Figure 1.

Transport system that incorporates IgG into colostrum is actively transcribed in the mammary gland postpartum. (A) Site of mammary gland biopsy at the midpoint of the right hind quarter of cows. Biopsies were collected after the first/colostrum milking, within 1 to 2 hr after parturition. Step of passing the needle guide, prior to the core biopsy procedure is shown. (B) Physiological expression of the FcRN heterodimer components, FcGRT and B2M, is significantly higher at day 0 compared with baseline levels at days 40 to 50 of lactation (*P < 0.05; ***P < 0.001). This is indicative of an active process extending to the period of transition milk secretion. As a control, expression of the IgA and IgM transporter, PIGR, was not different between day 0 and days 40 to 50 of lactation.