Where would the pork industry be today if a persistent Marion Dorset had not tested and proven the hog cholera serum process, then granted all patent rights to the U.S. government so it could be used for the good of all?

Or, where would the pork industry be today if, in the early '50s, L.N. Hazel and E.A. Kline had not taken the imaginative step of using a cheap, steel ruler to measure the fat depth of a pig?

These are but a couple of innovations and events that changed the course of the U.S. pork industry in the 20th century. Ninety-eight more appear on the following pages.

But, what of the hundreds of undocumented events, discoveries, new concepts and philosophies that have found their way into modern-day pork production?

Slotted floors, for example, are tough to tie to a specific date. I have a textbook, published in the late 1800s, with schematic drawings showing oak planks spaced an inch apart. A description explains the spacing allows hog manure to drop into the barn basement.

Retired agricultural engineer Art Muehling campaigned for slotted floors to make the list, noting slotted floors were "popularized" by Midwestern pork producers in the early '60s. Still, the date of their first installation remained elusive.

Numerous other developments were equally difficult to nail down. Consider these:

* Lagoons and deep pits for manure storage.

* Autogenous, killed or modified-live vaccines, vaccine adjuvants.

* Government, agricultural and foreign trade programs which ultimately affected feed supplies, cost of production and breakeven prices.

* First contract feeding/finishing agreements written.

* First direct sales to packers.

* Many variations of protective guard rails in farrowing pens that eventually became the prototypes for farrowing crates.

* Self-feeders, which continue to evolve today.

* Automatic waterers, nipple waterers, medicators and proportioners.

* Plywood, presswood, fiberglass wall lining, steel and aluminum siding, insulation in all of its forms.

* Hundreds of gate latches, and lest we forget, the invention of baling wire, which has never lost its usefulness.

It's been a fascinating journey, tracking these 100 events. Much of the swine health history was gleaned from the seventh edition of "Diseases of Swine." Excellent background and some photos were supplied by Palmer Holden, Iowa State University. Many others offered their thoughts, clippings and encouragement.

Although it is always good to review the past, I wonder what impact the Internet and e-commerce will ultimately have on pork production.

And, another major event looms large. It's likely U.S. pork producers will be asked to decide on the pork checkoff referendum this summer or fall. This vote will most certainly make the list of events that set the course of the 21st century pork industry.

1900 * First International Livestock Exposition held at the Union Stockyards in Chicago, demonstrating the advancements in livestock breeding.

1903 * Hog cholera serum first developed but was not introduced until 10 years later; USDA's Marion Dorset, W.B. Niles and C.N. McBryde tested and proved the vaccine from 1913-1934; Dorset patented the hog cholera serum process, then gave patent to the government for broad use by nation's farmers.

1906 * Food & Drug Act passed.

* Meat Inspection Act passed.

1908 * American Society of Animal Science established to promote research that expands knowledge in animal science and enhances the quality of animal products.

1914 * Brucellosis organism first isolated in aborted swine fetuses in Indiana by J. Traum, USDA. Swine brucellosis widely recognized as a major swine disease, 1920s to 1950s, causing considerable reproductive losses. By 1989, all states were participating in a federal eradication program.

1915 * First edition of Frank B. Morrison's Feeds & Feeding offered principles of livestock feeding and nutrition; abridged version published in 1917.

1917 * E.L. Quaife named first Iowa State College Swine Extension Specialist, believed to be the first in the U.S.

* The Chief of the Meat Division of the Food Administration, J.P. Cotton, announced a policy advising that the best yardstick to measure cost of production is a corn price-to-hog ratio of 13 to 1, an effort to stabilize prices.

* U.S. enters World War I, increasing demand for pork and lard. President Herbert Hoover asked for voluntary observance of porkless Thursdays and Saturdays.

1918 * World War I ends, Nov. 11, greatly affecting anticipated demand for pork and lard by the Federal Food Administration, later contributing to the post-war depression in 1921-22.

1921 * Packers & Stockyards Act passed.

1922 * National Live Stock & Meat Board organized to initiate and encourage human nutrition research and consumer education, promote and expand the role of red meats in a healthy diet.

1926 * First hybrid seed corn company organized; use of hybrid seed corn became common in the Corn Belt (1930-1935); by 1960, 96% of U.S. corn crop produced from hybrid seed.

1927 * National Barrow Show formed by prominent swine breeders and hog buyers to establish a standard for meat type hogs. First show held in conjunction with National Swine Show, Peoria, IL; rotated to various state fairs until 1946 when the show found a permanent home at the Mower County Fairgrounds, Austin, MN.

1928 * Swine erysipelas, first isolated by Theobald Smith in the late 1800s, was not considered important until a serious outbreak occurred in South Dakota in 1928; by 1937, acute swine erysipelas was present in 28 states.

1931 * Swine influenza virus (SIV) first isolated and identified by R.E. Shope.

1932 * Vesicular exanthema of swine was first described in California, confined there until 1951 when pork trimmings from an interstate California passenger train were fed to pigs in Wyoming; ensuing epidemic spread to 42 states and the District of Columbia. Finally controlled in 1956 at an estimated cost of $33 million for direct costs and indemnities.

* Geo. A. Hormel & Co. introduces grade-and-yield buying program.

1934 * Danish Landrace hogs imported by USDA for experimental testing.

1936 * Cooking whole soybeans improves pig performance; soybean meal developed.

* Rural Electrification Act (REA) greatly improved the quality of rural life, brought such conveniences as electric heat lamps to farrowing barns.

1937 * Regional Swine Breeding Laboratory originated, focused on the effects of inbreeding in various swine traits.

* Geo. A. Hormel & Co. trademarked SPAM, a new product developed from the picnic-shoulder of the carcass.

1938 * Essential amino acids identified at the University of Illinois.

1940 * American Pork Producers Association becomes the first national pork organization of record.

1941 * U.S. enters World War II, affecting pork demand, curtailing key industry events.

1943 * Vesicular stomatitis first appeared in pigs used for producing hog cholera antiserum in Missouri.

1944 * First National Research Council (NRC) Nutrient Allowances of Swine published.

1946 * Inbred Livestock Breeders Registry Association founded by L.M. Winters, University of Minnesota; recorded new breeds developed from crossbred foundations at experiment stations in Montana, Minnesota, Maryland (Beltsville) and Washington (Palouse). Served as the impetus for the development of crossbreeding and genetic improvement programs.

* Production Registry (PR) testing programs introduced to measure sow performance (litter size, 56-day litter weight); sire performance based on daughters' productivity. Program later extended to include progeny carcass testing, by which sires could be qualified as Certified Meat Sires.

* Transmissible gastroenteritis (TGE) first reported in the U.S. by L.P. Doyle and L.M. Hutchings based on cases occurring in 1945.

1947 * General Agreement on Tariffs and Trade (GATT) established working procedures that have substantially reduced tariffs between member nations and provided needed leverage to open foreign markets to U.S. pork.

1949 * Growth-stimulating effect of certain antibiotics on young animals discovered. Chlortetracycline received the greatest early testing in swine rations; Oxytetracycline, penicillin, bacitracin and streptomycin studies followed.

1953 * L.N. Hazel and E.A. Kline, Iowa State University, introduce the use of a cheap metal ruler as a simple tool to measure backfat, advancing the development of the meat-type hog.

1954 * National Swine Growers Council formed to advance the development of meat-type hogs and pork-specific promotion.

* First swine testing station opened at Ohio State University, Columbus.

1955 * The American Meat Institute, the USDA and the National Association of Swine Records suggest standard carcass measurements and percentages acceptable to represent the "meat-type hog." Meat Hog Certification Standards for a 215- to 230-lb. hog were: 1.3- to 1.7-in. backfat, at least 4.0 sq. in. loin muscle area and at least 29-in. carcass length.

1955 * Early work of G.A. Young and N.R. Underdahl, surgically removing pigs through abdominal/uterine incision to be raised in "germ-free" environment; credited for the development of Specific Pathogen Free (SPF) repopulating methods. (National SPF Accrediting Agency formed in 1964.)

* USDA adopts grade standards for slaughter hogs.

* Packers introduce rail grading, buying on cutout grade or buying on carcass grade programs. Early grade-and-yield programs derived by dividing the published live price for the weight class by the current standard yield for that weight class.

1956 * First issue of National Hog Farmer published as an eight-page newsletter providing news of the pork industry and serving as a vehicle to exchange pork production information.

* W.P. Switzer first isolated Bordetella bronchiseptica from pig's nasal cavity and suggested that turbinate atrophy associated with progressive atrophic rhinitis may be caused by several agents.

1957 * Actinobacillus pleuropneumonia first observed by I.H. Patterson. Originally called Haemophilus pleuropneumonia in 1964, the name was changed in 1983 recognizing it is from the actinobaccillus genus.

1958 * First National Swine Industry Conference held.

1960 * Early development of multi-herd breeding stock companies that would become a dominant source by the 1980s. Farmer's Hybrid Co. developed six new hybrid lines to be crossed in a rotational system in the early '60s.

* Pseudorabies first acknowledged in the U.S. in early '60s. (Disease first described in cattle in 1813; in 1903, Aujezsky established the etiologic agent; virus confirmed in 1911 and identified as a herpes virus in 1934.)

1962 * State-federal hog cholera eradication program begun in U.S. Last outbreak occurred in 1976. Cost of eradication estimated at about $140 million.

1963 * Early experimentation with injectable iron dextran by R.B. Talbot led to the replacement of udder swabbing with ferrous sulfate and other soluble iron salts as an anemia prevention practice in baby pigs.

* Amendment to Packers & Stockyards Act paves way to start a voluntary pork checkoff.

* National Porkettes, a national women's auxiliary, formed (later called National Pork Council Women); group merged with the National Pork Producers Council in 1992.

1964 * Delegates to the National Swine Growers Council annual meeting (Dec. 10-11), St. Louis, MO, vote in favor of name change to the National Pork Producers Council.

1965 * "Moline Meeting" held; "Blueprint for Pork" developed as a master strategy to organize pork producers.

* The term SMEDI introduced by H.W. Dunne to designate a group of viruses isolated in association with stillbirths, mummified fetuses, embryonic death and infertility (SMEDI).

* Mycoplasma isolated from pneumonic pig lung in the U.S. by C.J. Mare and W.P. Switzer. Mycoplasmal pneumonia remains one of the most common and economically important diseases in swine.

1966 * Chicago Mercantile Exchange began trading live hog contracts.

* Producer poll favors checkoff; 800 producers meet in Springfield, IL, endorse market checkoff (5cents /market hog, 3cents /feeder pig) to fund national pork promotion campaign. (First voluntary pork checkoff funds collected in six pilot counties in Illinois in 1967; national voluntary pork checkoff, "Nickels for Profit," launched in 1968.)

* Rolland "Pig" Paul became first, full-time executive of National Pork Producers Council and opens first headquarters in Des Moines.

1968 * USDA adopts new grade standards used for pricing slaughter hogs (U.S. No. 1 thru 4).

* Porcine Stress Syndrome symptoms first reported in the U.S. by Dave Topel.

1969 * American Association of Swine Practitioners organized by John Herrick, then president-elect of the American Veterinary Medicine Association.

1970 * First American Pork Congress held, joining the National Pork Producers Council annual meeting with the National Swine Industry Conference.

* First successfully farrowed pigs in the U.S. from frozen boar semen reported by E.F. Graham, University of Minnesota.

1971 * Swine dysentery, although originally described in 1921 by R.A. Whiting, the etiology of the disease remained unknown until 1971 - when D.J. Taylor and T.J.L. Alexander successfully propagated a pathogenic anaerobic spirochete.

1972 * Autosomal recessive inheritance of Porcine Stress Syndrome first proposed by Lauren Christian, who later championed the Halothane screening procedure in the U.S. for identifying stress susceptible pigs.

1973 * Pig Improvement Co. (PIC Inc.) introduced first genetic lines to American market; establishes first U.S. herd in Spring Green, WI.

N First National Barrow Show Production Tested Barrow Contest held at St. Ansgar, IA.

1974 * East Central Breeders Association, Waupun, WI, the first swine AI commercial boar stud to offer frozen boar semen.

* National Association of Swine Testing Stations organized with an objective to standardize swine testing programs; reorganized a year later as National Swine Improvement Federation (NSIF), published "Guidelines for Uniform Swine Improvement Programs" in 1976.

1975 * Development of new extender for fresh and deep frozen boar semen by L. Johnson and V. Pursel at USDA-ARS, Beltsville, MD.

1978 * Secretary of Agriculture Bob Bergland declared the U.S. hog cholera-free on Jan. 31, 1978.

1979 * Murphy Family Farms, Rose Hill, NC, builds first sow/breeding facility; ranked largest in the nation with an estimated 340,000 sows in 1998.

* National Pork Producers Council opens Washington, DC, office to represent pork producers on national public policy issues.

* National Pork Producers Council court action blocks USDA from banning nitrites as a safe preservation method for pork.

* D.L. Harris combined various disease eradication program features with a medicated early weaning program to eliminate a wide spectrum of infectious diseases from a herd; methods were later refined as the Medicated Early Weaning (MEW) and Segregated Early Weaning (SEW) programs popular today; in 1988, Harris introduced ISOWEAN, a 3-site production system using simplified MEW techniques to broaden their application.

* Early research reported on inducing parturition in sows by N.L. First and M.J. Bose.

1983 * USDA Secretary John Block implemented a payment-in-kind (PIK) program resulting in the third largest acreage reduction, greatly affecting grain supplies and agricultural programs in later years.

1985 * Rapid diagnostic test for trichinosis introduced by Murrell, USDA-ARS, Beltsville, MD.

* NPPC drafts legislative initiative, the Pork Promotion, Research and Education Act, to provide for a national, mandatory legislative checkoff program including imported hogs and pork products.

* Kansas State University research results in formulation of high-density diets for early weaned pigs.

1986 * National Legislative checkoff program begins at the rate of 25cents /$100 value of market hog receipts.

1987 * "Pork, the Other White Meat" campaign launched.

* Mystery Swine Disease first recognized in North Carolina, Minnesota and Iowa herds. Acknowledging the predominant reproductive and respiratory clinical signs results in new term, SIRS (Swine Infertility & Respiratory Syndrome); currently, more commonly referred to as PRRS (porcine reproductive and respiratory syndrome).

1988 * National Research Council cites medical recommendations that urges people to reduce their fat consumption - particularly of animal origin.

* First World Pork Expo held at Iowa State Fairgrounds, Des Moines.

1989 * Imported Chinese hogs arrive at the Harry S. Truman Import Center in Florida on March 26; 140 boars and gilts placed at the University of Illinois, Iowa State University and the USDA Meat Animal Research Center, Clay Center, NE, have lead to major swine gene mapping. First genetics linkage maps for swine reported by Rotter, USDA-ARS, Clay Center, NE, in 1994.

* PigCHAMP 1.1 recordkeeping system developed and released by the University of Minnesota.

* National Pseudorabies 5-Stage Eradication program begun with a targeted goal of eradicating the disease from all domestic swine in the U.S. by the end of 2000.

* McDonald's introduction of the McRib pork sandwich marks pork's introduction to the fast-food market.

* NPPC introduces Pork Quality Assurance program as a producer education and management tool emphasizing good management practices and the safe handling and use of animal health products.

1995 * Chicago Mercantile Exchange began trading futures and options on new lean hog contracts.

* NPPC-coordinated National Genetic Evaluation Program Terminal Sire Line results released.

* NPPC introduces Environmental Assurance Program to help pork producers successfully manage their operations in an environmentally conscious way.

1996 * President Bill Clinton signed new farm bill - the Federal Agricultural Improvement and Reform Act of 1996 - on April 4, cementing historic changes in agriculture policy, focusing on production and supply controls.

1998 * First pigs born from embryos deep frozen by vitrification, reported by J. Dobrinsky, USDA-ARS, Beltsville, MD.

* Results of the NPPC-coordinated Quality Lean Growth Modeling Project provided the pork industry with extensive information on lean:fat deposition rates, their impact on packer value-based buying programs, pork quality and eating quality measures.

* Live hog prices sink to a record, modern-day low in December.

n Industry reports indicated over 60% of all hogs contracted on some type of pre-delivery pricing agreement.

1999 * Campaign for Family Farms files petition with USDA calling for a national referendum on the mandatory pork checkoff.

* Smithfield Foods acquires the nation's No. 1 (Murphy Family Farms, Rose, Hill, NC) and No. 2 (Carroll's Foods Inc., Warsaw, NC) pork production systems, pushing Smithfield's sow total to roughly 785,000 sows.