Research published in the March Journal of Dairy Science suggests that may be the case.

Using embryo transfer techniques, scientists implanted, then recovered embryos from Holstein cows and heifers to determine fertility difference in the animals’ reproductive tracts. The study only featured eight cows and 10 heifers, but each received 100 embryos. The researchers think that the results show that the reproductive tract of the postpartum lactating dairy cows may be less capable of supporting early embryo development than that of the non-lactating heifer. They suggest that this may contribute to the lower conception rates observed in these animals.

In addition, the researchers also note that infertility in dairy cattle is a multifactorial problem that may be linked to suboptimal follicle development associated with reduced estrus expression and consequently, low detection. It’s also linked to suboptimal oocyte quality, altered sperm transport, problems at fertilization, a suboptimal reproductive tract environment to support embryo development or a combination of these factors.