A Diet Fortified with_l-lysine and_l-arginine Reduces Plasma Cortisol and Blocks Anxiogenic Response to Transportation in Pigs

Abstract

We studied the effects of diet fortified with L-lysine HCl (Lys) and L-arginine (Arg) on stress (transportation) responses in male finishing pigs (Landrace x LargeWhite x Duroc). Pigs (n = 16) were randomly divided into two equally sized groups so that the average starting body weight in the groups was identical. For 1 week immediately preceding the transportation, the first group of pigs received a control diet while the second group received a Lys and Arg fortified diet. Plasma aminogram, cortisol and body weight were evaluated. Behavior of pigs was measured with the help of a video camera, recorded for 2 h at the same time, as on the day, before a day and immediately after transportation. The study revealed main stimulatory effects of transportation and main inhibitory effect of Lys and Arg on plasma cortisol (P < 0.05) without transportation x treatment interactions. Pigs fed with Lys and Arg diet tend to have higher body weight at the end of the experiment, when compared to their normally fed counterparts, but the difference did not reach a significant level (P < 0.21). Lys and Arg diet significantly inhibited stress-induced increase in locomotion (P < 0.05), without affecting feeding pattern. Transportation stress decreased plasma Lys and Arg. This decrease was reversed in the fortified group, and what is more the plasma Lys and Arg levels were significantly higher than in controls (P < 0.05). Lys and Arg enhanced plasma urea production (P < 0.05), without regards to stress. The behavioral results indicate a reduction in stress-induced anxiety in pigs fed with Lys and Arg fortified diet, that parallels similar observations in research with rats and broilers. The mechanism probably involves a decreased plasma cortisol, and/or normalized plasma Lys, Arg levels.

Oral treatment with L-lysine and L-arginine reduces anxiety and basal cortisol levels in healthy humans

“…Although histochemical studies (26,27) revealed that the predominant source of salivary chromogranin A is salivary glands themselves, this protein directly reflects the sympathetic tone and sympathetic stress response (13,21,22,38). The results agree with previously obtained human data (34) and, at hormonal level, correspond to the results reported in pigs (37). While all subjects tested in the trial were found healthy by a physician, it was assumed that most of the participating subjects were concerned with the level of mental stress in their daily lives.…”

“…Recent results have indicated that the essential amino acid L-lysine (Lys), which is not a direct neurotransmitters precursor, reduces anxiety (34) and normalizes stress-induced hormonal responses in otherwise healthy subjects with relatively high perceived anxiety (11) and when applied with L-arginine (Arg), blocks stress-induced pathologies in laboratory and farm animals (31,32,37). Physiological mechanism underlining the above effects is probably coupled to Lys acting as a partial serotonin receptor 4 antagonist (9,33) and simultaneously as a partial benzodiazepine agonist (2,3).…”

The impact of the transport distance and season on losses of fattened pigs during transport to the slaughterhouse in the Czech Republic in the period from 1997 to 2004

“…By meeting the requirements of the transport conditions, the pig stress burden can be reduced. They are especially the conditions reported for example by Lambooy and Engel (1991), Schutte et al (1994), Fischer (1995), Troeger (1995), Perremans and Geers (1996), Geverink et al (1998), Warriss (1998b), Srinongkote et al (2003), Kozak et al (2004), Kuchenmeister et al (2005), which means especially that the careful and humane treatment of the animals, regular moving and handling, loading and unloading, mixing with unfamiliar conspecifics in the loading space, loading density, ambient temperature, transportation time, careful driving, and feeding pigs before transport. Genetic predisposition also has a significant impact on pre-slaughter pig mortality, as reported by Murray and Johnson (1998), Warriss (1998a), Werner et al (2005).…”

“…Mortality increased in pigs fed within 4 hours of transport. Srinongkote et al (2003) studied the impact of a diet fortified with L-lysine and L-arginine on the plasmatic levels of cortisol in transported pigs. In the pigs with L-lysine and L-arginine fortified diet, they determined lower plasmatic levels of cortisol than in the pigs with a diet without the addition of L-lysine and L-arginine.…”

Lysine fortification reduces anxiety and lessens stress in family members in economically weak communities in Northwest Syria

“…This study, which was a part of a larger wheat fortification trial, was based on a hypothesis that fortification of a lysine inadequate diet in poor communities may reduce anxiety and improve stress response, thereby potentially improving the quality of life. The hypothesis originated from studies that found worsening of stress-induced anxiety and colonic health in rats fed a lysine-deficient diet (9) and an improvement of stress responses in rats and pigs receiving lysine loads (10,11). The anxiogenic response to lysine inadequacy in rats was mediated via serotonin alterations in the central amygdala (9), the brain region functionally comparable in rodents and humans (12).…”