Preventing Dairy Cow Lameness

Due to the high incidence and cost of lameness, we need to continue to focus on lameness in dairy cattle.  We picked this time to talk about this subject because it is likely that many of you are currently seeing an increase in lameness as the adverse effects of heat stress continue to plague your herd.

Lameness is the 2nd most costly disease affecting dairy cows; mastitis is 1st.  The estimated cost of lameness per treated case ranges between $210-346 taking into account treatment costs, decreased milk production, reduced reproductive performance, involuntary culling, etc.  Hairy heel warts are estimated to cost $88/case, sole disease $369/case, horn disease $227/case. 

    

Production loss is the most important cost of lameness.  English workers have determined that production loss is 2.4#/d with most lameness disorders resulting in a 700# loss over the lactation.  Production loss can be more specifically quantitated based on individual locomotion scoring.  Locomotion scoring provides a lameness grade that is associated with a % reduction is dry matter intakes.  This reduction in dry matter intakes is then correlated with a % reduction in production.

    

Minnesota studies have seen an average incidence of lameness in freestall herds ~25%.  Goal incidence should be less than 15%.  Studies have seen that ~40% of all cull cows display obvious signs of lameness.

   

The reproductive impact is obvious.  Compared to herdmates without lameness, lame cows remain open on average 11 days longer and when relying on heat detection alone, days to 1st service increase 7 days.  A greater reproductive impact is seen if sole lesions develop between days 35-70 in milk with days to 1st service increasing 17 days and days open increasing 30 days.  Additionally, cows classified as lame in the first 35 days in milk were 3.5 x’s as likely to experience delayed ovarian activity due to secondary ketosis (lameness reduces dry matter intake leading to ketosis). 

The rest of this article will look at hoof anatomy, discuss etiologies of various foot disorders, and provide information on treatments and corrective trimming, and preventative measures.

The root cause of lameness on any dairy is multifactorial involving environmental, nutritional, and corrective hoof trimming issues.  A recent Minnesota study analyzing 5625 Holstein cows in freestall herds pinpointed 5 main factors associated with a higher incidence of lameness. 

Time away from pen: Obviously cows should spend as little time as necessary away from feed, water, and freestalls.  Base group size on the number of cows that can be milked in 1 hour.

Hoof trimming Frequency:  Herds that trimmed cows as needed had a greater incidence of lameness.  Maintenance trim entire herd at least 1-2x/year.

Cow Comfort Quotient (Stall Comfort Index):  Total number of cows lying properly in a stall/Total number of cows touching a stall measured ~2hrs after milking.  The higher the quotient, the lower the incidence of lameness.  Goal Index should be 85-90%. 

Type of Stall Surface:    Herds deeply bedded with sand had a lower incidence (17%) compared to herds with mattresses (24-28%).

 Height of the Brisket Board:  The higher the brisket board, the higher the incidence of lameness.    An additive association appears when the area behind the brisket board is filled with concrete.  The brisket board should be no higher than 4” from the stall surface with the area behind the brisket board at the same level as the stall surface

Keep Feet Clean & Dry...

Let’s get more in depth and first start with infectious causes of lameness such as foot rot and hairy heel warts.  Infectious foot disease can be effectively controlled through environmental management and a solid foot bath program.  Wet, manure contaminated conditions lead to infectious foot disease.  What can impact the degree of manure contamination:

Pen Design:  3-row barns have less alley square footage than 2-row barns leading to greater manure build-up.

Alley Scraping Frequency:  Scrape a minimum of 3x’s/day. 

Stocking Density:  Leads to more manure build-up/ft2 and also impacts lying times leaving the cow standing in manure longer. 

Stall Comfort and Lying Times:   The greater the stall comfort the less time the cow stands in manure.

Wet, manure-laden alleys lead to increased heel erosion and softer hooves.

Rest Weary Feet...

We should further analyze stall comfort and lying times, a deficiency seen on many modern dairies resulting in cows spending more time on hard, unforgiving concrete.  While the cow is standing, provide rubber mats in heavy use areas, esp. the feed alley and holding pen.  The constant drubbing of hooves on concrete from  excess standing and walking causes bruising and abnormal horn growth and inflammation of the laminae resulting in laminitis and ulcers.  Furthermore when a cow lays down, she chews cud more frequently, increasing buffering capacity, and milk flow to the udder increases 50%.

    

Increase lying times by providing clean, dry, comfortable stalls which decrease time walking and lead to cleaner, drier, healthier feet.  Target daily lying times should be 12 hours, 30% of which consists of sleep.  Your highest producing cows will average 14 hours.  1st calf heifers are a different beast because they are usually naïve to freestalls and possess an immature foot.  When exposed to freestalls for the first time post-calving, lying times average 6.25 hours/day with early lactation average of 9 hours/day.  Only by the time they become pregnant do they finally achieve the target for lying time.  How can we increase freestall lying times. 

Increase Stall Comfort/Padding:  Preference is for a deep bed of sand, granular lime,  kiln dried shavings, sawdust, straw over mattresses, rubber mats, waterbed, or concrete.  Research from British Columbia has shown that lying times can be increased 1.5 hours by adding more than 2# bedding/stall/day.  In fact they added 15#/day.  If cows posses hock abrasions and puffy hocks and your knees hurt when kneeling on the stall surface, you need more bedding. 

Provide Adequate Resting Area of Appropriate size Related to the Average Size of the Cow:  For a minimum size of 1400#, stall length should be 90-96” minimum and stall width should be 48” minimum.  Shorter stalls will lead to neck sores from rubbing against the neck rail and back sores around the hips from the cow lying at an angle.

Provide Adequate Room for Lunging with an Unobstructed “Bob Zone”:  The top of the brisket board should be no higher than 4” above the stall base with no concrete back-fill.  Additionally, there should be no lunging hindrance below 44” from the stall surface.

Provide Adequate Height Below and Behind the Neck-rail to Rise Without Hindrance:  Minimum neck rail height should be 48”.  Neck sores are seen with short stall length or lower neck rail height.

Provide a Curb Height no Higher than 8”:

Minimize Overcrowding Issues:  Aim for no more than 10% overcrowding based on freestalls.  Overcrowding minimizes lying times and also increases slug feeding which leads to acidosis and further exacerbation of foot problems.  Overcrowding in transition groups leads to stress and transition problems which causes foot problems.

Provide Heat Abatement:  Cows will stand more to improve air circulation and heat exchange.

Minimize Social Anxiety:  Intimidation and fear causes lower-ranking animals to stand more.  House L1 heifers and sick cows in separate groups.  Minimize overcrowding.  Increased irritability from housing design flaws like dead-end alleys and inadequate feed-bunk and water space will decrease lying times.

When a cow finally lies down in an uncomfortable stall, she will lie for longer durations than normal.  Anxiety exists due to the hardship of rising again.  Longer lying bouts leads to prolonged time between meals, leading to an increased risk for slug feeding, resulting in sub-acute ruminal acidosis (SARA).

Feed for Healthy Rumens and Healthy  Feet…

    Environmental problems can lead to SARA, but nutrition should always be analyzed.  Rumenal acidosis begins a vicious cycle that eventually leads to laminitis.  During these episodes, blood perfusion to the foot is disrupted and the endotoxins released activates an enzyme that breaks down the bonds between the epidermis of the hoof wall and the soft tissue of the corium.  The result is laminitis, sole ulcers, and abscesses.  Nutritional rumenal acidosis by definition is a rumen with lower than normal pH which is 6.0-6.2.  Factors that lower rumen pH include:

·       feeding high levels of rumen fermentable starch and sugar

·       high levels of unsaturated fatty acid

·       high dry matter intakes

·       slug feeding:  especially with rations containing grain >5-7# dry matter/meal.  Cows normally consume 9-12 meals per day.  Feed deprivation leads to slug feeding when feed is finally offered.  Cows slug feed immediately post-milking and when fresh feed is offered.

·       feeding high levels of forages low in buffering capacity (corn silage)

·       forages processed too short which decreases cud chewing

·       wet rations

·       high quality pasture

·       feed sorting

·       Lack of diet homogeneity:  The diet is improperly mixed.  Improper mix leads to more dense feeds like grain being delivered first with less dense feeds of longer particle size fed last.

·       heat stress:  Leads to excessive losses of sodium and potassium which affects the cows acid-base balance.  Additionally, increased respiration rates and excessive salivation further decreases buffering capacity.  Furthermore, cattle sort more under heat stress.

·       Poor transition management:  The rumen needs to adapt to the lactating cow ration during the close-up period.  Additionally, metabolic problems stemming from poor transition leads to a disruption in acid-base balance that disrupts digit blood perfusion. 

Feeding Guidelines for improved rumen and foot health from Mike Hutjens, University of Illinois, include:

Starch and sugar:  Limit starch to 25-28% total ration dry matter and sugar levels to 2-4% total ration dry matter.  Excessive fermentation of starches and sugars shifts fermentation away from fiber fermentation and increases levels of propionic and lactic acid.

Protein quality and quantity:  Excessive protein metabolism will lead to foot problems and therefore total ration dry matter should be limited to 17.5% crude protein of which 36% should be rumen undegradable.

Effective Fiber:  Provides the rumen mat optimizing rumenal passage rate and cud chewing (scratch factor).  5# total ration dry matter should be forage particles over 1” in length or provide 19-21% effective NDF.

Fats and Oils:  Excessive fats and oils reduce fiber fermentation and reduce rumen pH.  In low pH conditions, unsaturated fats turn to trans fats which can decrease butterfat levels.  Limit free vegetable oil acquired from corn distillers and extruded soybeans to 225 grams/cow/day.  Limit fish oil to 50 grams/cow/day.  Add rumen inert fat to increase fat levels to 6-7% of total ration dry matter.

Provide feed at least 22 hours/day:  Mix feed a minimum of 2x’s/day

Process forages:  Allows longer forage length

Transition ration:  Optimize dry matter intakes and balance to prevent metabolic disease.

Heat Stress Rations:  Feed more sodium and potassium in the form of sodium bicarb, potassium carbonate, potassium bicarb.  Because sorting is an issue, increase physically effective fiber by supplying forages of higher quality and better digestibility.  Include sodium bicarb at 0.8-1.0% dry matter.

Decrease Sorting:  Check by using a Penn State Forage Separator Box.  Make ration more palatable.  Make sure forage particle length is not too long.  Usually aim for maximum TMR forage length of 2” especially for hay and straw.

Properly mix ration:  Ensure that ration is consistent from one end of the feed  bunk to the other end by using a Penn State Forage Separator Box.

Zinc, Copper, Sulfur:  Trace minerals that maintain the integrity of epithelial and connective tissue.  Ration levels per cow per day are Zinc-40-60ppm, Sulfur-0.25-0.28%, Copper-10-15ppm.

Biotin:  Part of B-complex, aids in the normal development and function of epidermal tissue such as skin and hooves.

Breed for Better Feet and Legs...

O.K.  Time for a quick dairy judging lesson focusing an ideal set of feet and legs.  When viewed from the rear, the hocks should be straight and the cow should stand squarely on the rear legs.  The hocks should be free of coarseness and puffiness with adequate flexibility.  The cow should possess intermediate set to the hock when viewed from the side, have strong pasterns, deep heel, steep foot angle, and well-rounded, closed toes.  You can breed for this very description.  In fact, a steeper foot angle and straighter legs have been proven to be genetically correlated with increased longevity.  Mobility traits can be used as a prediction on a cow’s survivability.

    

Take a bull’s linear score for the above traits, multiply by the composites and add them together.  For every 1 point increase in Feet and Leg Composite, expect a 10 day increase in productive life.

As veterinarians, we should push you to select for longevity traits. 

Maintain Feet through Corrective Trimming...

    

Before we talk trimming let’s discuss hoof horn growth in relation to concrete and we will focus on the rear legs.  The outside claw of the rear foot bears the most weight.  Therefore, it receives the most trauma and concussive forces.  The unyielding nature of concrete irritates the hoof corium which increases blood flow leading to increased growth of claw horn.  This excessive hoof growth, especially of the outside rear toe, leads to overgrowth and overloading.  To alleviate the pressure and pain from the overgrowth and overloading, the cow assumes a base-wide or “cow-hocked” stance.  

    

Most of the sole overgrowth occurs at the toes.  When the toe is long, the sole is thicker towards the front of the overgrown toe forcing the weight-bearing axis backward towards the heel, concentrating weight over the sole and heel ulcer sites. 

   

 The horn of the wall grows faster than the sole leading to greater overgrowth of the outside wall, shifting weight-bearing forces onto the sole ulcer site.  Toe overgrowth coupled with outside wall overgrowth and the subsequent weight-redistribution, increases sole ulcer risk on the inside heel area.

     Consequently, the goal of corrective, maintenance foot trimming is weight-redistribution away from the sole ulcer areas.

    

Most cows benefit from trimming 1-2 times per year.  We will describe the “Dutch Method,” a basic 6-step plan towards corrective foot trimming.  By providing you with this information, you can become more critical of the quality of work you receive from your hoof trimmer.

1. Start with the more normal inner claw.  The front wall of the inner claw should be 3” long from the skin-horn junction to the tip of the toe.  This length should correspond to a sole thickness of 0.25”.  Trim the toe to the desired length and then pare the outer wall flat so that the weight-bearing surface is at right angles to the shin.  Do not trim the heel unless overgrown.  Maintain the heel of the inner claw to provide rest for the outer claw in case a problem exists in the outer claw.   If the sole “gives” under pressure, the sole was trimmed too thin.

2.     Repeat Step 1 on the outer claw using the inner claw as your guide.Shape and slope the sole to decrease entrapment of manure in the interdigital space.  Avoid weight-bearing surfaces and avoid excessive cupping and sloping.  Excessive cupping and sloping opens the toes and reduces weight-bearing surface area. 

3.     Balance the heels.  The weight-bearing surface across the toes, along the walls, and along the heels should be flat within the claw and across both claws.

4.     Pare damaged claw lower towards the heel to allow weight-bearing on the healthy claw.  Apply a footblock if needed.

5.     For hoof-horn lesions such as ulcers and abscesses, pare away all loose horn, no matter how extensive the separation is, and remove all hard ridges.  Never dig a hole towards the lesion.  Instead, slope the horn towards the lesion. 

Keep in mind that over-trimming can induce serious lameness.  Placing your cows on a routine 2 x’s/year maintenance trimming schedule will pay future dividends.

Give Your Feet a Bath…

One of the most frequent questions asked this year is “Doc, What can I use in a footbath in place of copper sulfate?”  Coming up with a cheaper answer is difficult because there really  is nothing better.  Clients that have decided to decrease the frequency of use have seen flare-ups of foot rot, hairy heel warts, and sole problems.  Formaldehyde is controlled and dangerous to human health.  Antibiotics are useless after 10 cows.  And the efficacy of Zinc sulfate is largely unknown.  Copper sulfate is proven to work so here are some recommendations:

·       Use a footbath.  It is an excellent means of treatment and prevention of infectious foot problems.

·       Replace the footbath after every 150-200 cows.

·       Frequency of use:  minimum of 4 days/week.  Preference is 6days/week

·       Provide a pre-bath containing water to rinse the feet prior to entrance into the bath containing solution.  By removing organic material, the efficacy of the footbath stretches. 

·       10% Copper Sulfate Footbath:  16# copper sulfate in 20 gallons water

·       20% Zinc Sulfate Footbath:  34# powdered agricultural grade zinc sulfate monohydrate (36%) in 20 gallons water

·       In a copper sulfate/zinc sulfate rotation, use zinc sulfate 2 days per week and use copper sulfate 4 days per week.

·       Europeans are experimenting with a recycled solution from the milk line acid wash cycle.

This has been a fairly lengthy discussion on lameness issues on the dairy.  Take the information in this newsletter and begin analyzing your dairy.  Ask questions.  Talk to your nutritionist, foot trimmer, and your veterinarian and ask their opinion on the level of lameness in your herd.  Look at possible sources for the lameness and put together a team to institute a plan to treat and prevent the disease.