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Highlights of the NAHMS Finishing Swine Survey

Livestock Update, April 1997

Allen Harper, Extension Animal Scientist, Swine, Virginia Tech

Pork producers are always interested in what other producers are doing -- what management and feeding practices are being used, what health problems exist, what waste management strategies are being employed. The National Animal Health Monitoring System (NAHMS) developed by the USDA Animal and Plant Health Inspection Service has produced a series of producer surveys that reveals a lot about what hog producers are doing. The most recent NAHMS survey was published in 1996 and focused specifically on grower-finisher pig management. There were 418 operations that participated in the survey. Among these, 211 were small farms marketing less than 2,000 hogs annually, 155 were moderate-sized operations marketing 2,000 to 9,999 hogs annually and 51 were large operations marketing 10,000 or more hogs annually. One operation's size was unspecified.

Most of the survey data was broken down by farm size and reveals differences in use of feeding technologies by smaller and larger operations. For example, penning and feeding growing-finishing barrows and gilts separately, also known as separate-sex feeding, is a technology that improves efficiency in market hog production. In this system the gilts can be fed to more accurately meet their nutrient requirements for lean growth. Also variation in growth rate within same-sex pens will be less than if gilts and barrows are fed within the same pens. The NAHMS survey shows that larger operations have a much higher adoption rate (71%) for separate-sex feeding technology than do smaller operations (10%, see Table 1). Moderate-sized farms marketing 2,000 to 9,999 hogs annually had an intermediate adoption rate of this technology with 42% utilizing separate-sex feeding management.

Another technology available to improve efficiency in grower-finisher pig feeding is phase feeding. Phase feeding involves changing dietary formulations to more accurately meet requirements for energy and amino acids as pigs advance in maturity. The survey showed that a majority of small producers (72%) made 3 or fewer diet changes during the growing-finishing period but a majority of larger producers (74%) made 4 or more diet changes during the grower-finisher period. Again, technology adoption for the medium size producers was intermediate, 43% made 3 or fewer diet changes for growing-finishing pigs and 57% made 4 or more diet changes.

The survey also reveals that large operations are more likely to be involved in multiple-site production than smaller operations. Of the pigs entering the grower-finisher buildings, 64% originated from off-site farrowing or nursery units in the large operations but only 16% and 10% originated from separate site farms in the moderate and small-size operations, respectively (Table 2).

In terms of herd health, the survey suggests that major disease concerns are different for large and small operations. More diseases had been diagnosed by veterinarians on the large farms than on medium or small-sized farms with porcine reproductive and respiratory syndrome (PRRS) being diagnosed on 71% of the large operations. This confirms the notion that PRRS is the predominant disease problem facing intensive swine production today. Other diseases frequently diagnosed on the large operations included Salmonella (34%), Actinobacillus (33%), and E. coli (16%). However, we cannot be certain from this data that small farms have significantly fewer disease problems than larger ones because the use of veterinarians to diagnose specific diseases could have been less on the smaller farms. Certainly any hog farm, small or large, can experience economically damaging disease problems when biosecurity and herd health management is poor.

The survey also indicates that anaerobic lagoons are a principle method of waste collection and treatment, especially on larger farms (82%). Lagoon popularity can be attributed to lower labor requirements, availability of pit recharge water and large waste treatment capacity. However, we know that poor lagoon planning, design and construction can result in odor or other waste management problems.

The NAHMS survey is interesting and can show us some areas where improvement needs to occur. Here at the Tidewater Swine Unit, we are using the NAHMS data to select which nursery and grower-finisher pig feed additives to evaluate in a cost-benefit feeding trial. For a reprint of the 1996 NAHMS survey, contact the Virginia Tech Tidewater AREC, 6321 Holland Road, Suffolk, VA 23437 (E-mail:

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