Due to the synepitheliochorial placental structure, bovines show no maternal antibody flow from mother to fetus during pregnancy, resulting in an agammaglobulemic newborn

This study examines the critical role of whole milk or milk replacer as a liquid diet (LD) with 15% solids in combination with different physical forms of starter as a solid diet (SD), on performance, health, and behavior of pre-weaned calves. Sixty male Holstein calves were used in a 2 × 2 factorial design, and randomly distributed into the following treatments: Whole milk powder diluted to 12.5% of solids and enriched with 25 g/L of milk replacer to achieve 15% solids, associated with either micropelleted stater (WM+micro) or texturized stater (WM+text); milk replacer diluted to 15% solids associated with either micropelleted stater (MRmicro) or texturized stater (MRtext). Starter intake and, consequently, total DMI were higher in the MRtext treatment compared to WM+micro. Calves fed texturized starter showed higher DMI, starter intake time, and rumination time. Calves in the WM+Text group showed greater ADG compared with MR treatments, regardless of starter type. Calves fed WM+ presented a lower number of days with fecal score ≥2, and the first day of diarrhea occurred at older ages. Calves fed MR showed more health challenges but similar feed efficiency with WM+, while texturized starter increased intake, eating duration, and rumination compared with micropelleted starter.