Effects of dairy cow metabolic profile and seasonality (spring × winter) on metabolism, health and immunity of their calves

Maternal status during the transition period can have lasting effects on several health and performance variables of Holstein dairy calves. However, the specific effects of maternal late gestation metabolic status and seasonality on the offspring are not well established. The general objective of this study was to evaluate the impact of maternal variables at calving on the performance, metabolism, and immunity of 28 dairy calves during the first month of life. Blood samples were collected from Holstein cows (n=28) at calving. The median values for maternal variables, such as non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), glucose, total protein (TP), albumin, triglycerides (TG), total cholesterol (TC), haptoglobin (Hp), body weight (BW), and body condition score (BCS) were calculated. These median values were used as a cut-off to distribute the offspring into two experimental groups. The 28 calves were classified based on their dams' high or low degree of each maternal factor. Additionally, the animals were categorized according to the season of birth (spring x winter). The responses of calves in each group were compared throughout their first month of life. Blood samples were taken from the calves at birth and on the 1st, 7th, 14th, and 28th day of life. These samples assessed IgG levels, biochemical parameters, acute-phase protein (Hp), and reactive oxygen species (ROS) production by polymorphonuclear cells stimulated by PMA, E. coli, S. aureus, and S. hyicus. Simultaneously, the calves were clinically evaluated for diarrhea, bovine respiratory disease, or other clinical findings. Despite the cows being healthy, differences in the behavior of calf parameters were observed between maternal groups (low and high). Heavier cows and high maternal BCS tended to calve bigger offspring, as indicated by the higher height at the withers and rump width. On the other hand, high maternal BCS was associated with high diarrhea prevalence in D28. Additionally, a low maternal BCS resulted in a higher ROS production, signifying a more robust innate immune response. Furthermore, calves from cows under metabolic changes, characterized by high NEFA and low glucose, exhibited elevated Hp concentrations. Concerning seasonality, spring-born calves were larger (weight at the withers and rump width), yet they displayed lower IgG levels and a reduced innate immune response. Moreover, they exhibited a higher level of inflammation (Hp) and a greater prevalence of diarrhea on D28. These findings were significant as they underscore the notion that a successful neonatal period commences during gestation. Further research is recommended to unravel the mechanisms by which metabolic parameters during late gestation influence the immune and metabolic responses of offspring, as well as the clinical consequences of these carryover effects on the health and growth of the offspring. In addition, exploring the calf's parameters later in life is suggested, making it possible to know the persistence of the maternal effects over time. This information allows for the development of management practices that promote the health of cows in the transition period and their calves, ultimately improving milk production and heifer replacement.