The effect of dietary L-Tryptophan on productive performance and behavion of weaned piglets

Keywords: rearing, stress, nutrition, aggressive behavior


This study was carried to determine if dietary tryptophan can be beneficial for piglets in period of weaning. Trial was conducted on 84 individuals (Landrace×Yorkshire) female and castrated male piglets, at 30 days of age, and of 9.78±0.42 kg. Test subjects were penned into four groups and allocated to four different diets. This was done opposite to standard farm procedure; all piglets penned in same group came from different litters. Animals were fed ad libitum for six days. Piglets in trial groups were fed with basically same mixture with different levels of digestible L-tryptophan (0.1; 0.2; 0.3%). Productive performance (FCR; ADG; ADFI) was calculated and behavior characteristics (postures, mounting, abnormal and aggressive behavior) were observed using CCTV cameras. For the purpose of production performance analysis one way ANOVA was used while the Tukey test served
to determine the statistical significance of the differences between individual means values. Considering that there is no normal
distribution for behavioral parameters, we used non parametric Kruskal-Wallis test with multiple comparisons of mean rank
between groups. Productive results showed that control group had significantly better results for average daily gain compared
to all trial groups (p<0.05), other productive parameters didn’t show any significant difference. On the other hand, statistically
significant results occurred for two behavioral characteristics. Fighting differed significantly (p<0.05), during first day of weaning
between control and trial groups, intensive ear biting occurred at day two and three after weaning, and different significantly
on day three (p<0.05). According to our results tryptophan had no positive effects on productive performance (feed intake, daily
weight gain and feed conversion), but had some positive effects on reducing aggressive behavior. Conclusion could be that implementing
small doses of tryptophan on weaning can be beneficial to reducing stress and behavioral anomalies of piglets. Further
more extensive studies should be carried to verify these results.

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