Awareness of the impact of lameness on dairy cow welfare and economics has grown massively in the last 30 years. Our understanding of the causes and risk factors have also improved. This article covers the major advances in our understanding of how to control lameness.
The majority of lameness is down to a small number of conditions. For the grazing herds white line separation leading to abscesses and infections under the wall is usually most common, followed by stone penetrations, with or without thin soles. For housed herds the problems tend to be sole bruising, sole ulcers, white line separation and digital dermatitis. Youngstock will be sporadically affected by interdigital necrobacillosis (otherwise known as foul, footrot or phlegmon), an acute infection between the claws, which can affect cattle of any age or type, including beef animals. Understanding the lesions that cause lameness will aid in identifying the major risk factors to focus on for control.
Digital dermatitis (DD) was first reported in Italy in 1974 and since then has undergone a global epidemic. Acute infections on the skin around the hooves progress, without treatment, to chronic wart-like lesions. With the moist anaerobic conditions created by slurry and mud on the feet, infections are hard to ascertain, so the mainstays of control include improving yard hygiene and regular foot disinfection using foot baths. Latest concepts in foot baths includes finding ways to maximise the number of foot plunges in disinfectants and ways to reduce particulate contamination. However, the greatest impact is made when combinations of, consistent yard hygiene, foot disinfection and proactive lesion detection with effective treatment are implemented. Treatment must include the newer group of severe necrotic claw lesions, such as toe necrosis and wall ulcers. There is some evidence to suggested there are many different bacteria involved in making infections more or less severe, and so biosecurity and biocontainment (to prevent spread between herds and management groups) remains a priority, even for herds with digital dermatitis.
Also interesting: Make lameness control a priority this winter
Sole ulcer is the term for when a full thickness defect in the horn develops in the mid-sole region of the outer hind claw or inner foreclaw. Mostly hind feet are affected. Historically a lot of emphasis was placed on control of acidosis and nutrition for preventing sole ulcers, but that failed to explain why mostly outer hind claws were affected and the link is still unproven and nutritional interventions have remained largely ineffective for control. More recently, a biomechanical hypothesis has stood up well to scientific scrutiny.
Most sole ulcers occur 2-4 months following calving. One research group demonstrated there are massive changes in the connective tissue within the hooves around calving which lead to failure of the ligament or attachments between bone and hoof, similar to laminitis in the horse. Compression of the soft tissues under the sole leads to inflammation and damage to horn producing cells. This may be compounded by a poorly developed digital cushion in heifers and thin cows. However, given the opportunity to rest, cows will recover from this initial bruising. If resting times become compromised because of poor cubicle comfort, heat stress or long penning times then a chronic inflammatory focus persists. Applying blocks to the opposite claw to rest the injured claw and giving anti-inflammatory drugs has been shown to successfully treat these cows but chronic scarring to the digital cushion means recurrence of lameness and bruising is highly likely.
Cows are naturally pasture based herbivores, and housing on concrete or walking on tracks presents great risks to foot health through trauma. Concrete will bruise soles and white lines, predisposing to sole ulcers and white line separation. Long distances walked on tracks or concrete can wear soles and heels so they are thin and prone to further bruising. Lameness reduces wear on a painful claw, increasing the overloading and predisposing to further lameness. There are many innovative ways in which dairy farmers have tried to reduce the impact of walking on hard surfaces, including the use of rubber matting and Astroturf. These materials are challenging to manage and in the case of rubber, expensive to lay.
The risks of hard walking surfaces are compounded when cows are penned or herded for milking, as dominant cows will bully and push heifers or low dominance cows. Slips and scrabbling behaviour is particularly problematic. Therefore, stocking rates, proper design of facilities, maintenance of grip and gentle stock handling all play a major part in reducing bruising and subsequent white line lesions.
Thankfully long-gone are the days when we would see cows with Aladdin slipper feet. The economics do not permit the neglect of foot health to that degree. If anything, we now see the effects of over-trimming more commonly. The published hoof trimming method has not changed much in 30 years, while the modern Holstein is 25% larger than the traditional Friesian. Given that the Dutch Five Step Method hoof trimming was first developed using Friesians it’s perhaps no surprise that changes are required. Various modifications to the trimming approach have been proposed but these remain scientifically un-tested. Precautionary principles should apply to sound animals undergoing routine foot checks 1-3 times per year, with heel, walls and sole thickness preserved in animals with good foot angle.
Also interesting: Cow management made simple with one bolus
The growing herd size has resulted in a growing sophistication and professionalism within the dairy industry. Innovation in housing design has demonstrated the significance of the environment to foot health. The proactive attitude of managers has shown lameness is not an inevitability of dairy farming. Many of the larger dairy units have applied routine foot checks by professionally trained trimmers, regular foot disinfection following strict protocols and regular screening for lameness using lameness scoring approaches. When using lameness and lesion data generated from large herds it is possible to identify risks and management factors leading to better foot health. The results have been revolutionary and have unlocked productivity in many herds hampered by lameness and consequential losses of fertility, premature culling and loss of milk yield due to lameness. The pace of changes within the industry means the next five years will be an exciting period for the advancement of precision livestock farming, with the introduction of new technology for quantifying and optimising foot health and herd management.