The technical bulletin on Low-Stress Loadouts provides an overview on how to reduce the stress caused by sorting and loading market-ready hogs, with a focus on people and facilities. The following provides more specific information on handling and transporting hogs. It also needs to be pointed out that the risk for severe losses during the marketing process can increase as the animals become more heavily muscled through genetic selection.

What Causes Losses?

Temple Grandin, a renowned expert in animal handling, has conducted an assessment of the short-term stresses of pigs during handling and transport and has determined there are many behavioral, physiological, and environmental factors interacting in complex ways that contribute to losses. These factors can come from improper pig handling, injury, high temperature and humidity, nutrition, ventilation, trucking, fighting, and disease.

Leading experts estimated at a recent symposium the incidence of transport losses in route to packing plants to be approximately 0.5%. A leading cause of these losses in the swine industry has been attributed to the inherited skeletal muscle disorder known as Porcine Stress Syndrome (PSS). The gene responsible for this syndrome proliferated in the industry because it was highly correlated with increased carcass leanness. Although efforts have been underway to eliminate this gene from breeding stock, the gene still exists in some commercial herds.

Signs of Stress

Pigs respond to stresses with excessive increases in aerobic and anaerobic metabolism, intense heat production, increased carbon dioxide and lactic acid production and excessive muscle contraction. These stress responses are observed as red, blotchy skin (vasodilation of blood vessels to aid in heat release), increased panting (release of CO₂), and muscle tremors. Other generalized responses include increased heart and respiration rates and higher frequency of vocalization.

E.A. Pajor, Purdue University, reports that high lean pigs demonstrate an increased response to the stress of transportation, leading to more deaths on arrival. It has also been observed that genetic selection for high lean gain pigs has resulted in pigs with more excitable temperaments and they may be more difficult to move and handle.

Minimizing Losses

The National Institute for Animal Agriculture (formerly the Livestock Conservation Institute) and other experts have suggested recommendations to ensure proper pig handling.

By following these recommendations, stress can be minimized and pork producers can reduce transportation losses.

Recommendations from Experts

Handling and Moving Pigs

• Minimize the use of electric prods.

• If an electric prod is used, do not prod several times in rapid succession.

• Avoid caning, clubbing, kicking, and slapping pigs.

• Spend five minutes a week in the pen during the entire finishing period to accustom the pigs to human contact.

• Ensure lighting is bright and evenly distributed in moving areas.

• Rely on the animals’ natural tendency to follow “leaders” into strange areas
  rather than forcing the entire group.

Loading Pigs

• Withhold feed six to eight hours prior to loading.

• Move very small groups of five or six at a time with a three foot wide
  alley and only three pigs at a time with a two ft. alley.

• Take each small group of pigs immediately from the finishing pen to the truck.

• Do not store large groups of finishing pigs in an alley or holding pen.

• The number of pigs per running foot of truck floor (on a 92 in. wide truck)
  should be 2.2 (200 lb pig), 1.8 (250 lb pig), and 1.6 (300 lb pig).

• Decrease stocking density for heavier muscled pigs and when trucking in hot,
  humid weather.

• Avoid sharp turns in alleys.

• Loading chutes should have less than 20o angles.

Transport Pigs

• Use partitions to divide the load.

• Do not allow pigs to stand in a fully loaded truck; get moving immediately.

• Drivers should stop and start smoothly.

• Transport pigs very early in the morning and at night during high heat and humidity. Schedule trucks so that pigs can be unloaded promptly at the packing plant.