Effect of short-term high tryptophan diet fed to sows on their subsequent piglet behavior

Abstract

Housing sows in groups creates the challenge of decreasing fighting amongst sows. One proposed method to do so is to feed a high tryptophan diet, but the effect on the fetus is unkown. To investigate this, 66 sows were fed 1 of 3 diets: Control (0.14 % SID tryptophan), Medium (0.28 % SID tryptophan), or High (0.4 2% SID tryptophan), from d 28 to 35 of gestation. Sows gestated in standard gestation stalls. Blood samples were taken on d 27 prior to and on d 35 after tryptophan supplementation. On d 1 and d 2, 3 nursing bouts were observed so as to record disputes and displacements from teat competition. The piglets’ activity and fighting were recorded on d 3, 7, and 11 from 0700 h to 1700 h. On d 12, 4 piglets per litter were blood sampled, 2 to be used in later behavior tests and 2 to act as controls for blood cortisol levels. On d 14, the 2 behavior test piglets from each litter were subjected to a 10-min Isolation Test and 5-min Human Approach Test. On d 15, the behavior test piglets were paired by sex and treatment (for example, a male Medium piglet paired with another male Medium piglet from a different crate) and each pair was subjected to a 10-min Social Challenge Test and immediately blood sampled. Piglet cortisol and serotonin did not differ among treatments (P > 0.10). There were no differences (P > 0.10) for number born (12.7 ± 0.4), born alive (11.7 ± 0.4), or mortality (1.1 ± 0.2). Behavior during nursing bouts was similar, with no treatment differences in number of disputes or displacements, and similar bout lengths among treatments (199.5 ± 4.6 s, P > 0.10). No differences were detected for any of the variables for Isolation or the Human Approach Tests (P > 0.10). During the Social Challenge Test, High piglets had more contacts approaching the head of the companion piglet than did either Medium or Control piglets (14.3 ± 1.1, 10.7 ± 1.1, and 9.69 ± 0.8 respectively, P < 0.02). Total number of aggressive interactions during the test tended to be greater for Medium piglets compared to High piglets (9.3 ± 1.5 vs 5.1 ± 0.9, P < 0.07). Time budget data of the litter indicate that piglets from all 3 treatments spent equal amounts of time active and inactive (P > 0.10). Aggression was low with 0.3 ± 0.04 % of piglets displaying aggressive behavior. Feeding high concentrations of tryptophan for a short duration early in gestation does not have a negative impact on sows’ subsequent offspring.

Intestinal tryptophan metabolism in disease prevention and swine production

“…(2010) Large White × Landrace 28 0.37% Reduced aggressive behavior Poletto et al. (2014) Large White × Landrace 28 Trp-enriched diet Increased exploratory activities Lay et al. (2021) Landrace × Yorkshire 0.35% in gestation and 0.48% in lactation Decreased head-to-head knocking behaviors Li et al.…”