Endocrine markers for identifying prolificacy potential and predicting fetal number in goats

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.

Temporal changes in plasma profile of pregnancy-associated glycoprotein, progesterone and estrone sulfate associated with fetal number during early- and mid-pregnancy in goats

This study was designed to investigate plasma profile of pregnancy-associated glycoprotein (PAG), progesterone (P4) and estrone sulfate (E₁S) during early- and mid-pregnancy. The goal was to explore the relationships with values for reproductive variables, to detect the most reliable predictor variable, and to identify the most desirable time point for blood collection for determining fetal number in goats. After ultrasonographic examination at d35-40 post-mating, blood sampling of 15 pregnant goats (total 18) was continued until d114. The PAG profile was characterized by gradual increase during early pregnancy from d26 to d51 and thereafter concentrations were relatively constant until d114 of gestation. The effect of fetal number on plasma PAG, P4 and E₁S was first evident on d28, d51 and d26, respectively. During mid-pregnancy, does with twins had a greater (P < 0.05) PAG (S-N = 2.54 ± 0.12 compared with 1.59 ± 0.11), P4 (18.91 ± 0.67 compared with 14.51 ± 0.47 ng/mL) and E₁S (16.34 ± 0.76 compared with 11.32 ± 0.44 ng/dL) as compared with does with a singleton fetus. Plasma PAG but not P4 and E₁S was positively correlated with fetal number and birth weight of kids during early pregnancy. Multivariate linear regression and discriminant function analyzes allowed for identification of plasma PAG as the most reliable predictor for fetal number and birth weight of kids. Furthermore, d58 was the most suitable single time point for prediction of fetal number using PAG as a biomarker. In conclusion, plasma profile of PAG, P4 and E₁S was affected by fetal count. Plasma PAG was identified as the most reliable predictor variable of fetal number and birth weight of kids as compared to plasma P4 and E₁S.

Ultrasonographic foetometry and maternal serum progesterone concentrations during pregnancy in Turkish Saanen goats

The objectives of the present study were (1) to generate reliable equations to estimate the gestational age of Saanen goats by measuring embryonic and foetal structures via B-Mode ultrasonography (USG), (2) determine the maternal serum progesterone (P₄) concentrations during pregnancy, and (3) compare the relationship between P₄ concentrations and gestational age, litter size, and birth weight of kids. Seven pregnant goats were used in this study. Ultrasonographic examinations were performed transrectally from Days 15 to 27 of pregnancy at 3-day intervals and transabdominally from Days 30 to 128 at 7-day intervals. Blood samples were collected daily between Day 15 and 24 of gestation, and weekly from Day 27 to 128 to determine the serum P₄ concentrations. Outer placentome diameter, biparietal diameter, occipito-nasal length, chest diameter, foetal heart rate, transversal heart diameter, orbit diameter, umbilical cord diameter, and kidney diameter were highly correlated with gestational age (P <  0.0001). Goats with twins had greater progesterone concentrations than those with a single foetus (P <  0.001). Furthermore, maternal serum progesterone concentrations detected on Days 51, 107, 114, and 128 of gestation were greater in goats carrying twins than those with a single foetus (P <  0.05). A negative correlation was evident between serum progesterone concentrations and birth weights of the kids (r = -0.78; P =  0.007). In conclusion, gestational age can be estimated using ultrasonographic foetometry, and litter size at specific times during pregnancy can be determined based on maternal serum progesterone concentration in Turkish Saanen goats.