|Cushman, Robert - Bob|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/4/2006
Publication Date: 8/20/2006
Citation: Echternkamp, S.E., Green, J.A., Vonnahme, K.A., Cushman, R.A., Allan, M.F. Relationship between concentrations of pregnancy-associated glycoproteins (PAG) in maternal blood and fetal number and status in pregnant cows. Journal of Animal Science. 84(Supplement 2):127. (Abstract #301) Interpretive Summary:
Technical Abstract: The use of PAG and progesterone concentrations in maternal blood to determine fetal number in utero was evaluated in MARC Twinner cows gestating one or two fetuses. Ovulation rate and fetal number were determined by ultrasonography at about 56 d postbreeding. Sequential jugular vein blood samples (10 ml) were collected by venipuncture at a mean interval of 56.6, 121.2, 191.6, and 233.6 d (range = ± 10 d) post-breeding (i.e., sample times 1, 2, 3, and 4, respectively). Plasma concentrations of PAG were measured by an indirect sandwich ELISA and of progesterone by RIA. Data were analyzed by Proc Mixed analysis; PAG data were log transformed. Table 1. Comparison of maternal plasma progesterone and PAG concentrations (ng/ml) between cows gestating single versus twin fetuses. Type of Sample times Pooled Pooled pregnancy n One Two Three Four sem Mean sem Progesterone Single 23 7.8 7.0 7.3 9.1 0.6 7.8a 0.4 Twin 17 9.3 8.3 8.6 11.0 0.6 9.3b 0.5 PAG Single 23 9.0 14.4 52.9a 125.7a 13.4 51.8a 9.3 Twin 17 11.1 16.2 116.4b 274.7b 15.9 104.6b 10.7 a,b Means differ between single and twin pregnancies; P < 0.01. Progesterone concentrations were greater for cows gestating twins and increased (P < 0.01) between times 3 and 4. The increase in PAG between sample times 2 and 4 was greater in dams with twins, resulting in greater PAG concentrations for twins versus singles at times 3 and 4 (type of pregnancy x time; P < 0.01). Total birth weight was correlated positively with PAG concentrations at sample times 3 and 4 (r = 0.48 and 0.59; P < 0.01). It is postulated that greater blood PAG concentrations in cows gestating twins were the result of a larger uteroplacental mass, including increased numbers of PAG-secreting binucleate cells, whereas progesterone concentrations were associated with CL number. Variability in PAG concentrations within birth groups limits use of PAG measurements for diagnosis of twin pregnancies.