Introduction

The care of the swine breeding herd in the US has come under increased scrutiny as more people question the care and housing practices used to manage these animals. In addition, the issue of sow lifetime as both an economical and welfare concern has experienced greater study. From PigChamp^TM DataShare (Figure 1) both US culling and mortality rates have increased since 2003.

As breeding herd management and housing practices come under greater scrutiny, pork producers will need to evaluate their management protocols and invoke changes to improve the management of the breeding herd.

Figure 1. US sow culling and mortality
^{(adapted from PigChamp DataShare)}

Culling and Mortality

As both industry personnel and society at large scrutinize animal well-being in pork production systems, the issue of sow longevity or sow lifetime has become an important concern. Certainly female culling and mortality rates are of great importance in this discussion. A recent paper from Japan evaluated a large industry database in which it determined the culling and mortality rates of gilts and sows in the breeding herd (Sasaki and Koketsu, 2008). This data set contained 105 herds and records from 65,621 females. Gilts were defined as females that had entered the herd but did not have a farrowing record and sows were females which had at least one farrowing record. Annual culling and mortality rates were 33.8 per cent and 3.9 per cent, respectively.

Gilts

Gilts were culled at an average age of 333.4 days, while those that died were 294.7 days of age and significantly younger than those gilts which were culled. Of those gilts that died, there was an increase in death rate at 33 and 50 weeks of age. This corresponds to the time shortly after herd entry and near the time of first farrowing.

Sows

Sows that were culled left the herd 61.3 days after their last farrowing, while for those that died, this event occurred at an average of 55 days after their last farrowing. The average parity at culling was 4.3, while the average parity at death was 3.2. There was an increase in death rates at and during the first two weeks after farrowing (Figure 2). In addition, older sows had an increased risk of mortality than younger sows.

Figure 2. Mortality rate after last farrowing
^{(adapted from Sasaki and Koketsu, 2008)}

Discussion

This study demonstrated that gilts have an increased risk of mortality at the time of movement into the breeding herd as well as near the time of their first farrowing. Sows had an increased mortality incidence at and within the first week or two after farrowing.

This study provides clues as to when females are experiencing increases in mortality risk and signals what portions of the management programme should be reviewed for improved animal care. Gilt management at herd entry should be reviewed and the appropriate steps taken to adequately evaluate any health concerns that gilts may have and the appropriate protocols put into practice. Management of gilts that are group housed after herd entry should be assessed. This evaluation should consider appropriate floor space, feeder space or feeding routines and animal mixing strategies. During gestation, gilts should be provided adequate nutrition so they are neither too fat nor thin at farrowing. At the time of their first farrowing, gilts should be routinely evaluated and adequate intervention strategies applied as necessary. However, in some cases gilts can be over managed at farrowing which also can produce negative results.

Sows experience increased mortality risk around the time of farrowing. It is imperative that gestation management be such as to have sows in the optimal body condition at the time of farrowing so that body condition (too much or too little) does not impede her ability to complete parturition. In addition, environmental temperature management should be an important consideration. In the summer, sows should be cooled as needed and in the winter, farrowing rooms should be maintained at the temperature necessary to maintain sow comfort. In addition, farrowing intervention strategies should be reviewed so that sows are appropriately cared for but not ignored nor over managed.

Conclusion

Gilts and sows have certain periods during their lifetime where they have an increased mortality risk. Management protocols should be reviewed so as to provide optimal management and care for both gilts and sows during these critical instances. Providing improved management oversight of females at these critical points in their life can reduce their mortality risk.

Literature Cited