Fetal growth restriction in cows is associated with intrauterine diselementosis

Fetal growth restriction (FGR) is prevalent in highly productive dairy herds and presents a considerable challenge for animal husbandry. One contributing factor to FGR is the deficiency of essential trace elements and impaired placental transport functions in pregnant cows. In this study, we performed a comparative analysis of 12 trace elements and their ratios in the hair of newborn calves with a history of FGR (Group I, n = 18) and those born to cows with a normal pregnancy (Group II, n = 24). FGR was diagnosed based on ultrasound examinations of the pregnant cows performed at 38–45, 60–65, and 110–115 days of gestation using an Easi-Scan-3 scanner with a 4.5–8.5 MHz linear sensor (BCF Technology Ltd., Great Britain) following a previously established and published protocol. Hair samples from the calves were collected from the tail switch immediately before their first colostrum feeding. The concentrations of arsenic, cadmium, cobalt, copper, iron, mercury, manganese, molybdenum, nickel, lead, selenium, and zinc in the hair were analyzed using inductively coupled plasma mass spectrometry (Nexion 300D, Perkin Elmer, USA). To evaluate intrauterine diselementosis based on the trace element levels in the hair, various ratios were calculated: arsenic/selenium, mercury/selenium, lead/selenium, lead/zinc, cadmium/selenium, nickel/zinc, and iron/copper. Calves in Group I had significantly higher levels of cadmium in their hair (increased by 66.7%, P 0.05) and mercury (increased by 15.0 times, P 0.05) along with lower levels of copper (decreased by 30.7%, P 0.05), selenium (decreased by 28.8%, P 0.05), and zinc (decreased by 26.4%, P 0.05) compared to calves in Group II. The concentrations of other trace elements in the hair did not differ significantly between the groups. These findings indicate that fetal development in calves during the last trimester of pregnancy occurs under conditions of an imbalance of essential and toxic trace elements. The mercury/selenium ratio in the hair of Group I calves was increased by 45.3 times (P 0.05) compared to Group II calves, while the lead/selenium ratio was 2.81 times higher (P 0.05), the cadmium/selenium ratio was 6.63 times higher (P 0.05), the nickel/zinc ratio was 2.91 times higher (P 0.05), and the iron/copper ratio was 2.64 times higher (P 0.05). In this study, we also examined the potential causes and mechanisms underlying these imbalances.