Mineral concentrations of cool-season pasture forages in north Florida during the winter-spring grazing season : I. macr...

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Mineral concentrations of cool-season pasture forages in north Florida during the winter-spring grazing season : I. macro minerals
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2009 Florida Beef Report
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Chelliah, G.
Myer, Bob
Carter, Jeff
McDowell, Lee
Wilkinson, Nancy
Blount, Ann
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Gainesville, Fla.
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Mineral Concentrations of Cool-Season Pasture Forages in North Florida
during the Winter-Spring Grazing Season: I. Macro Minerals

G. Chelliah1
Bob Myer
Jeff Carter
Lee McDowell
Nancy Wilkinson
Ann Blount


Pasture forage species and blend, pasture establishment method, year and, in particular, month of
grazing season can influence concentrations of calcium (Ca), phosphorus (P), magnesium (Mg), and
potassium (K), but not sodium (Na), in cool-season annual grass pasture forage. .


Summary
Concentrations of selected macro minerals (Ca,
P, Na, K, and Mg) were determined from cool-
season annual grass pasture forages over four
consecutive late fall-winter-spring grazing
seasons (2001-2005). Forage samples were
taken from eight experimental pastures used in
beef cattle grazing trials. Two, 2-yr experiments
were conducted; animal and pasture data were
reported previously (Myer and Blount, 2005 and
2007). Each experiment was of a similar 2x2
design comparing clean-tilled vs. sod-seeded
pastures with two different forage combinations
(Exp. 1, rye + oats vs. rye + oats + ryegrass;
Exp. 2, oats + ryegrass vs. ryegrass only).
Pastures were planted in Oct or Nov, and
grazed (and sampled) ,i,,, I,, Nov, Dec, Jan or
Feb and ending Apr or May. The overall mean
concentrations for Exp. 1 and 2, respectively
were (% of dry matter): Ca, 0.31 and 0.31; P,
0.42 and 0.35; Na, 0.03 and 0.04; K, 3.2 and
2.6; and Mg, 0.26 and 0.16. Year affected
(P<0.05) P, K and Mg concentrations within
each experiment, but not Ca or Na. Pasture
planting method affected (P<0.05) Ca and P in
Exp. 2, and Mg in Exp.l. Forage treatment
affected (P<0.05) Ca, K and Mg in Exp. 2.


Sampling month affected (P<0.05) all minerals
evaluated in both experiments except Na.
Results indicate that forage type, pasture
planting method, year, and especially month
within year can affect concentrations of macro
minerals of annual cool-season grass pasture
forages in the southeastern USA.

Introduction
Cool-season grass annuals, such as oats (Avena
sativa), rye (Secale cereale) and annual ryegrass
(Lolrum multifloram), are commonly planted to
provide forage for grazing by beef cattle during
the late fall to spring period in the southeastern
USA when permanent warm-season pastures are
dormant. Depending on moisture and weather,
the grazing period can start as early as late
November and last until early June, but the start
can be as late as February and can end as early
as late April. The annual forages are planted
during the fall (Oct or Nov), and can be seeded
directly into dormant warm-season pasture (sod-
seeding) or planted into a clean-tilled, prepared
seedbed. These forages are highly digestible
and high in energy and protein; however, there is
limited information in regards to concentrations
of various nutritionally important minerals. The


2009 Florida BeefReport










purpose of this study was to measure monthly
concentrations of selected macro and trace
minerals of annual cool-season grass pasture
forages of various combinations that were either
sod-seeded or planted into a clean-tilled,
prepared seed bed during the late fall-winter-
spring grazing season in north Florida.

This report will present the results of the macro
minerals of Ca, P, Na, K and Mg. A companion
paper published elsewhere in the 2009 Florida
Beef Report (Chelliah et al., 2009) will present
results of analyses of selected trace minerals.

Procedure
Pasture forage mineral concentrations were
determined as part of a grazing study. The study
consisted of two cool-season beef cattle grazing
experiments conducted at the North Florida
Research and Education Center (NFREC) of the
University of Florida located at Marianna (31 N
Lat.). Each experiment lasted two yr, resulting in
four consecutive yr of testing from 2001 to 2005
during the late fall-winter-spring grazing season.
Macro mineral concentrations were determined
from forage samples taken from eight, 3.2 ac
experimental pastures per yr used in the two
grazing experiments.

The two, two-year experiments conducted were
each of a similar 2x2 design comparing clean-
tilled vs. sod-seeded pastures with two different
forage combinations (simple vs. more complex
blend; Exp. 1, small grains only rye and oats
vs. small grains plus ryegrass; Exp. 2, ryegrass
only vs. ryegrass plus oats). There were two
pastures per treatment combination per yr within
each experiment. For the tilled pastures, the
forages were planted into a clean-tilled, prepared
seedbed, and for the sod-seeded pastures,
forages were planted, using a no-till seed drill,
into dormant bahiagrass. The experimental cool-
season pastures were planted in October or
November of each year, and grazed and sampled
starting in November, December, January or
February, and ending in April or May (the start
and end varied between years due to weather
conditions pastures were grown under dry land
conditions). University of Florida/IFAS
recommendations were followed in regards to
planting times of the various pasture


combinations and seeding rates. Within yr,
initial fertilization and liming was based on soil
fertility analysis; the pastures were top-dressed
twice with N, each time with 75 lb N/ac, within
each yr. The soils at the experimental site are
well drained, acidic, and sandy (fine loamy,
kaolintic, thermic Kandiudults) typical of the
Southern Coastal Plain. Soil type was consistent
across the eight pastures. Cattle were provided a
free choice mineral supplement at all times
while grazing (Purina Dixie H/M H/SE, Purina
Mills, St. Louis, MO).

Pastures were sampled twice mo and samples
were pooled by month for mineral analyses. Not
all months were represented for each yr,
however, the months of February, March and
April were represented for each yr of each
experiment; February, March and April data
were used to determine differences due to forage
treatment, pasture establishment method, and
year within experiment. More details about
pasture and grazing management, animal
information, and forage sampling procedures
can be found in previous publications (Myer and
Blount, 2005 and Myer and Blount, 2007).

Data were analyzed as a 2x2 randomized
complete block design. The models evaluated
pasture forage treatment and pasture
establishment method as fixed effects, and yr as
random. Monthly mineral concentrations for
each experiment also were analyzed using
repeated measures model with mo as the
repeated measure. The experimental unit was the
individual pasture.

Results
Animal and pasture results were reported
previously (Myer and Blount, 2005 and 2007).
Cool-season annual grass species chosen reflect
what is commonly grown in the Southern
Coastal Plain region of the southeastern USA.
Most cool-season annual pastures planted,
however, are mono-crops in this region. Average
monthly rainfall and daily temperatures over the
four study yr during October to May period were
similar to the 30-yr average at Marianna, except
for rainfall in January and May where amounts
averaged 30 to 50% less over the four yr.
October, November, April, and May tended to


2009 Florida BeefReport










be warmer than the 30-yr average. As expected,
there was yr to yr variation which probably
affected mineral concentrations noted for yr to
yr. As such, results were averaged over yr as
most producers are interested in what may be
expected for an average yr instead of for a
particular yr.

Pasture establishment method affected (P<0.05)
forage concentrations of Mg in Exp. 1, and Ca
and P in Exp. 2 (Table 1). Pasture forage
treatment affected (P<0.05) Ca, K, and Mg
concentrations in Exp 2 only (Table 1).The
significant differences noted above due to
pasture establishment method or forage
treatment, however, were small (Table 1).

Year affected (P<0.05) pasture forage P, K, and
Mg concentrations within each experiment, but
not Ca or Na (means not shown); Mg in
particular was affected by yr. No forage
treatment and pasture establishment interactions,
or pasture treatment by yr interactions (P>0.05)
were noted.

Month within yr affected (P<0.05) pasture
forage concentrations of all minerals evaluated
in both experiments except Na and possibly Ca.
Calcium was different in Exp.1 but not Exp. 2,
and if averaged over the two experiments, Ca
was fairly constant from mo to mo 0.29 to
0.33% (Table 2). Forage concentrations of P
and K were greatest during the winter and
declined during spring with lowest levels noted
in May; Mg was least in early spring (Table
2).There was considerable variation in forage
concentrations of each mineral evaluated within
experiment (Table 3).

Results indicated that annual cool-season pasture
forage treatment, pasture forage establishment
method, and year, while not consistent between
experiments, can influence pasture forage
concentrations of Ca, P, K, and Mg, but have
little influence on Na. Month within yr of the
grazing season appeared to have the greatest
influence on forage macro mineral
concentrations evaluated, especially P and K.
The low forage Mg, combined with high K, may
be a potential deficiency problem for beef cattle
which can result in grass tetany


(hypomagnesaemia), especially during the early
spring months.

Overall mean concentrations for each
experiment for each mineral measured in the
pasture forages is presented in Table 3. From the
results of both experiments, concentrations in
annual cool-season pasture forage averaged
(mean one standard deviation; dry matter
basis) 0.31 0.05% for Ca, 0.38 0.04% for P,
0.04 0.01% for Na, 2.9 0.3% for K, and 0.21
0.03% for Mg. The concentrations of Ca, P,
and Mg are at the low end of concentration
ranges previously reported, K at the high end,
and Na in the middle (Table 3). However, it
should be emphasized that much variation in
concentration was noted for each mineral
analyzed, especially for Mg (Table 3).

Overall, for beef cattle grazing cool-season
annual grass pastures evaluated in this study,
forage Na would be very deficient; Ca slightly
deficient, P and Mg marginally deficient, and K
would be in excess (Table 3).


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Literature Cited
Chelliah, G., et al. 2009 Florida Beef Report.
Ensminger M. E., et al. 1990. Feeds and Nutrition. The Ensminger Publishing Co., Clovis, CA,
USA. pp 1265-1511.
Myer, R. O., and A. R. Blount. 2005 Florida Beef Report. pp 19-24.
Myer, B., and A. Blount. 2007 Florida Beef Report. pp 23-27.
NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. Nat'l. Acad. Sci., Washington, DC,
USA.




Acknowledgment
The assistance of Harvey Standland, John Crawford, Meghan Brennan, Mary Maddox, Mary
Chambliss, Tina Gwin, Jeff Jones and the staff at the NFREC Beef Unit is gratefully
acknowledged. Partial support was provided by Orange Hill Soil Conservation District, Chipley,
FL.


'G. Chelliah, Former Graduate Student; Bob Myer, Professor, UF-IFAS, North Florida Research
and Education Center (NFREC), Marianna, FL; Jeff Carter, Former Assistant Professor, UF-IFAS,
NFREC, Marianna; Lee McDowell, Professor Emeritus, UF-IFAS, Department of Animal Sciences,
Gainesville, FL, Nancy Wilkinson, Chemist, UF-IFAS, Department of Animal Sciences,
Gainesville, Fl; and Ann Blount, Associate Professor, UF-IFAS, NFREC, Marianna, FL.


2009 Florida BeefReport


















Table 1. Main means of macro mineral concentrations of annual cool-season
pasture forages during the late fall-winter-spring grazing season in north Florida
(% of dry matter).

Cultivation Forage Trt. Significanceg
Mineral Exp.a SSb PSC Simpled Blende SEMf Cult.h Forage' CxFI
Ca 1 0.33 0.33 0.30 0.32 0.01 NS NS NS
2 0.34 0.28 0.35 0.27 0.02 NS
P 1 0.40 0.43 0.42 0.41 0.01 NS NS NS
2 0.34 0.36 0.35 0.34 0.01 NS NS
Na 1 0.03 0.03 0.03 0.03 0.002 NS NS NS
2 0.04 0.04 0.04 0.04 0.001 NS NS NS
K 1 3.2 3.3 3.2 3.3 0.06 NS NS NS
2 2.7 2.6 2.7 2.5 0.04 NS NS
Mg 1 0.23 0.28 0.26 0.25 0.01 NS NS
2 0.17 0.16 0.18 0.15 0.01 NS NS
aExp. 1, 2001-2002 and 2002-2003 grazing seasons; and Exp. 2, 2003-2004 and 2004-2005.
bSS = sod-seeded pastures

cPS = prepared seedbed (clean-tilled) pastures.
dSimple = mono-culture or simple blend of forage species in pastures (Exp. 1, small grains-rye
and oats; Exp. 2, ryegrass).
eBlend of forage species in pastures (Exp. 1, small grains plus ryegrass; Exp. 2, oats plus
ryegrass).
fStandard error of the mean; n = 8.
gSignificance of difference; = significantly different (P<0.05), and NS = non-significant
(P>0.05).
hPasture establishment method (SS vs. PS).
'Pasture forage type or treatment (simple vs. blend).
1Establishment method by forage treatment interaction.


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Table 2. Monthly concentrations of macro minerals in annual cool-season pasture forages during
the late fall-winter-spring grazing seasons in north Florida (% of dry matter).

Sampling month
Mineral Exp.a Nov Dec Jan Feb Mar Apr May SEMb Significancec
Ca 1 0.37 0.37 0.33 0.31 0.30 0.33 0.31 0.02 *
2 0.25 0.26 0.26 0.26 0.30 0.33 0.30 0.04 NS
P 1 0.43 0.43 0.47 0.44 0.43 0.38 0.32 0.02 **
2 0.44 0.44 0.32 0.34 0.34 0.36 0.36 0.02 **
Na 1 0.04 0.03 0.03 0.03 0.03 0.04 0.04 0.003 NS
2 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.004 NS
K 1 3.8 4.2 3.8 3.3 3.3 3.1 2.3 0.2 **
2 3.8 4.2 3.2 3.0 3.0 2.6 2.2 0.2 **
Mg 1 0.31 0.29 0.28 0.25 0.24 0.27 0.27 0.02 *
2 0.18 0.16 0.14 0.14 0.16 0.17 0.16 0.01 **
aExp. 1, 2001-2002 and 2002-2003 grazing seasons; and Exp. 2, 2003-2004 and 2004-2005.
bStandard error of the mean; average n = 8 (varied from 4 (Nov) to 16 (Feb, Mar, Apr) within
experiment).
CSignificance due to month within experiment: ** = highly significant (P<0.01), = significant
(P<0.05), and NS = non-significant (P>0.05).




Table 3. Overall means and ranges of macro mineral concentrations of annual cool-season grass
pasture forages from each experiment (% of dry matter).

Mineral Exp.a Meanb 1 S.D.c Ranged Requiremente Reported'
Ca 1 0.31 0.04 0.25 to 0.44 0.5 0.32 to 0.65
2 0.31 0.06 0.10 to 0.46
P 1 0.42 0.04 0.28 to 0.54 0.3 0.23 to 0.41
2 0.35 0.03 0.27 to 0.52
Na 1 0.03 0.01 0.02 to 0.05 0.1 0.01 to 0.11
2 0.04 0.01 0.02 to 0.05
K 1 3.2 0.3 2.0 to 5.4 0.6 1.7 to 3.4
2 2.6 0.2 2.0 to 4.3
Mg 1 0.26 0.03 0.18 to 0.42 0.1 0.20 to 0.35
2 0.16 0.02 0.11 to 0.22
aExp. 1, 2001-2002 and 2002-2003 grazing seasons; and Exp. 2, 2003-2004 and 2004-2005.
bOverall mean across all treatments (n = 16).

COne standard deviation.
dLowest or highest monthly concentration obtained from a treatment within year within experiment
(n = 2).
eSuggested requirement for growing beef cattle heifers (500 to 900 lb; NRC 2000).
fOther reported concentrations for rye, oats and ryegrass fresh forage (dry matter basis); data from
Ensminger et al., 1990, and NRC, 2000.


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Full Text

PAGE 1

Mineral Concentrations of Cool Season Pasture Forages in North Florida during the Winter Spring Grazing Season: I. Macro Minerals G. Chelliah 1 Bob Myer Jeff Carter Lee McDowell Nancy Wilkinson Ann Blount Summary Concentrations of selected macro minerals (Ca, P, Na, K, and Mg) were determined from coolseason annual grass pasture forages over four consecutive late fall-winter-spring grazing seasons (2001-2005). Forage samples were taken from eight experimental pastures used in beef cattle grazing trials. Two, 2-yr experiments were conducted; animal and pasture data were reported previously (Myer and Blount, 2005 and 2007). Each experiment was of a similar 2x2 design comparing clean-tilled vs. sod-seeded pastures with two different forage combinations (Exp. 1, rye + oats vs. rye + oats + ryegrass; Exp. 2, oats + ryegrass vs. ryegrass only). Pastures were planted in Oct or Nov, and grazed (and sampled) starting Nov, Dec, Jan or Feb and ending Apr or May. The overall mean concentrations for Exp. 1 and 2, respectively were (% of dry matter): Ca, 0.31 and 0.31; P, 0.42 and 0.35; Na, 0.03 and 0.04; K, 3.2 and 2.6; and Mg, 0.26 and 0.16. Year affected (P<0.05) P, K and Mg concentrations within each experiment, but not Ca or Na. Pasture planting method affected (P<0.05) Ca and P in Exp. 2, and Mg in Exp.1. Forage treatment affected (P<0.05) Ca, K and Mg in Exp. 2. Sampling month affected (P<0.05) all minerals evaluated in both experiments except Na. Results indicate that forage type, pasture planting method, year, and especially month within year can affect concentrations of macro minerals of annual cool-season grass pasture forages in the southeastern USA. Introduction Cool-season grass annuals, such as oats ( Avena sativa ), rye ( Secale cereale ) and annual ryegrass ( Lolrum multifloram ), are commonly planted to provide forage for grazing by beef cattle during the late fall to spring period in the southeastern USA when permanent warm-season pastures are dormant. Depending on moisture and weather, the grazing period can start as early as late November and last until early June, but the start can be as late as February and can end as early as late April. The annual forages are planted during the fall (Oct or Nov), and can be seeded directly into dormant warm-season pasture (sodseeding) or planted into a clean-tilled, prepared seedbed. These forages are highly digestible and high in energy and protein; however, there is limited information in regards to concentrations of various nutritionally important minerals. The Pasture forage species and blend, pasture establishment method, year and, in particular, month of grazing season can influence concentrations of calcium (Ca), phosphorus (P), magnesium (Mg), and potassium (K), but not sodium (Na), in cool season annual grass pasture forage.

PAGE 2

purpose of this study was to measure monthly concentrations of selected macro and trace minerals of annual cool-season grass pasture forages of various combinations that were either sod-seeded or planted into a clean-tilled, prepared seed bed during the late fall-winterspring grazing season in north Florida. This report will present the results of the macro minerals of Ca, P, Na, K and Mg. A companion paper published elsewhere in the 2009 Florida Beef Report (Chelliah et al., 2009) will present results of analyses of selected trace minerals. Procedure Pasture forage mineral concentrations were determined as part of a grazing study. The study consisted of two cool-season beef cattle grazing experiments conducted at the North Florida Research and Education Center (NFREC) of the University of Florida located at Marianna (31 N Lat.). Each experiment lasted two yr, resulting in four consecutive yr of testing from 2001 to 2005 during the late fall-winter-spring grazing season. Macro mineral concentrations were determined from forage samples taken from eight, 3.2 ac experimental pastures per yr used in the two grazing experiments. The two, two-year experiments conducted were each of a similar 2x2 design comparing cl ean tilled vs. sod-seeded pastures with two different forage combinations (simple vs. more complex blend; Exp. 1, small grains only rye and oats vs. small grains plus ryegrass; Exp. 2, ryegrass only vs. ryegrass plus oats). There were two pastures per treatment combination per yr within each experiment. For the tilled pastures, the forages were planted into a clean-tilled, prepared seedbed, and for the sod-seeded pastures, forages were planted, using a no-till seed drill, into dormant bahiagrass. The experimental coolseason pastures were planted in October or November of each year, and grazed and sampled starting in November, December, January or February, and ending in April or May (the start and end varied between years due to weather conditions pastures were grown under dry land conditions). University of Florida/IFAS recommendations were followed in regards to planting times of the various pasture combinations and seeding rates. Within yr, initial fertilization and liming was based on soil fertility analysis; the pastures were top-dressed twice with N, each time with 75 lb N/ac, within each yr. The soils at the experimental site are well drained, acidic, and sandy (fine loamy, kaolintic, thermic Kandiudults) typical of the Southern Coastal Plain. Soil type was consistent across the eight pastures. Cattle were provided a free choice mineral supplement at all times while grazing (Purina Dixie H/M H/SE, Purina Mills, St. Louis, MO). Pastures were sampled twice mo and samples were pooled by month for mineral analyses. Not all months were represented for each yr, however, the months of February, March and April were represented for each yr of each experiment; February, March and April data were used to determine differences due to forage treatment, pasture establishment method, and year within experiment. More details about pasture and grazing management, animal information, and forage sampling procedures can be found in previous publications (Myer and Blount, 2005 and Myer and Blount, 2007). Data were analyzed as a 2x2 randomized complete block design. The models evaluated pasture forage treatment and pasture establishment method as fixed effects, and yr as random. Monthly mineral concentrations for each experiment also were analyzed using repeated measures model with mo as the repeated measure. The experimental unit was the individual pasture. Results Animal and pasture results were reported previously (Myer and Blount, 2005 and 2007). Cool-season annual grass species chosen reflect what is commonly grown in the Southern Coastal Plain region of the southeastern USA. Most cool-season annual pastures planted, however, are mono-crops in this region. Average monthly rainfall and daily temperatures over the four study yr during October to May period were similar to the 30-yr average at Marianna, except for rainfall in January and May where amounts averaged 30 to 50% less over the four yr. October, November, April, and May tended to

PAGE 3

be warmer than the 30-yr average. As expected, there was yr to yr variation which probably affected mineral concentrations noted for yr to yr. As such, results were averaged over yr as most producers are interested in what may be expected for an average yr instead of for a particular yr. Pasture establishment method affected ( P<0.05 ) forage concentrations of Mg in Exp. 1, and Ca and P in Exp. 2 (Table 1). Pasture forage treatment affected ( P<0.05 ) Ca, K, and Mg concentrations in Exp 2 only (Table 1).The significant differences noted above due to pasture establishment method or forage treatment, however, were small (Table 1). Year affected ( P<0.05) pasture forage P, K, and Mg concentrations within each experiment, but not Ca or Na (means not shown); Mg in particular was affected by yr. No forage treatment and pasture establishment interactions, or pasture treatment by yr interactions ( P>0.05) were noted. Month within yr affected ( P<0.05 ) pasture forage concentrations of all minerals evaluated in both experiments except Na and possibly Ca. Calcium was different in Exp.1 but not Exp. 2, an d if averaged over the two experiments, Ca was fairly constant from mo to mo 0.29 to 0.33% (Table 2). Forage concentrations of P and K were greatest during the winter and declined during spring with lowest levels noted in May; Mg was least in early spring (Table 2).There was considerable variation in forage concentrations of each mineral evaluated within experiment (Table 3). Results indicated that annual cool-season pasture forage treatment, pasture forage establishment method, and year, while not consistent between experiments, can influence pasture forage concentrations of Ca, P, K, and Mg, but have little influence on Na. Month within yr of the grazing season appeared to have the greatest influence on forage macro mineral concentrations evaluated, especially P and K. The low forage Mg, combined with high K, may be a potential deficiency problem for beef cattle which can result in grass tetany (hypomagnesaemia), especially during the early spring months. Overall mean concentrations for each experiment for each mineral measured in the pasture forages is presented in Table 3. From the results of both experiments, concentrations in annual cool-season pasture forage averaged (mean one standard deviation; dry matter basis) 0.31 0.05% for Ca, 0.38 0.04% for P, 0.04 0.01% for Na, 2.9 0.3% for K, and 0.21 0.03% for Mg. The concentrations of Ca, P, and Mg are at the low end of concentration ranges previously reported, K at the high end, and Na in the middle (Table 3). However, it should be emphasized that much variation in concentration was noted for each mineral analyzed, especially for Mg (Table 3). Overall, for beef cattle grazing cool-season annual grass pastures evaluated in this study, forage Na would be very deficient; Ca slightly deficient, P and Mg marginally deficient, and K would be in excess (Table 3).

PAGE 4

Literature Cited Chelliah, G., et al. 2009 Florida Beef Report. Ensminger M. E., et al. 1990. Feeds and Nutrition. The Ensminger Publishing Co., Clovis, CA, USA. pp 1265 1511. Myer, R. O., and A. R. Blount. 2005 Florida Beef Report. pp 19 24. Myer, B., and A. Blount. 2007 Florida Beef Report. pp 23 27. USA. Acknowledgment The assistance of Harvey Standland, John Crawfo rd, Meghan Brennan, Mary Maddox, Mary Chambliss, Tina Gwin, Jeff Jones and the staff at the NFREC Beef Unit is gratefully acknowledged. Partial support was provided by Orange Hill Soil Conservation District, Chipley, FL. 1 G. Chelliah, Former Graduate Student; Bob Myer, Professor, UF IFAS, North Florida Research and Education Center (NFREC), Marianna, FL; Jeff Carter, Former Assistant Professor, UF IFAS, NFREC, Marianna; Lee McDowell, Professor Emeritus, UF IFAS, Department of Animal Sciences, Gainesville, FL, Nancy Wilkinson, Chemist, UF IFAS, Department of Animal Sciences, Gainesville, Fl; and Ann Blount, Associate Professor, UF IFAS, NFREC, Marianna, FL.

PAGE 5

Table 1 Main means of macro mineral concentrations of annual cool season pasture forages during the late fall winter spring grazing season in north Florida (% of dry matter). Cultivation Forage Trt. Significance g Mineral Exp. a SS b PS c Simple d Blend e SEM f Cult. h Forage i CxF j Ca 1 0.33 0.33 0.30 0.32 0.01 NS NS NS 2 0.34 0.28 0.35 0.27 0.02 * NS P 1 0.40 0.43 0.42 0.41 0.01 NS NS NS 2 0.34 0.36 0.35 0.34 0.01 NS NS Na 1 0.03 0.03 0.03 0.03 0.002 NS NS NS 2 0.04 0.04 0.04 0.04 0.001 NS NS NS K 1 3.2 3.3 3.2 3.3 0.06 NS NS NS 2 2.7 2.6 2.7 2.5 0.04 NS NS Mg 1 0.23 0.28 0.26 0.25 0.01 NS NS 2 0.17 0.16 0.18 0.15 0.01 NS NS a Exp. 1, 2001 2002 and 2002 2003 grazing seasons; and Exp. 2, 2003 2004 and 2004 2005. b SS = sod seeded pastures c PS = prepared seedbed (clean tilled) pastures. d Simple = mono culture or simple blend of forage species in pastures (Exp. 1, small grains rye and oats; Exp. 2, ryegrass). e Blend of forage species in pastures (Exp. 1, small grains plus ryegrass; Exp. 2, oats plus ryegrass). f Standard error of the mean; n = 8. g Significance of difference; = significantly different ( P<0.05 ), and NS = non significant ( P>0.05 ). h Pasture establ ishment method (SS vs. PS). i Pasture forage type or treatment (simple vs. blend). j Establishment method by forage treatment interaction.

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Table 2 Monthly concentrations of macro minerals in annual cool season pasture forages during the late fall winter spring grazing seasons in north Florida (% of dry matter). Sampling month Mineral Exp. a Nov Dec Jan Feb Mar Apr May SEM b Significance c Ca 1 0.37 0.37 0.33 0.31 0.30 0.33 0.31 0.02 2 0.25 0.26 0.26 0.26 0.30 0.33 0.30 0.04 NS P 1 0.43 0.43 0.47 0.44 0.43 0.38 0.32 0.02 ** 2 0.44 0.44 0.32 0.34 0.34 0.36 0.36 0.02 ** Na 1 0.04 0.03 0.03 0.03 0.03 0.04 0.04 0.003 NS 2 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.004 NS K 1 3.8 4.2 3.8 3.3 3.3 3.1 2.3 0.2 ** 2 3.8 4.2 3.2 3.0 3.0 2.6 2.2 0.2 ** Mg 1 0.31 0.29 0.28 0.25 0.24 0.27 0.27 0.02 2 0.18 0.16 0.14 0.14 0.16 0.17 0.16 0.01 ** a Exp. 1, 2001 2002 and 2002 2003 grazing seasons; and Exp. 2, 2003 2004 and 2004 2005. b Standard error of the mean; average n = 8 (varied from 4 (Nov) to 16 (Feb, Mar, Apr) within experiment). c Significance due to month within experiment: ** = highly significant ( P<0.01 ), = significant ( P<0.05 ), and NS = non significant ( P>0.05 ). Table 3 Overall means and ranges of macro mineral concentrations of annual cool season grass pasture forages from each experiment (% of dry matter). Mineral Exp. a Mean b 1 S.D. c Range d Requirement e Reported f Ca 1 0.31 0.04 0.25 to 0.44 0.5 0.32 to 0.65 2 0.31 0.06 0.10 to 0.46 P 1 0.42 0.04 0.28 to 0.54 0.3 0.23 to 0.41 2 0.35 0.03 0.27 to 0.52 Na 1 0.03 0.01 0.02 to 0.05 0.1 0.01 to 0.11 2 0.04 0.01 0.02 to 0.05 K 1 3.2 0.3 2.0 to 5.4 0.6 1.7 to 3.4 2 2.6 0.2 2.0 to 4.3 Mg 1 0.26 0.03 0.18 to 0.42 0.1 0.20 to 0.35 2 0.16 0.02 0.11 to 0.22 a Exp. 1, 2001 2002 and 2002 2003 grazing seasons; and Exp. 2, 2003 2004 and 2004 2005. b Overall mean across all treatments (n = 16). c One standard deviation. d Lowest or highest monthly concentration obtained from a treatment within year within experiment (n = 2). e Suggested requirement for growing beef cattle heifers (500 to 900 lb; NRC 2000). f Other reported concentrations for rye, oats and ryegrass fres h forage (dry matter basis); data from Ensminger et al., 1990, and NRC, 2000.