Limiting transport stress in US and NZ pig systems

Take-home message: Giving weaned pigs food and water during transportation could enhance welfare of animals in United States and New Zealand production systems

Transporting pigs at weaning from breeding to finishing units is an increasingly popular practice in US and New Zealand pig units to help reduce disease transfer and increase productivity.

However, transportation for long distances can affect pig health and welfare, especially amongst animals already experiencing weaning stress.

Transport duration, withdrawal from feed and water, fluctuating temperatures, stocking density, mixing with unfamiliar pigs and motion are some of the issues that have the potential impact the welfare of pigs transported at weaning.

Scientists from Texas Tech University aimed to investigate whether transport stress adds to weaning stress, or if weaning is already causes such stress that adding transport has little additional negative effect.

In the study 120 pigs aged between 18–22 days old were observed in groups of 24, with equal numbers of each sex. The males were castrated at three days old.

The study, published in the journal Animals, evaluated the effect of a 32-hour transport period and the provision of feed and water on the welfare of weaned pigs using measures based on behaviour (lying, standing, sitting, drinking and eating), changes in body weight and physiology.

The researchers from America and New Zealand found that the control pigs not weaned or transported had a 6.5% gain in body weight after 32 hours.

In weaned pigs their body weight decreased over time and this response was intensified by exposing them to a 32-hour transport period and withdrawing feed and water.

The neutrophil to lymphocyte ratio, a common blood test used to measure stress, was also elevated in pigs in response to an eight-hour transport period, or eight hours after weaning alone.

Except for the weaned pigs provided with feed and water, transported and weaned pigs continued to be different from control pigs until 16 hours after weaning or exposure to a 16 hours transport period.

Scientist Arlene Garcia said that the findings suggest that pigs experience an acute stress response due to transport and weaning, but these two stressors do not appear to be in addition to each other.

“Physiological measures associated with stress were identified along with significant changes in behaviour observed during and after transportation, which could also be an indication of stress,” she said.

“Overall, transportation has a negative effect on performance, physiology and behaviour of weaned and transported pigs, especially if not provided with feed and water for more than 24 hours.”

By Joanne Stocks, University of Nottingham

More information: Arlene Garcia, Glenna Pirner, Guilherme Picinin, Matthew May, Kimberly Guay, Brittany Backus, Mhairi Sutherland and John McGlone

Animals (Basel). 2015 Jun; 5(2): 407–425