Sixty head of crossbred heifers (614 lb initial BW) were individually fed one of five levels of phosphorus of 0.10, 0.17, 0.24, 0.31, 0.38 % of diet DM with supplemental P from monosodium phosphate. Heifers were fed an energy-dense diet composed primarily of corn starch and corn fiber to minimize P from corn. When compared to the other four levels, heifers fed at the 0.10 % P level had lower DMI, ADG and final BW. Heifers fed 0.10%P had lower plasma P concentration. Breakpoint analysis of ADG suggests that the P requirement for finishing heifers is 0.115% P of diet DM within the range of 8.2 to 10.3g P/day (0.104 and 0.127% P on a DM basis)

Erickson, Galen E.

Geisert, Bobbi Gene

Klopfenstein, Terry J.

Macken, Casey N.

English

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 2004 
Phosphorus Requirement for Finishing Heifers 
Bobbi Gene Geisert 
University of Nebraska-Lincoln 
Galen E. Erickson 
University of Nebraska-Lincoln, gerickson4@unl.edu 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
Casey N. Macken 
University of Nebraska-Lincoln 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Geisert, Bobbi Gene; Erickson, Galen E.; Klopfenstein, Terry J.; and Macken, Casey N., "Phosphorus 
Requirement for Finishing Heifers" (2004). Nebraska Beef Cattle Reports. 192. 
https://digitalcommons.unl.edu/animalscinbcr/192 
This Article is brought to you for free and open access by the Animal Science Department at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle 
Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
Page 49 — 2004 Nebraska Beef Report
Phosphorus Requirement for Finishing Heifers
Procedure
The experiment used 60 cross-
bred, large framed heifers (initial
BW= 614 lb). Two heifers were
taken off of the trial due to preg-
nancy. Heifers were fed individu-
ally using Calan gates from Nov.
14, 2002 to May 15, 2003 (180 days).
Heifers were stratified by weight
and assigned randomly to one of
five treatments. The treatments con-
sisted of five different P levels of
0.10, 0.17, 0.24, 0.31, 0.38 % of DM.
The five P levels were achieved by
feeding one base diet (0.10 % P) and
top dressing mono-sodium phos-
phate at feeding. The diet consisted
of 50% coarse brewers grits, 15%
high moisture corn, 15% corn bran,
10% sorghum silage, 5% tallow,
and 5% supplement. Limestone
was fed at 1.4% of diet DM to meet
the Ca requirement. In order to for-
mulate a diet low in P, coarse brew-
ers grits (0.05% P DM basis)
replaced corn (0.30% P DM basis).
The diet was balanced to 12.5% CP,
and it also contained 28 g/ton DM
Rumensin, 10g/ton DM Tylan, and
.46 mg/head/day MGA. Heifers
were adapted to treatment diets by
limiting intake at 1.5% of BW and
increasing 0.5 lb/day until ad
libitum intakes were achieved
(approximately 21 days). They were
implanted on day 1 with Revalor
IH and re-implanted with Revalor
200 on day 84.
Heifers were weighed three con-
secutive days following a 5-day
limit feeding period and averaged
for initial BW. Samples of blood
also were collected on day 0 and ev-
ery 28 days throughout the feeding
period. Blood was collected in the
morning, prior to feeding, in 10 ml (Continued on next page)
Bobbi Gene Geisert
Galen E. Erickson
Terry J. Klopfenstein
Casey N. Macken1
Summary
Sixty head of crossbred heifers (614
lb initial BW) were individually fed
one of five levels of phosphorus of
0.10, 0.17, 0.24, 0.31, 0.38 % of diet
DM with supplemental P from mono-
sodium phosphate. Heifers were fed an
energy-dense diet composed primarily
of corn starch and corn fiber to mini-
mize P from corn. When compared to
the other four levels, heifers fed at the
0.10 % P level had lower DMI, ADG
and final BW. Heifers fed 0.10%P had
lower plasma P concentration. Break-
point analysis of ADG suggests that
the P requirement for finishing heifers
is 0.115% P of diet DM within the
range of 8.2 to 10.3g P/day (0.104 and
0.127% P on a DM basis).
Introduction
Current recommendations on
the P requirement may be over-
estimated for finishing cattle. Pre-
vious research suggests the P
requirement for yearling steers is
less than 0.14% (DM basis; 1996
Nebraska Beef Report, pp. 78-80),
and steer calves is less than 0.16%
(DM basis; 2002 Nebraska Beef
Report, pp. 45-48). In both experi-
ments, P requirements were not
determined because performance
was similar across all levels of P
fed. The objective of our experiment
was to determine the P requirement
for calf-fed heifers.
vacutainers containing sodium
heparin. Samples were centrifuged
at 2500 RPM for 15 minutes.
Plasma was removed from the top
of the sample. Plasma was trans-
ferred into 2 ml conicles then frozen
at -20 degrees C for later analysis.
Plasma was analyzed using a com-
mercial kit (Diagnostic Chemicals
Limited) for plasma P concentra-
tion.
Final weights were calculated
from hot carcass weight using a
common dressing percentage of 62.
After a 24 hour chill 12th rib fat
thickness and marbling scores were
taken.
Results
Performance
Heifer performance data are
shown in Table 1. Significant qua-
dratic (P<0.01) effects were present
for DMI and ADG. Cattle on treat-
ments 0.10 and 0.38 had lower DMI
and consequently lower ADG com-
pared to cattle on the 0.17, 0.24, and
0.31 treatments. This indicates that
the heifers on the 0.10 treatment
were experiencing a P deficiency.
There were no significant qua-
dratic or linear effects in feed con-
version, despite differences in DMI
and ADG. No differences were
found in marbling score or 12th rib
fat thickness; however, heifers fed
0.10% P had numerically lower
marbling scores (linear effect:
P=0.10).
When calculated using non-
linear regression analysis for % P of
diet DM, the requirement for P was
estimated to be 0.115%, ranging
between 0.104 and 0.127% P of diet
2004 Nebraska Beef Report — Page 50
DM (Figure 1). When feed conver-
sion was plotted against P intake
(g/day), no significant differences
(P>0.05) were observed (Figure 2).
P intake was positively correlated
to ADG ( r = 0.13, P<0.01) and DMI
(r = 0.14, P<0.01). It was not corre-
lated to feed efficiency (r = 0.049,
P>.60).
Plasma P Concentration
There were no significant differ-
ences among treatments on day 0
(P>0.30), indicating all heifers were
at the same plasma P concentration
of 7.12mg/dL. A significant treat-
ment by time interaction (P<0.10)
occurred because the heifers fed
0.10% P had lower concentrations
from day 28 to market (Figure 3).
The heifers on the 0.10% P treat-
ment were different from the other 4
treatments on day 28 to slaughter
time (P<0.10). Heifers on the 0.10%
P treatments had an initial plasma
concentration of 6.98 mg/dL.
Plasma P concentrations for heifers
fed 0.10% P on day 28, 56, 84, 112,
140, and 180 were 4.49, 3.93, 4.82,
5.33, 4.32, and 4.18 mg/dL respec-
tively. Plasma P concentration
below 4.5 mg/dL are indicative of a
P deficiency (Minerals Levels in
Animal Health, R. Puls, p. 167).
These results indicate heifers on the
0.10 treatment were P deficient. The
plasma P concentration of cattle on
Table 1. Performance data for heifers consuming different levels of P.
P Intake (% of DM) P- value
0.10 0.17 0.24 0.31 0.38 SEM Linear Quadratic
P Intake 7.40 14.2 20.5 25.9 29.6 0.71 <.01 <.01
 (g/day)
Initial BW (lb) 619 613 616 617 612 12.0 0.77 0.98
Final BW (lb) 1086 1167 1163 1158 1114 24.00 0.52 <.001
DMI (lb/day) 16.2 18.3 18.7 18.3 17.0 0.60 0.38 <.01
ADG (lb/day) 2.58 3.06 3.03 2.99 2.78 0.09 0.26 <.01
F:G 6.24 5.94 6.15 6.10 6.13 0.12 0.85 0.35
HCWc 674 723 721 718 691 14.8 0.52 <.01
Marblinga 486 565 529 546 554 22.4 0.10 0.28
12th Ribb 0.35 0.38 0.42 0.34 0.39 0.03 0.76 0.42
aMarbling Scores: 400=Slight, 500=Small, 600 =Modest .
b12th Rib: Back fat thickness at the 12th rib measured in inches.
CHCW: Calculated hot carcass weight using a common dressing percent of 62, measured in pounds.
Figure 1. Non-linear effect of P% of diet DM on ADG of heifers. Breakpoint
determined at 0.115% P (0.104 to 0.127% P). Solid line is the breakpoint
(0.115% P) with the dashed line as the 95% confidence interval (0.104 to
0.127% P). Maximum ADG was 2.96 lb/day and the points represent ADG
over entire 180 days for 58 heifers.
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
A
D
G
, 
lb
/
d
ay
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
P, % of diet DM
8.00
6.00
4.00
2.00
0.00
FG
0.0  5.0 10.0  15.0  20.0  25.0  30.0   35.0   40.0
P Intake (g/day)
y = 0.0035x + 6.0419
R2 = 0.0005
Figure 2. Scatter plot of feed conversion of heifers fed different levels of P for 180
days.
Page 51 — 2004 Nebraska Beef Report
the 0.17% treatment on day 28, 56,
84, 112, 140, and 180 were 6.52,
6.42, 6.61, 6.91, and 6.90, respec-
tively, indicating that they were not
experiencing a P deficiency. The
other treatments stayed at approxi-
mately 7.07 mg/dL throughout the
entire feeding period. There were no
significant differences within the
other four P levels over time
(P>0.05)
Previous research indicates
cattle can tolerate Ca:P ratios of 1:1
to 7:1. The Ca level in these diets
was set at 0.70% of diet DM. The
Ca:P ratios for these diets ranged
form 1.8:1 to 7:1, suggesting the
Ca:P ratio did not effect DMI and
ADG. The performance and plasma
P concentration results indicate the
P requirement for finishing heifers
is between 8.2 and 10.3 g/day, or
0.10 and 0.17% P of diet DM. This is
supported by results from Erickson
et. al (2002 Nebraska Beef Report,
pp. 45-48), which indicated the P
requirement for calf-fed steers was
below 0.16% P of diet DM. There
were no differences in steer perfor-
mance in their study. However,
steers on the 0.16% P treatment did
have significantly lower plasma P
Figure 3. Plasma P concentration of heifers fed different levels of P. Significant treatment by time interaction (P<0.01).
9
8
7
6
5
4
3
2
1
0
P
la
sm
a 
P
, 
m
g/
d
L
% P in Diets
0.10
0.17
0.24
0.31
0.38
0 28 56 84 112 140 168 196
Days on Feed
concentrations (4.6 mg/dL) on day
56. However, by day 112 the blood
plasma concentrations raised to
above 5.5 mg/dL for the remainder
of the trial. The results of our trials
indicate corn-based finishing
rations supply adequate P levels for
finishing cattle and P supplementa-
tion is unnecessary.
1Bobbi Gene Geisert, graduate
student, Galen E. Erickson, assistant
professor, Terry J. Klopfenstein, professor,
Casey N. Macken, research technician,
Animal Science, Lincoln.


Phosphorus Requirement for Finishing Heifers

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2004 Phosphorus Requirement for Finishing Heifers Bobbi Gene Geisert University of Nebraska-Lincoln Galen E. Erickson University of Nebraska-Lincoln, gerickson4@unl.edu Terry J. Klopfenstein University of Nebraska-Lincoln, tklopfenstein1@unl.edu Casey N. Macken University of Nebraska-Lincoln Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Geisert, Bobbi Gene; Erickson, Galen E.; Klopfenstein, Terry J.; and Macken, Casey N., "Phosphorus Requirement for Finishing Heifers" (2004). Nebraska Beef Cattle Reports. 192. https://digitalcommons.unl.edu/animalscinbcr/192 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Page 49 — 2004 Nebraska Beef ReportPhosphorus Requirement for Finishing HeifersProcedureThe experiment used 60 cross-bred, large framed heifers (initialBW= 614 lb). Two heifers weretaken off of the trial due to preg-nancy. Heifers were fed individu-ally using Calan gates from Nov.14, 2002 to May 15, 2003 (180 days).Heifers were stratified by weightand assigned randomly to one offive treatments. The treatments con-sisted of five different P levels of0.10, 0.17, 0.24, 0.31, 0.38 % of DM.The five P levels were achieved byfeeding one base diet (0.10 % P) andtop dressing mono-sodium phos-phate at feeding. The diet consistedof 50% coarse brewers grits, 15%high moisture corn, 15% corn bran,10% sorghum silage, 5% tallow,and 5% supplement. Limestonewas fed at 1.4% of diet DM to meetthe Ca requirement. In order to for-mulate a diet low in P, coarse brew-ers grits (0.05% P DM basis)replaced corn (0.30% P DM basis).The diet was balanced to 12.5% CP,and it also contained 28 g/ton DMRumensin, 10g/ton DM Tylan, and.46 mg/head/day MGA. Heiferswere adapted to treatment diets bylimiting intake at 1.5% of BW andincreasing 0.5 lb/day until adlibitum intakes were achieved(approximately 21 days). They wereimplanted on day 1 with RevalorIH and re-implanted with Revalor200 on day 84.Heifers were weighed three con-secutive days following a 5-daylimit feeding period and averagedfor initial BW. Samples of bloodalso were collected on day 0 and ev-ery 28 days throughout the feedingperiod. Blood was collected in themorning, prior to feeding, in 10 ml (Continued on next page)Bobbi Gene GeisertGalen E. EricksonTerry J. KlopfensteinCasey N. Macken1SummarySixty head of crossbred heifers (614lb initial BW) were individually fedone of five levels of phosphorus of0.10, 0.17, 0.24, 0.31, 0.38 % of dietDM with supplemental P from mono-sodium phosphate. Heifers were fed anenergy-dense diet composed primarilyof corn starch and corn fiber to mini-mize P from corn. When compared tothe other four levels, heifers fed at the0.10 % P level had lower DMI, ADGand final BW. Heifers fed 0.10%P hadlower plasma P concentration. Break-point analysis of ADG suggests thatthe P requirement for finishing heifersis 0.115% P of diet DM within therange of 8.2 to 10.3g P/day (0.104 and0.127% P on a DM basis).IntroductionCurrent recommendations onthe P requirement may be over-estimated for finishing cattle. Pre-vious research suggests the Prequirement for yearling steers isless than 0.14% (DM basis; 1996Nebraska Beef Report, pp. 78-80),and steer calves is less than 0.16%(DM basis; 2002 Nebraska BeefReport, pp. 45-48). In both experi-ments, P requirements were notdetermined because performancewas similar across all levels of Pfed. The objective of our experimentwas to determine the P requirementfor calf-fed heifers.vacutainers containing sodiumheparin. Samples were centrifugedat 2500 RPM for 15 minutes.Plasma was removed from the topof the sample. Plasma was trans-ferred into 2 ml conicles then frozenat -20 degrees C for later analysis.Plasma was analyzed using a com-mercial kit (Diagnostic ChemicalsLimited) for plasma P concentra-tion.Final weights were calculatedfrom hot carcass weight using acommon dressing percentage of 62.After a 24 hour chill 12th rib fatthickness and marbling scores weretaken.ResultsPerformanceHeifer performance data areshown in Table 1. Significant qua-dratic (P<0.01) effects were presentfor DMI and ADG. Cattle on treat-ments 0.10 and 0.38 had lower DMIand consequently lower ADG com-pared to cattle on the 0.17, 0.24, and0.31 treatments. This indicates thatthe heifers on the 0.10 treatmentwere experiencing a P deficiency.There were no significant qua-dratic or linear effects in feed con-version, despite differences in DMIand ADG. No differences werefound in marbling score or 12th ribfat thickness; however, heifers fed0.10% P had numerically lowermarbling scores (linear effect:P=0.10).When calculated using non-linear regression analysis for % P ofdiet DM, the requirement for P wasestimated to be 0.115%, rangingbetween 0.104 and 0.127% P of diet2004 Nebraska Beef Report — Page 50DM (Figure 1). When feed conver-sion was plotted against P intake(g/day), no significant differences(P>0.05) were observed (Figure 2).P intake was positively correlatedto ADG ( r = 0.13, P<0.01) and DMI(r = 0.14, P<0.01). It was not corre-lated to feed efficiency (r = 0.049,P>.60).Plasma P ConcentrationThere were no significant differ-ences among treatments on day 0(P>0.30), indicating all heifers wereat the same plasma P concentrationof 7.12mg/dL. A significant treat-ment by time interaction (P<0.10)occurred because the heifers fed0.10% P had lower concentrationsfrom day 28 to market (Figure 3).The heifers on the 0.10% P treat-ment were different from the other 4treatments on day 28 to slaughtertime (P<0.10). Heifers on the 0.10%P treatments had an initial plasmaconcentration of 6.98 mg/dL.Plasma P concentrations for heifersfed 0.10% P on day 28, 56, 84, 112,140, and 180 were 4.49, 3.93, 4.82,5.33, 4.32, and 4.18 mg/dL respec-tively. Plasma P concentrationbelow 4.5 mg/dL are indicative of aP deficiency (Minerals Levels inAnimal Health, R. Puls, p. 167).These results indicate heifers on the0.10 treatment were P deficient. Theplasma P concentration of cattle onTable 1. Performance data for heifers consuming different levels of P.P Intake (% of DM) P- value0.10 0.17 0.24 0.31 0.38 SEM Linear QuadraticP Intake 7.40 14.2 20.5 25.9 29.6 0.71 <.01 <.01 (g/day)Initial BW (lb) 619 613 616 617 612 12.0 0.77 0.98Final BW (lb) 1086 1167 1163 1158 1114 24.00 0.52 <.001DMI (lb/day) 16.2 18.3 18.7 18.3 17.0 0.60 0.38 <.01ADG (lb/day) 2.58 3.06 3.03 2.99 2.78 0.09 0.26 <.01F:G 6.24 5.94 6.15 6.10 6.13 0.12 0.85 0.35HCWc 674 723 721 718 691 14.8 0.52 <.01Marblinga 486 565 529 546 554 22.4 0.10 0.2812th Ribb 0.35 0.38 0.42 0.34 0.39 0.03 0.76 0.42aMarbling Scores: 400=Slight, 500=Small, 600 =Modest .b12th Rib: Back fat thickness at the 12th rib measured in inches.CHCW: Calculated hot carcass weight using a common dressing percent of 62, measured in pounds.Figure 1. Non-linear effect of P% of diet DM on ADG of heifers. Breakpointdetermined at 0.115% P (0.104 to 0.127% P). Solid line is the breakpoint(0.115% P) with the dashed line as the 95% confidence interval (0.104 to0.127% P). Maximum ADG was 2.96 lb/day and the points represent ADGover entire 180 days for 58 heifers.4.003.503.002.502.001.501.000.500.00ADG, lb/day0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40P, % of diet DM8.006.004.002.000.00FG0.0  5.0 10.0  15.0  20.0  25.0  30.0   35.0   40.0P Intake (g/day)y = 0.0035x + 6.0419R2 = 0.0005Figure 2. Scatter plot of feed conversion of heifers fed different levels of P for 180days.Page 51 — 2004 Nebraska Beef Reportthe 0.17% treatment on day 28, 56,84, 112, 140, and 180 were 6.52,6.42, 6.61, 6.91, and 6.90, respec-tively, indicating that they were notexperiencing a P deficiency. Theother treatments stayed at approxi-mately 7.07 mg/dL throughout theentire feeding period. There were nosignificant differences within theother four P levels over time(P>0.05)Previous research indicatescattle can tolerate Ca:P ratios of 1:1to 7:1. The Ca level in these dietswas set at 0.70% of diet DM. TheCa:P ratios for these diets rangedform 1.8:1 to 7:1, suggesting theCa:P ratio did not effect DMI andADG. The performance and plasmaP concentration results indicate theP requirement for finishing heifersis between 8.2 and 10.3 g/day, or0.10 and 0.17% P of diet DM. This issupported by results from Ericksonet. al (2002 Nebraska Beef Report,pp. 45-48), which indicated the Prequirement for calf-fed steers wasbelow 0.16% P of diet DM. Therewere no differences in steer perfor-mance in their study. However,steers on the 0.16% P treatment didhave significantly lower plasma PFigure 3. Plasma P concentration of heifers fed different levels of P. Significant treatment by time interaction (P<0.01).9876543210Plasma P, mg/dL% P in Diets0.100.170.240.310.380 28 56 84 112 140 168 196Days on Feedconcentrations (4.6 mg/dL) on day56. However, by day 112 the bloodplasma concentrations raised toabove 5.5 mg/dL for the remainderof the trial. The results of our trialsindicate corn-based finishingrations supply adequate P levels forfinishing cattle and P supplementa-tion is unnecessary.1Bobbi Gene Geisert, graduatestudent, Galen E. Erickson, assistantprofessor, Terry J. Klopfenstein, professor,Casey N. Macken, research technician,Animal Science, Lincoln.

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Phosphorus Requirement for Finishing Heifers

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