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Title:   Author  item
                                            Vallet, Jeffitem
                                            Nienaber, Johnitem
                                            Brown-Brandl, Tamiitem
                                            Miles, Jeremy
  Submitted to: Midwestern Section of the American Society of Animal Science
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 11/8/2007
                                    Publication  Date: 9/20/2008
                                    Citation: Vallet, J.L., Nienaber, J.A., Brown Brandl, T.M., Miles, J.R. 2008. Maternal plasma progesterone and estradiol concentrations prior to farrowing are not associated with either birth intervals or stillbirth rates in pigs [abstract]. Journal of Animal Science. 86 (E-Supplement 3):107 (Abstract #234).Interpretive Summary:
                                Technical Abstract: Prolonged birth intervals are associated with stillbirth in pigs. Average birth intervals decrease as litter size increases, suggesting a cumulative negative effect of fetuses, placentas or both on average birth interval. Late gestation maternal plasma estrogen concentrations increase with litter size, suggesting that the litter size effect on farrowing interval might be estrogen mediated. The objective of this experiment was to determine associations between plasma progesterone or estradiol with gilt average birth interval and stillbirth rate. BX gilts (150) were mated at estrus and farrowing was monitored using cameras and videotaping equipment. The number of live and dead piglets born was recorded for each gilt. On d 110 and 113 of gestation, heparinized-citrated jugular blood samples were collected from each gilt and plasma was collected and frozen. Progesterone and estradiol were measured in each sample using radioimmunoassay. The average birth interval and stillbirth rate was calculated for each gilt, and relationships with plasma hormone concentrations were examined using PROC MIXED. After adjustment for the actual day of farrowing (range d 114 to 120), plasma progesterone concentrations began decreasing 3 days before farrowing, and estradiol concentrations increased linearly during the 10 days prior to farrowing. Plasma estradiol increased as litter size increased from 2 to 8 fully formed piglets, but did not change as litter size increased from 8 to 17 piglets. There were no significant relationships between plasma progesterone or plasma estradiol concentrations and either average birth interval or stillbirth rate. In addition, the significant relationship between average birth interval and litter size remained, even when plasma estradiol was simultaneously fit with litter size. These results indicate that progesterone or estradiol concentrations near the time of farrowing are unrelated to average farrowing intervals or stillbirth rate of gilts.


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