Influence of genotype-environment interaction on stress parameters during spontaneous farrowing in modern and traditional pig breeds housed in crates and pens

The transition from farrowing crates to farrowing pens aims to improve animal welfare by enabling the expression of maternal behavioural profiles. This study examines the spontaneous farrowing process in both farrowing crates and pens for modern German Landrace (GL) and traditional German Saddleback (GS) pigs - two breeds with different breeding histories and adaptations to housing systems. The goal is to investigate whether, and how, both breeds benefit equally from farrowing pens. From the birth of the first piglet until 1 h after the last delivery (intrapartum; ip), half-hourly blood samples were collected from catheterized sows in addition to blood samples retrieved from antepartum (ap) and postpartum (pp) periods. After spontaneous, non-induced farrowing, the traditional GS breed exhibited a significantly shorter gestation length, smaller litter weight, and a lower incidence of labour dystocia compared to modern GL sows. Breed effects were observed for profiles of heart rate (ip: GL > GS), cortisol (ap: GL < GS; ip: GL < GS), adrenaline (ap: GL < GS), noradrenaline (ip: GL < GS), non-esterified fatty acids (ap: GL < GS; ip: GL < GS), glucose (ap: GL > GS), and β-hydroxybutyrate (ap: GL < GS) at distinct peripartum periods. Effects due to housing appeared for heart rate (ap: crate > pen) as well as respiratory rate (crate < pen) and adrenaline (crate > pen) at distinct time points. Taken together, breed-specific endocrine control and energy-related metabolic properties might suggest a need for tailored housing conditions during parturition for modern and traditional sows.