Use of Schizochytrium spp. microalgae in suckling Holstein calves at different periods after birth

Abstract Calves are born immunologically immature and are highly susceptible to infectious diseases. For these reasons, suitable handling practices that favor health conditions and improve performance are necessary at this phase of life. The aim of this study was to evaluate whether the inclusion of Schizochytrium sp. microalgae for Holstein calves at different ages would improve dry matter intake (DMI), performance and health. Twenty-four newborn Holstein calves (34.0 ± 1.5 kg of BW) were allocated in a completely randomized design and were individually housed over 45 days. Starter and ryegrass hay and water were offered separately and ad libitum after the third day of life. Calves were daily fed five liters of whole milk divided in two equal meals. Treatments were as follows: whole milk without addition of microalgae (CON); addition of 6 g of microalgae/day over 45 days (ENT); addition of 6 g of microalgae/day from the 15th day of life until weaning (A15); and addition of 6 g of microalgae/day from the 30th day of life until weaning (A30). Calves that received microalgae (ENT, A15 and A30) had greater intake of starter in grams per day (P = 0.01) and metabolic weight (P = 0.02), and they tended (P = 0.07) to increase total DMI when compared with CON, without a difference in terms of feed efficiency (P = 0.20). Higher weaning thoracic perimeter (P = 0.03) for supplemented animals were observed. Serum lipid peroxidation (LPO) and reactive oxygen species (ROS) were reduced (P = 0.029 and P