Identifier

etd-04262011-083851

Degree

Master of Science (MS)

Department

Animal Science (Animal, Dairy, and Poultry Sciences)

Document Type

Thesis

Abstract

Equine embryo cryopreservation is unsuccessful in larger, more easily collected, day-7 embryos. It is imperative that methods to successfully cryopreserve large equine embryos or develop reliable methods to determine embryo size before collection. Therefore the objectives for this study were to quantify the amount of tritiated glycerol that would permeate various sizes of equine embryos and to determine if circulating progesterone concentration was correlated with in utero embryo size. Mean embryo diameter (± SEM) across treatments (1.4M and 3.4M tritiated glycerol) was 696.5µm ± 108.6µm and 925.9 µm ± 214.1µm, respectively and were not different (P=0.44). The percent permeation for 1.4M and 3.4M glycerol were not different (P=0.68). Embryos <400 µm in the 1.4M glycerol treatment group had higher (P=0.002) permeation than embryos >400 µm, 8.32% ± 3.85% and 0.35% ± 0.11%, respectively. Length of time, 60 or 120 minutes, did not affect amount of glycerol uptaken (P=0.26. Serum progesterone concentrations on day 7 post-ovulation were higher (P=0.009) for mares who produced two viable embryos from double ovulation (24.17±2.82ng/ml) compared with mares from which a single embryo (14.04±0.99ng/ml) was collected and control mares (13.53±1.80ng/ml). No differences (P=0.91) were detected in serum progesterone concentration on day 7 post-ovulation between mares from which a single embryo (14.04±0.99ng/ml) was collected and control mares (13.53±1.80ng/ml). Mares producing embryos >400µm tended to have higher (P=0.08) circulating progesterone concentrations than mares producing embryos <400µm. Serum progesterone concentrations day 7 post-ovulation in mares producing embryos >400µm and <400µm were not different (P=0.61 and P=0.68, respectively) than control mares. Single embryos <1000µm in diameter were correlated with circulating progesterone concentration day 7 post-ovulation (r=0.46, P=0.006). There was no significant correlation between embryo diameter, corpus luteum diameter, and serum progesterone concentration day 7 post-ovulation.This is the first study to quantify the amount of glycerol permeating into equine blastocysts and suggests that the capsule may be a barrier to cryoprotectant permeability. Maternal progesterone concentrations day 7 post-ovulation could be utilized in predicting embryo stage and size prior to collection for cryopreservation and in diagnosis of twin pregnancies as a result of double ovulation.

Date

2011

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Gentry, Glen T.

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