Grazing Improves Immune Parameters and Complete Blood Count in Calves

Grazing represents a sustainable option for rearing dairy male calves. Specifically, grazing strengthens immune function, while high-elevation pastures improve haemoglobin levels and red blood cell counts.

The management of dairy male calves remains a challenge, particularly in organic farming systems. Currently, these calves are often sold to conventional fattening units, where prophylactic and therapeutic antibiotic use is common. While organic farming seeks to rear these animals on-farm, significant challenges persist in terms of management, costs, and market access. Although such systems can offer health benefits, they also present difficulties. This study aimed to determine whether grazing improves the immune status—and thus overall health—of post-weaning calves.

Health of male calves: Effects of genotype and pasture conditions

The FiBL studied 72 calves weaned at four months of age, divided into three genotypes. From four to six months of age, calves were either grazed at three distinct sites or kept in an indoor control group. The genotypes included Brown Swiss (a classic dairy breed), Swiss Fleckvieh (a dairy-oriented dual-purpose breed), and Limousin × Brown Swiss crossbreeds (combining beef and dairy traits). The three grazing sites were located at elevations of approximately 500 m, 1000 m, and 2000 m, with forage production intensity decreasing as altitude increased.

Grazing fosters calf health

A key objective of this study was to assess animal health – evaluated through health scores, haematological parameters, and blood immunoglobulin levels – after three months of grazing. Results showed a higher incidence of diarrhea at the start of grazing compared to indoor housing; otherwise, no other health differences were observed between groups. Grazing significantly increased α- and γ-globulin levels in blood serum. Additionally, as hypothesised, higher-altitude pastures mitigated anaemia, with calves exhibiting elevated haemoglobin levels and red blood cell counts.