Estimation of Weight and Lipid Composition in Preimplantation Embryos from Jersey and Beef Breeds of Cattle

Abstract

Cryopreservation is the main functional means for storage of excess embryos produced from artificial reproductive technologies; the process assumes embryos chemical nature is highly conserved across embryos of the same species. However, in practice there appears to be a high degree of variability in embryo tolerance to cryopreservation, suggesting potential differences in embryo chemistry. The objective of the current study was to develop reproducible means of estimating relative embryos weight and associating those weights to lipid content. Relative embryo weights of frozen/thawed in-vivo Jersey and Crossbred beef breed embryos were determined using a modified specific gravity chamber. Embryo weights were then correlated with lipid content. Results suggest that beef cattle embryos are 20%-27% heavier than Jersey embryos (P < 0.001). Electron microscopy (EM) data suggest that these differences are due to divergent lipid content; Jersey embryos having approximately 36% lipid as compared to 8% in beef cattle embryos (P < 0.01); explaining the Jersey embryos lighter weight.

A Simple Test of Seminal Fluid Chemistry and Its Potential Impact on Cryopreservation

“…However, while maternal weight went up due to the addition of grams of lipid to an expanding body mass, the estimated weight of the early embryos, with their fixed volume, decreased, presumable as water in the cytoplasm was replaced by the lighter lipid compounds. These findings appear to confirm earlier results in a bovine model where breed differences in body composition were reflected in the oocyte and early embryo cytoplasm [8]. There can be little debate that significant changes in the oocyte/embryo cytoplasm would not only lead to changes in cellular function but would influence the uptake of cryoprotectants during the freezing process and change the freezing curve required for optimum cryopreservation rates.…”