Recently, I conducted a barn walk in a 300-cow robot-milking dairy and within 10 minutes I spotted more than a half-dozen limping cows. I did not know what caused them to limp, but after I talked to the dairy manager, I discovered that lameness was a significant problem on his operation and several of these cows showed up as “alarms” because they were not visiting the milking stations as programmed.
In this particular operation, I recommended he should identity lame cows immediately as well as set up an aggressive prevention program. That’s because lameness in dairy cattle, whether it appears in a robot-milking barn or any other milking system is always an obstacle to good milk and other dairy performance.
I believe solving and preventing common lameness starts with the observation of the first limping cow. When a cow is seen limping, the producer should take the time to observe her general behavior to get some idea of why she is limping before proceeding with corrective action.
One of the leading causes of lameness in dairy cattle is common physical injury. Direct injury takes on different forms such as punctures, ulcers, abscesses, or deep cuts to the horn and sole. When the hoof is damaged, a protective barrier against hoof disease is broken, in which anaerobic (lives without oxygen) bacteria such as Fusobacterium necrophorum, (foot rot), strep and staph organisms are allowed to enter and thrive. Similarly, anaerobic pathogens such as Treponema strains commonly known as “hairy heel warts” can also cause inflammation and painful lesions to the interdigital skin of the hoof.
Another leading cause of lameness in dairy cattle is laminitis, which is the inflammation of “living” laminar corium tissues within the hard hoof. It often leads to abnormal horn growth and wear, which makes walking difficult and is very painful for the animal. Such laminitis is classified upon severity into three main areas, namely: acute, sub-acute and chronic laminitis.
Acute laminitis is the most visible. It is the severe lameness that we frequently associate with cattle limping up to the feed bunk. For example, sole abscesses can result from cracks or holes originating from laminar corium damage in the hoof sole. This damage allows foreign material to enter the hoof and an abscess may form due to infection. White line disease can be another form of acute laminitis in which hemorrhages and poo- quality horn formation along the sole white line lets foreign bodies such as grit and sand to manifest itself into severe lameness.
During sub-acute laminitis, the clinical signs of typical laminitis are often visible. This form of lameness is a degeneration of the laminar corium of the hoof which leads to increased hoof wear and greater hoof injury. Sole ulcers are associated with sub-acute laminitis, which is a loss of horn sole and unhealthy exposure of the laminar corium.
Lastly, I view chronic laminitis as an extension of sub-acute laminitis by which hoof damage has become irreversible. Permanent damage to the laminar corium allows complete separation of bone from the horn wall. These dairy cattle have very broad hooves with the classic ridges (associated with high-grain diets). Hoof growth is altered so extensively the cow may walk on her heels rather than normally on her toes.
Feeding program is #1
The lactation feeding program has one of the biggest impacts on the cause and prevention of laminitis in milking dairy cattle. Feeding high-grain diets, low-forage diets or finely chopped forages can lead to sub-acute ruminal acidosis (SARA), a major cause of laminitis. SARA has also been implicated in greater rates of hoof wear, greater risk of physical hoof injury and thus increased potential for viral or bacterial invasion within the hoof.
As a ruminant nutritionist, I balance dairy diets by meeting the nutrient requirements of lactation, while preventing SARA at the same time. This means pH levels in the rumen are maintained above 5.5-6.0 by limiting the amount of non-fibre carbohydrates (NFC) originating from starch enriched grains digested by the cows, and also by feeding enough effective forage fibre that promotes good rumen fermentation and acid-buffering capacity. I target dietary NFC levels between 33 to 38 per cent, while assuring a minimum of 28 per cent dietary neutral detergent fibre (NDF) is fed and with 3/4 of this NDF coming from forages.
With such amounts of limited grain, and adequate forage going into the dairy mixer wagon, I often employ other nutrients that help strengthen hoof hardiness that has been scientifically shown to prevent invading foot-disease.
For example, I instructed a dairy producer a few years ago to add four grams per head per day of zinc methionine to his lactation dairy premix, which in turn was added to his daily milking TMR. After seven months of zinc addition, a successful reduction in lameness was observed and recorded. Even the hoof-trimmer made the comment — the general hardness of the hooves in the cow herd improved.
Cleanliness is key
Aside from these nutritional preventative measures to combat lameness, I am also a big advocate in improving barn sanitation.
A dairy producer operating a 150-cow dairy near Edmonton with three robot stations takes a big firehose, every morning and washes the concrete pad and metal grate under each milking station. I also know he worked with his veterinarian to set up the proper number of footbaths and protocols in his barn. As a result, I find the feet of his cows cleaner than most milking cows from my other barn visits and his farm has experienced a low incidence of ‘alarm’ cows due to lameness.
I guess that my friend figures that when it comes to healthy hooves, dairy cattle need all the help they can get. I can also help him and other dairy producers by setting up the proper dairy diets that keep lactation cows stand on their feed, eat lots of feed and produce lots of milk.