2001 December

Don't Forget the Macros

Macro minerals are probably the most under rated feed additive in terms of value for money.

Many producers spend thousands of dollars each year on ensuring their cows have adequate vitamin and trace element supplementation and neglect to provide the necessary macro minerals to ensure full metabolic efficiency during both the lactation and dry period.



A macro mineral is an inorganic element that is essential for normal function of the animal.
It is called a macro mineral because it is required in gram quantities per day by the cow.

The elements referred to as micro minerals or trace elements are required in milligram or microgram amounts.  That is one thousandth or one millionth of the macro mineral amount.

The macro minerals are calcium, phosphorous, sodium, chlorine, potassium, magnesium and sulphur.  These minerals are supplemented to a greater or lesser extent in most well formulated rations.  Usually calcium, sodium, chlorine and magnesium can be added relatively cheaply.  Phosphorous, potassium and sulphur are usually not supplemented but can be if required.

Calcium

  • Calcium is the most significant element for the dairy cow.  It is excreted in huge quantities in milk during lactation.  Despite this many herds do not get any supplementation to replace the calcium being lost every day.  So where does the calcium come from that is being excreted if it doesn't come from the diet?  The only place is from bones.  Calcium is removed from bones to keep blood levels up in early lactation.  This will occur regardless of how much calcium is offered to the cow during this time.  As she gets further into her lactation, her ability to absorb calcium from the gut increases and she is able to take in greater amounts than those being excreted in milk.  The process of removal of calcium from bones is similar to that seen in post-menopausal human females referred to as osteoporosis.
    This lactational osteoporosis seen in dairy cows is a natural phenomenon.  Our use of anionic salts in the transition period is designed to stimulate this process during the transition period.  This enables cows to provide adequate calcium to meet requirements when lactation starts.
    Supplementation with calcium should occur during the entire lactation.  In early lactation it is required to assist with immediate requirements.  In late lactation it is required to replenish stores that are drained during early lactation.  Supplementation is usually achieved with the use of ground limestone.  This is cheap and easy to source.  Different brands of limestone will have different solubility in water.  This has an affect on the availability of the calcium.  Other sources of calcium are available.  The most common used in this district is DiCalcium Phosphate (DCP).  DCP has less total calcium by weight than lime but is far more soluble.  This makes it more available to the cow and can make it more palatable.  As a result more calcium can be absorbed.  DCP is a far more expensive option than lime but has been used in cases of mid lactation hypocalcaemia outbreaks to good effect.
    As a general recommendation cows should receive 50-100 grams of lime per cow per day through their entire lactation to ensure adequate calcium is available for present and future use.

     

 

Magnesium

  • It will be a surprise to many that some herds are still not supplemented with magnesium.  The main stimulus for this article was our experience with a couple of herds that appear to have responded quite dramatically to magnesium supplementation.

    Magnesium cannot be stored by the cow for future use in the same manner as she does with calcium.  They need to have a source of magnesium every day.  This is more an issue when herds are grazing pasture.  This is the basis behind the name for clinical hypomagnesaemia, Grass Tetany.  Whilst the cases of grass tetany seen these days are low there is still a magnesium deficiency occurring in most herds that are unsupplemented.  This will show up as a higher incidence of other metabolic diseases such as milk fever or acetonaemia or just as a poor production problem.

    Magnesium supplementation is cheap and simple.  Mag Ox should be fed at 30 grams per cow per day.  A lot of farmers stop feeding it during late spring.  It is advisable to continue feeding it throughout the year to be safe.  If nothing else, the advantage of having a chemical of a pH of 8 going into the rumen at the same time as grain will help to combat lactic acid build up due to our slug feeding of grain in the dairy.

     


Sodium and Chlorine

  • Sodium and Chlorine are discussed together purely because they are usually supplemented together in the form of Sodium Chloride (salt).  Sodium is essential for all cell function and has many roles in the body.  It is excreted in large amounts in the milk.  It acts to enable the movement of most nutrients into cells in tissue.  If sodium is deficient these functions are impaired.  This includes absorption of other macro minerals such as calcium and magnesium.  In high producing dairy cows the diet will almost always be deficient in sodium.  The level of deficiency depends on the feeds being fed and the other minerals such as potassium and chlorine.  Excess intake of sodium can eventually cause problems but levels have to be much higher than those given in this district.

    As a general rule supplementation with 50 grams of salt per day will be required.  Sodium bicarbonate supplies a significant amount of sodium.  If Bicarb is replaced with Eskalin for acidosis control, salt supplementation will become more necessary to make up for the drop in sodium levels.

 

Summary
  • Macro minerals are essential for adequate milk production through the entire lactation.
  • Supplementation with the major macro minerals is relatively cheap.
  • It is better to feed a bit more of these minerals than not enough as they are safe.
  • If herd production levels are less than is expected, macro mineral levels should be investigated

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Preg Testing - Avoiding Errors

The process of using pregnancy diagnosis by rectal palpation to ascertain when a cow is going to calve is very useful and has become an integral part of dairy reproductive management.  The ability to use these results productively depends on a number of factors.  The most important of these is the confidence we can have in the expected calving date produced for a cow being the actual date the cow will calve.  Greater confidence in this aspect can make it easier to make decisions on dry off dates, induction programs and culling decisions.  Constantly we find that the accuracy of the relationship between an expected calving date produced from a PD session and the actual calving date of the cow varies from farm to farm.  Why is this so?

The process of presenting a cow for examination, having her examined, taking a record of the result and transferring that record to a reproducible and storable form has many steps.  It is essential to examine all those steps to ensure that as many deficiencies are eliminated.

Presenting the cow for examination

  • Identification - Having a reliable, readable and readily accessible identification.  ID is critical.  If cow identification is inadequate, PD examinations are useless.  The ideal is to have a readable freeze brand combined with an ear tag, preferably one in both ears.  Freeze brands and ear tags can both become illegible.  Having one backing up the other gives a good insurance against mistakes.  This may seem like a bit of overkill to some.  Let those skeptics be assured, in herds where this is done the entire process works far more efficiently.  There is less hassles with drafting cows, if required, and with preg testing them with out holdups to get an accurate ID on a cow.
  • Grouping - Ensuring the cows are in a manageable group.  Attempting to draft cows off during the PD session can be frustrating for all involved, including the cows.  With rotary systems, a subgroup of cows can be done in the herd during milking, however a small group may become expensive to do when it requires having a vet standing around for an entire milking.

Examination of the cow

  • Operator Competence - We strive to ensure any professional examining a cow is competent to give the result required.  Obviously we are going to have vets of different levels of experience available at any one time.  Each vet in the practice goes through a rigourous training and evaluation process to ensure they are competent.  The main difference in abilities seen, once adequate competency is gained, is in the number of PDs  different vets can do in one session
  • Operator Fatigue - With experience, greater number of PDs can be done in one session.  Nowadays we try to do any herds over 150 cows in teams of, 2 up to 5 vets to ensure fatigue is avoided.  From a clients point of view this not only ensures as good a result as possible is obtained but that the job is done as quickly as possible.  When booking herd PDs in, it is essential to give an accurate indication of the numbers involved to allow adequate arms are available.

  • Safe facilities - It is more difficult to concentrate on doing an accurate job when trying to avoid injury at the same time.  Facilities have improved significantly over the years.  Some farms still have dangerous aspects to their facilities.  We will be attempting to contact those enterprises this year to help them improve their facilities to make the entire process more enjoyable for man and beast.  If you are not sure of the adequacy of facilities please phone and ask for one of the partners to come out and discuss the options with you.  We have some comprehensive design diagrams that can be used.

Record Keeping

  • Storage - For many, heat and mating records can be stored on a simple wall chart and provide adequate information.  With increasing herd size and the advent of more split calving patterns this method can prove inadequate.  The use of computer record systems makes the job easier and more accurate.  Many programs are available.  For more information on this contact the office.

  • Retrieval - Obviously this is easier with a good computer system.  A good knowledge of computers is essential to avoid having the situation of loads of good information sitting in a broken down computer and inaccessible.  We are able to provide a service for computer herd reproductive recording if required.  Many farmers will use this if they are not familiar with computers but want  to be able to access data in this fashion.

  • Information on the day - The ideal situation is to have a list of all cows to be examined and the number of weeks since their last recorded service.  It is important not to spread this list out over too many pages.  We find that 150 cows to a page of three columns works pretty well.  With less pages, cows information can be found with out flicking through a large number of pages each time.

  • Adequate record keepers - It is very difficult for one person to keep up with more than one PD operator if they are retrieving service information for each cow.  Some herds have the system finely tuned to the stage where they can cope.   It is unwise to assume this is the case in your herd.  It will slow down the process and can be a potential source of major errors in the results.  It is surprising how often an incorrect result is recorded due to a record keeper trying to record information from more than one operator.

  • Transferal to storage - Ensure the process of transferring PD results to permanent storage is as easy and foolproof as possible.  Set aside specific time to do this with no interruptions and hopefully when not tired. Any errors in record keeping will not show up until calving time.  By then it is too late.  This is one of the most critical factors in poor results.  There is only one chance to get it right at this stage.


Obviously there are many aspects that have still have not been covered.  We would urge you to contact us if you have any questions.  It is more difficult to correct deficiencies in the system on the day of the session with a herd of cows in the yard.  Often we have not moved to help correct an obvious problem because it is often possible to get through with what is available and it is over for another year.  This has been at the cost to being able to help everyone do a slightly better job.
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Acidosis Trial

As some of you are aware, an acidosis trial involving some farms commenced in this area during October.  This trial is looking at the effects of sub-clinical acidosis on dairy cattle health and production and is being conducted in areas of both Victoria and NSW.  The study is being conducted by Bovine Research Australasia in conjunction with The University of Sydney with funding from the Dairy Research and Development Corporation, Dairy Industry Development Corporation, Murray Dairy, Elanco Animal Health and Wrightson's Seed Company.

The aim of the study is to identify factors in the diet and management of dairy cattle that may predispose to acidosis.  The results obtained will potentially allow changes in diet formulation and feed management where necessary, improving milk production, reducing weight loss and risk of low milk fat content and minimising lameness resulting from nutritional problems.

Clinical observations in the past have estimated the presence of acidosis to be as high as 40 percent in dairy herds around Southern Australia.  It is anticipated that this may be caused from a number of factors involving both pasture and concentrate feeding.  Of the farms sampled in this area so far, a significant amount of acidosis has been documented confirming the past clinical observations.

Some of you may have received letters in the mail regarding the survey and have not yet been contacted.  It is anticipated that a further sampling will be done in this area around June/July 2002 and you may still be contacted.
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Making the Most of a Wet Start to Summer

It is a pleasant change to be back to the seasonal conditions that dominated the early 90's. Now that we have accepted the consequences of a wet spring with late crops and poor quality silage, we can now reap the benefits of excellent early summer pasture availability.

Common management strategies being undertaken by good pasture managers now include:
  • Continuing applications of nitrogen on all but the lightest country to prolong effects of the moist soil profile. The response to nitrogen will vary with pasture type, grazing management, soil fertility and follow up moisture, however the risk of a non economic response this year is minimal. Typical applications are 70-100kg/ha urea every 4 weeks. In wet years, there is no reason why this strategy cannot extend well into the new year.
  • Topping. To maximise the quality and growth potential of pastures in early summer, removal of old tillers and seed heads will allow new tillers to develop. This becomes less likely the later in the season that topping takes place. If pastures have considerable clumping, pregraze topping may cause a drop in intake and milk yield. If only a small percentage of the pasture topped is of poor quality, then it may be a good option. If there is too much dry matter and there is enough ahead of the herd, such paddocks may be better off being cut and baled. In a year like this, topping all clumpy paddocks on the farm may prolong summer growth and be of great assistance to maintaining production.
  • Sowing of crops on less productive land despite the late spring. In the past, we have stressed the importance of sowing early to capture dwindling soil moisture. This year, the daylight length and ground temperature will give crops a rapid start. Crops such as pasja may be ready for grazing as soon as 5-6 weeks after sow date.
  • Keeping the rotation out to 15-20 days will optimise pasture growth and tiller development. In the next 8 weeks, pasture intakes will drop back so be quick to respond with increased grain supplements, crops, hay or silage. In a year like this, well fed herds maintain production at over 20 litres comfortably through summer. Typically milk solids decline in such herds at as low as 2 to 3 % per month once the summer feeding program is established. Despite the higher grain prices, the ratio of milk price to supplementary feed costs is still very attractive. At an average of 35-45 cents per litre for autumn milk this year, it is well worth maintaining that summer production for cows still milking in autumn.


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