|Rault, Jean-loup - Purdue University|
|Carter, Sue - University Of Illinois|
|Garner, Joseph - Purdue University|
|Richert, Brian - Purdue University|
|Lay, Jr, Donald - Don|
Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2011
Publication Date: 7/11/2011
Citation: Rault, J., Carter, S., Garner, J., Marchant Forde, J.N., Richert, B., Lay Jr, D.C. 2011. Effects of oxytocin administration in early life on the behavioral and physiological stress response of swine. Joint Abstracts of the American Dairy Science and Society of Animal Science. Proceedings.
Technical Abstract: The swine industry is moving toward the group-housing of sows. However, group-housing can result in increased aggression and social stress, with detrimental effects on swine health and productivity. In contrast, positive social relationships can reduce the adverse effects of social stress. This might be mediated by oxytocin (OT), a neuropeptide underlying social behavior, possibly by buffering the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesized that stimulating the oxytocinergic system of piglets early in life, by chronic post-natal OT administration, could provide long-term protective effects against social stress. In each of 6 litters, 2 piglets per litter received 0.25 mL (24 IU, or 50 µg) of OT intranasally (OT) and 2 control littermates received 0.25 mL of saline (SAL) on postnatal d 1, 2 and 3. Each piglet was weaned at d 19 and mixed into a pen with 4 unfamiliar piglets. This social mixing was repeated from the nursery to growing phase at 8 wk of age. On each occasion, we collected behavior and blood samples to analyze cortisol, adrenocorticotropic hormone (ACTH), and immunological parameters over 3 d post-mixing. The pigs were then submitted twice to a resident-intruder test at 10 wk of age, and finally to a dexamethasone-corticotropic releasing hormone (Dex-CRH) challenge at 11 wk of age. Results were analyzed using a mixed model in SAS. Pigs given OT had higher ACTH concentrations than SAL pigs at 24 h after weaning (P < 0.05) and mixing at 8 wk (P < 0.1). Yet, cortisol concentrations did not differ between treatments (P > 0.1). The Dex-CRH challenge revealed that OT pigs were less responsive to dexamethasone than SAL pigs (P < 0.05). At 24 h after weaning, OT barrows had a higher neutrophil:lymphocyte ratio compare to other pigs (P < 0.05). The behavior of OT pigs did not differ from SAL pigs after mixing (P > 0.1), nor did weight gain from birth to slaughter (P > 0.1). Administrating OT in early life modified the HPA axis. Contrary to our prediction, OT may have dysregulated the negative feedback loop of the HPA axis, leading to detrimental consequences in coping with social stress.