1.Ayad, A., Sousa, N. M., Sulon, J., Iguer-Ouada, M. and Beckers, J.F. 2007. Comparison of five radioimmunoassay systems for PAG measurement: ability to detect early pregnancy in cows. Reprod. Domest. Anim. 42(4): 433-440.

2.Butler, J.E., Hamilton, W. C., Sasser, R. G., Ruder, C. A., Hass, G. M. and Williams, R. J. 1982. Detection and partial characterization of two bovine pregnancy-specific proteins. Biol. Reprod., 26(5): 925-933.

3.Commun, L., Velek, K., Barbry, J.B., Pun, S., Rice, A., Mestek, A., Egli, C. and Leterme, S. 2016. Detection of pregnancy- associated glycoproteins in milk and blood as a test for early pregnancy in dairy cows. J. Vet. Diagn. Invest. 28(3): 207- 213.

4.Eckblad, W.P., Sasser, R.G., Ruder, C.A., Panlasigui, O.P. M. and Kuczynski, T.S. 1985. Localization of pregnancy- specific protein B (PSPB) in bovine placental cells using a glucose oxidaseanti-glucose oxidase immunohistochemical stain. Proc., West. Sec., Am. Soc. Anim. Sci., 36: 396-397.

5.Fricke, P.M. 2002. Scanning the future-Ultrasonography as a reproductive management tool for dairy cattle. J. Dairy Sci., 85(8): 1918-1926.

6.Fricke, P. M., Ricci, A., Giordano, J. O. and Carvalho, P. D. 2016. Methods for and Implementation of Pregnancy Diagnosis in Dairy Cows. Vet. Clin. North Am., 32(1): 165-180.

7.Friedrich, M. and Holtz, W. 2010. Establishment of an ELISA for measuring bovine pregnancyassociated glycoprotein in serum or milk and its application for early pregnancy detection. Reprod. Dom. Anim., 45: 142-146.

8.Gabor, G., Toth, F., Ozsvari, L., Abonyi-Toth, Z. and Sasser. R. G. 2007. Early detection of pregnancy and embryonic loss in dairy cattle by ELISA tests. Reprod. Domest. Anim., 42: 633-636.

9.Gajewski, Z., Sousa, N.M., Beckers, J.F., Pawlinski, B., Olszewska, M., Thun, R. and Kleczkowski, M. 2008. Concentrat ion of bovine pregnancy associat ed glycoprotein in plasma and milk: its application for pregnancy diagnosis in cows. J. Physiol. Pharmacol., 59(Suppl 9): 55-64.

10.Ginther, O. J. 1998. Ultrasonic imaging and animal reproduction: cattle. Book 3., Equiservices Publishing, Cross Plains, WI, pp. 33-37.

11.Green, J.A., Parks, T.E., Avalle, M.P., Telugu, B.P., McLain, A. L., Peterson, A.J., McMillan, W., Mathialagan, N., Hook, R. R. and Xie, S. 2005. The establishment of an ELISA for the detection of pregnancy-associated glycoproteins (PAGs) in the serum of pregnant cows and heifers. Theriogenology, 63: 1481-1503.

12.Humblot, P. 2001. Use of pregnancy specific proteins and progesterone assays to monitor pregnancy and determine the timing, frequencies and sources of embryonic mortality in ruminants. Theriogenology, 56: 1417-1433.

13.Humblot, P., Camous, S., Martal, J., Charlery, J., Jeanguyot, N., Thibier, M. and Sasser, R.G. 1988. Pregnancy-specific protein B, progesterone concentrations and embryonic mortality during early pregnancy in dairy cows. Reproduction, 83: 215-223.

14.Kamboj, M. and Prakash, B.S. 1993. Relationship of progesterone in plasma and whole milk of buffaloes during cyclicity and early pregnancy. Trop. Anim. Health Pro., 25(3): 185-192.

15.Karen, A., Bajcsy, A.C., Minoia, R., Kovacs, R., Sousa, N. M., Beckers, J.F., Tibold, J., Madl, I. and Szenci, O. 2014. Relationship of progesterone, bovine pregnancyassociated glycoprotein-1 and nitric oxide with late embryonic and early fetal mortalities in dairy cows. J. Reprod. Dev., 60(2): 162- 167.

16.Khatti, A., Mehrotra, S., Maurya, V., Singh, G. and Sarkar, M. 2017. Effect of vitamin E, selenium and increased energy allowance on steroids and reproductive performance in transition period of crossbred cattle. Int. J. Livest. Res., 7(12): 43-50.

17.Lobago, F., Bekana, M., Gustafsson, H., Beckers, J.F., Yohannes, G., Aster, Y. and Kindahl, H. 2009. Serum profiles of pregnancy-associated glycoprotein, oestrone sulphate and progesterone during gestation and some factors influencing the profiles in Ethiopian Borana and crossbred cattle. Reprod. Domest. Anim., 44(4): 685-692.

18.Masello, M., Lu, Z., Erickson, D., Gavalchin, J. and Giordano, J.O. 2020. A lateral flow-based portable platform for determination of reproductive status of cattle. J. Dairy Sci., 103(5): 4743-4753.

19.Muhammad, F., Sarwar, A., Hayat, C. S. and Anwar, M. I. 2000. Peripheral plasma progesteron concentration during early pregnancy in holstein feiesian cows. Pak. Vet. J., 20: 166- 168.

20.Nebel, R.L., Whittier, W.D., Cassell, B.G. and Britt, J.H. 1987. Comparison of on-farm and laboratory milk progesterone assays for identifying errors in detection of estrus and diagnosis of pregnancy. J. Dairy Sci., 70(7): 1471-1476.

21.Noakes, D.E., Parkinson, T.J. and England, G.C.W. 2009. Veterinary Reproduction & Obstetrics. 9th Ed., W B Saunders Company, London, pp. 80-111.

22.Northrop, E. J., Rich, J. J., Rhoades, J. R. and Perry, G. A. 2019. Comparison of two bovine serum pregnancy tests in detection of artificial insemination pregnancies and pregnancy loss in beef cattle. PloS one, 14(1): e0211179.

23.Piechotta, M., Bollwein, J., Friedrich, M., Heilkenbrinker, T., Passavant, C., Branen, J., Sasser, G., Hoedemaker, M. and Bollwein, H. 2011. Comparison of commercial ELISA blood tests for early pregnancy detection in dairy cows. J. Reprod. Develop., 57(1): 72-75.

24.Rioux, P. and Rajotte, D. 2004. Progesterone in milk: a simple experiment illustrating the estrous cycle and enzyme immunoassay. Adv. Physiol. Educ., 28(2): 64-67.

25.Reese, S.T., Pereira, M.C., Vasconcelos, J.L.M., Smith, M.F., Green, J.A., Geary, T.W., Peres, R.F.G., Perry, G.A. and Pohler, K.G. 2016. Markers of pregnancy: how early can we detect pregnancies in cattle using pregnancy-associated glycoproteins (PAGs) and microRNAs? Anim. Reprod. 13(3): 200-208.

26.Romano, J.E. and Larson, J.E. 2010. Accuracy of pregnancy specific protein-B test for early pregnancy diagnosis in dairy cattle. Theriogenology, 74: 932-939.

27.Sah, A.K., Bastola, R., Pandeya, Y.R., Pathak, L., Acharya, M. P. and Khanal, D.R. 2017. Accuracy of pregnancy diagnosis with commercially available progesterone kit in dairy cows. Nepalese Veterinary Journal, 34: 101-106.

28.Samsonova, J.V., Safronova, V.A. and Osipov, A.P. 2015. Pretreatment-free lateral flow enzyme immunoassay for progesterone detection in whole cows’ milk. Talanta, 132: 685-689.

29.Sasser, R.G. and Ruder, C.A. 1987. Detection of early pregnancy in domestic ruminants. J. Reprod. Fertil., 34: 261-271.

30.Sasser, R.G., Ruder, C.A., Ivani, K.A., Butler, J.E. and Hamilton, W.C. 1986. Detection of pregnancy by radioimmunoassay of a novel pregnancy-specific protein in serum of cows and a profile of serum concentrations during gestation. Biol Reprod., 35: 936-942.

31.Shemesh, M., Ayalon, N. and Lindner, H.R. 1973. Early pregnancy diagnosis based upon plasma progesterone levels in the cow and ewe. J. Anim. Sci., 36(4): 726-729.

32.Simersky, R., Swaczynova, J., Morris, D.A., Franek, M. and Strnad, M. 2007. Development of an ELISA-based kit for the on-farm determination of progesterone in milk. Vet. Med., 52(1): 19-28.

33.Szenci, O., Beckers, J.F., Humblot, P., Sulon, J., Sasser, G., Taverne, M.A., Varga, J., Baltusen, R. and Schekk, G. 1998. Comparison of ultrasonography, bovine pregnancy-specific protein B, and bovine pregnancy-associated glycoprotein 1 tests for pregnancy detection in dairy cows. Theriogenology, 50: 77-88.

34.Szenci, O., Gyulai, G., Nagy, P., Kovacs, L., Varga, J. and Taverne, M.A. 1995. Effect of uterus position relative to the pelvic inlet on the accuracy of early bovine pregnancy diagnosis by means of ultrasonography. Vet Q., 17: 37-39.

35.Thompson, J.A., Marsh, W.E., Calvin, J.A., Etherington, W.G., Momont, H.W. and Kinsel, M.L. 1994. Pregnancy attrition associated with pregnancy testing by rectal palpation. J. Dairy Sci., 77(11): 3382-3387.

36.Ushizawa, K., Herath, C.B., Kaneyama, K., Shiojima, S., Hirasawa, A., Takahashi, T., Imai, K., Ochiai, K., Tokunaga, T., Tsunoda, Y., Tsujimoto, G. and Kazuyoshi Hashizume, K. 2004. cDNA microarray analysis of bovine embryo gene expression profiles during the pre-implantation period. Reprod. Biol. Endocrinol., 2: 77.

37.Vasquez, M.I., Horta, A.E.M., Marques, C.C., Sasser, R.G. and Humblot, P. 1995. Levels of bPSPB throughout single and twin pregnancies after AI or transfer of IVM/IVF cattle embryos. Anim. Reprod. Sci., 38: 279-289.

38.Wooding, F.B. 1992. Current topic: the synepitheliochorial placenta of ruminants: binucleate cell fusions and hormone production. Placenta, 13: 101-113.

39.Zaied, A.A., Bierschwal, C.J., Elmore, R.G., Youngquist, R. S., Sharp, A.J. and Garverick, H.A. 1979. Concentrations of progesterone in milk as a monitor of early pregnancy diagnosis in dairy cows. Theriogenology, 12(1): 3-11.

40.Zemjanis, R. 1970. Pregnancy examination. In: Diagnostic and Therapeutic Techniques in Animal Reproduction. 2nd Ed., 29-Baltimore, Williams and Wilkins, pp. 29-46.

41.Zoli, A.P., Guilbault, L. A., Delahaut, P., Ortiz, W.B. and Beckers, J.F. 1992. Radioimmunoassay of a bovine pregnancy-associated glycoprotein in serum: its application for pregnancy diagnosis. Biol Reprod., 46: 83-92.