In which trimester does in-utero crooked calf disease occur?

In-utero crooked calf disease occurs specifically during the early gestation period of bovine development. This condition is primarily associated with certain viral infections, such as BVD (bovine viral diarrhea) virus or other teratogenic factors that affect the developing fetus during a critical time when organ systems are beginning to form. The most vulnerable period for the developing calf to be affected by agents that can lead to congenital defects is in the first trimester, particularly before the organogenesis phase is complete.

Disruptions during this time can lead to significant skeletal and other developmental abnormalities, collectively referred to as crooked calf disease. As such, exposure to harmful agents early in gestation can result in the characteristic deformities associated with this condition, illustrating the importance of maternal health and biosecurity during the early stages of pregnancy in cattle.