Waste milk consumption in Holstein calves: Effect on systemic adaptive immunity

Area of Science:

• Veterinary Immunology
• Animal Science
• Dairy Calf Nutrition

Background:

• Waste milk (WM) is frequently fed to dairy calves due to its unsuitability for human consumption.
• WM contains drug residues and has high microbial loads, raising concerns about its impact on calf health.
• Understanding WM's effects on calf immunity is crucial for optimizing calf-rearing practices.

Purpose of the Study:

• To investigate the impact of raw waste milk (WM) and pasteurized waste milk (PWM) compared to saleable milk (SM) on the humoral and cellular immune responses of Holstein calves.
• To assess the effects of different milk feeding regimens on calf health and immune cell function.

Main Methods:

• Calves were divided into three groups: SM, PWM, and WM (n=10 each).
• Immune responses were evaluated by measuring peripheral blood mononuclear cell (PBMC) proliferation and cytokine production (IL-4, IL-17, IL-10) after stimulation.
• Humoral immunity was assessed through serum total protein (STP), Brix refractometry, and IgG concentration.

Main Results:

• Calves fed PWM and WM had higher PBMC counts than SM-fed calves.
• Cellular proliferation was greater in SM and PWM groups in response to certain stimuli, while WM induced higher IL-17 production.
• WM feeding led to earlier and higher IgG levels, whereas SM promoted higher IL-10 production, suggesting differential immune modulation.

Conclusions:

• Waste milk feeding elicits an earlier and more pronounced pro-inflammatory immune response in calves.
• Pasteurized waste milk offers an intermediate immune profile, while saleable milk may promote anti-inflammatory responses.
• These findings highlight the distinct immunological impacts of different milk sources on calf development.