Comparison of Semen Quality in Young and Mature Holstein Bulls Measured by Light Microscopy and Flow Cytometry

Abstract

Random samples of cryopreserved, milk-extended semen, collected from 20 Holstein bulls at about 14 mo of age (young) and again at about 4 yr of age (mature), were evaluated at thawing and during 3-h incubation to compare semen quality of young versus mature bulls. Evaluation by differential interference contrast microscopy showed greater proportions of cytoplasmic droplets in semen from young versus mature bulls. Mature bulls exhibited greater proportions of intact acrosomes in freshly thawed semen than did young bulls. Evaluation of sperm chromatin structure by flow cytometry after staining with acridine orange showed lower values for mature versus young bulls, indicating resistance of DNA in nuclear chromatin to acid denaturation increased with age. Correlations between ages for most sperm morphology, acrosome integrity, and flow cytometry variables were high and positive. Nonreturn rate for young bulls was positively related to morphologically normal sperm and acrosomal integrity and negatively related to flow cytometry traits. Results suggest semen quality of young bulls was related to subsequent quality as mature bulls. With flow cytometry, differences were detected between semen samples that were not evident with light microscopy.

Variations in quality of frozen–thawed semen from Swedish Red and White AI sires at 1 and 4 years of age

“…That might indicate a higher ‘maturity’ of the semen in older bulls. Karabinus et al. (1990), using conventional tests, concluded that the quality of a randomly selected semen sample from young bulls was generally indicative of the quality of a random sample of their semen as mature bulls.…”

Prediction of bull fertility by combined in vitro assessments of frozen–thawed semen from young dairy bulls entering an AI‐programme

“…The production of normal spermatozoa changes with age (Chandler et al, 1985;Sta Êlhammar et al, 1989;Karabinus et al, 1990), and pathologies compromising spermatogenesis or the genital function of the sires can arise during the productive lifetime of the bulls at the bull stations. The production of normal spermatozoa changes with age (Chandler et al, 1985;Sta Êlhammar et al, 1989;Karabinus et al, 1990), and pathologies compromising spermatogenesis or the genital function of the sires can arise during the productive lifetime of the bulls at the bull stations.…”

Does sperm quality and DNA integrity differ in cryopreserved semen samples from young, adult, and aged Nellore bulls?

“…Studies evaluating how aging may affect sperm chromatin integrity in bovine species and the source of the damage are scarce. One study in which semen quality in young bulls and again later in the same mature bulls were evaluated found consistent improvement in semen parameters including sperm DNA integrity, morphology and percentage of intact acrosomes upon aging [9]. In a more recent study, no difference in chromatin integrity as assessed using the sperm chromatin structure assay (SCSA) was found in post-pubertal bulls with mean ages of 13, 18, and 24 months [10].…”