Mineral retention was measured in 76 beef steers. Cattle were grown at different rates of gain and then finished on a common diet. Calcium and P retention were not affected by treatment and were similar between the growing and finishing periods averaging 4.2 g P and 10.8 g Ca /100 g protein gain across both experiments. As ADG during the growing period was decreased, K, Mg, and S mineral retention during the finishing period were increased. Expressing mineral retention as g/100 g protein gain reducedvariation due to animal size and ADG and suggests that current NRC predictions are accurate

Erickson, Galen E.

Hales, Kristin E.

Harding, Jana L.

Hersom, Matt J.

Krehbiel, Clint R.

McCurdy, Matt P., Curdy

Watson, Andrea K.

English

UNL | Libraries

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Nebraska Beef Cattle Reports Animal Science Department
2015
Mineral Composition of Beef Cattle Carcasses
Andrea K. Watson
University of Nebraska-Lincoln, awatson3@unl.edu
Jana L. Harding
University of Nebraska-Lincoln
Matt P. McCurdy Curdy
University of Nebraska-Lincoln
Matt J. Hersom
University of Nebraska-Lincoln
Kristin E. Hales
University of Nebraska-Lincoln, kristin.hales@ars.usda.gov
See next page for additional authors
Follow this and additional works at: http://digitalcommons.unl.edu/animalscinbcr
Part of the Large or Food Animal and Equine Medicine Commons, Meat Science Commons, and
the Veterinary Preventive Medicine, Epidemiology, and Public Health Commons
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.
Watson, Andrea K.; Harding, Jana L.; McCurdy, Matt P. Curdy; Hersom, Matt J.; Hales, Kristin E.; Krehbiel, Clint R.; and Erickson,
Galen E., "Mineral Composition of Beef Cattle Carcasses" (2015). Nebraska Beef Cattle Reports. 808.
http://digitalcommons.unl.edu/animalscinbcr/808
Authors
Andrea K. Watson, Jana L. Harding, Matt P. McCurdy Curdy, Matt J. Hersom, Kristin E. Hales, Clint R.
Krehbiel, and Galen E. Erickson
This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/animalscinbcr/808
Page 108 — 2015 Nebraska Beef Cattle Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
Mineral Composition of Beef Cattle Carcasses
Andrea K. Watson
Jana L. Harding
Matt P. McCurdy
Matt J. Hersom
Kristin E. Hales
Clint R. Krehbiel
Galen E. Erickson1
Summary
Mineral retention was measured in 
76 beef steers. Cattle were grown at dif-
ferent rates of gain and then finished on 
a common diet. Calcium and P reten-
tion were not affected by treatment and 
were similar between the growing and 
finishing periods averaging 4.2 g P and 
10.8 g Ca /100 g protein gain across both 
experiments. As ADG during the grow-
ing period was decreased, K, Mg, and 
S mineral retention during the finish-
ing period were increased. Expressing 
mineral retention as g/100 g protein 
gain reduced variation due to animal 
size and ADG and suggests that current 
NRC predictions are accurate.
Introduction
Mineral requirements for growing 
beef cattle are not well understood, 
one component of which is require-
ments for gain. Very few carcasses 
have been analyzed to determine 
mineral retention, with Ca and P 
being the most commonly analyzed 
minerals. Other minerals such as K, 
Mg, and S are very rarely measured 
or reported in serial slaughter trials. 
Retention of minerals is important 
in order to identify mineral require-
ments at different rates of gain, in 
addition to maintenance require-
ments. Retention is also used to cal-
culate mineral excretion values, with 
excretion being predicted from the 
difference between intake and reten-
tion. Developing better estimates of 
mineral retention allows for better 
estimates of manure nutrient values, 
and thus better recommendations 
for manure application rates. This 
trial utilized existing serial slaughter 
samples in order to calculate mineral 
retention of beef cattle harvested at 
various time points and grown in 
several different production systems. 
Procedure
Seventy-six beef cattle were slaugh-
tered at Oklahoma State University, 
and whole carcasses were divided 
into carcass, offal, and viscera. These 
samples were ground and frozen and 
then analyzed for Ca, P, K, Mg, and S 
by Ward Laboratory (Kearney, Neb.). 
Sample analysis included acid diges-
tion of all organic matter, followed 
by mineral analysis using Inductively 
Coupled Plasma-Atomic Emission 
Spectroscopy. Total offal included 
blood, head, hide, feet, ears, internal 
organs, and trim. Visceral organs 
included reticulo-rumen, omasum, 
abomasum, small intestine, cecum, 
large intestine, pancreas, spleen, 
omental and mesenteric fat. Weights 
of total carcass, visceral organs, and 
offal were recorded. Cattle were on 
two separate experiments and were 
harvested at various time points after 
being grown in several different pro-
duction systems. 
Experiment (Exp.) 1 (Journal of 
Animal Science, 82:262) utilized 30 
British crossbred steers wintered at 
three different levels of gain and then 
finished on a common diet. Cattle 
grazed wheat pasture to gain 2.89 
lb/day (high gain wheat; HGW) or 
1.19 lb/day (low gain wheat; LGW), 
or grazed dormant native range 
supplemented with 2 lb of cottonseed 
meal each day and gaining 0.35 lb/
day (native range; NR). At the end of 
the winter grazing season, four steers 
were slaughtered from each treat-
ment group. The remaining steers 
were placed on a common finishing 
diet and six additional steers from 
each treatment were slaughtered at 
approximately 0.6 inches of backfat. 
Cattle from HGW reached 0.6 inches 
of backfat after 89 days on feed, LGW 
cattle after 116 days on feed, and NR 
cattle after 163 days on feed. Cattle 
performance during the growing and 
finishing phases is shown in Table 1; 
live performance measurements were 
taken on 48 steers, including the 30 
steers used for serial slaughter. 
Experiment 2 (Journal of Animal 
Science 88:1564) utilized 46 British 
crossbred steers grown at different 
rates and on different diets. Four 
steers were slaughtered at initiation of 
the trial to determine initial carcass 
composition. Remaining cattle were 
split between calf-feds placed directly 
into the feedlot (CF) and three grow-
ing treatments: grazing wheat pasture 
Table 1. Cattle performance during the growing and finishing phases of Experiment 11.
HGW2 LGW NR SEM P-value
Growing phase
 Days
 ADG, lb
 12th-rib fat, in
 HCW, lb
120
2.89
0.46a
522a
120
1.19
0.10b
381b
120
0.35
0.004b
302c
 —
 —
0.04
10.8
 —
 —
< 0.05
< 0.05
Finishing phase
 Days
 ADG, lb
 12th-rib fat, in
 HCW, lb
89
3.94
0.64
754a
116
3.97
0.62
701b
163
4.01
0.59
725ab
 —
0.13
0.07
8.2
 —
0.43
> 0.05
< 0.05
1All data measuring cattle performance collected by Oklahoma State University and published in 
Journal of Animal Science, 82:262.
2Treatments were due to diet fed during the growing phase and included cattle grazing wheat pasture at 
a high rate of gain (HGW), cattle grazing wheat pasture at a low rate of gain (LGW), and cattle grazing 
dormant native range pasture (NR). All cattle were finished on a common diet.
a-cMeans within a row without a common superscript differ (P < 0.05). 
© The Board of Regents of the University of Nebraska.  All rights reserved. 2015 Nebraska Beef Cattle Report  — Page 109 
Mineral retention within the 
body was calculated as the differ-
ence between mineral composition 
at slaughter and predicted mineral 
composition at day 0. Mineral com-
position at day 0 was predicted from 
body composition of steers harvested 
at day 0 multiplied by live weight of 
individual animals at day 0. For Exp. 
1, mineral retention was calculated 
for each treatment during the finish-
ing period. In Exp. 2, mineral reten-
tion was calculated for the growing 
and finishing periods separately for 
each treatment except CF, which only 
consisted of a finishing period. Min-
eral retention was then expressed as 
grams per day, grams per kg empty 
body weight (EBW) gain, and grams 
per 100 g protein gain. In live animals 
EBW is calculated as full BW mul-
tiplied by 0.855; however, for these 
trials EBW was measured by weighing 
the whole carcass after the contents 
of the gastrointestinal tract had been 
removed. 
For statistical analysis in Exp. 
1, mineral retention among treat-
ments was compared with individual 
animal as the experimental unit. In 
Exp. 2, mineral retention within the 
growing phase, within the finishing 
phase, and overall mineral retention 
were compared by treatment using an 
F-test with individual animal as the 
experimental unit. Because all com-
parisons within each of the phases 
were non-significant (P ≥ 0.19) only 
mineral retention for the growing and 
finishing phases combined is shown. 
Mineral retention within the growing 
phase was also compared to retention 
during the finishing phase, but was 
found to be non-significant (P ≥ 0.28). 
For both trials all differences were 
declared significant at P < 0.05.
Results
The NRC currently expresses P and 
Ca retention as g/100 g protein gain. 
In the current trials, expressing min-
eral retention on a protein gain basis 
reduced variation due to diet, rate of 
gain, and days on feed. 
Table 2.  Cattle performance during the growing and finishing phases of Experiment 21.
WP2 SF PF CF SEM P-value
Growing phase
 Days
 ADG, lb
 12th-rib fat, in
 HCW, lb
112
2.54a
0.17
489ab
112
2.43b
0.20
467a
112
2.60a
0.23
522b
 —
 —
 —
 —
 —
0.04
0.03
17.2
 —
0.01
0.32
0.10
Finishing phase
 Days
 ADG, lb
 12th-rib fat, in
 HCW, lb
123
3.62a
0.53a
851
104
4.45b
0.50a
836
104
4.08c
0.49a
829
196
3.59a
0.64b
818
 —
0.09
0.019
9.7
 —
< 0.01
< 0.01
0.12
1All data measuring cattle performance collected by Oklahoma State University and published in 
Journal of Animal Science, 88:1564.
2Treatments were due to diet fed during the growing phase and included grazing wheat pasture (WP), 
a sorghum silage based diet (SF), program fed a high concentrate diet (PF), or placed directly into the 
feedlot as calf-feds (CF). All cattle were finished on a common diet.
a-cMeans within a row without a common superscript differ (P < 0.05). 
Table 3.  Mineral retention within the empty body of beef cattle during the finishing phase while on 
a common high concentrate diet (Experiment 1).
HGW1 LGW NR SEM P-value
Calcium
 g/day
 g/kg EBW gain
 g/100 g protein gain
31.8
17.1
9.8
58.9
30.4
17.3
24.6
14.9
13.1
15.38
8.06
6.06
0.09
0.15
0.48
Phosphorus
 g/day
 g/kg EBW gain
 g/100 g protein gain
14.8
8.0
4.1
9.8
5.0
3.2
10.2
6.2
5.1
2.70
1.48
1.32
0.15
0.17
0.39
Potassium
 g/day
 g/kg EBW gain
 g/100 g protein gain
1.6b
0.9b
0.5b
4.9a
2.5a
1.4ab
5.2a
3.2a
2.9a
0.821
0.494
0.746
< 0.01
< 0.01
0.02
Magnesium
 g/day
 g/kg EBW gain
 g/100 g protein gain
-0.2b
-0.1b
-0.1b
1.3a
0.7a
0.4a
0.7a
0.5a
0.4a
0.330
0.176
0.141
< 0.01
< 0.01
0.01
Sulfur
 g/day
 g/kg EBW gain
 g/100 g protein gain
1.2b
0.6b
0.3b
4.1a
2.1a
1.2a
3.6a
2.2a
1.9a
0.546
0.308
0.365
< 0.01
< 0.01
< 0.01
1Treatments were due to diet fed during the growing phase and included cattle grazing wheat pasture at 
a high rate of gain (HGW), cattle grazing wheat pasture at a low rate of gain (LGW), and cattle grazing 
dormant native range pasture (NR). All cattle were finished on a common diet; mineral retention was 
calculated for the finishing phase. 
a-cMeans within a row without a common superscript differ (P < 0.05). 
(WP), fed a sorghum silage growing 
diet (SF), or program fed (PF) a high 
concentrate (steam-flaked corn) diet 
to gain at a similar rate as SF cattle. 
At the end of 112 days, six steers from 
each of the three growing diets were 
slaughtered, and remaining cattle 
were placed onto the finishing diet 
CF cattle were already on. At approxi-
mately 0.5 inches of backfat, six calves 
from each of the four treatments were 
slaughtered. Cattle on the CF treat-
ment were on feed for 196 days. After 
the 112 day growing phase, cattle on 
WP were on feed for 123 days, SF and 
PF for 104 days. Cattle performance 
during the growing and finishing 
phases is shown in Table 2; live per-
formance measurements were taken 
on 260 steers, including the 46 steers 
used for serial slaughter. 
(Continued on next page)
Page 110 — 2015 Nebraska Beef Cattle Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
Experiment 1
Mineral retention was calculated 
for the finishing period following 
three different diets being fed during 
the growing phase. There were no 
differences due to treatment for P or 
Ca retention (P ≥ 0.15 and P ≥ 0.09, 
respectively) expressed as g/day,  
g/kg EBW gain, or g/100 g protein 
gain (Table 3). Retention of P and Ca 
averaged 4.1 g P/100 g protein gain 
and 13.4 g Ca/100 g protein gain, 
respectively , over all three treatments. 
Mineral retention was significantly 
different among treatments for K, 
Mg, and S (P < 0.02) during finishing. 
Potassium, Mg, and S retention were 
greatest for NR and LGW cattle and 
least for HGW cattle. This indicates 
an increase in mineral retention dur-
ing the finishing period because diet 
quality and ADG during the growing 
period were reduced.
Experiment 2
Mineral retention was calculated 
for the growing and finishing periods 
separately for each treatment, except 
CF, which consisted only of a finishing 
period. There were no differences due 
to treatment for combined mineral 
retention in the growing and finishing 
periods and no differences between 
the growing and finishing periods  
for P (P ≥ 0.36), Ca (P ≥ 0.23), K  
(P ≥ 0.38), Mg (P ≥ 0.12), or S  
(P ≥ 0.20) retention when expressed 
as g/kg EBW gain, or g/100 g pro-
tein gain (Table 4). Retention of Mg 
was impacted by treatment when 
expressed as g/day (P = 0.05). Phos-
phorus retention over the growing 
and finishing periods combined aver-
aged 4.3 g P/100 g protein gain for all 
four treatments. Calcium, K, Mg, and 
S retention averaged 8.2, 1.3, 0.3, and 
1.1 g/100 g protein gain for all four 
treatments, respectively. Cattle were 
on different diets during the growing 
period, but small differences in ADG 
during the growing period (< 7%;  
P < 0.01) resulted in no differences in 
mineral retention due to treatment. 
Table 4.  Mineral retention within the empty body of beef cattle during the growing and finishing 
phases combined (Experiment 2).
WP1 SF PF CF SEM P-value3
Calcium2
 g/day
 g/kg EBW gain
 g/100 g protein gain
12.5
15.2
7.2
21.1
26.3
10.7
17.5
20.0
8.3
12.9
13.9
6.7
5.34
6.34
3.03
0.34
0.23
0.56
Phosphorus
 g/day
 g/kg EBW gain
 g/100 g protein gain
7.0
8.8
4.0
10.3
12.9
5.3
8.9
10.2
4.2
6.9
7.5
3.6
2.55
3.05
1.44
0.50
0.36
0.70
Potassium
 g/day
 g/kg EBW gain
 g/100 g protein gain
2.5
3.5
1.3
2.4
3.0
1.2
2.9
3.2
1.3
2.4
2.5
1.2
0.514
0.785
0.220
0.73
0.61
0.88
Magnesium
 g/day
 g/kg EBW gain
 g/100 g protein gain
0.5
0.7
0.3
0.6
0.8
0.3
0.8
0.9
0.4
0.5
0.5
0.3
0.095
0.144
0.056
0.05
0.12
0.37
Sulfur
 g/day
 g/kg EBW gain
 g/100 g protein gain
2.1
2.8
1.1
2.0
2.5
1.0
2.4
2.7
1.1
2.2
2.3
1.2
0.222
0.402
0.112
0.34
0.56
0.50
1Treatments were due to diet fed during the growing phase and included grazing wheat pasture (WP), 
a sorghum silage based diet (SF), program fed a high concentrate diet (PF), or placed directly into the 
feedlot as calf-feds (CF). All cattle were finished on a common diet.
2Mineral retention was calculated separately for the growing and finishing phases. Combined mineral 
retention for the growing and finishing phases is shown, except for the CF treatment which consisted 
only of a finishing phase. 
3P-values shown compare mineral retention of treatments for the combined growing and finishing 
phases. There were no differences in mineral retention due to treatment during the growing phase  
(P ≥ 0.19) or comparing the growing and finishing phases (P ≥ 0.28).
The current NRC (2000) reports P 
retention as 3.9 g P/100 g protein gain 
and Ca retention as 7.1 g Ca/100 g pro-
tein gain. These values are calculated 
from serial harvest data and represent 
retention within 132 dairy cattle at 
various stages of growth. Data from 
the current two trials complement 
these data, with similar overall values, 
4.2 g P/100 g protein gain and 10.8 
g Ca/100 g protein gain, suggesting 
little change in mineral retention 
within cattle or in the methods used 
to measure mineral retention. Varia-
tion among animals, measurement 
techniques, or a combination of both 
appears to be greater than variation 
due to diet as no differences were 
detected by treatment for P and Ca 
retention. Retention of other miner-
als (K, Mg, and S) can be impacted 
by diet quality and ADG during the 
growing period, as shown in Exp. 1. 
Expressing mineral retention rela-
tive to rate of gain equalizes changes 
in retention due to rate of gain and 
decreases variation due to treatment. 
These data suggest that the current 
method of expressing mineral reten-
tion as g/100 g protein gain used by 
the NRC is the most appropriate.
1Andrea K. Watson, research technician; 
Jana L. Harding, research technician, University 
of Nebraska–Lincoln (UNL) Department 
of Animal Science, Lincoln, Neb.; Matt P. 
McCurdy, former graduate student; Matt J. 
Hersom, former graduate student; Clint R. 
Krehbiel, professor, Oklahoma State University 
Department of Animal Science, Stillwater, Okla.; 
Kristin E. Hales, Meat Animal Research Center, 
Clay Center, Neb.; Galen E. Erickson, professor, 
UNL Department of Animal Science, Lincoln, 
Neb.


Mineral Composition of Beef Cattle Carcasses

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnNebraska Beef Cattle Reports Animal Science Department2015Mineral Composition of Beef Cattle CarcassesAndrea K. WatsonUniversity of Nebraska-Lincoln, awatson3@unl.eduJana L. HardingUniversity of Nebraska-LincolnMatt P. McCurdy CurdyUniversity of Nebraska-LincolnMatt J. HersomUniversity of Nebraska-LincolnKristin E. HalesUniversity of Nebraska-Lincoln, kristin.hales@ars.usda.govSee next page for additional authorsFollow this and additional works at: http://digitalcommons.unl.edu/animalscinbcrPart of the Large or Food Animal and Equine Medicine Commons, Meat Science Commons, andthe Veterinary Preventive Medicine, Epidemiology, and Public Health CommonsThis Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It hasbeen accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.Watson, Andrea K.; Harding, Jana L.; McCurdy, Matt P. Curdy; Hersom, Matt J.; Hales, Kristin E.; Krehbiel, Clint R.; and Erickson,Galen E., "Mineral Composition of Beef Cattle Carcasses" (2015). Nebraska Beef Cattle Reports. 808.http://digitalcommons.unl.edu/animalscinbcr/808AuthorsAndrea K. Watson, Jana L. Harding, Matt P. McCurdy Curdy, Matt J. Hersom, Kristin E. Hales, Clint R.Krehbiel, and Galen E. EricksonThis article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/animalscinbcr/808Page 108 — 2015 Nebraska Beef Cattle Report  © The Board of Regents of the University of Nebraska.  All rights reserved.Mineral Composition of Beef Cattle CarcassesAndrea K. WatsonJana L. HardingMatt P. McCurdyMatt J. HersomKristin E. HalesClint R. KrehbielGalen E. Erickson1SummaryMineral retention was measured in 76 beef steers. Cattle were grown at dif-ferent rates of gain and then finished on a common diet. Calcium and P reten-tion were not affected by treatment and were similar between the growing and finishing periods averaging 4.2 g P and 10.8 g Ca /100 g protein gain across both experiments. As ADG during the grow-ing period was decreased, K, Mg, and S mineral retention during the finish-ing period were increased. Expressing mineral retention as g/100 g protein gain reduced variation due to animal size and ADG and suggests that current NRC predictions are accurate.IntroductionMineral requirements for growing beef cattle are not well understood, one component of which is require-ments for gain. Very few carcasses have been analyzed to determine mineral retention, with Ca and P being the most commonly analyzed minerals. Other minerals such as K, Mg, and S are very rarely measured or reported in serial slaughter trials. Retention of minerals is important in order to identify mineral require-ments at different rates of gain, in addition to maintenance require-ments. Retention is also used to cal-culate mineral excretion values, with excretion being predicted from the difference between intake and reten-tion. Developing better estimates of mineral retention allows for better estimates of manure nutrient values, and thus better recommendations for manure application rates. This trial utilized existing serial slaughter samples in order to calculate mineral retention of beef cattle harvested at various time points and grown in several different production systems. ProcedureSeventy-six beef cattle were slaugh-tered at Oklahoma State University, and whole carcasses were divided into carcass, offal, and viscera. These samples were ground and frozen and then analyzed for Ca, P, K, Mg, and S by Ward Laboratory (Kearney, Neb.). Sample analysis included acid diges-tion of all organic matter, followed by mineral analysis using Inductively Coupled Plasma-Atomic Emission Spectroscopy. Total offal included blood, head, hide, feet, ears, internal organs, and trim. Visceral organs included reticulo-rumen, omasum, abomasum, small intestine, cecum, large intestine, pancreas, spleen, omental and mesenteric fat. Weights of total carcass, visceral organs, and offal were recorded. Cattle were on two separate experiments and were harvested at various time points after being grown in several different pro-duction systems. Experiment (Exp.) 1 (Journal of Animal Science, 82:262) utilized 30 British crossbred steers wintered at three different levels of gain and then finished on a common diet. Cattle grazed wheat pasture to gain 2.89 lb/day (high gain wheat; HGW) or 1.19 lb/day (low gain wheat; LGW), or grazed dormant native range supplemented with 2 lb of cottonseed meal each day and gaining 0.35 lb/day (native range; NR). At the end of the winter grazing season, four steers were slaughtered from each treat-ment group. The remaining steers were placed on a common finishing diet and six additional steers from each treatment were slaughtered at approximately 0.6 inches of backfat. Cattle from HGW reached 0.6 inches of backfat after 89 days on feed, LGW cattle after 116 days on feed, and NR cattle after 163 days on feed. Cattle performance during the growing and finishing phases is shown in Table 1; live performance measurements were taken on 48 steers, including the 30 steers used for serial slaughter. Experiment 2 (Journal of Animal Science 88:1564) utilized 46 British crossbred steers grown at different rates and on different diets. Four steers were slaughtered at initiation of the trial to determine initial carcass composition. Remaining cattle were split between calf-feds placed directly into the feedlot (CF) and three grow-ing treatments: grazing wheat pasture Table 1. Cattle performance during the growing and finishing phases of Experiment 11.HGW2 LGW NR SEM P-valueGrowing phase Days ADG, lb 12th-rib fat, in HCW, lb1202.890.46a522a1201.190.10b381b1200.350.004b302c — —0.0410.8 — —< 0.05< 0.05Finishing phase Days ADG, lb 12th-rib fat, in HCW, lb893.940.64754a1163.970.62701b1634.010.59725ab —0.130.078.2 —0.43> 0.05< 0.051All data measuring cattle performance collected by Oklahoma State University and published in Journal of Animal Science, 82:262.2Treatments were due to diet fed during the growing phase and included cattle grazing wheat pasture at a high rate of gain (HGW), cattle grazing wheat pasture at a low rate of gain (LGW), and cattle grazing dormant native range pasture (NR). All cattle were finished on a common diet.a-cMeans within a row without a common superscript differ (P < 0.05). © The Board of Regents of the University of Nebraska.  All rights reserved. 2015 Nebraska Beef Cattle Report  — Page 109 Mineral retention within the body was calculated as the differ-ence between mineral composition at slaughter and predicted mineral composition at day 0. Mineral com-position at day 0 was predicted from body composition of steers harvested at day 0 multiplied by live weight of individual animals at day 0. For Exp. 1, mineral retention was calculated for each treatment during the finish-ing period. In Exp. 2, mineral reten-tion was calculated for the growing and finishing periods separately for each treatment except CF, which only consisted of a finishing period. Min-eral retention was then expressed as grams per day, grams per kg empty body weight (EBW) gain, and grams per 100 g protein gain. In live animals EBW is calculated as full BW mul-tiplied by 0.855; however, for these trials EBW was measured by weighing the whole carcass after the contents of the gastrointestinal tract had been removed. For statistical analysis in Exp. 1, mineral retention among treat-ments was compared with individual animal as the experimental unit. In Exp. 2, mineral retention within the growing phase, within the finishing phase, and overall mineral retention were compared by treatment using an F-test with individual animal as the experimental unit. Because all com-parisons within each of the phases were non-significant (P ≥ 0.19) only mineral retention for the growing and finishing phases combined is shown. Mineral retention within the growing phase was also compared to retention during the finishing phase, but was found to be non-significant (P ≥ 0.28). For both trials all differences were declared significant at P < 0.05.ResultsThe NRC currently expresses P and Ca retention as g/100 g protein gain. In the current trials, expressing min-eral retention on a protein gain basis reduced variation due to diet, rate of gain, and days on feed. Table 2.  Cattle performance during the growing and finishing phases of Experiment 21.WP2 SF PF CF SEM P-valueGrowing phase Days ADG, lb 12th-rib fat, in HCW, lb1122.54a0.17489ab1122.43b0.20467a1122.60a0.23522b — — — — —0.040.0317.2 —0.010.320.10Finishing phase Days ADG, lb 12th-rib fat, in HCW, lb1233.62a0.53a8511044.45b0.50a8361044.08c0.49a8291963.59a0.64b818 —0.090.0199.7 —< 0.01< 0.010.121All data measuring cattle performance collected by Oklahoma State University and published in Journal of Animal Science, 88:1564.2Treatments were due to diet fed during the growing phase and included grazing wheat pasture (WP), a sorghum silage based diet (SF), program fed a high concentrate diet (PF), or placed directly into the feedlot as calf-feds (CF). All cattle were finished on a common diet.a-cMeans within a row without a common superscript differ (P < 0.05). Table 3.  Mineral retention within the empty body of beef cattle during the finishing phase while on a common high concentrate diet (Experiment 1).HGW1 LGW NR SEM P-valueCalcium g/day g/kg EBW gain g/100 g protein gain31.817.19.858.930.417.324.614.913.115.388.066.060.090.150.48Phosphorus g/day g/kg EBW gain g/100 g protein gain14.88.04.19.85.03.210.26.25.12.701.481.320.150.170.39Potassium g/day g/kg EBW gain g/100 g protein gain1.6b0.9b0.5b4.9a2.5a1.4ab5.2a3.2a2.9a0.8210.4940.746< 0.01< 0.010.02Magnesium g/day g/kg EBW gain g/100 g protein gain-0.2b-0.1b-0.1b1.3a0.7a0.4a0.7a0.5a0.4a0.3300.1760.141< 0.01< 0.010.01Sulfur g/day g/kg EBW gain g/100 g protein gain1.2b0.6b0.3b4.1a2.1a1.2a3.6a2.2a1.9a0.5460.3080.365< 0.01< 0.01< 0.011Treatments were due to diet fed during the growing phase and included cattle grazing wheat pasture at a high rate of gain (HGW), cattle grazing wheat pasture at a low rate of gain (LGW), and cattle grazing dormant native range pasture (NR). All cattle were finished on a common diet; mineral retention was calculated for the finishing phase. a-cMeans within a row without a common superscript differ (P < 0.05). (WP), fed a sorghum silage growing diet (SF), or program fed (PF) a high concentrate (steam-flaked corn) diet to gain at a similar rate as SF cattle. At the end of 112 days, six steers from each of the three growing diets were slaughtered, and remaining cattle were placed onto the finishing diet CF cattle were already on. At approxi-mately 0.5 inches of backfat, six calves from each of the four treatments were slaughtered. Cattle on the CF treat-ment were on feed for 196 days. After the 112 day growing phase, cattle on WP were on feed for 123 days, SF and PF for 104 days. Cattle performance during the growing and finishing phases is shown in Table 2; live per-formance measurements were taken on 260 steers, including the 46 steers used for serial slaughter. (Continued on next page)Page 110 — 2015 Nebraska Beef Cattle Report  © The Board of Regents of the University of Nebraska.  All rights reserved.Experiment 1Mineral retention was calculated for the finishing period following three different diets being fed during the growing phase. There were no differences due to treatment for P or Ca retention (P ≥ 0.15 and P ≥ 0.09, respectively) expressed as g/day,  g/kg EBW gain, or g/100 g protein gain (Table 3). Retention of P and Ca averaged 4.1 g P/100 g protein gain and 13.4 g Ca/100 g protein gain, respectively , over all three treatments. Mineral retention was significantly different among treatments for K, Mg, and S (P < 0.02) during finishing. Potassium, Mg, and S retention were greatest for NR and LGW cattle and least for HGW cattle. This indicates an increase in mineral retention dur-ing the finishing period because diet quality and ADG during the growing period were reduced.Experiment 2Mineral retention was calculated for the growing and finishing periods separately for each treatment, except CF, which consisted only of a finishing period. There were no differences due to treatment for combined mineral retention in the growing and finishing periods and no differences between the growing and finishing periods  for P (P ≥ 0.36), Ca (P ≥ 0.23), K  (P ≥ 0.38), Mg (P ≥ 0.12), or S  (P ≥ 0.20) retention when expressed as g/kg EBW gain, or g/100 g pro-tein gain (Table 4). Retention of Mg was impacted by treatment when expressed as g/day (P = 0.05). Phos-phorus retention over the growing and finishing periods combined aver-aged 4.3 g P/100 g protein gain for all four treatments. Calcium, K, Mg, and S retention averaged 8.2, 1.3, 0.3, and 1.1 g/100 g protein gain for all four treatments, respectively. Cattle were on different diets during the growing period, but small differences in ADG during the growing period (< 7%;  P < 0.01) resulted in no differences in mineral retention due to treatment. Table 4.  Mineral retention within the empty body of beef cattle during the growing and finishing phases combined (Experiment 2).WP1 SF PF CF SEM P-value3Calcium2 g/day g/kg EBW gain g/100 g protein gain12.515.27.221.126.310.717.520.08.312.913.96.75.346.343.030.340.230.56Phosphorus g/day g/kg EBW gain g/100 g protein gain7.08.84.010.312.95.38.910.24.26.97.53.62.553.051.440.500.360.70Potassium g/day g/kg EBW gain g/100 g protein gain2.53.51.32.43.01.22.93.21.32.42.51.20.5140.7850.2200.730.610.88Magnesium g/day g/kg EBW gain g/100 g protein gain0.50.70.30.60.80.30.80.90.40.50.50.30.0950.1440.0560.050.120.37Sulfur g/day g/kg EBW gain g/100 g protein gain2.12.81.12.02.51.02.42.71.12.22.31.20.2220.4020.1120.340.560.501Treatments were due to diet fed during the growing phase and included grazing wheat pasture (WP), a sorghum silage based diet (SF), program fed a high concentrate diet (PF), or placed directly into the feedlot as calf-feds (CF). All cattle were finished on a common diet.2Mineral retention was calculated separately for the growing and finishing phases. Combined mineral retention for the growing and finishing phases is shown, except for the CF treatment which consisted only of a finishing phase. 3P-values shown compare mineral retention of treatments for the combined growing and finishing phases. There were no differences in mineral retention due to treatment during the growing phase  (P ≥ 0.19) or comparing the growing and finishing phases (P ≥ 0.28).The current NRC (2000) reports P retention as 3.9 g P/100 g protein gain and Ca retention as 7.1 g Ca/100 g pro-tein gain. These values are calculated from serial harvest data and represent retention within 132 dairy cattle at various stages of growth. Data from the current two trials complement these data, with similar overall values, 4.2 g P/100 g protein gain and 10.8 g Ca/100 g protein gain, suggesting little change in mineral retention within cattle or in the methods used to measure mineral retention. Varia-tion among animals, measurement techniques, or a combination of both appears to be greater than variation due to diet as no differences were detected by treatment for P and Ca retention. Retention of other miner-als (K, Mg, and S) can be impacted by diet quality and ADG during the growing period, as shown in Exp. 1. Expressing mineral retention rela-tive to rate of gain equalizes changes in retention due to rate of gain and decreases variation due to treatment. These data suggest that the current method of expressing mineral reten-tion as g/100 g protein gain used by the NRC is the most appropriate.1Andrea K. Watson, research technician; Jana L. Harding, research technician, University of Nebraska–Lincoln (UNL) Department of Animal Science, Lincoln, Neb.; Matt P. McCurdy, former graduate student; Matt J. Hersom, former graduate student; Clint R. Krehbiel, professor, Oklahoma State University Department of Animal Science, Stillwater, Okla.; Kristin E. Hales, Meat Animal Research Center, Clay Center, Neb.; Galen E. Erickson, professor, UNL Department of Animal Science, Lincoln, Neb.

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Mineral Composition of Beef Cattle Carcasses

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