Relationship between pre-partum relaxin concentrations and farrowing intervals in the pig.
Gilts were treated on Day 112 of gestation with saline or a prostaglandin (PG) F-2 alpha analogue. In control gilts there was a rise in the relaxin concentration from 48 h before the onset of delivery, peaking between 12 and 28 h pre partum followed by a steep fall. The relaxin concentrations at each 1-h time interval were analysed in relation to the farrowing interval for each gilt using correlation analysis. There was a significant (at least P less than 0.05) positive correlation between the relaxin concentration and the farrowing interval at every time period from 14 to 2 h before delivery. In contrast there was little relationship between concentrations of progesterone, oestrone and oestradiol-17 beta and farrowing intervals. The gilts treated with PGF-2 alpha analogues had steroid profiles indistinguishable from those in controls but differing relaxin secretion patterns. Relaxin concentrations peaked at 1-2 h after PGF-2 alpha injection and this was followed by a second smaller increase closer to the time of delivery in 7 out of 12 gilts. The 'two-peak' gilts had significantly higher relaxin concentrations at farrowing and took significantly longer to farrow than did the 'one-peak' gilts (P less than 0.005). These results suggest that high relaxin concentrations during the last 14 h before the onset of parturition are associated with increased farrowing times, but are not associated with any increase in neonatal mortality.
Wathes
D C
DC
Department of Anatomy, Medical School, Bristol, UK.
King
G J
GJ
Porter
D G
DG
Wathes
C M
CM
D000818:Animals; D003008:Cloprostenol / Q000494:pharmacology; D015237:Dinoprost / Q000494:pharmacology; D005260:Female; D007743:Labor, Obstetric / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D012065:Relaxin / Q000097:blood*; D013552:Swine / Q000097:blood*; D013997:Time Factors
D003008:Cloprostenol; D012065:Relaxin; D015237:Dinoprost