Masters Theses

Date of Award

8-2001

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

J. Lannett Edwards

Committee Members

Jim Godkin, F. Neal Schrick

Abstract

Overall objective of this thesis was to use aging as a way of investigating potential biological differences between X- and Y-bearing sperm. Specific objectives included the following: 1) examine effects of aging sperm 19.5 h postthaw in an incubator at 38.5°C by evaluating embryonic development after fertilization: 2) examine effects of aging sperm within an artificial insemination (Al) straw for 8 and 14 h post-thaw in a water bath at 34.4°C or 23 h post-thaw in a refrigerator at 4°C by evaluating sperm motility and embryonic development after fertilization; 3) investigate effects of aging sperm within an Al straw 14 h post-thaw in a water bath or 23 h in a refrigerator for altering sex ratio of embryos after fertilization; and 4) examine effects of aging sperm within an Al straw 8 and 14 h post-thaw in a water bath for altering sex ratio of embryos after fertilization. Fertilization of oocytes with sperm aged 19.5 h in an incubator reduced proportion of putative zygotes (PZ) cleaved (P<0.05). However, ability of cleaved embryos to develop to 8-16 cell (P>0.1) or blastocyst was not compromised (P>0.1). Aging sperm in an Al straw 14 h post-thaw in a water bath or 23 h post-thaw in a refrigerator reduced proportion of motile sperm (P<0.0001). Moreover, fertilization of oocytes with sperm aged in an Al straw 14 h post-thaw in a water bath reduced proportion of PZ which cleaved (P<0.05); however, ability of cleaved embryos to develop to 8-16 cell (P>0.1) and blastocyst was not compromised (P>0.1). Interestingly, fertilization of oocytes with sperm aged in an Al straw 14 h post-thaw in a water bath altered sex ratio of embryos, resulting in more females (P<0.05). In contrast, fertilization of oocytes with sperm aged in an Al straw 23 h post-thaw in a refrigerator did not alter sex ratio. Surprisingly, fertilization of oocytes with sperm aged in an Al straw only 8 h post-thaw in a water bath did not alter sex ratio of embryos. Blastomere numbers in male and female embryos did not differ (P>0.2). Results suggest the possibility that biological differences may exist between X- and Y-bearing sperm. If results are shown to be repeatable, such differences between X- and Y-bearing sperm may be exploited for the development of alternative methods of sex selection.

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