Fertility-Associated Antigen in Peripubertal Beef Bulls
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abstract
2006 American Registry of Professional Animal Scientists. Ejaculates from peripubertal bulls (n = 468) in 5 different populations were analyzed individually for the presence of fertility- associated antigen (FAA) using a lateral flow cassette. Bull age, scrotal circumference, ejaculate volume, sperm cells per milliliter of ejaculate, percentage of motile sperm, percentage of normal sperm, and number of sperm in the ejaculate were recorded at each collection. These data were compared in bulls with and without FAA in the ejaculate. The percentage of bulls that were FAA-positive (FAA present in the ejaculate) ranged from 65 to 86% among the 5 populations. The only variable that differed across all bulls at first semen collection was ejaculate volume with FAA-negative (FAA not detected in the ejaculate) bulls having a greater volume (P < 0.001) than FAA-positive bulls. However, among subsets of bulls (n = 134) that were serially collected (3 times at 30-d intervals) at 3 ranches, ejaculate volume was greater in FAA-negative bulls in only 1 of 3 collections at each ranch. Additionally, the fact that a bull was capable of passing a breeding soundness exam did not affect the likelihood that FAA would be detected in the ejaculate. Among bulls that had not reached puberty, 70% were FAA-positive. Ten bulls had no detectable sperm in the ejaculate at their first collection, and 70% of those bulls were FAA-positive. These data suggest that the production of FAA in semen is not affected by any variable typically measured during a breeding soundness exam. The presence of FAA can be determined in an ejaculate either with or without sperm in peripubertal bulls.
