Document Type

Thesis - Open Access

Award Date

1960

Degree Name

Master of Science (MS)

Department / School

Dairy Science

Abstract

During the period between 1940 and 1960 artificial insemination of dairy cows grew from the experimental stage to an extensive business enterprise in the United States. According to the Dairy herd Improvement Letter (Vol. 36, No. 3, A.R.S., U.S.D.A.) only 7,359 cows and heifers were artificially inseminated in 1939, but by 1959 this number had increased to 6,932,249. Along with the extended use of superior sires, a logical conclusion was that some attention should be directed toward increasing the use of good female germ plasm. If this could be accomplished, a more rapid improvement in the quality of dairy cattle would be possible. The problems of increasing the use of female germ plasm are many. The fact that females usually shed only one ovum at a time makes the problem very complicated when compared to insemination where millions of sperm are released per ejaculate of the male. The techniques of gathering the ovum from the donor and transferring it into the uterus of the recipient have been investigated (35, 36, 41, 99, 115, 123). However, this process is in the experimental stage and if it is to become of practical value, methods must be developed for storing ova over long periods of time. The early experiments by Heape (61, 62, 63), Pincus and others (85-93) have shown that ova can be removed from the female reproductive tract and stored at refrigerator temperatures for as long as one week, but if ova transfer is to become as economically feasible as artificial insemination has, longer and better storage facilities will need to be discovered. Since frozen semen stored for many months is being used extensively, it seemed logical that similar techniques might be used with ova. Because long time storage is so desirable many attempts were made to find the most suitable conditions for freezing and storing ova. The rabbit was the experimental animal chosen for these experiments with the hope that the techniques developed could be applied to dairy cattle. The procedures and results of these experiments are described in this manuscript. Three phases of work have been investigated and are reported here. These include: (1) recovery of ova from fertilized donor rabbits, (2) freezing and storage of the ova, and (3) transplantation of the ova. This three-fold approach allows for an assessment of the importance of several steps in the technique to successful ova transplant work.

Library of Congress Subject Headings

Ovum
Rabbits
Embryology -- Mammals

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

65

Publisher

South Dakota State University

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