The concentration of estradiol-17 beta in bovine semen

This study was conducted to evaluate the influence of age, breed, epididymectomy and semen processing on the concentration of estradiol-17 beta (E2) in bovine semen. Semen was collected either by electroejaculation or with an artificial vagina. Neat semen samples were stored at -20 C until analysis. Processed, frozen semen and an egg yolk-citrate semen extender were obtained from a commercial semen processing firm and stored in liquid nitrogen at -196 C. The concentration of E2 in semen was determined by radioimmunoassay. Semen from mature (greater than 24 mo), fertile Brahman (n = 19), Brangus (n = 16), Charolais (n = 29), Holstein (n = 15) and Santa Gertrudis (n = 25) bulls was analyzed for E2 concentration, and no difference (P greater than .10) between breeds was found. There was no difference (P greater than .10) in seminal E2 concentration between mature, fertile bulls (n = 104) and epididymectomized bulls (n = 22). In semen collected from prepuberal (12 to 16 mo, n = 21), peripuberal (17 to 20 mo, n = 17) and mature (greater than 24 mo, n = 19), Brahman bulls, the mature bulls had a lower (P less than .01) semen E2 concentration than peripuberal and prepuberal bulls. There were no differences (P greater than .10) in seminal E2 concentration among peripuberal Angus (n = 8), Hereford (n = 8) and Brahman (n = 17) bulls.(ABSTRACT TRUNCATED AT 250 WORDS)