Singh Shiva Pratap, Natesan Ramachandran, Sharma Nandini, Goel Anil Kumar, Singh Manoj Kumar, Kharche Suresh Dinkar
Animal Physiology and Reproduction Division, Indian Council of Agricultural Research-Central Institute for Research on Goats, Makhdoom, Farah, Mathura, U.P., 281122, India.
Animal Genetics and Breeding Division, Indian Council of Agricultural ResearchCentral Institute for Research on Goats, Makhdoom, Farah, Mathura, U.P., 281122, India.
Anim Biosci. 2021 Jan;34(1):26-35. doi: 10.5713/ajas.19.0399. Epub 2020 Jan 13.
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.
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).
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.
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.
本研究旨在评估全脂和脱脂牛奶样本中妊娠相关糖蛋白（PAG）的水平，以及其在山羊早期妊娠诊断中的适用性。
开发并验证了一种用于估计牛奶中PAG的两步夹心酶联免疫吸附测定（ELISA）系统，该系统采用了山羊PAG特异性多克隆抗血清。从15只经产山羊中每隔一天采集全脂和脱脂牛奶样本（各n = 210），从配种后第10天至第30天，此后每周采集直至配种后第51天。通过ELISA估计牛奶样本中的PAG水平，并在配种后第40天通过经直肠超声检查（TRUS）确认妊娠情况。
在配种后第24天之前，怀孕和未怀孕山羊的全脂和脱脂牛奶样本中PAG水平均低于阈值。此后，怀孕山羊的全脂和脱脂牛奶中PAG浓度稳步上升，而未怀孕母羊的PAG浓度则持续低于阈值。怀孕山羊全脂和脱脂牛奶中的PAG谱几乎相似，呈现出强正相关关系（r = 0.891；p<0.001）。配种后第26天被确定为怀孕山羊牛奶中PAG浓度显著高于（p<0.05）未怀孕山羊的第一个时间点。与TRUS妊娠诊断检查相比，使用全脂和脱脂牛奶样本的PAG ELISA的准确性和特异性分别为94.5%和95.4%；以及95.3%和100%。曲线下面积的高值（全脂牛奶为0.904，脱脂牛奶为0.922）表明牛奶检测具有出色的区分能力。在所选的采样日期中，配种后第37天被确定为采集牛奶样本以检测山羊妊娠的最合适时间点。
在配种后第26天至第51天之间采集的山羊全脂和脱脂牛奶中的PAG浓度可用于准确预测妊娠，可能有助于山羊群的管理决策。
