Measuring bovine pregnancy associated glycoprotein (BoPAG)
Inventors
Lucy, Matthew C. • Mathialagan, Nagappan
Assignees
University of Missouri System • Monsanto Technology LLC • University of Missouri St Louis
Publication Number
US-7575861-B2
Publication Date
2009-08-18
Expiration Date
2022-11-20
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Abstract
The invention provides improved assays for detection of pregnancy. In the assays, pregnancy associated glycoproteins are analyzed in conjunction with progesterone analysis. The techniques of the invention overcome limitations in the prior art by reducing the rate of false positive results. The assays provided by the invention can be implemented to increase the efficiency of commercial animal breeding programs.
Core Innovation
The invention provides improved methods for the early detection of pregnancy in livestock, particularly bovine animals, by analyzing pregnancy associated glycoproteins (BoPAGs) in conjunction with progesterone levels. The method involves obtaining a biological sample from the animal, measuring the level of at least one BoPAG, and measuring the level of progesterone in the same sample. Elevated levels of both BoPAG and progesterone indicate that the animal is pregnant.
Current pregnancy detection methods for cattle have notable drawbacks such as late detection windows, high rates of false positives, and complications from the persistence of certain antigens after pregnancy loss or postpartum. Existing tests relying solely on either progesterone analysis or detection of a single BoPAG isoform often result in unsatisfactory accuracy, especially at early post-insemination days where embryo loss can confound results.
By combining detection of multiple BoPAG isoforms, especially those expressed early in pregnancy and absent post-partum, with simultaneous progesterone quantification, the invention significantly reduces the rates of false positive and negative results compared to tests using either biomarker alone. This dual biomarker strategy enables accurate early diagnosis from around day 25 post-insemination, facilitating timely and informed breeding management decisions in cattle.
Claims Coverage
There are two independent claims in this patent, each defining a primary inventive feature involving the combined measurement of BoPAG and progesterone, with specialized diagnostic thresholds and procedural elements.
Early detection of pregnancy in bovine animals using combined BoPAG and progesterone measurements
A method comprising: - Obtaining a biological sample (saliva, serum, blood, milk, or urine) from a bovine animal. - Measuring the level of at least one bovine pregnancy associated glycoprotein (BoPAG) in the sample. - Measuring the level of progesterone in the sample. - Utilizing immunologic detection (including ELISA, RIA, or Western blot), or nucleic acid hybridization methods for BoPAG measurement. - Applying specific quantitative thresholds (e.g., BoPAG level of about 5 to 10 ng/ml, progesterone about 2 ng/ml) for determining elevated status. - The method can include detection of multiple BoPAG isoforms, the use of polyclonal or monoclonal antibodies (including those lacking substantial binding activity to BoPAG1), and collecting samples at specific days post-insemination, especially around day 25. - Additional steps include comparison with positive/negative control samples, repeat sampling at multiple time points, and measurement of progesterone biosynthesis pathway enzymes.
Breeding decision method using BoPAG and progesterone measurement at 16–30 days post-insemination
A method comprising: - Obtaining a sample from a bovine animal suspected of being pregnant at days 16 to 30 post-insemination. - Measuring the level of at least one BoPAG and the level of progesterone in the sample. - Following a decision protocol based on test results: - Elevated BoPAG and progesterone: animal is pregnant; no further steps. - Non-elevated BoPAG and progesterone: animal is not pregnant; inject GnRH, then after ~7 days, inject PGF, and re-inseminate. - Elevated BoPAG, non-elevated progesterone: indicates early embryo death; inject GnRH, then after ~7 days, inject PGF, and re-inseminate. - Non-elevated BoPAG, elevated progesterone: animal is not pregnant; inject PGF, and re-inseminate. - Optional: In step (ii), (iii), and (iv), an additional GnRH injection 48 hours after PGF and before re-insemination. - The method may further include prior insemination of the animal and specific timing for PGF injection and re-insemination.
The claims establish methods for early pregnancy detection in bovines through the combined measurement of BoPAG and progesterone, optionally including specified sample timing, multiple detection chemistries, and a clinical decision protocol guiding breeding management actions based on test outcomes.
Stated Advantages
The method reduces the rate of false positive and false negative pregnancy test results to below 3% when compared to progesterone or BoPAG analysis alone.
Pregnancy can be detected earlier than with traditional methods, as soon as day 25 post-insemination.
Early detection allows for timely rebreeding of non-pregnant animals, improving reproductive management efficiency.
The assay detects BoPAG isoforms absent in postpartum cows, avoiding misclassification due to lingering antigen post-calving.
The invention supports the implementation of efficient breeding protocols by reducing economic losses associated with delayed pregnancy detection.
Documented Applications
Early detection of pregnancy in cattle to guide breeding and reproductive management decisions in commercial animal breeding programs.
Use in resynchronization protocols for timely re-insemination of non-pregnant cows following detection.
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