Effects of tryptophan supplementation on aggression among group-housed gestating sows1

Abstract

The objective of this study was to determine the effects of dietary Trp supplementation on mixing-induced aggression and the associated stress, and on reproductive performance in gestating sows. After weaning, sows were mixed in pens with electronic sow feeders on concrete-slatted floors. Each pen housed 21 ± 2.8 sows, with approximately 2.7 ± 0.43 m(2)/sow of floor space allowance. Multiparous sows (n = 168) from 8 breeding groups were used, with 4 groups assigned to a control diet and 4 groups assigned to a high-Trp diet. Control sows received corn- and soybean meal-based diets throughout gestation (0.15% Trp) and lactation (0.21% Trp). Three days before and after mixing, sows assigned to the high-Trp treatment received approximately 2.3 times the dietary Trp (0.35% in the gestation diet and 0.48% in the lactation diet) fed to control sows. Six focal sows (2 sows from each of parity 1, 2, and 3 or greater) in each pen were designated and videotaped for 72 h after mixing to determine the type and number of aggressive interactions among sows. Before and 48 h after mixing, saliva samples were collected from focal sows, and scratches were assessed on all sows. Data were analyzed using the FREQ and GLIMMIX procedures (SAS Inst. Inc., Cary, NC). Aggression among sows was intense during the initial 6 h and decreased between 6 and 72 h after mixing. The initial aggression caused scratches and increased cortisol concentrations (P < 0.05). Mature sows tended to fight for longer periods (112 vs. 52 s/h per sow, SE = 23.8; P < 0.10) but had fewer scratches caused by aggression (injury score = 4.3 vs. 6.5, SE = 1.13; P < 0.01) than parity-1 sows. Supplementation of dietary Trp reduced the total duration of head-to-head knocking (P < 0.05) but did not affect other aggressive behaviors. There was no difference between dietary treatments in injury scores or saliva cortisol concentrations. Sows in the high-Trp treatment had more total piglets born (12.5 vs. 10.5 pigs/litter, SE = 0.55; P < 0.05) and more stillborn piglets (1.5 vs. 0.8 pigs/litter, SE = 0.20; P < 0.05), but had no significant change (P = 0.12) in piglets born alive (10.8 vs. 9.7 pigs/litter, SE = 0.42) compared with control sows. The results indicate that the initial aggression after mixing caused more injuries in young sows than in mature sows. Supplementation of dietary Trp at 2.3 times the control amount for a short period did not effectively reduce aggression and the associated stress in sows at mixing.

Effects of distillers‘ dried grains with solubles on behavior of sows kept in a group-housed system with electronic sow feeders or individual stalls

“…Parity 2 sows were more aggressive, fought more frequently, tended to fight for longer periods, and won more fights at mixing compared with parity 1 sows. These results are consistent with previous studies in which older sows were more aggressive at mixing compared with younger sows (Strawford et al 2008;Li et al 2011). Since focal sows were young (in parity 1 and 2) in the group, focal sows won few fights (ranged between 26 and 8% of total fights) in which they were involved, which agrees with results of previous studies that younger sows won few fights compared with older sows (Krauss and Hoy 2011;Li et al 2012).…”

“…Since focal sows were young (in parity 1 and 2) in the group, focal sows won few fights (ranged between 26 and 8% of total fights) in which they were involved, which agrees with results of previous studies that younger sows won few fights compared with older sows (Krauss and Hoy 2011;Li et al 2012). Focal sows were also less aggressive during nighttime than daytime, as reported previously (Arey and Edwards 1998;Li et al 2011).…”

“…In this study, one of the major findings was that DDGS sows were more aggressive than CON sows at mixing in the group-housed system. Sows fed DDGS fought more frequently and for longer periods in parallel pressing fights, which are the most intense and aggressive interaction and cause most injuries in sows (Turner et al 2006;Li et al 2011). To our knowledge, this is the first published study to investigate the effect of dietary DDGS on aggression among group-housed sows.…”

Effects of short term supplementation of l-tryptophan and reducing large neutral amino acid along with l-tryptophan supplementation on growth and stress response in pigs

“…However studies with rainbow trout have shown that dietary supplementation with l-Trp for 7 days before mixing-stress resulted in an inhibition of aggressive behavior and a reduced secretion of stress hormones, whereas 3 days of l-Trp supplementation before mixing-stress have no effects (Winberg et al, 2001;Lepage et al, 2003). Li et al (2011) shown dietary supplementation of l-Trp (0.29%) at 2.3 times of the control amount for 3 days prior social stress did not effectively reduce aggression of gestation sows at mixing. Therefore, the necessity and the amount of time for short term supplementation of l-Trp before mixing on controlling stress of pigs facing stress need to be further investigated.…”

Tryptophan diet reduces aggressive behavior in male mice.

“…Such behavior can be modulated by supplementation with low doses of tryptophan (Trp). Diets rich in Trp can modulate behavior in various species, including fish (matrinxã Brycon amazonicus; Wolkers, Serra, Hoshiba, & Urbinati, 2012), sows (Li, Baidoo, Johnston, & Anderson, 2011), dogs (Bosch, Beerda, Hendriks, van der Poel, & Verstegen, 2007), horses (Grimmett, & Sillence, 2005), Wistar rats (Kantak, Hegstrand, Whitman, & Eichelman, 1980), and mice . Tryptophan deficiency might also lead to an intensification of aggression in several species, including humans .…”