DAIRY HERD HEALTH AND PRODUCTIVITY SERVICE

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					                  DAIRY HERD HEALTH AND
                   PRODUCTIVITY SERVICE
Newsletter 2008, Q2                                                                                        May 2008
Using milk to monitor nutrition                                         Butterfat levels are mainly a reflection of
                                                                        rumen health, and the amount of effective long
With both NMR and CIS offering nutritional
                                                                        fibre eaten by the cows.
monitoring using milk records, many farmers
and advisors are looking to make best use of                            Milk protein levels depend primarily on the long
these records. But what do they indicate…?                              term supply of energy, hence levels tend to
                                                                        drop when the diet has not been supplying
Urea levels in the blood and milk reflect the
                                                                        enough energy for some time. This is the basis
amount of Effective Rumen Degradable Protein
                                                                        behind the “3.2% milk protein intercept”
(ERDP) eaten by the cow, and the balance of
                                                                        graphs used by both NMR and CIS, which
energy and protein in the rumen. All milk
                                                                        attempt to assess the levels of milk protein
purchasers record bulk tank urea levels, but
                                                                        production in relation to yield as a measure of
the problem is that they are not very accurate
                                                                        energy balance.
– as they are the average for the whole herd.
                                                                        When cows are in negative energy balance (or
Individual milk urea levels (reported by both
                                                                        ketosis), milk protein levels tend to drop – and
CIS and NMR) are more useful – especially if
                                                                        butterfat levels often rise (as when the cow
results are looked at according to days calved.
                                                                        mobilizes body condition, some of the fat is
Low urea levels (below 200 ppm) may indicate
                                                                        diverted into the milk). So a high fat : protein
that the diet is short of ERDP, which could
                                                                        ratio suggests that the cows may be suffering
reduce yields. High urea levels (above 400 ppm)
                                                                        from negative energy balance. However, if the
suggest that the diet has more protein than
                                                                        butterfat levels fall and the fat : protein ratio
energy for the rumen – either because they are
                                                                        is low, this suggests problems with rumen
on a high protein diet (for example, when they
                                                                        health and possible subclinical acidosis.
are out at grass), or there is not enough energy
to use the protein fully. Speak to your                                 Targets for fat:protein ratios are different in
nutritionist before making any changes – and                            every herd (due to the genetics of the cows,
note that urea levels have absolutely nothing to                        milk yields and stage of lactation etc.). Be very
do with fertility!                                                      careful if the milk recording is factored – this
                                                                        affects the butterfat levels (and cell counts)
                                                                        from month to month.
                                                                        The best use of milk records is to compare the
                                                                        values in each herd month by month – and any
                                                                        sudden changes in the milk quality should alert
                                                                        you to possible problems. Beware of over-
                                                                        relying on milk quality figures – it is a simple
                                                                        but crude way of keeping an eye on nutrition,
                                                                        and is all another piece of the jigsaw to assess
                                                                        nutrition on farm! Follow up with a blood test
                                                                        to see where the problem(s) are.


   Dairy Herd Health and Productivity Service, Division of Veterinary Clinical Sciences, Royal (Dick) School of
         Veterinary Studies, University of Edinburgh, EBVC, Easter Bush, Roslin, Midlothian EH25 9RG
           The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336

Tel - 0131 445 4760                             Fax - 0131 445 5728                           E-mail DHHPS@ed.ac.uk

                                          www.vet.ed.ac.uk/dhhps                                                         1
                  DAIRY HERD HEALTH AND
                   PRODUCTIVITY SERVICE
Fertility in summer calvers                                             Managing transition dry cows at grass is also
                                                                        not without its problems! If your dry cows are
This spring seems to be dragging on and on,                             out at grass and being fed a TMR for the 3-4
with the cold weather and poor grass growth in                          weeks prior to calving, it is vital that they are
many parts of the country delaying turnout to                           stocked tightly enough to keep grass growth
grass. So you will need to forgive us when we                           under control - full or partial housing of dry
start to look ahead to the summer…….                                    cows for the last 3 weeks of pregnancy may be
                                                                        necessary. This is particularly important when
However, every year we are involved in
                                                                        using a “high straw” dry cow approach. If you
investigations of poor fertility in summer
                                                                        were a cow and got the choice between
calvers at grass - problems which appear to be
                                                                        cardboard and fresh grass, what would you
increasing, possibly exacerbated by the recent
                                                                        choose…..?
trend to all year round calving patterns. The
result is that summer calvers one year end up                           Watch out for mastitis in the dry cow
being autumn calvers the next.                                          paddocks as well – current thinking is that
                                                                        pathogens such as Strep. uberis can be
In almost all of these cases, the underlying
                                                                        transmitted by cows lying in the same spots in
cause is negative energy balance and body
                                                                        the field.
condition loss in either late pregnancy and/or
early lactation. Why? Surely grazed grass is                            The key to managing cows at grass to ensure
the best food for dairy cows? Whilst fresh                              optimum fertility is to keep a close eye on the
grass can work well for relatively modest                               cows,    and    supplement     correctly    with
yields, cows that are giving over 40 litres of                          appropriate buffer feeding to minimize body
milk in the first couple of months of lactation                         condition loss in early lactation (see our
are going to struggle to eat enough grass to                            “Buffer Feeding Handout” on the website – link
meet their energy requirements. So they milk                            at bottom of page). Many high yielding herds
off their backs in early lactation, especially                          are going to the extent of either partially or
with the high protein levels in the grass                               fully housing cows in early lactation, to ensure
stimulating milk production at the expense of                           good feed intakes.
body condition. And this loss of body condition
                                                                        Especially when the sun is shining and grass is
harms fertility in the coming months….
                                                                        green, cows can lose substantial amounts of
                                                                        condition – and by the time fertility is hit, it is
                                                                        too late. The quickest way to check on what the
                                                                        cows think of current feeding arrangements at
                                                                        grass is to blood test.

                                                                        DHHPS charges
                                                                        Please note that there has been a modest
                                                                        increase in our charges from 1st April 2008 –
                                                                        our first price rise in four years! The cost of a
                                                                        “one-off” test is now £200, and the cost of
                                                                        annual membership has gone up to £500 (an
                                                                        increase of £5 per quarter).


   Dairy Herd Health and Productivity Service, Division of Veterinary Clinical Sciences, Royal (Dick) School of
         Veterinary Studies, University of Edinburgh, EBVC, Easter Bush, Roslin, Midlothian EH25 9RG
           The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336

Tel - 0131 445 4760                             Fax - 0131 445 5728                           E-mail DHHPS@ed.ac.uk

                                          www.vet.ed.ac.uk/dhhps                                                         2

				
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