Introduction

The ability of sows to produce and nurture large litters is vital for successful production in the swine industry. Hence, when replacement sows are selected, their capacity to nurse large litters is considered; those with underline defects such as blind or inverted teats will be discriminated against. Therefore, producers who are raising replacement females have an interest in preserving the underlines of their gilts.

Discussion

Neonatal Teat Necrosis

According to Stevens (1984), there is a significant correlation between underline defects observed at the time of replacement gilt selection and the previous incidence of neonatal teat necrosis. This teat necrosis occurs when the newborn’s teats suffer abrasion from her environment, generally in the first 24 hours of life. The teat end reddens from the trauma, and then transitions to black as the teat sphincter dies, scabs, and sloughs off (The PigSite, 2010). The teat eventually heals, but its potential for normal function is severely impaired and sometimes eliminated.

There are multiple factors influencing the occurrence of neonatal teat necrosis; some are inherent to the piglet and others are external. Knowledge of these allows consideration of either active or passive measures to prevent necrosis and subsequent underline losses. Passive measures of prevention consist of addressing the aggravating factors and decreasing or eradicating them.

Inherent factors

Breeds or lines with prominent teats at birth are predisposed to teat necrosis (Lemmon, personal communication), as are those born from sows who have consumed feeds containing mycotoxins (Lemmon, Strittmatter; personal communications). The mycotoxin zearalanone elevates estrogen levels in the sow, and some of the hormone is transferred to the piglets around parturition. This causes abnormal estrogen levels in the piglets as well, creating swollen teats with increased exposure and subsequent risk of injury. To prevent this, gestating sows nearing parturition should be fed only high quality feeds.

Irritation

Environmental factors which can be controlled include irritants that initiate swelling or increase the sensitivity of the teats. Common culprits are excessive amounts of disinfectants used in farrowing room washing leading to residues on crate surfaces and piglet drying agents containing lime (Strittmatter, personal communication). Valid preventative measures will address these details.

Flooring

One of the biggest environmental contributions to teat necrosis occurrence, however, is crate flooring. In a study backed by Agriculture Canada, 333 sows raised litters on heated concrete crate floors and 325 sows raised their litters on plastic coated flooring. Teat necrosis in the piglets was assessed at 3 days of age; the rates of the litters were 17.5 per cent and 3.4 per cent, respectively. This significant difference allowed the researchers to conclude that if producers switched from concrete to plastic coated flooring, an 80 per cent reduction in teat necrosis could be expected (Stevens, 1984). The current consensus among producers also is that flooring type is critical, and that plastic coated, woven wire or tribar flooring are adequate alternatives to concrete (Higbee, Strittmatter, Tafs; personal communications). Because flooring type can have the largest impact on the incidence of teat necrosis, it should be the primary consideration of producers looking to decrease underline defects.

There are also secondary flooring factors to consider, including heated (Stevens, 1984) and wet, slippery floors (Strittmatter, personal communication). Heated concrete encourages the piglets to lie directly on the abrasive concrete. Ensuring that the crate floor is dry and that piglets have a comfortable micro-zone with suitable flooring will help prevent teat necrosis.

Other Factors

Finally, excessive competition among piglets for milk increases the “wear time” of their teats (Lemmon, personal communication), and small litter size can also increase teat necrosis (Stevens, 1984) as there is less piling among the piglets and more underline contact with the floor. Ensuring that the sow is producing a sufficient quantity of milk for the number of piglets she is feeding and evening litter sizes through cross fostering can help minimize underline damage.

Taping

Active measures of neonatal teat necrosis include covering the piglets’ teats by placing tape on them or by covering each of the teats with a tar based glue for a few days postpartum. In the former, the gilts are dried, and a length of tape (i.e. 2" masking tape) is wrapped around their middle to keep teats from rubbing against the floor or other piglets (Lemmon, personal communication). Taping is advantageous because it is quick and easy. Early attention is key, however, as most teat damage occurs within the first 72 hours after birth (Strittmatter, personal communication). Because the effectiveness of taping is proportional to how soon it is done after birth, this short time frame necessitates that personnel be available to carry out the procedure soon after birth. Another consideration is that if the gilts are taped, the tape must be removed after a few days (Tafs, personal communication).

Cost Analysis

A cost analysis of taping, when done in conjunction with additional piglet processing procedures, shows an increased cost of about half a dollar to a dollar per litter of five gilts. This estimate was calculated with one foot of 2-inch masking tape per gilt and 2 minutes of labor per litter at a labor rate of $7.40 per hour (Tafs, personal communication). However, it does not account for the resources that must be used to train personnel on the procedure and it also assumes a 100 per cent tape efficiency use. Finally, if the taping is not done at the same time as other processing procedures, labor, and consequently the cost per litter, will be higher.

A 1984 evaluation of how much revenue replacement producers could lose due to poor underlines on their potential replacement gilts placed losses at $360 per sow per year. The analysis used gilt premiums of $100 with 40 per cent of possible replacement gilts not being qualified for one due to unacceptable underlines (Stevens, 1984).

Conclusion

Because neonatal underline abrasions diminish the value of replacement gilts, it is undeniable that replacement gilt producers must take measures to prevent neonatal teat necrosis. Whether or not this prevention should be passive or active, however, is debatable, and the answer will be farm specific. Passive measures addressing environmental factors such as flooring and sow feed quality are easily incorporated and should be the first steps taken so that unnecessary production costs from active prevention are not incurred.

If teat necrosis occurrence remains high despite these changes, or if converting from concrete to an alternative flooring is not practical due to investment costs, the economics favor utilizing an active measure of prevention such as taping as well. Granted, the economic value of taping will vary between operations, depending on factors such as whether or not an employee is already present at farrowing to dry (and tape piglets) or if untapping can successfully be incorporated into the existing processing schedule. However, it will at least remain positive regardless of the operation. In summary, taping is a worthwhile and valuable management tool which should be employed to reduce high rates of neonatal teat necrosis.

Bibliography

Higbee, Phil. Personal Communication. 12 November 2010.

Lemmon, Mike. E-mail Interview. 18 November 2010.

Schoneweis, D. A. (1978). Teat necrosis in newborn gilts. Kansas State University AES and CES. Conference paper, 39. Web. 13 November 2010. Retrieved from http://hdl.handle.net/2097/3931

Staff. “Teat Necrosis,” “Udder.” (n.d.). The PigSite. Web. 10 November 2010. Retrieved from http://www.thepigsite.com/pighealth/article/298/teat-necrosis, http://www.thepigsite.com/pighealth/article/222/udder

Stevens, R. W. C. (1984). Neonatal teat necrosis in pigs. Pig News and Information, 5(1), 19-22. Web. 14 November 2010. AGRIS, MSU Database.

Strittmatter, Joseph. E-mail Interview. 12 November 2010.

Tafs, Marlon. E-mail Interview. 12 November 2010.