Efficacy of interferon-stimulated genes and pregnancy-associated glycoproteins for pregnancy diagnosis within an estrus resynchronization protocol for dairy cattle
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Reproductive management is a major economic concern in the dairy industry. Long intervals between TAI increases the days open and decrease the 21 day pregnancy rate. A major factor that causes long intervals between TAI is pregnancy detection technique. Common methods of pregnancy detection are palpation per rectum and transrectal ultrasonography. Chemical pregnancy detection is uncommonly used in the dairy industry but has the potential to decrease the interval between TAI by reducing the days to pregnancy detection. Certain genes have greater transcription in response to interferon-T (IFNT). Measurement of mRNA for three genes [interferon-stimulated gene 15 kDa protein (Isg15), myxovirus resistance gene 2 (Mx2), and 2'-5' oligoadenylate synthetase 1 (Oas1)] that are up-regulated in response to IFNT was used to diagnose pregnancy in cows and heifers. This pregnancy diagnosis approach was used in a 21 day resynchronization program with similar results in pregnancy per AI (P/AI) as conventional programs. An enzyme-linked immunosorbent assay (ELISA) for pregnancy-associated glycoproteins (PAG) was highly accurate regardless of parity, breed, or stage of gestation ([greater than or equal to] 25 days). This PAG ELISA was used in a 28 day CIDR Ovsynch resynchronization protocol and compared with a 35 day CIDR Ovsynch resynchronization protocol that used transrectal ultrasonography for pregnancy diagnosis. Shortening the interval between inseminations by using a chemical method of pregnancy diagnosis improved reproductive rates in dairy cattle.
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