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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2009-2033v1 87/10/3218    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Kojima, C. J. Articles by Kattesh, H. G. PubMed PubMed Citation Articles by Kojima, C. J. Articles by Kattesh, H. G.

Effects of syndyphalin-33 on feed intake and circulating measures of growth hormone, cortisol, and immune cell populations in the recently weaned pig^1,2

C. J. Kojima^*,3, S. J. Jenkins^*, T. A. Cooper^*, M. P. Roberts^*, J. A. Carroll and H. G. Kattesh^*

^* Department of Animal Science, University of Tennessee, Knoxville 37996; and Livestock Issues Research Unit, USDA-ARS, Lubbock, TX 79403

³ Corresponding author: ckojima{at}utk.edu

The synthetic met-enkephalin syndyphalin-33 (SD-33) increases feed intake in sheep and transiently increases circulating GH concentrations in sheep, rats, and pigs. Two experiments were performed to evaluate the effects of SD-33 on recently weaned pigs. In a preliminary experiment, pigs were administered SD-33 (0.5 µmol/kg, given intramuscularly) or saline immediately before a 3-h transport and subsequent placement into group pens. Treatment with SD-33 increased (P = 0.01) daily feed intake; cumulatively, pen intake over 7 d postweaning tended (P = 0.06) to be greater than in control pens. In Exp. 2, pigs were weaned and fitted with jugular catheters. The following day, pigs were treated with SD-33 or saline as described above. Transient increases (P < 0.05) in circulating concentrations of GH (at 1 and 1.5 h postinjection) and cortisol (at 3.5 and 4 h postinjection) were observed in pigs treated with SD-33 relative to controls. No difference in feed intake was observed between treatments over 4 d postinjection. Increased (P < 0.05) numbers of circulating neutrophils, lymphocytes, and monocytes were observed in both treatment groups over 4 d postinjection, and treatment with SD-33 tended (P = 0.07) to selectively increase monocyte numbers. Although SD-33 has potential to be used to increase feed intake and decrease the negative effects of stress during weaning in pigs, further investigation is needed to better understand the timing of effect and to rule out possible immunosuppressive effects.

Key Words: appetite • opioid • pig • stress • weaning