1. Detection of the embryonic loss in dairy cattle by ELISA tests György Gábor 1* - Fruzsina Tóth 1 – László Ózsvári 2 – Garth Sasser 3 1 Research Institute for Animal Breeding and Nutrition, Herceghalom, Hungary, 2 Faculty of Veterinary Sciences, SZIE, Budapest, Hungary, 3 Biotracking LLC, Moscow, ID, US Introduction Improvement of reproductive management in the dairy industry is essential. The continuous elevation of milk production is associated with a simultaneous dramatic decrease of reproductive performance. Delayed post-partum interval, poor heat expression, inefficient detection of estrus and fertilization failure are probably the major causes of the reproductive wastage; but early embryonic death is recognized as the major cause of reproductive wastage in cattle. The most common methods for early pregnancy check /rectal palpation (35-42 days PI), B-mode ultrasonography (25-30 days PI) and examination of pregnancy specific proteins (PSPB, PAG, 29-30 days PI)/ are used for the decreasing of the calving interval in cattle. BioPryn TM (BioTracking LLC, Moscow, ID, US), an ELISA test has been developed and is distributed for the detection of PSPB in the circulation of pregnant cows. Pregnancy detection by BioPryn TM is already routinely used in the author’s laboratory. Objectives The objective of this study was to develop a method for the recognition of embryonic loss (EL) at the time early pregnancy detection (approximately 30-36 days post insemination) by serum PSPB and serum P4 assays. Material and Methods Blood samples were assayed for the determination of the serum PSPB and P4 concentrations months at three Hungarian large scale dairy farms 30 to 36 days post insemination. BioPryn was used for the early pregnancy detection (EPD) and retention of pregnancy was determined by rectal palpation (RP) on Day 60 (day of AI=0). After the early pregnancy diagnosis, open cows were immediately injected with either PGF2  (presence of the corpus luteum, CL) or were put into an Ovsynch regimen (non-cycling cows). Lower than expected optical density (OD) values for BioPRYN (+10 % of cutoff OD) and the serum concentration of progesterone were used for prediction of embryonic loss. If the OD value of a sample (PSPB) was ± 10 % to the cutoff OD for determining pregnancy, the same sample was checked by a progesterone (P4) ELISA test (QuantiCheck, Veterinorg Ltd., Budapest, Hungary). According to serum P4 concentration, cows were assigned to 3 categories: high (>4 ng/ml; maintenance of pregnancy), medium (2-4 ng/ml; possible EL) and low (<2 ng/ml; EL) serum progesterone (see Figure 1). Real embryonic losses were determined at the time of rectal palpation (EPD – RP). Figure 1: The prediction process for embryonic loss and for the treatment methods of open cows and cows returning in estrus Results Pregnancies (n=1575) were detected from 3833 blood samples between 30-36 days post AI and 13.5 % of the pregnancy samples were tested by the P4 assay. A total of 269 ELs were detected (17.1 %) after palpation on Day 60 and 50.9 % of them were predicted by ELISA at 30 to 36 days after AI. The rate of EL among the progesterone categories were 83.8 % (low), 64.9 % (medium) and 37.5 % (high) respectively. Discussion It was found that the BioPRYN, with OD an indicator of PSPB level, and serum P4 concentration could identify EL. Lower PSPB serum level significantly refers for LEL (p < 0.0001). Most of the cows with low serum PSPB level and have < 2 ng/ml serum P4 concentration lost the embryo between the first and second pregnancy check (p < 0.0001). The most effective prediction rate was found in low P4 category (~ 90 %) while prediction rate in the medium and high P4 category varied among the farms. Conclusion It can be concluded that BioPryn was useful for prediction of part of EL in dairy cows and that P4 concentration in these was related to rate of EL. Farm No. of pregnant cows No. of real EL'sEL % No. of non predicted EL (NEL)NEL % No. of predicted EL (PEL)PEL % 163411518,15144,36455,7 259111719,86555,65244,4 33503710,61643,22156,8 Total157526917,113249,113750,9 Serum progesterone Level LowMediumHigh FarmPredicted ELTrue ELPredicted ELTrue ELPredicted ELTrue EL 133273929178 219 3427146 31611247174 Total685797634818 Prediction %83,8 64,9 37,5 Table 1: Number of predicted and non predicted embryonic loss by Biopryn Table 2: Efficiency of the EL prediction based on the serum P4 concentration *email: h12617gab@helka.iif.hu