Risk Factors Associated with Lameness, Subclinical Mastitis and Hock Wounds in Tie-Stall Dairy Cows across Four Production Regions of Sri Lanka

In the world of dairy farming, the comfort of the cow is not merely a matter of kindness; it is the foundation of a healthy, productive herd. When a cow is in pain or discomfort, her body diverts energy away from producing milk and toward healing, leading to lower yields and higher costs for the farmer. Three specific problems often plague dairy herds: lameness, which is pain in the feet or legs that makes walking difficult; subclinical mastitis, a hidden infection of the udder that does not always show visible swelling but still harms milk quality; and hock wounds, which are sores on the back of the leg where the animal bends. These issues are deeply connected to the environment the cow lives in. If the floor is too slippery, the animal cannot walk safely; if it is too dirty, bacteria can infect the udder; and if the space is poorly designed, the animal may injure itself while trying to lie down or stand up. Understanding how these physical surroundings interact with daily management is essential for keeping cows healthy, especially in tropical climates where conditions can be particularly challenging.

Researchers in Sri Lanka set out to uncover exactly how these factors play out in real-world settings. They focused on tie-stall farms, a common housing system where cows are tethered in individual stalls, across four distinct regions of the country: the cool highlands, the mid-country, the coconut-growing triangle, and the western province. These areas differ significantly in temperature and humidity, ranging from the cool, misty highlands to the hot, humid lowlands. The team visited 597 farms and examined 1,240 cows, using a combination of direct observation, standardized scoring systems, and thermal imaging cameras to detect invisible injuries. They looked closely at the condition of the floors, the cleanliness of the animals, and the design of the stalls to see what drove the prevalence of these three welfare issues.

The investigation revealed that the problems were not evenly distributed across the country. Lameness, for instance, was most severe in the highland region, affecting nearly 28 percent of the cows there, while it was least common in the coconut triangle, where only about 6 percent of the animals were affected. The researchers found that the condition of the floor was a primary driver of these differences. Dirty, slippery, or cracked floors were strongly linked to lameness in every region. When a floor is slick, a cow must constantly adjust her gait to avoid falling, which puts stress on her joints and hooves. When the floor is cracked or uneven, the animal shifts her weight awkwardly, damaging sensitive tissues. The study showed that these physical hazards did not act alone; they interacted with how clean the cow was and whether she already had wounds. For example, in the highlands, a cow with dirty legs standing on a slippery, cracked floor was at a much higher risk of becoming lame than a cow in the same environment with clean legs.

The researchers also discovered that keeping the cows clean was vital for preventing hidden infections. Subclinical mastitis, the silent udder infection, was significantly more common when the cows' flanks, legs, and udders were dirty. This makes sense because bacteria from manure and mud on the legs can easily transfer to the udder when the animal lies down. The study confirmed that in the highlands and the coconut triangle, the cleanliness of the cow was a major predictor of whether she would develop this infection. Similarly, hock wounds were heavily influenced by the floor. Very slippery floors increased the likelihood of these sores by more than half, while dry flooring reduced the risk by a similar margin. The type of floor mattered as well; hard, abrasive concrete surfaces caused more injuries than softer bedding, and in some regions, having too much extra space in the bedding area actually led to more wounds, likely because the design encouraged awkward movements.

Perhaps the most encouraging finding was that these problems are not inevitable. By analyzing how different factors combined, the researchers calculated that under optimal conditions—where the floor is clean, dry, and has good grip, and the cow is free of wounds and dirt—the probability of a cow becoming lame could drop by nearly 97 percent in the highlands. In other regions, similar improvements in flooring and hygiene could reduce the risk of lameness by roughly half. This suggests that the solution does not require a complete overhaul of the farming system, but rather targeted adjustments to the environment. A farmer in the wet, hot west might need to focus on keeping floors dry and clean, while a farmer in the cool highlands might need to prioritize fixing cracks and ensuring the floor provides enough grip. The study concludes that by tailoring housing designs and management practices to the specific climate and conditions of each region, dairy farmers can significantly improve the welfare of their cows and support a more sustainable milk production system.