Interference of stress with the somatotropic axis in pigs – lights on new biomarkers

Abstract

The acceptance of animal products is increasingly associated with standardized animal welfare, which relates to appropriate animal husbandry from birth to slaughter. In particular, shipment to the slaughterhouse is considered as a critical process exposing the animals to a number of, in part severe, stressors. New biomarkers may be useful for the assessment of animal welfare. The IGF-system has been assessed in a commercial pig transport in conjunction with established markers of stress response. Furthermore, the effect of repeated restraint as an experimental model for repeated acute stress was investigated. During shipment from farm to slaughterhouse, plasma concentrations of IGFBP-3 and IGFBP-2 were significantly reduced (p < 0.01). After shipment, the plasma concentrations of IGFBP-5, glucocorticoids and IL-2 increased but decreased after lairage (p < 0.05) whereas IGF-1 decreased after shipment (p < 0.01). Repeated acute stress increased concentrations of IGFBP-3 and IGF-1 in exsanguination blood (p < 0.05). Differential IGF- signatures can indicate altered endocrine or metabolic control and thus contain complex animal-related information. The somatotropic axis may be of particular interest when established biomarkers such as cortisol, glucose, or lactate cannot be used for the assessment of animal stress or welfare.

Effects of Transport Duration and Environmental Conditions in Winter or Summer on the Concentrations of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Plasma of Market-Weight Pigs

“…Food was removed from pigs transported for 6 and 12 or 18 h for 20 and 24 h, respectively. As previously described, fasting did not affect the circulating levels of IGF-1 and IGFBPs within the time frame of this experiment ( 9 ). The pigs had no access to water on the truck, but water was available in lairage.…”

“…The collection of exsanguination blood directly after the slaughtering of pigs is a suitable, non-invasive technique for the evaluation of the physiological response to different transport durations and preslaughter conditions. As described in preliminary studies ( 9 ), cortisol concentrations, measured in exsanguination blood, were not affected after prolonged duration of shipment. Though, insulin-like growth factor-binding protein (IGFBP)-2 concentrations decreased over time due to the length of shipment indicating biomarker potential for components of insulin-like growth factor (IGF) system.…”

“…Due to a stronger reduction of IGFBP-2, the ratio of IGFBP-3/IGFBP-2 increased after 18 h of transportation. An increase of IGFBP-3/IGFBP-2 ratio was also reported in plasma of pigs subjected to repeated restraint stress in the preslaughter period ( 9 ) indicating that this ratio might reflect increased stress conditions before slaughtering. In fact, in a previous study ( 24 ), 18 h of transportation were considered as a more stressful condition because the animals were characterized by higher body temperatures or greater drinking and differential resting behavior, compared to 6 or 12 h transports.…”

“… Effect of transport duration on insulin-like growth factor (IGF)-axis: insulin-like growth factor-binding protein (IGFBP)-2 (A) , with kind permission from Nature Publishing Group as previously published in Ref. ( 9 ), IGFBP-profile (B) , IGFBP-3 (C) , IGFBP-5 (D) , IGF-I (E) , and IGF-II (F) . Quantitative data are presented as LS-Means + SE and include the summarized data of the trials in January/February and July due to the absence of the significant interaction duration × environment (* p < 0.05, ** p < 0.01, *** p < 0.001, # p < 0.1, rh: recombinant human, quality control: pig plasma sample).…”

Exploring the mechanistic link between corticosterone and insulinlike growth factor-1 in a wild passerine bird

“…For instance, in response to 5 minutes of restraint, circulating IGF-1 levels decreased by 21% within 60 minutes in Yorkshire pigs Sus crofa domesticus and remained suppressed for up to 150 minutes (Farmer et al, 1991). A more recent study in pigs also found that restraint stress caused a drop in circulating IGF-1 levels and affected other components of the IIS pathway, suggesting that the IGFsystem represents a physiologically relevant biomarker of stress response (Wirthgen et al, 2017).…”