Climatic factors affecting quantity and quality grade of in vivo derived embryos of cattle

The present study investigated the effects of climatic variables on the quality grade and quantity of in vivo derived cattle embryos in the Midwestern United States. Climatic information included greatest and least daily temperature, average daily wind speed and average temperature-humidity index for each of the 765 records. The response variables included the number of ovarian structures, viable embryos, quality grade 1 embryos, quality grade 2 embryos, quality grade 3 embryos, freezable embryos (sum of quality grade 1 and quality grade 2 embryos), transferable embryos (sum of quality grade 1–3 embryos), degenerate embryos and unfertilized ova. Measures for variables among the breeds of donors and sires grouped by geographical origin were compared. A negative effect of greater temperatures during the early embryonic development stage tended (P