Pathophysiology of nematodiasis in cattle

Area of Science:

• Veterinary Medicine
• Animal Physiology
• Parasitology

Background:

• Gastrointestinal nematode infections in cattle lead to weight loss and reduced carcass value.
• These effects are linked to significant alterations in host metabolism, particularly protein metabolism.

Purpose of the Study:

• To investigate the metabolic changes in cattle infected with gastrointestinal nematodes.
• To differentiate between protein loss and altered protein metabolism as causes of weight loss.

Main Methods:

• Analysis of physiologic and metabolic changes in infected cattle.
• Assessment of protein metabolism, including muscle synthesis and nitrogen excretion.
• Evaluation of protein loss in feces versus postabsorptive catabolism.

Main Results:

• Infections cause decreased muscle synthesis and increased urinary nitrogen excretion.
• Protein loss into the gut lumen is less significant than postabsorptive protein catabolism, except in infections involving the colon and cecum.
• Parasite-induced alterations in gut hormones and macrophage activation (cachectin) are proposed mechanisms.

Conclusions:

• Weight loss in cattle with gastrointestinal nematode infections is primarily due to postabsorptive protein catabolism, not direct protein loss.
• Altered gut hormone levels and cachectin production by activated macrophages may mediate these metabolic changes.
• Understanding these mechanisms is crucial for managing parasitic infections and improving cattle health and productivity.