Shedding Some Light on Newly-Weaned Pigs

Weaning is one of the most stressful times in a pig's life. Not only does it mean big adjustments in social, thermal and physical environment, but it also means a huge change in diet form and composition. As a result, piglets often suffer from poor feed intakes and performance during this initial period following weaning, until they are able to adapt. To reduce stress during this period, many different techniques have been tried to encourage pigs to consume dry feed and to stimulate the development of digestive capacity. The goal is to minimize the potential for postweaning health problems, like diarrhea, and mortality.

Researchers have recently demonstrated that the majority of newly-weaned pigs do not start eating when it is dark. Armed with this information, the same researchers decided to investigate whether or not a prolonged period of light could stimulate feed intake during the first days of weaning. Forty 4-week-old crossbred weanling barrows, weighing approximately 8 kg, were randomly allotted to one of two lighting schedules for two weeks - 8 hours light:16 hours darkness or 23 hours light:1 hour darkness. The pigs were allowed ad libitum access to water and a commercial weaner ration for the duration of the experiment. Table 1 summarizes some of the performance results.

Lighting schedule did not affect the timing of the first visit to the feeder, or subsequent first feed intake, by newly-weaned pigs. However, this study showed that performance of weanling pigs is strongly affected by the lighting schedule used in the weaner room. A prolonged photoperiod (23 hours vs. 8 hours within a 24-hour period) resulted in an increase in feed intake and average daily gain (Table 1), as well as increased metabolizability of energy and decreased energy requirements for maintenance. Metabolizability refers to the ratio between metabolizable energy and gross energy intake.

The researchers suggested that pigs housed in the shorter photoperiod might have required more energy for recovery of the gut wall. Consequently, pigs that were exposed to a prolonged photoperiod were able to retain more energy and protein for growth and development. These effects were most pronounced during the second week after weaning. Considering performance and energy metabolism as a direct reflection of the health of the weanling pig, this study provides some clues for the use of lighting schedules within weaner rooms to optimize postweaning health and performance.

Table 1a. Growth performance of weanling pigs under different lighting schedules in Average Daily Feed Intake, g/d

Table 1b. Growth performance of weanling pigs under different lighting schedules in Average Daily Gain, g/d

Table 1c. Growth performance of weanling pigs under different lighting schedules in Gain:Feed

* 8L:16D = 8 hours of light followed by 16 hours of darkness; ** 23L:1D = 23 hours of light followed by 1 hour of darkness

^a,b = Within a row, means without a common superscript letter differ (P<0.05)

Source: Bruininx, E.M.A.M. et al. 2002. A prolonged photoperiod improves feed intake and energy metabolism of weanling pigs. J. Anim. Sci. 80: 1736-1745.