May, 2012

If some of your cows are slow to breed back you might want to check their feet. That’s right – their feet. In addition to being associated with reduced milk production, lameness can put the hurt on fertility and reproduction.

Research indicates that lame cows show poor signs of heat (preferring to stay off their feet); require more services per conception; demonstrate increased presence of ovarian cysts; and show an overall decrease in pregnancy rate than non-lame cows. Progressive Dairyman, April 19, 2012 states: the average time to conception was 40 days longer in lame cows with claw lesions compared with healthy cows. According to Jeff DeFrain, PhD, Zinpro Performance Minerals, non-infectious claw lesions (sole ulcers, white line disease) tend to be more damaging to reproduction than infectious claw diseases (digital dermatitis). One study found that cows with sole ulcers were open 63 days longer than cows without such claw disorders. Older cows are generally at greater risk for both severe lameness and corresponding reproduction problems than younger animals.

Severely lame cows have lower maximum progesterone concentrations, which is responsible for maintenance of pregnancy, compared to non-lame cows. “Lameness is a chronic stressor. Once a stress is detected by the animal, chemical signals are sent to the brain in the form of pro-inflammatory mediators…Therefore, until the stressor is removed, levels of hormones ..will not return to normal” (DeFrain, Bovine Veterinarian Magazine, March 5, 2012)

Bottom line: Addressing the lameness issue before insemination would save time, money, and frustration.

Going from the old adage that goes: What gets measured gets addressed, one of the best ways to get a handle on lameness is to train workers in locomotion scoring. Routine locomotion scoring provides a measurement of both the level and the severity of lameness within the heard. Animals identified as lame should be examined and treated by a qualified hoof trimmer as soon as possible. Hoof trimmer records along with locomotion scores are valuable tools for: 1) assessment of the types of claw lesions in the herd; 2) development of a lameness prevention protocol that addresses infectious and non-infectious claw diseases. Lameness prevention programs are most effective when developed and implemented by a team that includes: owner, manager/herdsman, hoof trimmer, veterinarian, nutritionist, and a dairy worker(s) trained in locomotion scoring. Environmental and nutritional factors, along with animal handling procedures, and hoof-trimming schedules and procedures are essential components of any lameness prevention program. A locomotion-scoring chart with excellent photos is available through Zinpro.

April, 2012

Last week, while at the Central Plains Dairy Expo in Sioux Falls, South Dakota, I attended a breakout session entitled: Practical Ways to Meet Heat Stress Challenges. The presenter, Tom Bailey, DVM, dairy technical advisor, Elanco Dairy Business did an excellent job of raising awareness of the signs, symptoms, and costs of heat stress in dairy cows. His strategies for keeping cows cool via soaking and airflow were also eye openers for me.

Dr. Bailey sited research demonstrating that cows undergo heat stress at
68º F. High producing cows will begin to show signs of heat stress at even lower temperature/humidity levels. So, just when I think that it might be warm enough to unzip my jacket, the cows are already feeling the heat!

To find out about heat stress in your herd, Dr. Bailey suggests that you “ask the cows.” Check your feed and water intake records, milk production, and standing times. Dr. Bailey demonstrated an easy way to gauge a cow’s body temperature by counting her respirations. Early morning was suggested as the best time to pick out a few cows per pen and check their respiration rates. You can check again after milking, and again in the evening. The collection area was cited as “the most hostile environment on the dairy” in terms of heat stress to the cow. Internal body temperatures consistently peaked in conjunction with time spent in the collection area, and could take hours to fall, depending on outside temperatures and heat abatement practices.

A respiration rate of about 40 breaths per minute indicates a normal body temperature of around 101.5ºF. A respiration rate of 60 breaths per minute indicates a body temperature of 102ºF; 80 breaths per minute = a body temperature of 103ºF and 100 respirations per minute indicate a body temperature of 104º F. In other words what you’ve got is a very hot and uncomfortable cow! Her open mouth panting is costing her valuable carbon dioxide and bicarbonate – which in addition to slug feeding can set her up for acidosis, and she is probably spending 3+ hours on her feet more than she would if her body temperature was a cool 101.5. What its costing you is about 10 pounds of milk per day/cow, lameness from abscess producing conditions such as laminitis and white line disease which will show up through early fall, and lost pregnancies particularly for days 1-6. Not good.

I was somewhat surprised to see how ineffective fans alone, and even water alone were in reducing body temperatures. Dr. Bailey’s presentation demonstrated that soaking (shoulder to hooks) + airflow (4 -5 mph) from fans (cleaned and maintained – not full of dust and cobwebs) + time (25 -35 minutes) produced the fastest drop in elevated body temperatures. When the cows’ body temperatures were closer to normal, guess what they did? They lay down!

I am often asked if the footbath can play a role in reducing lameness associated with heat stress. The answer is: not really. Footbaths address infectious claw conditions – primarily digital dermatitis aka hairy heel warts/footwarts. The majority of lameness that develops during the summer through fall is due to abscesses associated with laminitis and white line disease. These are non-infectious conditions. Some footbath chemicals including formaldehyde, copper sulfate, and zinc sulfate can offer some very superficial, temporary hardening of the hoof horn. This may help to somewhat offset the softening of the horn that occurs when the soakers are turned on. More effective ways of preventing non-infectious lameness involve increasing cow comfort, which leads to an increase in lying/resting time. Effective cow cooling can play a key role in accomplishing this. So lets all “chill.”

Footbath Volume: It is imperative to know the volume of your footbaths. How else do you know how much chemical to use and for how many cow passes it will remain effective? The formula is: Length x width x depth (all in inches) ÷ 231 = volume in gallons. Be sure to take the depth measurement from the center of the footbath and measure 1” below the curbing.
What to Use: Most producers use copper sulfate, formaldehyde, or zinc sulfate – either alone or in rotation. Each of these products has pluses and minuses. Formaldehyde comes with serious health risks and can cause severe burns. It is also less effective in cold or wet conditions. Copper sulfate is effective but presents environmental challenges in terms of long term build-up in the soil and water run off. Except in very dry environments, dairy producers are typically less satisfied with zinc sulfate for wart control than they are with copper. In addition, zinc sulfate can be very difficult to dissolve. Copper and zinc sulfates are often used with chemically engineered additives such as Hoof-Tec 1000 which maximize their solubility, thereby improving performance and extending the efficacy of the bath.
How Much to Use: When used alone, the typical amount of copper sulfate is .5 pounds per gallon of footbath water (25# per 50 gallon footbath). Zinc sulfate amounts can range from 35 pounds to 50 pounds per 50 gallon footbath. If using a chemically engineered acidifier with copper or zinc sulfate, check with the manufacturer for recommended dosage. These products typically reduce the amount of copper/zinc necessary for good results. If using formaldehyde consult with your veterinarian on dosage.
How Many Cows: This is a big issue. Nobody likes having to change the footbath during the milking. However, walking cows through a “spent” footbath (manure slurry) can do more harm than good. It re-exposes the feet to the very bacteria you spend money trying to kill! The number of cows that can effectively pass through a footbath largely depends on 1) how much manure gets into the bath and 2)how much water gets splashed out. An “average” 50 gallon footbath using only copper/zinc sulfate or formaldehyde should be changed after about 200-250 cow passes.
How Often: A number of researchers now recommend running footbaths 7 days per week. The comparison is made between footbathing and teat dipping. However when the footbaths are managed properly, many dairies do well on a 3-5 day per week footbath program.

Merry Christmas and a Happy Healthy New Year!

I used to think that a pre-bath, filled with plain water, was a useful tool in foot bathing - not because it helps clean the feet (I believe its useless for this), but because it primarily acts as a cow toilet. We’ve all seen it – upon leaving the parlor, the cow lifts her tail and well – you know - in the first body of water that she comes to. Logic would dictate that if the cows deposited manure in the pre-bath, the chemical bath would take less of a “hit.”

Several small field trials I conducted confirmed that the chemical baths remained effective longer if a pre-bath was located 6 – 9 feet before the chemical bath. If the pre-bath was located adjacent to the chemical bath, there was little to no benefit for extending the life of the chemical bath. The cow usually was not done “taking care of business” in the pre-bath before she entered the treated bath – so both baths were affected. In addition to the “direct deposit” method of contamination, the chemical bath is negatively impacted by dirty, un-treated water being dragged in from the pre-bath.

I am now questioning the use of pre-baths at all. As I see it, the main problem with a pre-bath is how quickly it is contaminated thus becoming a possible means of spreading the bacteria associated with foot lesions. Does walking the cow through a dirty pre-bath (slurry) actually increase the bacterial loading on the hoof skin prior to exposing it to the anti-bacterial agent of the treated bath? I don’t have an answer for this – but it seems possible.

Some experts have suggested putting soap or detergent in the pre-bath for the purpose of loosening the dirt and manure on the feet. Far be it from me to contradict those with PhD’s – but I am not convinced. Its not like we are talking about walking the cows through a whirlpool bath here. Even getting a spot out of a shirt requires some water agitation in addition to the detergent. While adding soap to the pre-bath may be a useful practice for very small herds these materials break down pretty quickly in heavy organic matter. In addition, most soaps and detergents have a higher than neutral pH. If consistently splashed into an acid based chemical bath, soaps will reduce the bath’s level of effectiveness. I also question whether soap/detergents make the bath and exit area surfaces too slippery.

Bottom line: If you have built in pre-baths, I suggest you consider leaving them empty. If you have to change the footbath during milking – rinse out the pre bath as well – then leave it empty. Don’t neglect hosing the entrance and exit areas of the footbaths.

If your footbaths and pre-baths are adjacent to each other, and each holds less than 50 gallons of water, you could consider putting chemical in both. This would effectively create a longer footbath and increase the chemical contact time. While more expensive to set up – this method may get more cows through an effective footbath.

When your footbath chemical is depleted it is important to do one of three things: 1) change the footbath 2) clean it out and leave it dry, or 3) gate around it. Avoid having the cows walk through an exhausted bath full of manure slurry, as this may due more harm than good in the fight against footwarts.