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

Veterinary Services 

Centers for Epidemiology and Animal Health March 2008 

_________________________________________________________________________________________________________________________ 

Vaccination Against 

Mycoplasma Pneumonia, Swine 

Influenza, and PRRS in Breeding 

Females, 2000 and 2006 

In 2000 and 2006, the USDA’s National Animal 

Health Monitoring System (NAHMS) conducted 

studies on swine health and management practices 

from a random sample of swine production sites 

with 100 or more pigs in 17 States*. These States 

represented approximately 94 percent of U.S. pig 

inventory and 94 percent of U.S. pork producers 

with 100 or more pigs. 

Vaccination against Mycoplasma 

pneumonia 

 

Overall, about one in five sites (20.9 percent) 

and one in three sites (34.9 percent) vaccinated 

breeding females against Mycoplasma pneumonia 

in 2000 and 2006, respectively (figure 1). In 

general, a higher percentage of large sites usually 

vaccinated breeding females against Mycoplasma

than small sites in both 2000 and 2006. 

_______________ 

*States 

Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Michigan, 

Minnesota, Missouri, Nebraska, North Carolina, Ohio,

Oklahoma, Pennsylvania, South Dakota, Texas, and Wisconsin. 

In both 2000 and 2006, most sites vaccinated gilts 

prior to entering the breeding herd, and about half 

vaccinated gilts at time of entering the breeding 

herd. The reproductive time period that sites 

vaccinated breeding females against Mycoplasma

pneumonia was similar in 2000 and 2006 (table 1). 

Table 1. For Sites that Vaccinated Breeding Females 

Against Mycoplasma Pneumonia, Percentage of 

Sites that Usually Vaccinated During the Following 

Time Periods 

Time Period 2000 2006 

Prior to entering the 

breeding herd 75.0 84.4 

As gilts at time of entering 

the breeding herd 44.2 57.3 

During gestation up to 

4 weeks before farrowing 24.0 10.7 

During the last 4 weeks 

of gestation 22.3 21.5 

From farrowing to weaning 4.8 3.9 

After weaning through 

breeding/mating 5.7 11.8 

At regular intervals, 

regardless of reproductive 

stage* 7.5 5.3 

*Once or twice a year in 2000.

Vaccination against porcine reproductive 

and respiratory syndrome (PRRS) 

The use of PRRS vaccine in breeding females 

on medium and large sites dropped by 

approximately one-half from 2000 to 2006. 

However, overall the use of PRRS vaccination did 

not change substantially (figure 2). 

0

20

40

60

80

2006

2000

15.3

23.7

43.6

39.7

46.2

62.5

20.9

34.9

Small 

(fewer than 250)

Medium 

(250-499)

Large 

(500 or more)

All Sites

Size of Site (Sow and Gilt Inventory)

Percent

Figure 1. Percentage of Sites that Usually Vaccinated Breeding 

Females Against Mycoplasma Pneumonia
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

0

20

40

60

80

2006

2000

30.6

60.8

69.4

37.1

24.4

28.6

34.0

27.3

Small 

(fewer than 250)

Medium 

(250-499)

Large 

(500 or more)

All Sites

Size of Site (Sow and Gilt Inventory)

Figure 2. Percentage of Sites that Usually Vaccinated Breeding 

Females Against PRRS, By Size of Site

Percent

The timing of when PRRS vaccine is given to 

breeding females changed from 2000 to 2006 in 

three areas: 1) the percentage of sites that 

vaccinated breeding females against PRRS during 

the last 4 weeks of gestation decreased from 17.5 

percent in 2000 to 3.5 percent in 2006; 2) the 

percentage that vaccinated from farrowing to 

weaning decreased from 43.0 percent in 2000 to 

6.8 percent in 2006; and 3) the percentage that 

vaccinated at regular intervals increased from 9.1 

percent in 2000 to 47.0 percent in 2006 (table 2). 

Table 2. For Sites that Vaccinated Breeding Females 

Against PRRS, Percentage of Sites that Usually 

Vaccinated During the Following Reproductive Time 

Periods 

Time Period 2000 2006 

Prior to entering the 

breeding herd 27.0 38.1 

As gilts at time of entering 

the breeding herd 80.8 69.2 

During gestation up to 

4 weeks before farrowing 13.3 10.9 

During the last 4 weeks of 

gestation 17.5 3.5 

From farrowing to weaning 43.0 6.8 

After weaning through 

breeding/mating 23.4 28.2 

At regular intervals, 

regardless of reproductive 

stage* 9.1 47.0 

*Once or twice a year in 2000.

Since vaccinating for PRRS on medium and 

large breeding sites decreased from 2000 to 2006, 

it follows that other measures to control PRRS 

would have changed on these sites as well. 

For example, the percentage of medium sites 

that exposed incoming gilts to PRRS decreased 

from 45.6 percent in 2000 to 13.2 percent in 2006, 

while the percentage of large sites that did so 

decreased from 57.1 percent in 2000 to 20.9 

percent in 2006. The percentage of large sites that 

obtained replacement gilts from a PRRS-negative 

source increased from 46.7 percent in 2000 to 71.7 

percent in 2006, and the percentage of large sites 

that tested replacement gilts for PRRS increased 

from 32.2 percent in 2000 to 57.9 percent in 2006. 

Additionally, a higher percentage of large sites 

used only PRRS-negative semen/boars in 2006 

than in 2000 (table 3). 

Table 3. Percentage of Sites by Measures 

Specifically Used to Control or Prevent PRRS in 

Breeding Females, and by Size of Site 

Percent Sites 

Size of Site (Sow and Gilt Inventory) 

 Small 

(Fewer 

than 250)

Medium 

(250-499)

Large 

(500 

or More 

All 

Sites 

Control 

Measure 2000 2006 2000 2006 2000 2006 2000 2006

Obtain 

replacement 

gilts from 

PRRSnegative 

source 18.4 19.0 48.2 27.8 46.7 71.7 23.9 33.0

Test 

replacement 

gilts for PRRS 4.5 4.0 24.6 15.0 32.2 57.9 9.0 18.5

Expose 

incoming gilts 

to PRRS 8.8 5.6 45.6 13.2 57.1 20.9 16.7 10.2

Herd closed to 

new gilt 

introduction 26.2 48.2 16.6 35.8 28.1 38.1 25.4 44.5

Use only 

PRRSnegative 

semen or 

boars 28.2 50.5 53.2 63.7 56.9 81.0 33.3 59.4

Other 

measures not 

including 

vaccination 0.8 11.0 1.0 14.2 5.1 12.5 1.2 11.7

Any of 

the above 50.4 69.1 86.2 73.9 89.9 92.2 57.4 75.3
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Vaccination against swine influenza 

Sites often vaccinated their breeding herd 

against one or both of the current serotypes of 

swine influenza (H1N1 and H3N2) [table 4]. 

Table 4. Percentage of Sites that Usually Vaccinated 

Breeding Females Against Swine Influenza H1N1 

and/or H3N2, by Size of Site 

Percent Sites 

Size of Site (Sow and Gilt Inventory) 

Small 

(Fewer 

than 250)

Medium 

(250-499)

Large 

(500 or 

More) All Sites 

Vaccinated 

Against... 2000 2006 2000 2006 2000 2006 2000 2006

Swine 

influenza 

H1N1 4.4 11.5 39.4 33.2 42.4 69.3 11.2 27.9

Swine 

influenza 

H3N2 5.0 12.8 29.4 33.6 41.5 65.2 10.6 27.8

Both 

H1N1and 

H3N2 2.9 11.5 28.5 29.7 28.1 64.5 7.6 26.4

Either H1N1 

or H3N2 6.5 12.8 40.2 37.1 55.8 70.0 14.2 29.3

Table 5 shows the most common timing for 

vaccinating breeding females against swine 

influenza H1N1 and H3N2. The percentage of sites 

that vaccinated breeding females against H1N1 

prior to entering the breeding herd increased from 

42.6 percent in 2000 to 64.7 percent in 2006. 

Similarly, the percentage of sites that vaccinated 

breeding females against influenza H3N2 increased 

from 32.8 percent in 2000 to 63.0 percent in 2006. 

Table 5. For Sites that Vaccinated Breeding Females 

Against Swine Influenza H1N1 and H3N2, Percentage 

of Sites that Usually Vaccinated During the 

Following Time Periods 

 Percent Sites 

 H1N1 H3N2 

Time Period 2000 2006 2000 2006 

Prior to entering the 

breeding herd 42.6 64.7 32.8 63.0 

As gilts at time of 

entering the breeding 

herd 71.2 67.9 74.9 68.8 

During gestation up to 

4 weeks before 

farrowing 21.6 27.4 24.4 33.0 

During the last 

4 weeks of gestation 35.4 25.0 36.8 25.9 

From farrowing to 

weaning 14.8 3.5 22.8 4.3 

After weaning through 

breeding/ mating 11.7 8.7 1.8 8.7 

At regular intervals, 

regardless of 

reproductive stage* 13.6 21.6 11.1 21.7 

*Once or twice a year in 2000.

Complete descriptive reports and other 

information sheets from NAHMS Swine Studies are 

available at: http://nahms.aphis.usda.gov

______________________________ 

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 

#N501.0308 

____________________________________ 

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