Improvement of reproductive efficiency in the early postpartum cow using embryo transfer /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Experiment I was conducted at the Texas Agricultural Experiment Station in McGregor, Texas where an estrous synchronization and superovulation protocol was tested on two groups of range cows. Estrus was synchronized and superovulation was performed prior to detection of the first postpartum natural estrus. It was demonstrated that estrous synchronization and superovulation were possible in beef cows with embryo recovery by day 37 postpartum. Embryo recovery results were not different from results in the previous year (2.5 vs 2.3) with the same group of cattle but using them after the first postpartum estrus. It was further determined that estrous synchronization in recipient animals was possible by day 30, with or without the use of PMSG. Experiment II was conducted at the Texas A&M University Beef Cattle Center using registered Hereford and Angus cattle. The same estrous synchronization and superovulation protocol as in experiment I was tested on registered cattle. Under improved nutritional and management schemes, it was demonstrated that the success of the program was improved over experiment I. Angus donors yielded 5.5 embryos and Hereford donors yielded 11.3 embryos vs 2.5 for the McGregor donors. Experiment III was conducted at the Texas A&M University Dairy Center and the Texas Department of Corrections Dairy Center, Eastham Unit, Lovelady, Texas. This study demonstrated the adverse effects of nutrition in the form of a negative energy balance on superovulation and embryo production. It was shown that Holsteins under a negative energy balance produced significantly fewer embryos than beef cows in a positive energy balance (1.2 Holstein embryos vs 5.5 Angus embryos and 11.3 Hereford embryos). Experiment IV was conducted on registered Simmental donors and demonstrated the success of extremely early embryo collections when under a high degree of management. Embryos were recovered as early as day 31 postpartum. The average recovered was 6.3 embryos. Overall the study demonstrated that ovarian function can be limited when inadequate energy is provided to the early postpartum cow. It also demonstrated that the early postpartum uterine environment (Day 25-30) is capable of providing embryonic nourishment prior to the completion of involution. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Physiology of reproduction." |
| Physical Description: | xiv, 107 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |