Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2000
Publication Date: N/A
Interpretive Summary: When a pregnant sow is stressed, stress hormones cross through the placenta to possibly affect the fetus. Because modern production has the potential to stress sows, we examined the physiology of pigs whose dams were subjected to an artificial stressor during gestation. Findings from this study indicate that administering a compound to the sows to mimic prenatal stress results in a hyperactive stress system in the pigs such that later in life, they may overreact to a stressor. This suggests that prenatal stress in swine can detrimentally affect the pig in a manner which would compromise growth, health, reproduction and well-being during stressful situations later in life. Thus, an evaluation of the level of stress to which sows are exposed during gestation and the potential implications on physiology and behavior of the offspring is essential in order to enhance growth, reproduction, health and well-being, all of which could potentially yimprove the economic viability of swine production. Both industry and academic scientists working in the area of neonatal stress in swine will find that this information adds to our current knowledge base regarding the effects of prenatal stress on piglet health and well-being. This information will be particularly interesting to swine producers who are considering different management strategies and facilities for their gestating sows.
Technical Abstract: Modern livestock production is potentially stressful to swine. When a pregnant sow is stressed, cortisol (CS) crosses the placenta which can affect fetal development. This study examined the physiology and behavior of pigs from dams injected with adrenocorticotropic hormone (ACTH) during gestation, which replicates the effects of prenatal stress. Sows were given neither no treatment (Cont) or ACTH (1 IU/kg BW) weekly from 6 to 12 wk of gestation. A pig was sacrificed from each sow at 1, 30 and 60 d of age. Tissues were obtained to determine corticotropin releasing hormone (CRH), beta-endorphin (beta-END) content, and mRNA for pro-opiomelanocorticotropin (POMC, ACTH receptor (ACTH-R), and insulin-like growth factor 1 (IGF-1). Pituitary corticotrope and somatotrope cells and adrenal cortex-to-medulla ratios (CORT:MED) were also determined. Pig behaviors were recorded at 6 and 8 wk of age. At 75 d of age, blood was taken and a biopsy puncture created on one pig from each litter, then pigs were stressed by mixing. Blood was sampled every other day for 10 d to determine plasma CS and differential leukocyte counts. Biopsy damage was evaluated for healing. At 1 d of age, Cont pigs tended to weigh more, have lower ACTH-R mRNA and IGF-1 mRNA, and smaller CORT:MED. At 30 d of age, Cont pigs had greater beta-END, and tended to have lower CRH and IGF-1 mRNA. At 60 d of age, Cont pigs tended to have lighter pituitaries, lower POMC mRNA, and smaller CORT:MED. At 8 wk of age, Cont pigs performed more belly nosing and oral vice behaviors. In response to mixing stress, Cont pigs had lower CS and healed faster than ACTH pigs. Thus, exogenous ACTH during gestation causes a hyperactive HPA axis in the offspring and may compromise growth, health and welfare during stressful situations later in life.