Welcome to The Dairy Mail

by Rykie Visser, Africa Development and Sales Manager: Agrinet

Mastitis robs the dairy industry of millions of rand each year. According to Shannon Linderoth, recent data from the University of Minnesota indicate that more than 75% of all clinical and subclinical mastitis cases cultured are the result of environmental pathogens such as E. coli, Strep. uberis, Strep. dysgalactiae and various environmental Staph. species. Your choice of bedding type, manure removal and housing all shape the risks that affect the frequency of environmental mastitis on your farm. One can take steps to cut your herd’s exposure, improve herd health and reclaim some of those losses. Be proactive rather than reactive in your approach. Conduct a risk assessment at least quarterly if not more often.

Step 1: Check cow cleanliness
A cow-cleanliness audit is a visual assessment of how clean – or dirty – each cow is. Focus on the udder, feet and legs of the cow. The dirtier the cow, the greater the risk for environmental mastitis and high somatic cell counts. Set aside a specific time to conduct this audit. Conduct future audits around the same time of day, so results are comparable.

Don’t combine it with other management activities, such as herd checks. Focus on the audit. Ask your veterinarian, herd manager and other key consultants such as feed consultants, to help. Walk through each housing system or group pen and look intently at the cows and take notes. Focus on the cleanliness of cow feet, lower legs and udders. Hygiene scores udder and rear leg composite scores are significant for increased mastitis risk but not for tail head, flank and belly. Use a udder-hygiene scoring card. If a pen contains less than 100 cows, score all the cows. For pens that contain more than 100 cows, score 25% of cows.

Cows with udder-hygiene scores equal to or greater than 3 are at increased risk for mastitis, where 5 is very dirty and 1 is totally clean. A cow’s risk exposure for mastitis increases with the number of teats covered with manure, the frequency of contamination and duration of exposure. Once you’ve rated cow cleanliness, assess the results with the evaluation.

Step 2: Check housing facilities
In assessing free-stall housing, alleys are a good starting point. Observe how much manure slurry cows walk through. Slurry levels above a cow’s coronary band on the foot are undesirable. If practical, increase alley-scraping or flushing frequency or relieve any overcrowding problems you have.

Use the udder-hygiene score to help assess the effects of overcrowding in each pen. A rule of thumb is to allow a minimum 50 m² per adult cow. If scores are consistently outside the desired parameters, consider shifting overcrowding to later-lactation cows. Fresh cows, early lactation cows and dry cows are most vulnerable to pathogens.

For dry lots, look at pen management. Ask the following:
• Are pens maintained daily?
• Are areas where cows concentrate, such as under shades, cleaned more frequently?
• Do pens have mud holes?
• Do cows have a clean, dry place to rest?
• Do pens have adequate slope for drainage? (Most experts recommend a 2 to 3% slope perpendicular to the feed troughs.)

Make a note of any problems and schedule repairs.
Walk through each holding area to determine the level of manure build up. Use the same gauge to judge manure levels as you did in the free-stall alleys.

Step 3: Evaluate the sleep cubicles
Some environmental hazards are obvious. However, find out if the problems stem from something upstream such as poor cubicle design. Ensure the cubicle dimensions are according to the breed of cow as well.

Next, assess cubicle management. How often are cubicles cleaned? Ideally, this should occur every time you milk the cows. How often are cubicles bedded? Organic materials, such as sawdust or straw, should be added daily. Inorganic materials, such as sand, may be added less frequently. Is the entire stall cleaned or just the rear? If possible, observe stall cleaning in action. Ensure that the sand is levelled on a daily base if sand is used as bedding. Use a stall-scoring system. According to research, herds with somatic cell counts greater than 250 000 cells per millilitre have more manure in stalls, do a worse job of cleaning and use less bedding than herds with lower scores.

Step 4: Check bedding
While bedding may look clean, there is no correlation between appearance and bacterial load. So, assess the following parameters and ask yourself:
• Is bedding material kept clean and dry?
• Have you taken all possible measures to decrease bedding-moisture content?
• Is bedding stockpiled away from barns or pens so that the contamination risk is minimised before material is added to stalls?

Run culture samples on the bedding. Test stored material. Fresh, clean bedding should have bacteria counts lower than 5 000 colony-forming units per millilitre according to standards available. Counts above 1 million colony-forming units per millilitre indicate that bedding management should be adjusted. Check with your lab to conduct this test. Also, monitor bulk-tank somatic cell counts, to gain an overall view of how well you’re managing your risk. Once the entire assessment is completed, share the results with your management team. Empower employees to make positive changes.

Develop a cubicle scorecard
Is the cubicle dirty? Is it adding to your environmental-mastitis risk? The answer is somewhat subjective. To create a more objective measuring stick, try this cubicle scorecard. Think in terms of low, medium and high risk. A low risk is a cubicle that appears to be clean, with no visible manure present. A medium risk is a cubicle with dark bedding areas and some obvious manure in part of the cubicle. A high risk is a cubicle with manure present throughout the cubicle.

The majority of cubicles must fall into low risk, with less than 10% medium-risk stalls. You should not see any high-risk cubicles.

For any further information, please contact Rykie Visser at 082 596 8416 or at rykiev@agrinet.co.za.

Conclusion
It is important to do physical check-ups on the housing areas to establish potential hygiene problems. These check-ups should involve all levels of management on the farm to ensure proactive steps to combat these problems effectively.