Four experiments were conducted to evaluate the viability and fertility of bovine spermatozoa encapsulated in microcapsules and microgels. In Experiment I, one of two morphologically distinct sperm types i.e. marker or unmarked bull spermatozoa (100 x 10⁶ sperm/bull) were encapsulated in protamine sulfate microcapsules and simultaneously inseminated with the reciprocal sperm type unencapsulated. Insemination of both sperm types unencapsulated served as a control. Accessory sperm embedded in the zona pellucida were counted and morphologically classified 6 to 7 d post insemination. From microencapsulated inseminates, accessory sperm populations did not increase over the unencapsulated controls, but contributed 25.7% of the accessory sperm population. ln Experiment 2, an in vitro study was performed to evaluate the maintenance of viability for bovine spermatozoa encapsulated in PIPES, HEPES, or saline microgels. Neat semen was pooled from five bulls (50 x 10° sperm/bull), encapsulated in alginate microgels, and incubated at 37 C for 8 h. The unencapsulated control displayed greater maintenance of viability for percent intact acrosomes and motility when compared to all treatments. By 8 h incubation, PlPES and HEPES were not significantly different, but demonstrated greater maintenance of viability when compared to saline microgel treatments. In Experiment 3, PIPES microgels were heterospermically inseminated with equal numbers (20 x l0⁶ sperm/bull) of frozen-thawed marker bull and normal bull spermatozoa as explained in Experiment 1. Microencapsulated treatments contributed significantly lower numbers of accessory sperm when compared to unencapsulated controls. In Experiment 4, one of the two morphologically distinct sperm types (20 x l0⁶ frozen-thawed sperm/bull) were encapsulated in protamine sulfate microcapsules and the reciprocal sperm type was encapsulated in PIPES microgels. A total of 21 accessory sperm were recovered from 30 embryos which demonstrates the ability of microencapsulated spermatozoa to fertilize an oocyte. / Master of Science