Pubertal changes in the expression of fertility associated antigen in Bos indicus and Bos taurus bulls
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Fertility Associated Antigen (FAA) produced by the accessory sex glands and contained within the seminal fluid binds heparin and facilitates capacitation in ejaculated sperm, resulting in improved fertility in bulls capable of producing the protein. In this study, a total of 206 bulls derived from three populations were evaluated for the presence or absence of FAA through utilization of the Repro Test at three semen collections over a 60-d period. Across all collections, the percentage of FAA Negative bulls ranged from 13.64 to 36.11%. Within the three populations, 32, 33, and 67 bulls were observed at three different collections, of which 3.03, 9.09 and 4.48% were FAA Negative at all three collections, respectively. Furthermore, 27.27, 33.33, and 20.90% of bulls were observed to have variations within their FAA status after providing an initial FAA Positive result, respectively. Bull age, sperm concentration, progressive forward motility, percent normal sperm, ejaculate volume, and scrotal circumference were determined to be significantly different between FAA Negative and FAA Positive bulls in at least one collection. However, no consistent trend was observed across populations, or collections within a population, with regard to a relationship between these variables and FAA. Furthermore, of fourteen bulls that produced an ejaculate in which no sperm was detected, 78.57% (n=11) were FAA Positive despite the lack of sperm within the ejaculate. No single variable commonly measured to determine bull fertility was consistent in predicting the FAA status of bulls. The ability to produce FAA precedes puberty and the Repro Test can be used to identify FAA in prepuberal bulls. However, a large percentage of bulls, both prepuberal and peripuberal, are capable of displaying variation in their FAA status (as determined by the Repro Test) over time.
Novosad, Aaron M. (2005). Pubertal changes in the expression of fertility associated antigen in Bos indicus and Bos taurus bulls. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from