Toxicology
SCSA Animal Data
Bulls
ORIGINAL SPERM DNA FRAGMENTATION (SCSA) MANUSCRIPT (including bulls)
Evenson, D.P., Darzynkiewicz, Z. and Melamed, M.R. (1980) Relation of mammalian sperm chromatin heterogeneity to fertility. Science 240:1131-1133
The first report in Science [1980, 240:1131-1133] on sperm DNA fragmentation and loss of fertility potential included an evaluations of bulls. The level of DFI predicted the known fertility level at Eastern Artificial Insemination Cooperative. This was followed by:
Ballachey, B.E., Hohenboken, W.D. and Evenson, D.P. (1987) Heterogeneity of sperm nuclear chromatin structure and its relationship to fertility of bulls. Biol. of Reprod. 36:915-925.
Ballachey, B.E., Saacke, R.G. and Evenson, D.P. (1988) The sperm chromatin structure assay: Relationship with alternate tests of sperm quality and heterospermic performance of bulls. J. Andrology 9:l09-115.
Heterospermic insemination., i.e., mixing an equal number of motile sperm from two or more bulls of different phenotypes and inseminating cows provides a direct comparison between sperm reproductive potential. Thus, if sperm were mixed between a black bull and a white bull, and if there were 80 black calves and 20 white calves born, a sperm fertility index can be derived to show the difference. The SCSA DFI values were highly predictive of the pregnancy outcome (r= -0.94, P <0.01). This type of study avoids the many potential confounders of the female.
- Effect of external testicular heat on bull sperm DNA fragmentation
It is well known that external heat causes lower bull fertility efficiency. Several studies have clearly shown that such heat causes sperm DNA fragmentation that can be detected about 3 days after the insult where light microscope evaluation does not detect damage until about 11 days post heat.
Karabinus, D.S., Vogler, C.J., Saacke, R.G. and Evenson, D.P. (1997) Chromatin structural changes in bovine sperm after scrotal insulation of Holstein bulls. J. Androl 18:549-555.
- Effects of semen extenders
Semen extenders have received extensive research for maximizing sperm quality and efficiency. Two studies have shown different effects with regard to preserving DNA integrity.
Karabinus, D.S., Evenson, D.P. and Kaproth, M.T. (1991) Effects of egg yolk-citrate and milk extenders on chromatin structure and viability of cryopreserved bull sperm. J. Dairy Sci. 74:3836-3848.
Krzyzosiak, J., Evenson, D., Pitt, C., Jost, L., Molan, P., and Vishwanath, R. (2001) Changes in susceptibility of bovine sperm to in situ DNA denaturation during prolonged storage at ambient temperature under conditions of exposure to reactive oxygen species and nuclease inhibitor. Reproduction, Fertility and Development 12: 251-261.
- Age of bull and sperm DNA integrity
- Loss of DNA integrity in aging bulls prior to changes seen with light microscope
Sailer, B.L., Jost, L.K. and Evenson, D.P. (1995) Mammalian sperm DNA susceptibility to in situ denaturation associated with the presence of DNA strand breaks as measured by the Terminal Deoxynucleotidyl Transferase Assay. J Andrology. 16:80-87.
- Young vs. older bull
Samples of cryopreserved semen were collected at 14 months of age and again at about four years of age for comparison of semen quality of young vs. mature bulls. The results suggest that semen quality of young bulls was related to subsequent quality as mature bulls. Knowing the relationship between the quality of semen produced by the mature bull would improve the ability to evaluate potential AI sires at an early age.
Karabinus, D.S., Evenson, D.P., Jost, L.K., Baer, R.K. and Kaproth, M.T. (1990) Comparison of semen quality in young and mature Holstein bulls measured by light microscopy and flow cytometry. J. Dairy Sci. 73:2364-2371.
- Effects of growth implants on sperm DNA integrity
Zeranol implants were given to two groups of bulls 1) one implant at 30 days of age and 2) two implants, one at 30 and the second at 120 days of age. Sperm from implanted bulls vs. control group had altered chromatin structure, indicated by higher (p<0.05) DFI values.
Ballachey, B.E., Miller, H.L., Jost, L.K., and Evenson, D.P. (1986) Flow cytometry evaluation of testicular and sperm cells obtained from bulls implanted with zeranol. J. Animal Sci. 63:995-1004.
Gordon, S.J., H.L. Miller, D.P. Evenson, and D.H. Gee. (1988) Comparison of anabolic implants on reproductive function, performance and carcass characteristics in weaned beef bulls. Can. J. Anim. Sci. 68:367-376.
- Counting sperm cell concentration
This method is considered the most accurate means to determine sperm concentration; up to several fold difference seen by other methods including simple haemocytometer counts.
Karabinus Evenson, D.P., Parks, J.E., Kaproth, M.T., and Jost, L.K. (1993) Rapid determination of sperm cell concentration in bovine semen by flow cytometry. J. Dairy Sci. 76:86-94.