Lameness in Grazing Dairies

Published on Tue, 11/26/2019 - 10:14am

 Lameness in Grazing Dairies

 By Michael Cox

 What causes lame cows in grazing dairy herds? Suggestions such as infectious diseases, abrasions, injuries, poorly balanced diets, genetics etc. all spring to mind when we think of the causes of lameness, however the two primary reasons are; People and Infrastructure.

According to Dairy NZ (New Zealand) research, people and infrastructure are the two root sources of nearly all lameness issues across New Zealand’s thousands of grazing dairies, and the same can be said for grazing dairies across the world. Understanding the reasons behind poor locomotion in the herd is the first step in being able to identify what’s causing the (somewhat) avoidable levels of lameness on our own individual farms.

Understanding Behavior
Given the fact that wild animals such as buffalo and deer rarely become acutely lame, it’s clear that the human-animal relationship in grazing domesticated cows is a major cause of lameness. Our management changes the natural behavior of how, where and when cows walk. Having staff trained on cow behavioral issues such as ‘flight zones’ is the first step in making sure people aren’t ‘rushing’ cows and forcing them to walk so fast that they cannot avoid obstacles and abrasions. Tools and websites such as CowSignals can be a great way of learning how a cow views a person, and how a cow typically reacts to a person’s movements.

Pushing Cows
When moving cows on horseback or on a 4-wheeler along a roadway/track, it is recommended to stay at least 20 yards back from the last cow. Cows have a dominance hierarchy, and ‘lead’ cows along the group decide when to slow down, when to speed up, and which cows get to walk in-front and behind them. The dominant cows act in a push-pull manner. They decide when to walk forwards and ‘pull’ the herd mates behind them, and they also decide when to stop, causing the cows to the rear to ‘push-up’ closer together. Rushing, pushing and bunching cows up tightly forces submissive cows too close to the ‘personal space’ of dominant cows, invoking aggression from the dominant cows and ‘escape’ behavior in submissive cows. When cows are bunched too tightly together, they raise their heads and therefore they cannot see where to place their feet – leading to treading on sharp objects along the road surface. Therefore, rushing cows from the rear is a pointless exercise in an attempt to speed up cow movement, and in fact it will have the opposite effect of actually slowing down the speed of the herd, as they jostle to reestablish natural dominance positions.

Physical Results
The effect of people on cow behavior can’t be underestimated. Research from New Zealand suggests that cows milked by ‘stressful’ milking staff had a 6% reduction in annual milk yield compared to similar cows milked in a calm environment. Stress induced cows had higher blood cortisol levels, which reduces the milk let-down process during milking. Handling cows in a calm and efficient manner results in less stress on both staff and animals, and more milk in the bulk tank.

Hard surface areas
Concrete is not a natural surface for cows to walk on regularly, and it can cause excessive wear to the sole of the hoof if the surface is too rough. Grooving concrete is a specialist operation, as too deep of grooves will wear down hooves too fast and cause white line disease and other lameness issues; while shallow grooves can provide too little grip for cows – increasing their risk of slipping and falling. People behavior can also increase lameness risk to cows walking on concrete. For example, Dairy NZ highlights that milking staff leaving the parlor to go outside into the collecting yard/loafing area to push cows into the milking barn can greatly increase lameness in the herd. The dominance hierarchy of the herd plays a role in the collecting yard; with dominant cows deciding when and which cows get to enter the milk barn. A person walking amongst the cows disturbs this order, resulting in stressed cows, jostling cows and excessive wear on hooves. When cows are disturbed in a small area, they can turn sharply to avoid a person or dominant cow. This sharp turn effectively ‘grinds’ the sole of the hoof off the concrete and will weaken the hoof structure over time. Tight turns at any stage of a cow’s walk from barn or pasture to milking barn will cause this same type of undesirable hoof action.
Apart from providing correct grooving on hard surfaces, dairymen should also aim to limit the amount of debris that is found on concrete. Solid debris such as small pebbles and grit on concrete can easily injure the hoof and cause ulcers if trod upon. Dairy NZ explains that when a cow steps on a pebble on concrete, the pebble cannot sink into the hard surface, so therefore the cows weight forces the pebble to push upwards into the sole of the hoof. For anyone who has ever trod on a piece of Lego or a phone charger, this pain is all too recognizable. The best way to prevent pebbles being dragged and kicked onto the yard as the herd enters is to install a ‘nib wall’ where the concrete area begins. Nib walls are typically a small square wall, 4 or 5 inches high and wide, that forces the cow to lift their hooves up over the wall. This action prevents pebbles from being kicked onto the yard; instead they hit the nib wall. Accumulated debris in-front of the nib wall can be cleared away as necessary throughout the year. Square nib walls are recommended over round nib walls, as the flat surface is easier judged by the cow and allows for better foot placement as she steps over the wall.

Rubber and Foam Mats
Rubber and foam mats offer a great solution for stall bed comfort, while also serving a dual purpose of excellent loafing and walking surface to cows. In free stall barn situations, a rubber mat of approximately two inches thick is installed on top of the concrete bed to provide additional comfort and cushion for lying. The matt can then be sprinkled with sawdust, lime, straw or paper to improve cow cleanliness and comfort. Mats provide a very simple and effective comfort option which can be quickly and easily installed and maintained. Mat options include flat solid rubber mats, rubber filled mats and also foam filled mats.
Lying time in stalls can be increased by providing a deep bed of sawdust or similar material to make the stall as attractive as possible to the cow. Rubber filled mattresses offer a slightly different option than solid mats. The mattress is more flexible and molds under the cow’s body. Maximizing lying time has enormous benefits to the cow, through increased rumination, more blood flow to the udder and lower incidence of lameness. Quite simply, when cows are not on their feet, they have little opportunity to become lame. Mats also offer a clean and dry resting area for hooves and will reduce the time spent standing in damp conditions and the chance for bacteria growth around the hoof.
Several research studies have highlighted the benefits of rubber and foam mats for use in alley ways. The softer underfoot conditions provided by mats reduces physical injuries to the hoof compared to concrete floors, and therefore a reduction in lameness overall.
If installing mats along the entire alleyway is cost prohibitive for producers, corners, holding areas and other areas where cows turn should be prioritized for mat use. Cows turning corners on concrete has the most effect on wear and tear on the hoof, which can lead to bruising, ulcers and other lameness issues. The act of turning a corner can ‘grind’ the hoof against concrete; rubber and foam mats will reduce this issue. Research studies have shown alley mats can improve locomotion scores and cows take longer strides, indicating that they feel comfortable and assured of foot placement when walking on the mats. Many modern mats have a non-slip surface and this will improve cow’s confidence and willingness to move around regularly from feed to water to the free stall.  Hygiene on mats can also be easier to maintain. Lameness issues such as digital dermatitis can be more easily controlled in an alley mat environment as hygiene can be improved.  
Mats have a wide array of benefits to offer the dairy cow, such as, better hygiene, improved cow cleanliness, improved locomotion, improved feed intake if headlock mats are installed, greater lying time and reduced physical abrasions and injury. Before installing mats either in alleyways or on stalls, producers should visit other dairies with experience of mat use and learn the pros and cons of the system.