Polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are bioaccumulative pollutants
that endanger bovine food safety. Bioaccumulation depends, among others, on the physiological dynamics of
the cow’s reproductive cycle. However, recent studies have focused only on near steady-state situations. Thus,
the effects of animal physiology on PCB + PCDD/F transfer from grass silage and soil to cows’ blood, adipose
tissue, and milk and subsequently to suckling calves during gestation and lactation were investigated. In the
exposed group, nine cows ate a grass silage/contaminated soil mixture (6.6 ± 0.8 μg iPCBs and 2.6 ± 0.4 ng
dlPCB + PCDD/F TEQ kgDM 1) for 109 days prepartum until 288 days in milk (DIM). Four of these cows underwent
decontamination after DIM164, receiving the same clean grass silage as the four control cows during the
experiment. Calves were fed the milk of their respective mothers. In the exposed group, transgenerational bioaccumulation
occurred until DIM164, with calf blood and adipose tissue PCB + PCDD/F concentrations reaching
levels twice as high as those in their respective mothers. Transfer rates from oral intake to milk ranged from 0.1
up to 42%, depending on pollutant congener, dietary treatment, and reproductive parity of the cow. Congener and parity also influenced the decontamination half-lives of milk. In decontaminated calves, declines in adipose
tissue PCB + PCDD/F concentrations coincided with increases in body fat mass. Therefore, it is essential to know
the physiological characteristics of cattle, exposure dose and duration, and physicochemical compound properties
to perform reliable transfer assessments.