United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Veterinary Services 

Centers for Epidemiology and Animal Health January 2009 

_________________________________________________________________________________________________________________________ 

Sow and Gilt Management in 

Swine 2000 and Swine 2006 

In 2000, the USDA’s National Animal Health 

Monitoring System (NAHMS) conducted a study on 

swine health and management practices from a 

random sample of swine production sites in 

17 States divided into 4 regions.*

 These States 

represented 94 percent of the U.S. pig inventory 

and 92 percent of U.S. pork producers with 100 or 

more pigs. 

 The same 17 States participated in NAHMS 

latest study of the U.S. swine industry, Swine 2006. 

In 2006, these States accounted for 94 percent of 

the U.S. pig inventory and 94 percent of U.S. pork 

producers with 100 or more pigs. 

 The following provides a comparison of sow 

and gilt management practices in 2000 and 2006 

using data collected during both studies. 

For estimates in this information sheet, small, 

medium, and large sites refer to sites with fewer 

than 250, 250 to 499, and 500 or more breeding 

females, respectively. 

Sow and gilt management

 Similar percentages of sites by region (about 40 

percent) had a gestation phase in 2006. However, 

since 2000 there has been a general decline in the 

percentages of sites with a gestation phase, most 

notably in the West Central region (figure 1). 

 

* States/ Regions

North: Michigan, Minnesota, Pennsylvania, and Wisconsin 

West Central: Colorado, Kansas, Missouri, Nebraska, and South 

Dakota 

East Central: Illinois, Indiana, Iowa, and Ohio 

South: Arkansas, North Carolina, Oklahoma, and Texas

0

20

40

60

80

Swine 2006

Swine 2000

Region

Percent

Figure 1. Percentage of Sites with a Gestation Phase, by Region 

and by Study 

North West Central East Central

Study

South All Sites

50.2

39.3

65.9

48.8 50.5

38.0

42.6

33.9

52.6

39.8

 The South region had the highest percentage of 

sites that specialized exclusively in breeding pigs in 

2000 and 2006 (figure 2). Together, figures 1 and 2 

show that pork production continues to be 

segmented, with various production phases 

occurring on separate sites. 

0

10

20

30

Swine 2006

Swine 2000

Region

Percent

Figure 2. Percentage of Sites that Specialized Exclusively in 

Gestation and Farrowing Phases, by Region and by Study

North West Central East Central

Study

South All Sites

4.6 3.8

6.5 7.1

3.7

6.9

14.2

20.7

5.1

7.6
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Biosecurity

 Table 1 shows the types of housing and flow 

systems used for breeding animals in 2000 and 

2006. The percentage of sites that housed 

gestating animals in total confinement increased 

from 2000 to 2006. However, there was also an 

increase in the percentage of sites that kept 

gestating sows outside with no housing. In 2000 

and 2006, continuous-flow management was used 

in the gestation phase by 71.4 and 61.5 percent of 

sites, respectively, and in the farrowing phase by 

38.7 and 33.5 percent of sites, respectively. 

Table 1. Percentage of Gestation and Farrowing 

Sites, by Facility Type and by Management Style

 Percent Sites 

 Gestation Farrowing 

 2000 2006 2000 2006 

Facility Type 

Total 

confinement 22.4 34.6 64.8 67.7 

Management Style

Continuous 

flow 71.4 61.5 38.7 33.5 

All in/all out 23.5 23.7 56.9 59.8 

No housing 5.1 14.8 4.4 6.7 

 

 Initial isolation or quarantine of new breeding 

stock is one method used to prevent disease 

transmission when animals come from another site 

or from a different health management system. 

About one-third of sites always isolated or 

quarantined new breeding females in 2000 and 

2006 (figure 3). 

0

10

20

30

40

50

Swine 2006

Swine 2000

Frequency of Isolation

Percent

Figure 3. Percentage of Sites by Frequency New Breeding Females 

Were Typically Isolated or Quarantined, and by Study

Always Sometimes Never

Study

No new arrivals

32.0

34.3

8.1

5.0

16.9 17.0

43.0 43.7

 For sites that isolated or quarantined new 

breeding females, large sites isolated breeding 

females longer than small sites in 2000 and 2006. 

(table 2). 

Table 2. For Sites that Isolated or Quarantined New 

Breeding Females, Site Average Number of Days 

New Arrivals were Isolated or Quarantined, by Size 

of Site: 

Site Average Number of Days 

Size of Site (Sow and Gilt Inventory)

Small 

(Fewer 

than 250)

Medium 

(250-499) 

Large 

(500 or 

More) 

All 

Sites 

Study Avg. Avg. Avg. Avg. 

Swine 2000 35.1 43.1 51.1 38.7 

Swine 2006 30.3 36.1 49.7 37.0 

Culling in the breeding herd

 Culling occurs for many reasons and is part of 

any breeding herd management practice. In 2000, 

a higher percentage of breeding-age females (20.3 

percent) were culled on medium sites compared 

with large and small sites (18.1 and 15.0 percent, 

respectively). In 2006, a higher percentage of 

breeding-age females (21.1 percent) were culled on 

large sites compared with medium and small sites 

(12.7 and 12.4 percent, respectively). Overall, 17.5 

percent of breeding-age females were culled in 

2000, and 19.5 percent were culled in 2006 

(figure 4). 

 

0

10

20

30

Swine 2006

Swine 2000

Size of Operation (Sow and Gilt Inventory)

Percent

Figure 4. Percentage of Breeding-age Females Culled*, by Size of 

Site and by Study

Small

(fewer than 250)

Medium

(250 to 499) Large (500 or more)

Study

All operations

15.0

12.4

20.3

12.7

18.1

21.1

17.5

19.5

*Culled from December through May and as a percentage of June 1 sow and gilt inventory. 
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

 Age and reproductive failure were the most 

common reasons breeding-age females were 

culled in 2000 and 2006 (figure 5). 

0

10

20

30

40

50

Swine 2006

Swine 2000

Reason Culled

Percent

Figure 5. Percentage of Culled Breeding-age Females by Reason 

Culled* and by Study

Age Reproductive failure

Lameness

Study

Performance Other**

41.9

36.6

21.3

26.3

16.0 15.2

12.0 13.0

8.8 8.9

**In 2006, injury was included in the "Other" catergory. 

*Culled from December 1 through May 31, 2006

_____________ 

For more information, contact: 

USDA:APHIS:VS:CEAH 

NRRC Building B, M.S. 2E7 

2150 Centre Avenue 

Fort Collins, CO 80526-8117 

970.494.7000 

E-mail: NAHMS@aphis.usda.gov 

http://nahms.aphis.usda.gov 

#N495.0109 

____________________________________ 

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