Bovine Gallstones Worldwide: Biology, Epidemiology, Supply Chains, and Key Issues
1) Introduction: What Are We Talking About?
Bovine gallstones (or choleliths) are solid concretions formed in the gallbladder or bile ducts. In cattle, they result from the aggregation of elements present in bile—pigments, cholesterol, bile salts, calcium, proteins—under particular physico-chemical and biological conditions. They have long been known to veterinarians, pathologists, and slaughterhouse professionals. Unlike in some other species, most gallstones in cattle remain silent and are discovered incidentally during slaughter.
However, their importance goes beyond anecdote: certain parallel markets value these concretions highly (often referred to as niú-huáng in Asian pharmacopoeia), creating economic incentives and ethical questions.
2) Composition and Formation Mechanisms
2.1 Chemical Composition
Bovine gallstones are broadly classified into:
- Pigment stones: rich in calcium bilirubinate (and other calcium–pigment complexes). They are often dark brown to black, with a concentric structure and a surface that may be smooth or granular.
- Cholesterol stones: less common in cattle than in humans, composed mainly of crystalline cholesterol.
- Mixed stones: alternating layers of pigment, cholesterol, and protein, sometimes with inclusions of mucins and mineral salts.
Traces of bile acids (cholate, taurocholate), phospholipids (notably lecithin), proteins (mucins, glycoproteins), and minerals (Ca, Mg, P) complete the architecture.
2.2 Pathophysiology
Bovine bile is a micellar mixture stabilized by bile acids and phospholipids. For a gallstone to form, three steps are required:
- Nucleation – the appearance of a solid “seed.” In pigment stones, bile pigments precipitate with calcium, sometimes favored by cellular debris or bacteria. In cholesterol stones, cholesterol supersaturation and micellar destabilization initiate crystal formation.
- Growth – layer-by-layer deposition, promoted by bile stasis (reduced gallbladder motility), mucosal inflammation (which releases mucins), and variations in pH and ion concentration.
- Aggregation and remodeling – microliths clump together, are polished by friction, and may fracture and heal over time.
2.3 Role of Microflora and Inflammation
Certain bacteria producing β-glucuronidase can deconjugate bilirubin, facilitating pigment precipitation. Ascending infections or chronic cholecystitis alter mucin secretion and gallbladder dynamics, creating a favorable environment for pigment concretion.
Next week we will address the following topic: Global epidemiology: variation by regions, systems, and races.