Assessment of pregnancy-associated glycoprotein profile in milk for early pregnancy diagnosis in goats

Abstract

Objective: This study was conducted to assess the level of pregnancy-associated glycoprotein (PAG) in whole and skim milk samples, and its suitability for early pregnancy diagnosis in goats.Methods: A two-step sandwich enzyme-linked immunosorbent assay (ELISA) system for estimation of milk PAG was developed and validated, which employed caprine-PAG specific polyclonal antisera. Whole and skim milk samples (n = 210 each) from fifteen multiparous goats were collected on alternate days from d 10 to d 30, and thereafter weekly till d 51 postmating. PAG levels in milk samples were estimated by ELISA and the pregnancies were confirmed at d40 post-mating by transrectal ultrasonography (TRUS).Results: The level of PAG in whole and skim milk samples of both pregnant and nonpregnant goats remained below the threshold values until d 24 after mating. Thereafter, PAG concentration in whole and skim milk increased steadily in pregnant goats, whereas it continued below the threshold in non-pregnant does. The PAG profiles in whole and skim milk of pregnant goats were almost similar and exhibited strong positive relationship (r = 0.891; p<0.001). Day 26 post-mating was identified as the first time-point for significantly (p<0.05) higher milk PAG concentration in pregnant goats than to non-pregnant goats. When compared to TRUS examination for pregnancy diagnosis, the accuracy and specificity of PAG ELISA using whole and skim milk samples were 94.5% and 95.4%; and 95.3% and 100%, respectively. The high values of area-under-curve (0.904 [whole milk] and 0.922 [skim milk]), demonstrate outstanding discrimination ability of the milk assays. Among the sampling dates chosen, d 37 post-mating was identified as the best suitable time point for collection of milk samples to detect pregnancy in goats.Conclusion: The PAG concentration in whole and skim milk of goats collected between days 26 and 51 post-breeding can be used for the accurate prediction of pregnancy and may be useful for assisting management decisions in goat flocks.

Using Pregnancy-Associated Glycoproteins (PAGs) to Improve Reproductive Management: From Dairy Cows to Other Dairy Livestock

“…PAGs are also detectable from day 32 after conception in the milk of pregnant goats, while they are almost absent in non-pregnant goats [ 104 ]. A very recent study using ELISA [ 105 ] reported day 26 post-mating as the first time-point for significantly higher milk PAGs’ concentrations and day 37 post-mating as the best suitable time point to detect pregnancy in goats. Doğan and Köse [ 106 ], utilizing the visual PAG-ELISA test, reported that it was able to diagnose pregnancy in goats starting from the 28th day after breeding, but its reliability still needs to be verified, since visual results are subjective.…”

Evaluating estrus synchronization and early pregnancy detection in Ossimi sheep: The influence of fluorogestone acetate treatment duration and dosage

“…During the gestation period, the mononucleate and binucleate cells of the ruminant trophectoderm generate pregnancy-associated glycoproteins (PAGs), which originate from the placenta ( Sousa et al, 2006 ). Around day 18 or day 20 following breading, PAGs can be observed in the serum of pregnant ewes ( Barbato et al, 2009 ) and are a reliable indication of pregnancy among ruminants, such as goats ( Singh et al, 2021 ), sheep ( Akköse et al, 2021 ), and cattle ( Silva et al, 2007 ). Progesterone (P 4 ) is a crucial hormone for determining pregnancy in ewes ( Schneider & Hallford, 1996 ).…”

The prediction of lambing rate in Awassi sheep using a rapid visual PAG ELISA test

“…Pregnancy-associated glycoproteins (PAG) aresynthesized in the mono-and binucleate cells of the ruminant's trophectoderm (Sousa et al, 2006). PAG can be used for pregnancy diagnosis in ruminants by detecting their presence or concentrations in the maternal blood circulation (Akköse and Cebi-Sen, 2019;Chaves et al, 2017;Silva et al, 2007;Singh et al, 2021). de Carolis et al (2020), reported that the cutoff value of PAG concentrations (radioimmuno assay, RIA-706 and RIA-srPool) are ≥ 1.0 ng/mL in order to distinguish between pregnant and nonpregnant Sarda and Lacaune ewes.…”