title: Effects of egg yolk-citrate and milk extenders on chromatin structure and viability of cryopreserved bull sperm.
abstract: Semen from four Holstein bulls was evaluated to compare effects of four extender treatments on postthaw semen quality. Extender fractions A and B, either heated whole milk or 20% egg yolk-citrate, were combined to yield the extender treatments 1) milk and milk, 2) milk and egg yolk-citrate, 3) egg yolk-citrate and milk, and 4) egg yolk-citrate and egg yolk-citrate. Semen was evaluated at thawing and after 30, 60, 120, and 180 min of incubation at 38.5 degrees C. Flow cytometry showed that acridine orange-stained sperm were most susceptible to in situ DNA denaturation when fraction A was milk. For sperm stained with rhodamine 123, flow cytometry showed that the proportion with intact mitochondrial membrane potential was lowest of all treatments at thawing but greatest at 180-min incubation with milk and milk extender. Flow cytometry of propidium iodine-stained sperm showed greatest proportion of cell membrane intact sperm when fraction A was egg yolk-citrate. Light microscopy showed the lowest proportion of cell membrane intact sperm with milk and milk extender after eosin-aniline blue vital staining. Postthaw motility scores tended to be reduced when both extender fractions were egg yolk-citrate. Results demonstrate differential extender effects on postthaw semen quality and indicate that altering extender composition or sequence of adding extender components may improve postthaw quality of cryopreserved sperm.
authors.affiliation: Department of Chemistry, South Dakota State University, Brookings 57007.
authors.forename: D S
authors.initials: DS
authors.lastname: Karabinus
authors.forename: D P
authors.initials: DP
authors.lastname: Evenson
authors.forename: M T
authors.initials: MT
authors.lastname: Kaproth
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002843:Chromatin / Q000187:drug effects* / Q000648:ultrastructure; D002951:Citrates / Q000494:pharmacology*; D015925:Cryopreservation; D004530:Egg Yolk / Q000737:chemistry; D005434:Flow Cytometry; D008297:Male; D008892:Milk / Q000502:physiology*; D012662:Semen Preservation; D013081:Sperm Motility; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D013194:Staining and Labeling
chemical_list: D002843:Chromatin; D002951:Citrates