Date Full Report Received


Date Abstract Report Received



Primary Investigator:
Co-Investigators: Brian Richert, Avi Sapkota

Laws have been passed in several states requiring group housing for pregnant sows. However, the predominant problem with group housing sows is aggression. Different approaches, such as changing group size, space per sow, advanced technologies (such as electronic sow feeding), and change in diet and feeding pattern etc., are still being evaluated to reduce aggression and improve sow welfare. One of the approaches taken to reduce aggression and improve welfare of the pregnant sows could be feeding high-tryptophan diets. A high tryptophan diet has been shown to reduce aggression and fights and thus improve welfare of grow-finish gilts and nursery pigs. A diet high in tryptophan could also be used to decrease aggression in pregnant sows, however, the impact of such a diet on her subsequent offspring has not been studied. This research examined the effect of feeding high tryptophan diets during the fourth week of pregnancy on production, behavior, performance, and welfare of the piglets. During gestational days 28 to 35, York x Landrace multiparous sows were fed 1 of 3 diets: Control (0.14% tryptophan), Medium (0.28% tryptophan), or High (0.42% tryptophan). Blood samples were taken prior to and after tryptophan supplementation. Sows were gestated in standard gestations stalls and then were transferred to farrowing stalls at 112 days of gestation. Time budgets of the sows and pigs were recorded for 24 hours, during three separate days prior to weaning. To determine how their subsequent piglets responded to novelty, fear, and social situations, starting at 14 days of age the piglets were challenged with an isolation test, a human approach test, and a social challenge test. Behavior and vocalizations were recorded. Blood samples were taken from the pigs prior to the tests and immediately after the social challenge test. Productivity of the sows proved to be equal, with sows producing similar sized litters and weaned pigs. Teat aggression during nursing bouts did not differ among treatments. High pigs performed fewer nursing bouts than did pigs in the other two treatments. The Isolation Test, Human Approach Test, and Social Challenge Test were all used to determine how the pig coped with stress and novelty. The first two tests found that pigs from all three treatments reacted similarly to these challenges. The Social Challenge test found that High pigs confronted the head of another pig more often, with Medium pigs in between. The time budget data indicated similar amounts of activity for pigs in all three treatments, showing that the nervous system in general had not been altered. In conclusion, feeding high concentrations of tryptophan for a short duration early in gestation does not have a negative impact on sows’ subsequent offspring.