Effects of Photoperiod (light) on Weanling Pig Performance - A summary

by 5m Editor
10 February 2003, at 12:00am

By Christina Wiggins, MU Animal Sciences student - Weaning time is stressful for every animal. Large amounts of stress can be damaging to an animal's future performance. During this time there is a high potential for morbidity and mortality. To lessen the adverse effects of stress on weanlings every precaution should be taken to make the transition as easy as possible.

The length of the photoperiod (light) can have a significant effect on the performance of weanling pigs

It has been shown that pigs experience a decrease in feed intake shortly after weaning. The decrease in feed intake is associated with atrophy and inflammation of the small intestine.

Damage to the small intestine can cause health problems and a decrease in nutrient absorption. It has also been discovered that weanling pigs do not start eating during the dark periods of the day. A study was conducted in the Netherlands to observe the effects of an extended photoperiod on feed intake and energy metabolism of weaned pigs (Bruininx et al., 2002).

Two groups tested
Two groups of twenty pigs each were assigned to one of two lighting schedules: 8 hours light with 16 hours dark and 23 hours light with 1 hour dark. After removal from the farrowing house the pigs were placed in climate controlled respiration chambers. These specially designed pens are capable of maintaining a constant temperature and humidity and a means of measuring heat production and energy metabolism. Feeders constructed to minimize spillage were placed on scales for measurement of feed consumption, and pigs were allowed unrestricted access to feed and water.

During the first 48 hours of the experiment the pigs were filmed to determine the time before visiting the feeder, and scales were placed under the feeders to measure the amount of feed consumed during these visits.

Both groups began the experiment in darkness. Total trial time was two weeks. During the first week no significant differences were seen between the two groups, though several trends were noticed. During the second week the pigs receiving 23 hours of light performed better than those only receiving 8 hours of light.

Average daily gain
Average daily feed intake of the 23-hour pigs was 1.56x10-5 pounds per day higher than the 8-hour pigs, thus average daily gain was also higher for the 23-hour group.

Feed efficiency was higher during the second week for the 23-hour pigs, though when averaged over the entire trial length was not significantly different between the groups.

Video records of the pigs during the first 48 hours of the experiment revealed no difference in the time of the first visit to the feeder or the moment of the first feed intake.

Energy intake and metabolizability
Differences in energy intake and metabolizability (energy left after losses to feces, urine and gases divided by energy consumed) were similar to those seen with feed intake. The 23-hour pigs had a 3.2% higher metabolizability than the 8-hour group. The 23-hour group also had higher energy retention as protein or fat and a higher hourly feed intake when compared to the other group.

The trend of a lower feed intake of the 8-hour group may have impaired digestive function of the pigs due to an atrophy of the small intestine. Because the small intestine is not working to its potential the pigs would not be able to efficiently digest their feed, resulting in the decrease in metabolizability and retention of energy as protein or fat. The damaged intestines would also increase their maintenance energy requirements because more energy is required for the repair of the gut wall.

In summary
The effects of a prolonged photoperiod can have an influence on average daily feed intake, average daily gain and feed to gain ratios. When using these values as an indicator of the health of weanlings, lighting schedules can have a strong influence on the performance and post-weaning health of the pigs. This study demonstrated that the amount of time a pig spends in the light could affect their feed intake, energy metabolism and health, and leaving the lights on a little longer is a simple management practice.

Bruininx et al. A Prolonged Photoperiod Improves Feed Intake and Energy Metabolism of Weaned Pigs. Journal of Animal Science, 2002, 80:1736-1745

Source: AgEBB, Swine Production News, Christina Wiggins, University of Missouri Animal Sciences student - Jan 2003