Relationship of foetal number and parity in Barbari goats to plasma profile of caprine pregnancy-associated glycoprotein (caPAG) during gestation and the early postpartum period

The Utilization of a Pregnancy-Associated Glycoprotein Profile and PAG/P4 Ratio Biomarker for the Diagnosis of Pseudopregnancy in Dairy Goats

Pseudopregnancy (PPG) is a common reproductive disorder in dairy goats, characterized by the accumulation of sterile fluid in the uterus and persistence of a corpus luteum, leading to temporary infertility and reduced farm efficiency. This study aimed to determine the pregnancy-associated glycoprotein (PAG) profile in dairy goats and to evaluate the PAG/P4 ratio as a potential novel biomarker for PPG diagnosis. A total of 605 Saanen and crossbreed mated goats were evaluated via transabdominal ultrasonography between 31 and 52 days after the removal of bucks in four intensive dairy farms, presenting an overall PPG incidence of 7.8%. Blood samples from PPG (n = 47), nonpregnant (NPG; negative control; n = 11), and pregnant (PG; positive control; n = 10) does were collected for PAG and P4 analysis. The PAG plasma levels were 0.08 ± 0.02, 0.13 ± 0.04, and 1.45 ± 0.04 OD (optical density) in the PPG, NPG, and PG groups, respectively (p < 0.001). The PAG/P4 ratio was lower in the PPG group (0.01 ± 0.11; p < 0.001) than in the NPG (0.24 ± 0.23) and PG (0.18 ± 0.23) groups. This difference allows for the establishment of a new methodological diagnostic approach to PPG. The area under the curve (AUC) was 0.996 for a cut-off of 0.04 and 97.9% and 100% sensitivity and specificity, respectively. This study suggests that the PAG/P4 ratio can serve as a reliable biomarker for PPG diagnosis, helping to distinguish it from pregnancy and nonpregnancy and improving reproductive management in dairy goats.

Ovarian Dynamics and Changes in Estradiol-17β and Progesterone Relationship with Standing Estrus, Preovulatory Follicles, and Ovulation Using Single Prostaglandin F2α Injection in Barbari Goats

The purpose of the present research was to define ovarian follicular dynamics and plasma endocrine profiles in response to a single PGF2α injection, administered indiscriminately during the breeding season of Barbari goats. Ovarian dynamics were observed at every 12 h interval by using B mode ultrasonography, blood samples for hormonal analysis such as estradiol 17β and progesterone were collected at every 12 h interval, and bucks with aprons were used to identify standing estrus at every 6 h interval. Relative to PGF2α, the start of standing estrus and ovulation differ (p < 0.05) between early- (n = 7), intermediate- (n = 6), and late-responding (n = 6) goats. The highest plasma level of estradiol 17β was detected 12 h prior to ovulation. The average diameter of the ovulatory follicle and length of standing estrus were comparable (p > 0.05) between the goats. The corpus luteum degenerated more quickly (p < 0.05) in early- than intermediate- and late-responding goats. Dominant follicle diameter and estradiol 17β concentration also differ (p < 0.05) among groups. Although the plasma level of progesterone did not vary (p = 0.065), the variation in progesterone concentration with time differed (p < 0.05) amongst the goats. As a result, this research indirectly reveals that the beginning of standing estrus, end of estrus, and ovulation after PGF2α might fluctuate in Barbari goats because of follicular and hormonal dynamics during the luteal phase.

Changes in milk and plasma progesterone and pregnancy-associated glycoprotein and their relationships with the foetal number during early pregnancy in Jakhrana goats

This study was designed to investigate milk and circulating profiles of progesterone (P4) and pregnancy-associated glycoprotein (PAG) during early pregnancy and to determine their associations with the foetal numbers in Jakhrana goats. For this, milk (whole and defatted milk) and blood samplings from10 pregnant and 3 non-pregnant Jakhrana goats were continued from the day 7 until day 51 post-mating. The PAG profile in both milk and plasma increased gradually from day 26 to 51 of gestation. Whereas, circulating P4 remains unchanged during early pregnancy in pregnant goats. The P4 and PAG concentrations in blood plasma, whole milk and defatted milk were 1.30, 1.24 and 2.04, 1.98, 1.99 and 1.88 folds higher in twin foetus than the single foetus bearing does, respectively. The P4 and PAG in plasma and milk samples were positively correlated with the foetal number. However, the results of stepwisemultivariate linear regression analyses indicated milk and circulating P4 as better predictors of foetal numbers than plasma PAG. The defatting of milk samples resulted in about 2-folds decline in the P4 concentration, however, the PAG level remains unaffected. In conclusion, milk and plasma profiles of P4 and PAG were affected by the foetal number and P4 is a reliable predictor of foetal number during early pregnancy in Jakhrana goats.

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

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 post-mating. 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 non-pregnant 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.