Design and implementation of the United States National Animal Health Monitoring System 1995 National Swine Study.

The United States Department of Agriculture's National Animal Health Monitoring System 1995 National Swine Study was designed to estimate management, health and productivity parameters on pig operations in the United States. Sixteen major swine-producing states that accounted for nearly 91% of June 1, 1995 swine inventory and nearly three-fourths of United States swine producers were included in the study. In the initial phase of the study, National Agricultural Statistics Service enumerators collected information from 1477 producers involved in all phases of swine production (farrowing, nursery, and grower/finisher). Of these, 405 operations with > or = 300 finisher pigs (with at least one finisher pig > or = 54 kg) participated in the subsequent component of the study, which involved on-farm visits by state and federal veterinary medical officers and animal health technicians, and which concentrated on the grower/finisher phase of production. Of those eligible to take part in the second phase of the study, participation was higher among independent producers (48.3%) than among contract producers (15.3%). Participation was also higher among operations that used advanced record-keeping systems (such as record cards for individual breeding hogs or a computer-based record-keeping system). Thus, study results could have been influenced by response biases. As a biosecurity measure, 40.5 +/- 2.1% of operations restricted entry to employees only. For operations that permitted non-employees to enter the premises, relatively few enforced other biosecurity measures on visitors (0.4 +/- 0.1% required feed-delivery personnel and livestock handlers to shower before entering the premises; 3.3+/- 0.9% required a footbath; and 7.0 +/- 1.5% required feed-delivery personnel and livestock handlers not to have visited another operation with pigs on that day). The most common method of waste storage (used by 49.9 +/- 3.8% of operations with > or = 300 finisher pigs) was below-floor slurry or deep pit.