A survey of the phosphorus and calcium contents of pastures and the serum inorganic phosphorus and calcium contents of cows on four Manawatu dairy farms


Betteridge, K.

New Zealand Veterinary Journal 37(2): 51-55

1989


Serum inorganic phosphorus (Pi) and calcium (Ca) concentrations were assessed in 20 cows on each of four Manawatu factory supply dairy farms. Blood was taken from each cow before calving and at six-week intervals during lactation. Bleeding coincided with herd testing. Herds of Friesian or Friesian X cows and Jersey or Jersey X cows were compared on adjacent farms on a Central Yellow-brown Sand and on adjacent farms on a Peat Loam overlying a Central Yellow-brown Earth soil. Pasture mass and composition were estimated to grazing height in the next two paddocks to be grazed in the rotation. Mean serum Pi concentration was higher in cows on sandy soils (1.55 mmol Pi/l than in cows on the peat loam (1.34 mmol Pi/l (P<0.001). Concentrations were highest before calving (1.69 mmol Pi/l) but fell to low levels at peak lactation (1.17mmol Pi/l when 70% of cows were below the minima of the 'normal range', and during the drought (1.29 mmol Pi/l. Pasture phosphorus (P) concentrations were adequate to support cow nutrition for lactation (>0.33% DM, ad lib. feeding) until the summer drought when low herbage mass would have restricted milk production. Serum Ca was adequate for lactating cows and changed little between months or between cows (mean 2.12 mmol Ca/l). No metabolic disorders relating to mineral deficiencies were observed. It appears that serum Pi in a high proportion of cows falls below the normal range during peak lactation without cows displaying clinical deficiency symptoms or a depression in butterfat production.

1989
NEW
ZEALAND
VETERINARY
JOURNAL
51
A
survey
of
the
phosphorus
and
calcium
contents
of
pastures
and
the
serum
inorganic
phosphorus
and
calcium
contents
of
cows
on
four
Manawatu
dairy
farms
K.
Betteridge*
N.Z.
vet.
J.
37:
51-55
ABSTRACT
Serum
inorganic
phosphorus
(Pi)
and
calcium
(Ca)
concentrations
were
assessed
in
20
cows
on
each
of
four
Manawatu
factory
supply
dairy
farms.
Blood
was
taken
from
each
cow
before
calving
and
at
six-week
intervals
during
lactation.
Bleeding
coincided
with
herd
testing.
Herds
of
Friesian
or
Friesian
X
cows
and
Jersey
or
Jersey
X
cows
were
compared
on
adjacent
farms
on
a
Central
Yellow-brown
Sand
and
on
adjacent
farms
on
a
Peat
Loam
overlying
a
Central
Yellow-brown
Earth
soil.
Pasture
mass
and
com-
position
were
estimated
to
grazing
height
in
the
next
two
paddocks
to
be
grazed
in
the
rotation.
Mean
serum
Pi
concentration
was
higher
in
cows
on
sandy
soils
(1.55
mmol
Pi/E)
than
in
cows
on
the
peat
loam
(1.34
mmol
Pi/E)
(P<0.001).
Concentrations
were
highest
before
calving
(1.69
mmol
Pi/E)
but
fell
to
low
levels
at
peak
lactation
(1.17mmol
Pi/E)
when
70%
of
cows
were
below
the
minima
of
the
'normal
range',
and
during
the
drought
(1.29
mmol Pi/C).
Pasture
phosphorus
(P)
concentrations
were
adequate
to
support
cow
nutritional
P
requirements
for
lactation
(>0.33%
DM,
ad
lib.
feeding)
until
the
summer
drought
when
low
herbage
mass
would
have
restricted
milk
production.
Serum
Ca
was
adequate
for
lactating
cows
and
changed
little
between
months
or
between
cows
(mean
2.12
mmol
Ca/C).
No
metabolic
disorders
relating
to
mineral
deficiencies
were
observed.
It
appears
that
serum
Pi
in
a
high
proportion
of
cows
falls
below
the
normal
range
during
peak
lactation
without
cows
displaying
clinical
deficiency
symptoms
or
a
depression
in
butterfat
production.
INTRODUCTION
Two
recent
New
Zealand
surveys
have
indicated
that
over
80%
of
pasture
silages
in
Northland"
)
and
25%
of
rycgrass/
white
clover
pastures
in
the
North
Island,'
19)
when
fed
as
sole
diets
to
lactating
dairy
cattle,
may
not
meet
their
phosphorus
(P)
requirements."
)(5)
In
the
Manawatu
it
was
found
that
of
122
pasture
samples
34%
did
not
meet
the
minimum
P
requirement
of
lactating
cows."'"
Because
the
date
of
sampling
was
not
reported
in
that
survey,
the
potential
seri-
ousness
of
suboptimum
pasture
P
levels
on
the
performance
of
lactating
dairy
cows
could
not
be
assessed.
Only
one
instance"
of
clinical
P
deficiency
in
a
New
Zealand
dairy
herd
has
been
reported.
In
that
study
in
the
Manawatu
region,
classical
P
deficiency
symptoms
of
low
pro-
duction,
ill-thrift,
infertility
and
osteophagia
were
observed.
In
the
above
90
cow
herd
the
mean
serum
inorganic
phosphorus
(Pi)
level
of
ten
cows
in
December
was
1.11
mmol/f.
The
'normal
range'
of
serum
Pi
used
by
MAFQUAL,
North
Central
was,
at
the
time,
1.3-2.3
mmol/C.
P
deficiency
is
said
to
occur
at
serum
Pi
concentrations
below
1.3
mmol/C.
(6)
Two
beef
herds
in
Canterbury
have
also
been
reported
to
have
had
classical
P
deficiency
signs
of
bone
chewing,
loss
of
weight,
lameness
and
infertility,
and
this
was
associated
with
serum
Pi
concentrations
ranging
from
0.58-1.19
mmol/t.
(7)
In
another
survey,
cows
on
ten
Northland
dairy
farms
(4)
were
found
to
have
serum
Pi
levels
within
the
normal
range
before
calving
and
from
after
peak
lactation
through
to
a
summer
drought.
At
peak
lactation
the
mean
serum
Pi
level
of
all
100
cows
in
the
survey
was
below
the
lower
limit
of
the
normal
range
with
some
levels
being
as
low
as
0.34
mmol/C.
Drought
lowered
mean
monthly Pi
levels
to
1.28-1.38
mmol/C.
Pasture
phosphorus
concentrations
were
adequate
(>0.33%
P)
for
cows
producing
20e
milk/day"
)(5)
from
calving
up
until
the
drought,
but
were
probably
insufficient
for
high-producing
cows
during
the
drought
when
dry
matter
(DM)
intake
would
*
Grasslands
Division,
DSIR,
Private
Bag,
Palmerston
North.
also
have
limited
production.
There
was
a
significant
dif-
ference
in
Pi
levels
between
herds
on
Northern
Yellow-brown
Earths
and
Brown
Granular
Loams,
but
none
between
cattle
breeds.
It
was
concluded
that
dairy
cows
exhibit
low
serum
Pi
concentrations
at
peak
lactation,
despite
having
an
adequate
intake
of
dietary
P.
Doubt
was
raised
as
to
the
applicability
of
normal
range
values
for
lactating
dairy
cows
at
pasture.
The
survey
reported
here
monitored
serum
Pi
and
Ca
levels
of
20
cows
in
each
of
four
herds
in
the
Manawatu
during
11
months,
with
the
objective
being
to
determine
whether
regional
differences
exist
in
serum
Pi
levels
of
cows.
Results
are
discussed
in
relation
to
the
suitability
of
using
serum
Pi
levels
alone,
to
determine
the
P
status
of
dairy
cows
during
lactation.
MATERIALS
AND
METHODS
Farms
Farms
were
chosen
on
the
basis
of
locality,
breed
of
cow
farmed
and,
that
none
had
chronic
metabolic
problems
in
their
herd.
Butterfat
production
per
cow
was
above,
at,
or
only
slightly
lower
than
the
district
average
of
all
cows
tested
by
the
Livestock
Improvement
Division
of
the
NZ
Dairy
Board
(unpublished
statistics).
Two
adjacent
farms
were
located
on
a
Himitangi
Central
Yellow-brown
Sand,
(Carnarvon-Foxton
series)
with
a
Pukepuke
Silt
Loam
between
sand
dunes."
3)
These
soils
have
a
low
P
retention
and
require
30-50
kg
P/ha/a
for
maintenance
of
high-producing
pastures.
The
farmer
of
herd
3
(Table
I)
applied
37
kg
P/ha/a
and
the
farmer
of
herd
4,
15
kg
P/ha/a.
Soils
are
winter-wet
between
sand
dunes,
but
support
good
cool-season
growth
on
the
dunes.
Dunes
dry
out
rapidly
in
the
summer,
while
reasonable
growth
is
supported
between
Junes.
In
this
paper
these
soils
are
loosely
referred
to
as
sandy
soils'.
Two
other
adjacent
farms
were
located
on
a
Peaty
Loam
overlying
a
Central
Yellow-grey
Earth
(Marton-
Tokomaru
series)
which
is
winter-wet
and
prone
to
summer
drought.
These
peaty
loans
have
a
high
P
availability
but
4
/
\
/ \
4'
\
/
V
y,
/4
V
/
/
r-
-1
11\
en
/
1000
lu
re
mo
ss
(
kg
DM/
ho
)
4000
2000
0.45
0.40
0.35
cn
cn
0.30
13
0.25
a.
52
NEW
ZEALAND
VETERINARY
JOURNAL
1989
maintenance
P
requirement
of
the
underlying
soil
is
about
28-
38
kg
ha/a.
(
"
)
The
farmer
of
herd
1
(Table
I)
had
not
applied
fertilizer
P
during
his
three
years
on
the
farm,
while
his
neighbour
(herd
2)
applied
32
kg
P/ha/a.
These
soils
are
hereafter
referred
to
as
peaty
loams.
Pasture
composition
was
dominantly
ryegrass
(Lolium
spp.)
and
white
clover
(Trifoliwn
repens)
on
all
four
farms.
Pasture
sampling
Pasture
samples
were
clipped
to
estimated
grazing
height
at
six-weekly
intervals
across
a
transect
from
each
of
the
next
two
paddocks
in
the
grazing
rotation.
These
were
analysed
for
total
P
and
Ca,
and
samples
were
dissected
into
legume,
grass,
litter
and
other
species.
Pasture
mass
was
measured
from
two
0.5
m
2
quadrats,
which
were
placed
to
represent
the
available
mass
in
each
paddock.
Cows
and
blood
sampling
On
each
soil
type
one
herd
was
comprised
predominantly
Friesian
or
Friesian
X
cows,
while
the
other
herd
comprised
predominantly
Jersey
or
Jersey
X
cows.
Within
each
herd,
three
of
the
20
cows
sampled
were
two-year
olds.
The
average
age
of
all
cows
sampled
was
4.8
years.
Cows
were
bled
and
condition
scored
at
six-weekly
intervals
from
before
calving
in
August
1984
through
to
June
1985.
During
lactation
blood
sampling
took
place
on
the
day
of
the
six-weekly
production
test
by
the
Livestock
Improvement
Division
of
the
NZ
Dairy
Board.
Bleeding
was
done
between
0830-1100
h.
Blood
was
drawn
from
the
coccygeal
blood
vessels
in
the
tail
into
evacuated
ten
ml
tubes
without
additives.
These
samples
were
centrifuged
within
three
hours
and
serum
stored
at
-20°C
until
analysed.
Butterfat
production
Herd
test
data
were
obtained
from
each
cow
at
six-weekly
intervals
except
in
February
and
March
when
sampling
was
less
frequent.
All
data
were
combined
to
produce
an
average
lactation
curve
across
all
farms.
Analyses
Serum
Pi
and
Ca
were
automatically
analysed
(Hitachi
705)
using
Boehringer
Mannheim
kits
by
the
Whangarei
Animal
Health
Laboratory.
International
standard
reference
samples
were
used.
Pasture
P
was
analysed
by
auto-analyser
following
a
kjeldahl
digestion.
Pasture
Ca
was
analysed
on
an
atomic
absorption
spectrophotometer
after
dry
ashing.
Data
were
subjected
to
analysis
of
variance
and
Duncan's
multiple
range
test
was
used
to
describe
differences
between
means.
RESULTS
AND
DISCUSSION
Pastures
Low
'green
pasture'
mass
in
October
(Fig.
1)
reflects
the
high
intake
and
rapid
grazing
rotation
of
cows
at
their
peak
lactation
(Fig.
2).
Rotations
were
rapid
during
November
and
December
as
some
paddocks
on
each
farm
were
shut
up
for
conservation.
This
resulted
in
relatively
low
pasture
mass
in
the
paddocks
sampled.
The
sharp
decline
in
pasture
mass
after
February
reflects
the
very
dry
autumn
experienced
on
all
farms.
As
a
result
cows
were
dried
off
in
late
April.
Silage
and/
or
kale
crops
were
fed
to
cows
in
February
and
March,
while
in
June
all
cows
were
on
a
long
rotation
which
was
sup-
plemented
with
hay
or
silage.
Litter
content
ranged
from
<1-19%
across
all
farms
during
the
trial,
being
highest
during
March
and
April.
Legume
content
ranged
from
1-41%
with
highest
levels
occurring
during
the
drought
months.
There
was
a
negative
correlation
(r
=
-0.53,
P<0.01)
between
litter
content
and
the
P
content
of
herbage.
This
value
is
similar
to
that
found
in
the
Northland
survey
(r
=
-0.41)
in
which
the
litter
content
of
herbage
on
offer
ranged
between
0-62%.°
)
Phosphorus
During
January,
February
and
April,
P
content
in
pasture
(Fig.
1)
was
below
the
0.33%
DM
recommended
for
cows
producing
201?
milk/day."
)
Prior
to
calving
(August)
and
during
peak
lactation,
P
content
in
pasture
was
apparently
adequate
for
high-producing
cows.
Averaged
over
all
months
0.20
0
te'll[1111
AUGUST
JANUARY
JUNE
Month
of
sampling
Fig.
I:
Pasture
mass
(
),
pasture
phosphorus
(P)
(-----)
and
calcium
(Ca)
concentrations
(---).
Data
are
means
of
pooled
data
from
four
Manawatu
dairy
farms
sampled
at
four
to
six
week
intervals.
TABLE
I:
MEAN
SERUM
INORGANIC
PHOSPHORUS
CONTENT
OF
UP
TO
20
COWS
IN
EACH
OF
FOUR
HERDS
(MMOL/e).
Herd
Aug
Sep
Oct
Nov
Month
of
sampling
Dec
Jan
Feb
Mar
Apr
May
Jun
Herd
mean
(SD)
Central
Yellow-grey
Earths
1
1.71
1.44
0.97
1.26
1.03
1.39
1.58
1.42
1.35
c
(0.34)
2
1.70
1.33
1.03
1.18
1.34
1.20
1.46
1.37
1.32
c
(0.35)
Central
Yellow-brown
Sands
3
1.62
1.43
1.49
1.62
1.31
1.89
1.78
1.72
1.61
a
(0.30)
4
1.69
1.36
1.19
1.35
1.69
1.45
1.69
1.36
1.48
b
(0.33)
Monthly
mean
1.69
a
1.40
b
1.17
c
1.35
b
1.34
b
1.29
be
1.68
a
1.63
a
1.47
b
(SD)
(0.29) (0.26)
(0.29)
(0.31)
(0.35)
(0.27)
(0.36)
(0.30)
(0.29)
Monthly
and
herd
means
having
different
letters
are
significantly
different
(1'<0.01)
Herds
1
and
3
comprise
Jersey
or
Jersey
X
cows
while
herds
2
and
4
comprise
Friesian
or
Friesian
X
cows
-A
1\
v
/ \
ti
-
0.9
\//
00
1989
NEW
ZEALAND
VETERINARY
JOURNAL
53
there
was
no
difference
in
the
P
content
of
pastures
between
farms
(P>0.05)
despite
the
differences
in
application
of
phosphatic
fertilisers.
Calcium
Pasture
Ca
content
(Fig.
1)
was
low
during
early
lactation
(0.20%)
but
rose
to
high
levels
during
summer
(0.33%).
These
levels
were
at
all
times
adequate
for
lactating
cows."
)
This
pattern
was
inversely
related
to
the
change
in
pasture
P
content
and
followed
previously
described
seasonal
pat-
terns."
Ca:P
ratio
Studies
have
shown
that
pastures
containing
Ca:P
ratios
of
1:1,
4:1
or
8:1
did
not
affect
the
production
or
feed
utilisation
of
lactating
cows."
())
With
the
exception
of
preventing
milk
fever,
the
diet
of
dairy
cows
can
contain
ratios
of
Ca:P
of
up
to
4:1
provided
the
minimum
P
requirement
is
met."
In
the
present
survey
19
of
63
pasture
samples
had
a
Ca:P
ratio
>2:1,
with
the
average
being
2.0:1.
Only
two
samples
were
>4:1.
A
review
article
on
P
nutrition
of
dairy
cattle"
showed
that
a
range
of
1:1-2:1
in
Ca:P
ratio
was
optimum
for
preventing
milk
fever.
Although
there
was
some
apparent
risk
of
cows
suffering
milk
fever,
none
was
reported.
Serum
Pi
1.
Among
herds
Mean
serum
Pi
concentrations
of
herds
are
given
in
Table
I.
There
were
significant
differences
among
herds
with
cows
on
sandy
soils
having
a
higher
serum
Pi
concentration
(1.55
mmol/e)
than
those
on
peaty
twins
(1.34
mmol/e)
(P<0.001).
The
differences
in
serum
Pi
concentration
of
cows
on
the
two
soil
types
was
seen
only
during
lactation
but
it
is
not
known
whether
this
was
due
to
lactation
per
se,
to
P
availability
in
the
plant,
or
to
P
absorption
from
the
gastro-intestinal
tract.
The
latter
seems
most
likely
as
the
herbage
Ca:P
ratio
was
higher
on
the
peaty
loams
than
on
the
sandy
soils
during
lactation
(P<0.001)
and
a
high
Ca:P
ratio
in
the
diet
can
depress
P
absorption."'
)
Insufficient
Zn,
Cu
or
Mo
in
the
diet
may
also
depress
P
absorption
but,
although
these
are
often
found
in
lower
concentrations
on
peat
soils,"
herbage
concentrations
were
not
measured.
The
Jersey
X
herd
on
the
sandy
soil
had
a
higher
serum
Pi
concentration
than
the
Friesian
X
herd
on
the
neighbouring
farm
whereas
there
was
no
difference
between
the
two
breeds
on
the
peaty
loams.
During
the
lactation
period
only,
Jersey
X
cows
had
a
5%
higher
serum
Pi
than
Friesian
X
cows
(P<0.05).
This
contrasts
with
other
reports
showing
no
between-breed
differences."
)(
"
))
These
data
do
not
enable
an
explanation
to
be
given
for
the
difference
in
serum
Pi
found
between
the
two
soil
types.
Although
there
was
12%
more
herbage
on
offer
on
the
peaty
loams
than
on
the
sandy
soil,
P
concentrations
in
pasture
were
similar
on
all
farms
and
were
apparently
adequate
for
lactating
cows"
)
until
January.
During
summer,
drought
affected
pasture
growth
and
P
concentrations
fell
to
0.29%
in
DM.
As
there
was
no
consistency
in
stocking
rate,
area
conserved
for
silage,
or
in
utilization
of
pasture
between
the
four
farms,
it
was
not
possible
to
estimate
the
cows'
daily
intake
of
P.
Butterfat
production
per
cow
was
5%
greater
for
Friesian
X
herds
than
Jersey
X
herds
(P<0.05)
but
similar
on
both
soil
types
(mean
0.67
kg
BF/cow/day),
so
the
P
sink
in
butterfat
(and
therefore
in
milk)
cannot
be
considered
as
the
cause
of
the
difference
in
serum
Pi.
Milk
and
blood
sampling
of
herds
on
the
two
soil
classes
took
place
on
consecutive
days
except
in
February,
when
only
herds
on
peaty
loams
were
bled
arid
herd-tested,
and
March,
when
only
herds
on
sandy
soils
were
sampled.
Mean
serum
Pi
concentrations
(Fig.
2,
Table
I)
were
highest
prior
to
calving
and
fell
to
their
lowest
level
at
peak
lactation
in
October.
3
1.7
/
1
.
1.1
AUGUST
JANUARY
JUNE
Month
of
sampling
Fig
2:
Serum
inorganic
phosphorus
(Pi)
(-----),
and
serum
calcium
(---)
concentrations
and
daily
butterlat
(8F)
production
)
from
up
to
80
cows
on
four
Manalvant
dairy
farms.
Plots
are
based
on
means
of
pooled
data
collected
from
all
farms
within
each
month.
After
peak
lactation,
mean
serum
Pi
concentrations
rose
to
he
within
the
normal
range
of
1.3-2.3
mmol/e.
By
March,
when
milk
production
was
very
low
due
to
dry
summer
conditions,
serum
Pi
concentrations
had
regained
their
high
pre-calving
concentration.
In
June
this
level
had
fallen
somewhat,
probably
as
a
result
of
break-grazing
feeding
regimes
coupled
with
supplementary
feeding.
These
seasonal
trends
are
very
similar
to
those
found
in
the
Northland
survey"
)
except
that
the
decline
during
the
summer
drought
in
this
present
survey
was
not
so
marked.
In
the
Northland
survey
pasture
P
concen-
tration
fell
to
0.22%
DM
when
litter
content
rose,
in
some
pastures,
to
62%.
In
the
Manawatu
survey
the
lowest
average
monthly
IP
content
of
pasture
was
only
0.28%
DM
in
January
and
February
but
litter
content
didn't
exceed
19%.
It
therefore
seems
likely
that
the
higher
minimum
serum
Pi
con-
centration
of
cows
in
the
Manawatu
survey
was
a
reflection
of
a
higher
pasture
P
content.
This
must
however
remain
con-
jecture
as
daily
P
intake
by
cows
was
not
measured.
The
cor-
relation
between
butterfat
production
and
serum
Pi
concen-
tration
was
small
and
negative
(r
=
—0.26,
P<0.001)
and
the
regression
of
serum
Pi
on
butterfat
production
significant
(P<0.01).
Because
of
the
weakness
of
this
relationship
it
appears
that
the
transition
from
pregnancy
to
lactation,
rather
than
the
magnitude
of
lactation
is
the
biggest
factor
causing
the
post
partum
depression
in
scrum
Pi.
Serum
Pi
concentractions
declined
with
age
from
1.56
mmol/f
in
two-year-olds,
to
1.25
mmol/e
in
seven-year-olds.
This
pattern
was
similar
to
that
found
elsewhere.""
Cows
older
than
seven
years
had
a
higher
serum
Pi
concentration
(P<0.005),
but
there
were
few
cows
in
this
age
bracket.
2.
Numbers
of
cows
below
'normal'
Table
II
summarised
the
distribution
of
animals
within
serum
Pi
concentration
categories
in
relation
to
the
lower
limit
of
the
normal
range
(viz.
<1.3
mmol/e).
Thirty-one
percent
of
cows
sampled
in
September
were
below
the
normal
range;
70%
were
below
in
October;
and
44-53%
below
from
November
through
January.
Lowest
serum
Pi
concentrations
were
more
than
50%
below
the
lower
limit
of
the
normal
range.
These
results
show
more
cows
to
be
below
the
normal
range
54
NEW
ZEALAND
VETERINARY
JOURNAL
1989
TABLE
II:
PERCENTAGE
OF
ALL
COWS
SAMPLED
WITHIN
EACH
MONTH
FALLING
WITHIN
EACH
OF
THREE
SERUM
INORGANIC
PHOSPHORUS
CATEGORIES.
Month
of
sampling
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
>1.3
mmolif
0.8-1.29
mmol/f
<0.8
mmol/e
No.
of
cows
Lowest
serum
Pi
concentration
(mmol/e)
93
4
3
80
0.53
69
30
1
66
0.57
30
64
6
80
0.51
56
43
1
80
0.78
0
49
50
1
80
0.61
47
50
3
40
0.77
85
15
0
39
0.95
84
16
0
74
0.95
0
67
33
0
60
0.86
than
in
the
Northland
survey.
(4)
However,
normal
range
values
are
determined
by
each
analytical
laboratory
from
several
hundred
healthy
animals
drawn
from
within
its
region
(H.V.
Brooks,
personal
communication).
Allowance
was
not
made
for
the
different
normal
ranges
used
by
different
laboratories
in
the
interpretation
of
data
collected
in
the
Northland
survey.
A
lower
limit
of
1.4
mmol/f
should
have
been
used,
so
as
a
result,
more
cows
were
in
fact
below
the
normal
range
than
stated
in
Table
II
of
that
paper.t
41
However
the
difference
in
values
for
the
lower
limit
determined
by
these
two
New
Zealand
laboratories
is
small
and
importantly,
they
are
in
close
agreement
with
lower
limits
found
in
overseas
studies
of
lactating
dairy
cows.
(5)(17)
"
Scores
of
cow
body
condition
during
early
lactation
(data
not
presented)
showed
no
cow
to
be
in
poor
condition
although
poor
condition
is
a
classical
symptom
of
P
deficiency
along
with
loss
of
weight
and
lameness.
(5)
Results
from
both
New
Zealand
surveys
are
similar
to
results
from
concentrate-fed
cows
in
an
American
study,
(8)
but
contrast
with
those
of
British
research,
which
showed
very
small
seasonal
and/or
stage
of
lactation
effects
on
serum
Pi
concentrations
within
herds.
(14)(15)(17)
These
differences
may
reflect
differences
in
feed
quantity
and
quality
associated
with
continuous
outdoor
grazing
of
dairy
cows
in
New
Zealand
compared
with
British
animals
which
spend
a
considerable
time
indoors,
and
which
frequently
receive
P
supplemen-
tation.
3.
General
The
mean
serum
Pi
level
in
the
ten
cows
sampled
in
a
Kimbolton
dairy
herd,
which
is
the
only
reported
instance
of
P
deficiency
in
a
New
Zealand
dairy
here,
was
1.11
mmol/E.
This
was
similar
to
the
October
mean
value
in
this
survey
(1.17
mmol/E)
from
80
cows.
The
lowest
value
in
the
Kimbolton
case
study
was
0.60
mmol/f
while
in
this
survey
lower
levels
were
found
in
August,
September
and
October
(Table
II).
By
contrast,
the
mean
serum
Pi
concentration
was
lowest
at
around
peak
lactation
and
had
recovered
to
be
within
the
normal
range
by
December,
whereas
the
Kimbolton
herd
had
the
low
serum
Pi
level
in
December.
It
is
not
known
how
long
serum
Pi
had
been
below
the
normal
range
in
that
herd
but,
in
this
survey,
pasture
P
concentrations
were
considered
adequate
for
high
producing
cows°
whereas
pastures
were
apparently
deficient
in
three
of
four
pastures
in
the
Kimbolton
case
study
(e.g.
0.25,
0.27,
0.29%
P
in
DM
respectively).
(61
The
farmer
of
herd
1
(Table
I)
had
not
applied
phosphatic
fertilizer
in
the
five
years
to
1988
(viz.
from
two
years
before
the
survey
started)
and
yet
his
herd
production
has
risen
from
441
kg
BF/ha
in
1983-4
to
531
kg
BF/ha
in
1987-8.
This
has
occurred
despite
his
herd
having
had
the
lowest
mean
serum
Pi
level,
at
peak
lactation,
of
the
four
herds
in
the
1984-85
survey.
By
contrast,
it
was
concluded
that
inadequate
fertilizer
P
applications
precipitated
the
P
deficiency
syndrome
in
the
Kimbolton
herd.t
61
Poor
conception
was
the
major
concern
of
the
Kimbolton
farmer.
This
was
improved,
apparently,
following
dusting
of
pastures
with
bone
flour
and
treating
water
troughs
with
monosodium
acid
phosphate.
Although
P
supplementation
of
the
herd
reduced
the
number
of
anoestrus
cattle
from
39
to
11
after
three
weeks
of
treatment,
four
of
the
11
cows
still
had
serum
Pi
concentrations
below
1.3
mmol/e.
Interestingly
though,
there
was
no
increase
in
either
the
herd's
milk
production
or
mean
cow
condition.
This
may
have
been
because
the
P
supplementation
came
too
late
into
the
lactation
or
because
summer
feed
supply
was
low.
Crude
protein
contents
of
<12%
DM
can
also
limit
milk
production
when
there
is
an
adequate
quantity
of
feed
available.
(20)
However
crude
protein
content
in
the
Kimbolton
case
study
was
29%
of
DM
and,
in
the
present
survey,
19%
of
DM
at
its
lowest
point
in
November.
It
is
thus
unlikely
that
a
low
dietary
protein
intake
could
be
implicated
in
the
low
serum
Pi
status
of
these
Manawatu
cows.
Alternatively,
it
is
possible
that
milk
production
is
not
responsive
to
P
supplementation
given
cows
whose
herd
mean
serum
Pi
was
25%
below
the
normal
range
a
view
which
con-
tradicts
with
other
literature.
(5)
In
a
recent
trial,
cows
with
a
mean
serum
Pi
concentration
of
1.2
mmol/e,
at
peak
lactation,
did
not
increase
milk
production
during
the
four
weeks
in
which
they
received
a
supplement
of
25
g
P/cow/day
(Bet-
teridge,
in
preparation).
The
skeleton
is
a
major
source
of
P
and
Ca
and
is
used,
in
conjunction
with
dietary
supply,
to
maintain
blood
home-
ostasis
of
these
minerals.
(20)
Whereas
serum
Ca
was
maintained
within
a
relatively
narrow
range
during
the
survey
period
while
pasture
Ca
levels
(and
therefore
dietary
intake
of
Ca)
changed
markedly,
this
was
not
so
with
serum
P
which
fell
28%
from
the
pre-calving
high
of
1.6
mmol/E.
Because
of
the
low
negative
correlation
between
serum
Pi
and
butterfat
production
throughout
the
season,
it
appears
that
the
early
lactation
depression
is
more
of
a
physiological
phenomenon
than
a
response
to
high
butterfat
production.
Serum
Ca
Changes
in
serum
Ca
were
small
(range
1.99-2.22
mmol/E;
Table
III)
although
there
was
a
significant
decline
in
October
when
cows
reached
peak
lactation,
in
March
when
milk
pro-
duction
was
very
low
and
in
June
when
cows
had
dried
off.
The
spring
decline
occurred
later
than
expected,
as
such
drops
are
normally
found
only
at
calving
and
last
for
less
than
seven
days.
(2)(9)
Concentrations
were
higher
in
Jersey
X
than
in
Friesian
X
cows
(P<0.01),
but
did
not
differ
significantly
between
soil
types.
The
relatively
constant
levels
of
serum
Ca
concentrations
contrast
with
changes
in
pasture
Ca
content
which
was
low
in
early
spring,
increased
substantially
in
summer
and
fell
again
in
winter
(Fig.
1).
Thus,
these
data
Central
Yellow-grey
Earths
1
2
Central
Yellow-brown
Sands
3
4
2.09
2.14
1.81
2.18
1.99
2.04
2.03
2.16
2.16
2.14
2.07
2.18
2.11
1.96
2.04
2.00
2.11
2.27
2.23
2.13
2.24
2.08
2.31
2.09
2.12
ab
(0.23)
2.10
2.09
2.10
ab
(0.23)
2.11
2.28
2.03
2.15
a
(0.23)
2.07
2.19
1.83
2.05
b
(0.26)
1989
NEW
ZEALAND
VETERINARY
JOURNAL
55
TABLE
III:
MEAN
SERUM
CALCIUM
CONTENT
OF
UP
TO
20
COWS
IN
EACH
OF
FOUR
HERDS
(MMOLI(').
Month
of
sampling
Herd
Herd
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
mean
(SD)
Monthly
mean
2.09
be
2.09
bc
1.99
d
2.13
a
2.16
ab
2.20
a
2.09
b
2.22
a
2.02
cd
(SD)
(0.25)
(0.16)
(0.26)
(0.20)
(0.18)
(0.16)
(0.
8)
(0.22)
(0.33)
Monthly
and
herd
means
having
different
letters
are
significantly
different
(P<0.01)
Herds
I
and
3
comprise
Jersey
or
Jersey
X
cows
while
herds
2
and
4
comprise
Friesian
or
Friesian
X
cows
support
the
view
that
cows
have
a
better
homeostatic
control
over
serum
Ca
than
over
serum
Pi
concentrations.
(1
'
Australian
results
have
also
shown
little
variation
between
herds
or
classes
of
stock
in
serum
Ca
concentrations.
[
2)
It
is
known
that
1,25
dihydroxyvitamin
D
plays
a
major
role
in
the
homeostatic
control
of
Ca
and
P.'
2
'
)
As
intake
of
Vitamin
D
by
grazing
cattle
in
New
Zealand
is
generally
high,
low
pasture
levels
of
Ca
and
P
are
more
likely
to
limit
animal
performance
than
the
ratio
of
Ca:P
per
se
(N.D.
Grace,
personal
communication).
Although
during
the
summer
drought
pasture
Ca
rose
as
P
fell
(r
=
-
0.52;
P<0.01);
it
was
never
below
0.35%
of
DM
which
is
considered
the
minimum
requirement
of
lactating
dairy
cattle."
CONCLUSION
Serum
Pi
concentrations
were
below
the
normal
range
in
a
large
proportion
of
cows
throughout
lactation.
At
peak
lactation
this
apparent
deficit
was
severe
in
some
animals,
falling
to
a
half
of
that
considered
normal
for
lactating
cows,
and
yet
no
clinical
signs
of
P
deficiency
were
observed.
These
results
follow
the
same
pattern
as
those
in
the
Northland
survey
of
200
dairy
cows.
It
appears
that
serum
Pi
is
not,
as
stated
in
the
literature,
restrained
within
a
narrow
range
after
peak
lactation.
Further,
high
butterfat
production
is
achieved
by
herds
which
have
a
mean
serum
Pi
concentration
up
to
25%
below
the
normal
range
in
early
lactation
and
which
can
have
43%
of
cows
below
the
normal
range
even
in
November.
(It
is
not
valid
to
relate
January-April
levels
to
a
normal
range
during
the
drought
because
conditions
were
not
'normal).
Serum
Pi
concentrations
determined
from
a
single
bleeding
should
not
be
used
as
the
sole
determinant
of
P
deficiency.
Cognisance
should
also
be
taken
of
other
clinical
signs;
P
content
in
pasture,
the
fertilizer
history
and,
where
possible,
results
of
serial
bleeding
over
a
period
of
time.
There
is
a
need
for
detailed
production
trials
where
P
supplemented
cows
are
compared
to
control
animals
in
terms
of
milk
production
to
define
the
relationships
between
serum
Pi
concentration
and
milk
yield.
ACKNOWLEDGEMENTS
Thanks
are
due
to
Mr
B.P.
Devantier
for
technical
assistance,
Mrs
H.
Dickins
for
pasture
chemical
analyses,
and
Mr
G.
Carthew
at
the
Animal
Health
Laboratory,
MAFTech,
Whangarei
for
serum
analyses.
Mr
D.
Sellars,
NZ
Dairy
Board
provided
farmer
contacts
and
the
Livestock
Improvement
Division
of
the
NZ
Dairy
Board
provided
milk
production
records
for
the
survey
cows.
This
survey
was
only
made
possible
by
the
co-operation
given
and
interest
shown
by
each
co-operating
farmer,
to
whom
I
am
most
grateful.
REFERENCES
(1)
Agricultural
Research
Council
(1980):
The
nutrient
requirements
of
ruminant
livestock.
Published
Commonwealth
Agricultural
Bureau.
England.
(2)
Barton.
B.A.;
Horst,
R.L.;
Jorgenson,
N.A.;
Dc
Luca,
H.F.
(1981):
Con-
centration
of
calcium,
phosphorus,
and
1,25-Dihydroxyvitamin
D
in
plasma
of
dairy
cows
during
the
lactation
cycle../.
Dairy
Sri.
64:
850-2.
(3)
Betteridge,
K.;
Sedeole,
J.R.
(1982):
A
survey
of
silage
quality
on
Northland
dairy
farms.
NZ
Grassland
Association
Proc.
43:
85-92.
(4)
Betteridge,
K.
(1985):
A
survey
of
the
phosphorus
content
of
pastures
and
the
serum
inorganic
phosphorus
content
of
dairy
cows.
N.
Z.
veil
.14:
22-
26.
(5)
Blood,
D.C.;
Henderson,
J.A.:
Radostitis,
D.M.
(1979):
Veterinary
Medicine,
5th
edn.
Published
Lea
and
Febiger,
Philadelphia.
(6)
Brooks,
H.V.;
Cook,
TG.;
Mansell,
C.P.;
Walker,
G.A.
(1984):
Phosphorus
deficiency
in
a
dairy
herd,
N.Z.
vet.J.
32:
174-6.
(7)
Clark,
R.O.
(1974):
Phosphorus
deficiency
on
two
farms
in
Canterbury.
N.Z.
vet.J.
22:
14-6.
(8)
Forur,
EL.;
Kincaid,
R.I.;
Preston,
K.L.;
Millers,
J.K.
(1982):
Variation
in
inorganic
phosphorus
in
blood
plasma
and
milk
of
lactating
dairy
cows.
J.
Dairy
Sri,
65:
760-3.
(9)
Kemp,
A.;
Mart,
M.L.
(1957):
Grass
tetany
in
grazing
milking
cows.
Netherlands
J.
Agric.
Sri.
8:
281-304.
(1(1)
Kitchenham,
B.A.;
Rowlands,
G.J.;
Shorbagi,
H.
(1975):
Relationships
of
concentrations
of
certain
blood
constituents
with
milk
yield
and
age
of
cows
in
dairy
herds.
Res.
vet.
Sci.
249-52.
(II)
Metson,
A.J.;
Saunders,
W.M.
H.
(1978):
Seasonal
variations
in
chemical
composition
of
pasture.
N.Z.
J.
Agric.
Res.
21:
341-53.
(12)
Mylrea,
P.J.;
Bayfield,
R.E
(1968):
Concentrations
of
some
components
in
the
blood
and
serum
of
apparently
healthy
dairy
cattle.
I.
Electrolytes
and
minerals.
Aust.
Vet.
J.
44.•
565-9.
(13)
New
Zealand
Soil
Bureau
Bulletin
26
(1968):
Published
N.Z.
Department
of
Scientific
and
Industrial
Research,
Wellington.
(14)
Payne,
I
.M
;
Rowlands,
G.J.;
Mansion,
R.;
Dew,
S.M.
(1973):
A
statistical
appraisal
of
results
of
metabolic
profile
tests
on
75
dairy
herds.
Brit.
vet.
J.
129:
370-81.
(15)
Payne,
J.M.;
Rowlands,
GT;
Dew,
S.M.;
Parker,
W.H.
(1974):
A
statistical
appraisal
of
the
results
of
metabolic
profile
tests
on
191
herds
in
the
BVA/ADAS
joint
exercise
in
animal
health
and
productivity.
Brit.
vet.
J.
130:
34-44.
(16)
Reid,
R.L.
(1980):
Relationship
between
phosphorus
nutrition
of
plants
and
the
phosphorus
nutrition
of
animals
arid
man.'
The
role
of
phosphorus
in
agriculture.
Editors:
Khasawnch,
FE.;
Sample,
E.C.;
Kamprath,
E.J.
Published
American
Society
of
Agriculture.
p.
847-86.
(17)
Rowlands,
G,J.;
Manston,
R.;
Pocock,
R.M.;
Dew,
S.M.
(1975):
Relationship
between
stage
of
lactation
and
pregnancy
and
blood
com-
position
in
a
herd
of
dairy
cows
and
the
influence
of
seasonal
changes
in
management
on
these
relationships.
J.
Dairy
Sri.
42:
349-62.
(18)
Simesen,
M.G.
(1980):
Calcium,
phosphorus
and
magnesium
metabolism.
Clinical
Biochemistry
of
Domestic
Animals.
3rd
Edition.
Editor
Jiro
J.
Kaneko.
Published
Academic
Press
p.
575-648.
(19)
Smith,
C.S.;
Cornforth,
I.S.
(1982):
Concentrations
of
nitrogen.
phos-
phorus,
sulphur,
magnesium,
and
calcium
in
North
Island
pastures
in
relation
to
plant
and
animal
nutrition.
N.Z.
.1.
exp.
Agric.
2.5:
373-87.
(20)
Stobbs,
T.H.
(1971):
Quality
of
pasture
and
forage
crops
for
dairy
pro-
duction
in
tropical
regions
of
Australia.
Tropical
Grasslands
.5:
159-70.
(21)
Wasserman,
R.H.;
"Taylor,
A.N.
(1973):
Intestinal
absorption
of
phosphate
in
the
chick:
Effect
of
Vitamin
1J
3
and
other
parameters../.
Nutr
/03:
586-
99.
Accepted
for
Publication
22nd
March,
1989.