1999 February

Autumn Pregnancy Testing

Many farmers now choose to pregnancy test their herds in late spring or early summer. This provides them with a more accurate estimation of stage of pregnancy for their cows. Farmers who do not pregnancy test until late summer or autumn, are well advised to pregnancy test their herd as soon as possible.

As pregnancy becomes more advanced the ability to accurately age the pregnancy deteriorates. The result of this will be that we can not consistently differentiate whether a cow is in calf to AI or the bull hence, it will not be possible to supply expected calving dates accurate enough to dry early calving cows off for a seven to eight week dry period.

By waiting until March or April when the early calvers are only two months from calving, our estimates can be out by six weeks or more on some cows due to the large variation that occurs in uterine and foetal development at this stage. It is necessary to dry these cows off to their AI dates. Some cows will have a longer spell because they have conceived to a bull mating three to six weeks after their last AI. This is unfortunate, but less of a problem than having cows calve earlier than expected.

Earlier pregnancy testing will also permit a more accurate identification of the cows to be induced and their anticipated induction date can be arranged. If these cows, which are August to October calvers are pregnancy tested in mid February, they will be six to sixteen weeks in calf. If they are not pregnancy tested until late March, at 12 to 22 weeks, it is much more difficult for us to be accurate with their estimated calving date.

If bulls are left with the herd through January or February there will be a handful of pregnant cows undetectable at a February pregnancy test. These will be late October-November calvers and most cases will be culled. Younger cows in this group that could be kept and induced can be rechecked in April or May.

What to do with that continually elevating BMCC

Summer is the toughest time for farmers with a high BMCC. As production drops, the cell count rises even if there is no change in the level of mastitis in the herd.

A herd with a cell count of 250,000 producing 18 litres in January will have risen to 375,000 by the time cows drop to 12 litres. This is because cows produce a fixed number of cells per day independent of production. As volume drops, the concentration of cells increase.

Previous newsletter articles have explained the effect of culling high cell counts on the BMCC. The message was that unless an individual cow has a continually elevated cell count and is a big producer, she will have little impact on the BMCC. In most herds it will require at least 3% of the herd to be culled to reduce the cell count by 30-40% (300,000 to 200,000). The increase in milk income due to a higher quality payment is in most factories about 3% difference. In herds where the BMCC is over 500,000 the penalties may be more severe. If your herd is in this category, it is advisable to discuss the available options with us.

A herd test in late summer or early autumn may identify a number of cows with elevated counts. Rather than drying off or culling these cows do the calculations on how many cows need to be removed. Remember if it is greater than 3% of the herd the drop in milk income will outweigh the benefits of higher quality. By next month, the BMCC may be higher again, so not only is production lower due to culled cows but milk quality is still not premium.

Example: The effect of a high ICCC cow in a 200 cow herd.: Herd BMCC with cow included 290,000; Production of cow 12 litres; Herd Average 17 litres; Her ICCC 1.5 million; Her contribution to herd BMCC 5,000; Herd BMCC with cow removed 285,000

To reduce the BMCC to 230,000 12 cows would need to be removed from the herd (6%). This is obviously not an economic proposition.

Launch of Countdown Downunder

There has been considerable media coverage of the "Countdown Downunder" program since its launch in December. The comprehensive Farm Guidelines manual is now available and supporting technical information is being written and will be published as a companion book in early 1999. During this year a series of technical up-dates for advisers and farmers will run in all of the dairying regions of Australia with the first sessions being held in Western Victoria after March. The program will been driven by regional teams ensuring that the Countdown Downunder activities are matched to the needs of each locality.

What is Countdown Downunder?

The Countdown Downunder plan consists of a set of recommendations to assist dairy farmers with profitable control of mastitis. The program is targeted at all people who influence the harvesting of milk, primarily the people who milk the cows, but also farm owners, managers and dairy extension officers, veterinarians, and machine technicians.

Clear Farm Guidelines to Control Mastitis

The core of the Countdown Downunder program is a consistent set of "best practice" mastitis control and milk quality guidelines.

The guidelines cover each period of the cow's milking year:

what has to be done;
why it should be done;
how to do it;
how to check that it has been achieved.

Who's behind Countdown Downunder?

Countdown Downunder has been developed by the Australian Mastitis Advisory Council which includes representatives of:

Australian Dairy Farmers' Federation
Australian Dairy Products Federation
Australian Milking Machine Trade Association
Australian Dairy Equipment Council
Avcare
Australian Veterinary Association
National Herd Improvement Association
Australian Dairy Herd Improvement Scheme
State Agriculture Departments
Australian Milk Harvesting Program
Dairy Research and Development Corporation

Each recommendation has a Technote that summarises the experimental and observational data that underpins that recommendation. The Technotes are presented in a separate manual designed especially for dairy service providers.

The Countdown Downunder: Farm Guidelines for Mastitis Control, are now available from the Timboon Veterinary Group at a cost of $20.

You can also view the guidelines at the Countdown Downunder web site

December 1998 - program launch at the Australian Dairy Industry Conference
January 1999 - distribution of the Farm Guidelines and Technotes to be published
February to June 1999 - regional launches and seminars for advisers and farmers
July to December 1999 - continuing seminars, and adviser and farmer training workshops

at least 90% of Australian dairy farms supplying milk with a cell count of less than 250,000 cells/ml in all milk supply periods;
100% of Australian dairy farms supplying milk with a cell count of less than 400,000 cells/ml in all milk supply periods.

The Milking Herd - A Depreciable Item

When it comes to repair and maintenance it is easy to compare a herd of dairy cows with an item of farm machinery such as a tractor. Just as a tractor will be reliable if well maintained and driven with care so will a herd of cows continue to perform if the right management strategies are regularly implemented.

Age:: There is a wide variation in the percentage of cows in each age bracket across herds. There are some herds with no cows older than seven years whilst others may have at least 30% of their herd in this age bracket. This has implications for BMCC, metabolic disease, fertility and clinical mastitis.
Type:: Breed, size, condition score, genetics and temperament vary between herds. All have a potential impact on performance.
Fertility:: The simple measure of the percentage of the herd that maintain a pregnancy in the first six weeks of mating, combines most fertility parameters. It varies from 80% to well below 40%.
Production:: Average litres, fat and protein production per cow is often used to compare herds. Herd test recording provides the opportunity to describe individual cow performance.
Milk Quality:: The BMCC is a reliable indicator of the level of mastitis in the herd. It gives indirect clues to many aspects of herd management such as clinical mastitis, milking harvesting equipment and milking management.
Death Rate:: It is surprising how much variation occurs in death rates between herds. Some farms lose up to 10% of the herd annually, many from metabolic disease at calving. Other farms consistently have less than 2% per year.
Disease Status:: Johnes Disease and Enzootic Bovine Leucosis have statutory control in Victorian dairy herds. For diseases like salmonellosis, there will be different immune status between herds. The Major Stresses on the Herd
Calving:: This has the potential to shorten the life of the cow or reduce her ability to lactate because of complications, such as mastitis or uterine infections. Heifers and older cows will be most prone to these losses.
Production:: The physiological process of lactating at the high level bred into our dairy herds has a significant impact on their health. Apart from susceptibility to conditions specific to lactation such as acetonaemia, it also increases susceptibility to other diseases.
Bulling:: Injury and lameness are potential complications.
Lameness:: Tracks and dairy yards, rough or hasty movement of cows and use of dogs contribute.
Illnesses:: Metabolic disease, mastitis and salmonella are the three more significant diseases causing stress on herds.
Undernutrition:: Most cows in the district are not fed to their potential. Undernutrition causing stress and subsequent losses occurs frequently in winter and summer.

Maintenance vs. Repair

The tractor analogy explains the difference between herds performing well with few losses compared with herds where deaths, reproductive losses and mastitis are constant problems.

Like a tractor, the herd undergoes a major service at the start of each season when new heifers are brought into the herd. If they are well grown, calving early and in plentiful supply they will adequately replace the worn parts of the herd. The older cows, the chronic high cell counts, the repeat clinical mastitis cases and the late calvers or non pregnant cows are culled. A tractor that has had a busy year and needs four new tyres will not perform as well next year if only two retreads are put on. This often happens in herds when there is a shortage of high quality replacement heifers. The maintenance requirement of the herd will be greater when wear and tear has been high. For example, if the herd is underfed we could expect many late calvers next year. Similarly when poor milking machine function or milking management occurs, a higher level of clinical and subclinical mastitis results. Both situations lead to high maintenance requirements.

To maintain a static size, a herd will need 20-30% replacements annually to avoid a gradual decline in herd quality. It is important that the replacements are not small, late calving heifers (retreads).

The well maintained herd, just like the tractor, will require fewer repairs through the year between major services. Fertility performance will be high, few cows will be culled for mastitis, less deaths will occur so the replacement rate will be lower. Many of these herds still introduce at least 25% of heifers to the herd each year and in doing so can apply pressure to the lower performing cows in the herd.

Electronic Identification of Dairy Cows

Get Started for Free

Over the last five years, a number of dairy farmers, mostly rotary dairies, have opted to enter into the electronic age for cow identification. Systems are available to suit herringbone dairies. This has not only allowed permanent identification of cows through a microchip implanted ear tag, but also given them options if the automated systems are also purchased to selectively feed, draft and identify groups of cows.

As part of the National Livestock Identification System, dairy farmers in Victoria will have free access to these microchipped tags at no charge, normally retailing at $12 per tag. This is the first part of a program designed to permanently and accurately identify every animal and its property of origin from birth to slaughter. They will be "whole of life" tags for single use only.

Adoption of electronic ID will provide us with a significant technological advance. Although the tags are only a small part of the cost of a system their availability now, free of charges is an opportunity that should be considered by every farmer. It is hoped that the normal retail cost of these tags will come down in the future.

If you are further interested in the tags, contact your local DNRE representative to receive an application form.

Monitoring and Maintaining milking machine function

The most common reason for milking machine problems is inadequate routine maintenance of mechanical components and rubberware. A series of regular, systematic checks gives a simple method of finding problems and guiding preventative maintenance. If more than one person milks in your shed, it is important to assign these checking tasks to particular people, and ensure that the right person is alerted to any problems that are found or suspected. Daily and weekly checks should be conducted by milking staff as part of their regular list of responsibilities. The herd owner or manager or other skilled observer should do the monthly checks. Recording the results of monthly checks enables subtle changes due to wear and age to be detected more easily.

Check the air admission holes (air vents). If the air vent is blocked, the claw bowl fills with milk and leads to more cup falling, slow or incomplete milking, and difficulty removing clusters even after the vacuum is cut off. Remove any debris with the probe designed for the task. Avoid using drill bits or other tools that may enlarge the holes.
Read the vacuum gauge. Tap the face of the gauge to ensure that the needle isn't sticking.
Listen to pulsators. The sound of air entering the external air port should be both regular and intermittent. It should be the same sound for all pulsators.
Watch milk entering the receival can. Flow should be even, without flooding or slugging.
Check teats as the cups come off at the end of milking. Look for discolouration (reddish, bluish or purplish teat skin colour). Look or feel for swelling or hardness at the top, middle or end of the teats. Examine teat openings for signs of cracking, sores or teat canal lining pulled out of the opening. Observe if teats are unusually sensitive to touch.
Check cow behaviour. Are cows nervous and uncomfortable when teatcups are put on or removed from teats, or during milking? Weekly checks
Check for twisted liners. Align marks on mouthpiece and stem of liner, or place your thumb in each liner.
Check liner condition. Look particularly for distortion of the mouthpiece lip or holes in the short milk tube. Split liners lead to fluid between the liner and the teatcup shell.
Check filters on pulsator airlines especially on rotary dairies where the filters are close to the feeders.
Listen to the regulator(s).

Check 'effective reserve' of vacuum and regulator function. With the machine running, open one set of cups (or if more than 32 units, open two sets). If vacuum drops more than 2 kPa, then effective reserve is not adequate. During this test, check that the regulator closes or almost closes. The hiss of air entering the regulator should be greatly reduced when the cups are opened. If this does not happen, check the regulator filter and clean if necessary. If cleaning does not improve the regulator response, call your AMMTA milking machine technician.
Measure completeness of milking and milking times. If cups are applied before milk let-down, these average milking times should be extended by approximately one minute.
Count cup squawks and slips requiring correction by milker. A running tally over 15 minutes of milking provides a guide. To assess machine function, exclude cows with very poor udder conformation which always have cups slip.

Preferred machine function:
no more than five slips per 100 cows.

Machine requires service:
more than 10 slips per 100 cows.