Masters Theses

Date of Award

8-1982

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Hugo Eiler

Committee Members

Robert L. Murphee, John D. Smalling

Abstract

Exogenous oxytocin has been found to increase sperm output in several species of animals when given prior to mating. However, the effect of oxytocin given to bulls prior to electrojaculation was not found in the literature review. Also, it has been documented that small molecules of different chemical nature pass from the blood into the ejaculate. The objectives of this study were to investigate if oxytocin, given prior to electroejaculation would increase sperm output and to find if oxytocin is transferred into the electrojaculate by measuring the uterotonic effect of semen from bulls injected with oxytocin.

In experiment I, five Angus bulls were injected (IM) with 0, 2, 20, or 200 lU of synthetic oxytocin and electroejaculated at 15 and 75 minutes post injection. Collections were kept on ice and sperm were counted in the laboratory using a hemocytometer. Results were expressed as total output of sperm.

In experiment II, four bulls were used. Bulls were injected with 400 lU oxytocin (IV) and 200 lU oxytocin (IM). Semen was collected by electroejaculation at 0, 5, 15, 30, and 60 minutes post injection. Blood was taken from an indwelling jugular catheter at 0, 15, and 60 minutes The uterotonic effect of semen and plasma samples was tested by using the rat uterus preparation bioassay. Thioglycolate was used to break the disulfide bonds in the oxytocin molecule to test if oxytocin was responsible for the uterotonic effect of the blood and semen samples.

The results of experiment one showed that oxytocin, given prior to electroejaculation increased the total sperm output of the group up to 415 percent as compared to the non-injected bulls. However, the mean difference between groups was not statistically significant, probably due to individual variation.

Experiment two indicated that the uterotonic effect of the ejaculate was not affected by the injection of oxytocin prior to electroejaculation. Therefore, if there is release of oxytocin in the male during mating, it is doubtful oxytocin is passed into the ejaculate in significant concentrations.

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