It was inspired by John M. Cowden’s “Some Haphazard Aphorisms for Epidemiology and Life,” which appeared in the January 2010 issue of Emerging Infectious Diseases.¹

For instance, Cowden’s memorable and entertaining article, which the Scottish doctor described as a “ragbag of quotations relevant to epidemiology.” It had nothing to do with broiler-feed withdrawal and its impact on yield or a load of Salmonella pathogens heading from live production to the processing plant.

But like him, I’ll sprinkle my observations and advice on this topic with a few pithy quotations known as aphorisms to playfully underscore my points.

There is a large body of scientific research about broiler-feed withdrawal. A substantial amount of what I use came from poultry scientist Stan Savage, Ph.D., with the University of Georgia.

Broiler-feed withdrawal “In one word, he told me the secret of success…: Plagiarize.”
— Tom Lehrer (musician, satirist, and mathematician, 1928-).²

Over the years, many papers have been published about how feed withdrawal before processing affects broiler yield. However, specific findings vary somewhat, but the authors generally agree that the longer a broiler is without feed and water, the greater the yield loss. Off-target withholding not only affects yield but also increases the likelihood of contamination in the processing plant. Hence, it may affect compliance with the USDA Food Safety and Inspection Service’s microbiological performance standard.

J.K. Northcutt and others published a study in 2003 that showed an average live shrink — catch weight minus dock weight — of 3.8% at 8 hours.³ Northcutt also commented on earlier studies by other researchers who found live shrink ranged from 0.18% to 0.43% per hour of feed withholding. Mathematically, live-shrink loss means diminished feed conversion.

The takeaway: Optimizing the feed-withdrawal period is bankable.

“I hate math…but I love counting money!”
— anonymous Internet and tee-shirt meme.⁴

That large body of scientific research I mentioned earlier has shown a direct link between time without feed and the incidence of fecal contamination at the plant. It’s a common broiler-industry practice to withhold feed and water to empty the intestinal tract before birds process. Therefore, it increases the load of foodborne pathogens like Salmonella.

Throughout the industry, there are many arbitrary ways used to calculate the feed-withdrawal period. However, the only correct way is the one that measures the elapsed time from final consumption to slaughter.

The time it takes to catch a house and transport birds from the farm to the processing plant — plus the time in the holding shed once they arrive — must be factored in. On the other hand, those activities do not affect the optimal time between the flock’s last meal and the stunning period.

The takeaway: An optimized feed-withdrawal period minimizes fecal contamination.

Broiler-feed withdrawal“Belief is no substitute for arithmetic.”
— Henry Spencer (computer programmer and Internet pioneer, 1955-)⁵

A prerequisite for optimal feed withdrawal is steady feed consumption. Broilers in a comfortable environment with full lighting or near full lighting consume feed and water steadily throughout the day and night. As a result, they will eat about every 4 hours and drink several times during that 4-hour cycle.

Feed outages, light interruptions, and cold or hothouse temperatures result in binge eating and engorgement. That makes feed-withdrawal optimization almost impossible. In this case, any disturbance in steady-state consumption will affect intestinal tract emptying. Consequently, sanitary dressing at the processing plant.

Again, that large body of scientific research cited above has shown a broiler with steady-state feed consumption and full access to water will have an empty crop about 4 hours after feed withdrawal. Afterward, birds caught 4 hours after feed removal and processed 3 to 4 hours later will have tight, contracted gizzards. It contains a small amount of dry feed that’s sometimes mixed with litter.

With steady-state feed consumption, feed leaving the gizzard and entering the duodenum exits the intestine in about 2 hours. Additionally, if normal intestinal contractions occur, the lower intestine and cloaca will be empty 2 hours after the feed has stopped leaving the gizzard.

The takeaway: An optimized feed-withdrawal period is 8 hours.

“Brevity in writing is the best insurance for its perusal.”
— Rudolf Virchow (pathologist and polymath, 1821–1902).⁶

For more information on strategic feed withdrawal and other management practices to reduce the flow of Salmonella from live production into processing, contact the author at [email protected].