Infertility in dairy cattle is a multifactorial problem that may be linked to a number of causes, including:
|•||Follicle development and the quality of the ovulated oocyte.|
|•||Sperm transport and fertilization.|
|•||The reproductive tract environment.|
|•||A combination of these factors.|
Using transvaginal oocyte recovery techniques coupled with in vitro fertilization, researchers in Ireland recently attempted to examine the impact of what happens to cows metabolically after they calve—during which time cows typically undergo negative energy balance—on oocyte quality. This quality was assessed in terms of morphology and development. Their findings were reported in the March 2012 Journal of Dairy Science.
The researchers tracked bodyweight and body condition score at approximately two weeks before expected calving date, at calving, and then weekly until the end of the experiment (approximately 80 days postpartum). Blood plasma samples were collected and analyzed weekly, starting two weeks before the expected calving date and continuing until the end of the experiment.
Despite differences in metabolic profiles during the postpartum period, the researchers found no evidence of an effect of lactation-induced metabolic stress on oocyte quality. This means other factors, like those listed previously, may have more influence on oocyte quality than metabolic stress.
Source: April 2012 Dairy Cattle Reproduction Council Newsletter