Detection of late embryonic mortality by means of ovine pregnancy-associated glycoproteins
Conference Contribution ResearchOnline@JCUAbstract
In sheep, conception rates of 80% are obtained after first mating. Some of the ewes that were not pregnant may have conceived, but underwent embryonic mortality. Embryonic mortality can be distinguished as early (EEM) or late (LEM) embryonic mortality. When EEM occurs, sheep return to estrus 17 ± 2 days after mating, which makes the detection of EEM very difficult. Because determination of ovine pregnancy-associated glycoprotein (ovPAG) concentration can be used for pregnancy diagnosis from Day 25 of conception, with a specificity and sensitivity of 100% and 99%, respectively, it possibly could be used for detection of LEM (Verberckmoes et al., 2003. Pregnancy diagnosis in sheep by means of ultrasound and ovine pregnancy associated glycoproteins (ovPAG), 10th International Symposium on Veterinary Epidemiology and Economics (ISVEE 10), 17–21 November, 2003.). Therefore, in this study the prevalence of LEM and the usefulness of ovPAG concentration for the detection of LEM were examined. In a field trial, serum samples of 160 Texel and 127 Suffolk ewes were collected at the moment of estrus synchronization (T0), and at 25 (T25), 35 (T35), and 45 days (T45) after mating. Concentrations of ovPAG were determined by means of homologous RIA using ovine PAG as standard and tracer, and rabbit antibodies against ovPAG as antiserum. Ewes were considered as being pregnant when ovPAG concentrations were higher than 2ngmL⁻¹. The F-test in a mixed model with ewe as random effect was used to compare the mean PAG concentrations. Of the 287 ewes examined, 5 Suffolk and 2 Texel ewes showed an abnormal PAG profile which was indicative of LEM. The average ovPAG concentration of the 7 former ewes at T25 was 5.6±2.0ngmL⁻¹, which indicates that they were pregnant. However, in contrast to the normal pregnant ewes, they had significantly lower ovPAG concentrations at T35 (2.8 ± 1.5ngmL⁻¹ v. 9.5 ± 2.3ngmL⁻¹) and T45 (0.9 ± 0.3ngmL⁻¹ v. 9.0 ± 1.9ngmL⁻¹)(P<0.01), and they did not lamb at 145±5 days after mating. In conclusion, late embryonic mortality occurred in 2% of the ewes. Determination of the ovPAG concentration by means of homologous RIA is a useful tool for the detection of LEM in sheep.
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Volume
16
ISBN/ISSN
1448-5990
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Pages Count
1
Location
Portland, Oregon, USA
Publisher
CSIRO
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Publisher Location
Ghent, Belgium
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DOI
10.1071/RDv16n2abs