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Identification of Anorexic Piglets During the First Week After Weaning

16 April 2014

A study at the University of Guelph has revealed a biochemical marker, which could be used to identify piglets that are not eating solid feed after weaning. This would improve husbandry at this critical stage, they said, as visible clues are easy to overlook.


Weaning can be a challenging and stressful event for piglets as they transition from a liquid milk diet to ingestion of solid feed, Terri O’Sullivan of the University of Guelph told the 2014 Centralia Swine Research Update meeting. Piglets that remain healthy and transition smoothly onto solid feed after weaning are more likely to continue to thrive through the nursery period.

There are a variety of factors that influence the transition period such as the underlying health of the herd and management strategies.

Yet, despite optimum health and management policies, there still seems to be a small proportion of piglets that do not readily adapt to solid feed, experience a period of extremely low voluntary feed intake, and subsequently fail to thrive1. This period of under-eating can lead to health and welfare concerns and compromise growth and production.

Maximising our ability to rapidly identify off-feed piglets and to further understand the factors that contribute to a successful transition would aid in minimizing these production, health, and welfare concerns.

The objectives of this project were to investigate behavioural and biochemical changes associated with anorexia in piglets at weaning and to determine their response, once fasted, to the re-introduction of feed.


The following studies were reviewed, approved and monitored by the University of Guelph Animal Care Committee.

Study 1

Twelve piglets, all exactly 21 days of age, were randomly assigned to one of two treatment groups and matched by litter and sex. Piglets were housed individually. Group 1 (FED; n=6) was fed a weaned pig diet free-choice for eight days. Group 2 (FAST; n=6) was fasted for up to eight days.

Free-choice access to water was available to all piglets.

Piglets were monitored twice daily and closely examined for evidence of hypothermia, weight loss/gain, general demeanor/posture, infectious disease and behavioural changes. All piglets had blood samples taken on days 0, 4 and 7 during the study to measure changes in biochemical parameters. Environmental conditions of the room were monitored.

At the completion of the trial, all piglets were humanely euthanised and comprehensive post mortem examinations were performed.

Study 2

A separate group of piglets, all exactly 21 days of age, were randomly assigned to one of two treatment groups and matched by litter and sex. These piglets were housed in an identical manner to the piglets in Study 1.

Group 1 (FED; n=6) was fed a weaned pig diet and water free-choice for eight days. Group 2 (FAST-FED; n=6) was fasted for up to eight days, had access to water free-choice and then had the weaned pig diet introduced on day 8.

All piglets had the same monitoring and blood sampling schedule as for Study 1 with the addition of blood sampling after re-introduction of solid feed.


Study 1

All FAST piglets developed behavioural changes and displayed repetitive chomping and licking starting as early as three days fasted with all piglets demonstrating the behaviour by five days fasted. None of the FED piglets developed these behavioural changes.

The most predominant biochemical change noted between the groups was a higher level of beta-hydroxybutyrate (BHBA), a serum ketone, in FAST piglets by four days fasted (P<0.001, using multilevel linear regression).

Two FED piglets developed mild diarrhoea by day 5. None of the FAST piglets exhibited any clinical disease. Body condition scoring was an insensitive method of determining which pigs were fasted, even after seven days of fasting.

Study 2

The FAST-FED piglets developed the same behavioural and biochemical changes as did the FAST piglets in Study 1.

None of the piglets developed clinical disease.

All FAST-FED piglets consumed feed when re-introduced, following which their BHBA levels rapidly normalised from elevated levels experienced during the fasting period.

Take Home Message

This study demonstrated that off-feed piglets will develop high levels of the ketone, BHBA, in their blood and that this will normalise when eating resumes. This is a potential biochemical marker that could be used for on-farm management and future studies focused on anorexia in the post-weaning period.

In this study, body condition scoring and general observations for clinical disease were insensitive measures for identifying off-feed piglets.

It was interesting to observe that the fasted piglets looked similar to the pigs that had free choice of food.

This suggests that when we identify piglets on-farm that appear to be off-feed in the first week after weaning, there is likely some other factor beyond just “not eating” contributing to their lack of feed intake.

Further research is being done to investigate the utility of using BHBA measurements and behavioural observations on-farm for identifying these off-feed piglets.

O'Sullivan and co-authors concluded that improving our ability to identify piglets that experience a voluntary fast is imperative for the continued understanding of the risk factors associated a smooth transition onto solid feed.

Reference cited: O’Sullivan T.L., Harding J.C.S., Friendship R., et al. 2014. Estimated prevalence and impact of periweaning failure to thrive syndrome in Canada and the United States. J Swine Health Prod. 22(1):24–28.

Acknowledgements: This study was funded by the Canadian Swine Health Board and the University of Guelph-OMAFRA Research Partnership.


O’Sullivan T., R. Friendship, J. DeLay and J. Harding 2014. Identification of anorexic piglets during the first week after weaning. Centralia Swine Research Update 2014. I-27–I-28.

Further Reading

You can view the full paper by clicking here.
Read other papers from the Centralia Swine Research Update 2014 by clicking here.

April 2014

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