Changes in in vitro organic matter digestibility and digestible organic matter of corn residue were evaluated throughout the fall grazing and spring grazing seasons. In vitro organic matter digestibility and digestible organic matter were greatest at the beginning of fall grazing and declined over time. Slight weathering resulted in lower quality corn residue available at the beginning of spring grazing compared to the beginning of fall grazing. The in vitro organic matter digestibility of available residue declined 21% over the fall grazing season and 51% throughout the spring grazing season. As the availability of nutrients declines over time, adjustments in feeding management or rotational grazing may be necessary to meet energy requirements of grazing cattle

Bondurant, Robert G., Bondurant

Gardine, Shelby E.

Gramkow, Jana L.

Harsh, Gavin L.

Klopfenstein, Terry J.

Watson, Andrea K.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnNebraska Beef Cattle Reports Animal Science Department2017Corn Residue Quality throughout the GrazingSeasonShelby E. GardineUniversity of Nebraska-Lincoln, sgardine2@unl.eduGavin L. HarshUniversity of Nebraska - Lincoln, gharsh_20@hotmail.comRobert G. Bondurant BondurantUniversity of Nebraska-Lincoln, robby.bondurant@unl.eduJana L. GramkowUniversity of Nebraska - LincolnAndrea K. WatsonUniversity of Nebraska-Lincoln, awatson3@unl.eduSee 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.Gardine, Shelby E.; Harsh, Gavin L.; Bondurant, Robert G. Bondurant; Gramkow, Jana L.; Watson, Andrea K.; and Klopfenstein,Terry J., "Corn Residue Quality throughout the Grazing Season" (2017). Nebraska Beef Cattle Reports. 944.http://digitalcommons.unl.edu/animalscinbcr/944AuthorsShelby E. Gardine, Gavin L. Harsh, Robert G. Bondurant Bondurant, Jana L. Gramkow, Andrea K. Watson,and Terry J. KlopfensteinThis article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/animalscinbcr/94460 · 2017 Nebraska Beef Cattle Report©  Th e Board Regents of the University of Nebraska. All rights reserved.spectively. To determine changes in forage quality throughout each grazing period, 6 ruminally fi stualed steers were allowed to graze the fi eld replications at the initiation and completion of each grazing season. Prior to sampling, rumen contents were removed from each steer. Fistulated steers were then transferred to the corn residue fi eld where 3 steers per replication were allowed to graze. Aft er approximately 30 minutes of grazing, freshly consumed feed was collected from each steer’s rumen and placed in a cooler for later analysis. Former rumen contents were returned to the rumen. Collected samples were analyzed for in vitro organic matter digestibility (IVOMD) using the Tilley and Terry meth-od, which was modifi ed with the inclusion of 1 gram of urea to the buff er. Th e IVOMD values were also adjusted using in vivo corn residue and grass hay standards. Digestible organic matter (DOM) was then calculated by multiplying the IVOMD and percent or-ganic matter of the original residue sample. A starch analysis (Megazyme Total Starch Assay, Megazyme International Ireland Ltd., Ireland) was conducted to determine the percentage of grain within diet samples.All data were analyzed using the mixed procedure of SAS. Corn plant data included treatment (spring and fall grazed), crop ro-tation, and plant part (husk, leaf blade, and leaf sheath) as fi xed eff ects. Data from corn residue diet samples included treatment (spring and fall) and time (beginning and end of grazing season) as fi xed eff ects.Th erefore, the direct objective of this study was to determine diet quality of a corn residue fi eld throughout fall and spring grazing periods. A secondary objective was to evaluate the eff ects of crop rotation on subsequent corn residue quality.ProceduresCorn plant samplesAn irrigated cornfi eld located at the Eastern Nebraska Research and Exten-sion Center (ENREC) was utilized in the study. Th e fi eld consisted of 2 sections with diff erent crop rotations: 1) corn- corn rota-tion and 2) corn- soybean rotation. Th ree treatments (fall grazed, spring grazed, and non- grazed) with four replications of each treatment have been applied to the fi eld annually. Ten consecutive whole corn plant samples harvested above the anchor root were collected from each fi eld replica-tion prior to grain harvest. Plant samples were separated into individual plant parts (leaf, sheath, husk) and weighed for DM. Plant parts were then composited within replication and analyzed for in vitro organic matter digestibility (IVOMD), digestible organic matter (DOM), and starch.Corn residue diet samplesFollowing grain harvest of the corn fi eld, cow- calf pairs grazed the fall grazed (November to February) and the spring (March) fi eld replications at a stocking rate of 1.4 and 0.5 acres per cow- calf pair, re-Shelby E. GardineGavin L. HarshRobert G. BondurantJana L. GramkowAndrea K. WatsonTerry J. KlopfensteinSummary with ImplicationsChanges in in vitro organic matter digest-ibility and digestible organic matter of corn residue were evaluated throughout the fall grazing and spring grazing seasons. In vitro organic matter digestibility and digestible organic matter were greatest at the beginning of fall grazing and declined over time. Slight weathering resulted in lower quality corn residue available at the beginning of spring grazing compared to the beginning of fall grazing. Th e in vitro organic matter digest-ibility of available residue declined 21% over the fall grazing season and 51% throughout the spring grazing season. As the availability of nutrients declines over time, adjustments in feeding management or rotational grazing may be necessary to meet energy require-ments of grazing cattle.IntroductionWith the conversion of much grassland to cropland, supply of traditional forage resources has been challenged. However, an increase in acres being planted for corn production has resulted in greater availabil-ity of corn residue, which can be a valuable feed resource for grazing situations. Over time, corn residue quality will vary due to selective grazing of the higher quality plant parts (husk and leaves) and weath-ering. Characterizing a corn residue fi eld for nutrient quality throughout a grazing period is important because adjustments in feeding management or rotational grazing may be necessary to meet the nutrient requirements of animals grazing the fi eld.  Corn Residue Quality throughout the Grazing SeasonTable 1. Yield of residue measured by clipping individual corn plants (% of grain)Treatment1Fall grazed Spring grazed Non- grazed SEM P- valueHusk 5.8 6.1 5.3 0.32 0.22Leaf 17.6 18.2 16.9 1.04 0.68Sheath 8.6 8.7 8.2 0.49 0.77Cob 9.1 9.4 8.5 0.39 0.311 Treatments were due to timing of cattle grazing residue 2 years prior to these samples being collected. Ten plants were collected from each of 4 replications per treatment.2017 Nebraska Beef Cattle Report · 61 decline in quality over time was greater for spring grazing, 51 and 52% for IVOMD and DOM, respectively.Starch in the diet samples ranged from 0.04% to 6.44% (average of 1.6%) at the be-ginning of both grazing seasons. Th e broad range in starch content indicates signifi cant variability expressed in grazing selection among steers. Given that corn consists of 70% starch, approximately 2.2 % of the steer’s diet contained corn at the start of the grazing season.Th e higher DOM of the corn residue diet samples observed at the beginning of both grazing seasons would suggest that cattle are selectively eating the husk and grain within the fi eld. Th e diff erence in DOM observed between the beginning and end of both grazing seasons is evident that as the availability of husk and grain de-creases, cattle begin to consume the leaves. Leaves are lower in IVOMD than husks and even lower in DOM because they have a high ash content (approximately 15% ash). In addition, the lower DOM observed at the beginning of the spring grazing compared to the beginning of the fall grazing would indicate that weathering may be responsible for a portion of DOM reduction.ConclusionTh e energy content that a corn residue fi eld provides to grazing cattle is greatest at the beginning of the fall grazing season. However, as cattle selectively consume the higher digestible plant parts and weather-ing deteriorates the corn residue, the fi eld provides less and less energy to the cattle. Characterizing a fi eld for its nutrient profi le is important during the grazing season. As the availability of nutrients declines over time, adjusting feeding management or uti-lizing rotational grazing may be necessary to continue to meet energy requirements of the grazing cattle.Shelby E. Gardine, graduate studentGavin L. Harsh, undergraduate studentRobby G. Bondurant, research technicianJana L. Gramkow, research technicianAndrea K. Watson, research assistant professorTerry J. Klopfenstein, professor, University of Nebraska- Lincoln Department of Animal Science, Lincoln, NEwere greatest for the husk, intermediate for leaf blade, and least for leaf sheath.A treatment by time interaction was ob-served for IVOMD of the corn residue diet samples (P < 0.01; Table 4). Th e IVOMD was greatest at the beginning of the fall and spring grazing seasons, intermediate at the end of the fall grazing, and least for the end of the spring grazing season.A treatment by time interaction was also observed for DOM of the corn residue (P = 0.01). Th e beginning of the fall grazing season had the greatest DOM compared to all other time points within both grazing seasons. Th e beginning of spring grazing had greater DOM than the end of fall grazing. Digestible OM was least for the end of the spring grazing compared to all other grazing time points. From initiation of grazing to the end of the grazing season, IVOMD declined 21% while DOM declined 32% for the fall grazed treatment. Th e ResultsAmount of residue (as a percentage of grain) per plant is shown by treatment (Table 1). Th e average amount of leaf blade, leaf sheath, and husk was 31.8 % of the grain. Th at is 21 lb of residue dry matter/bu of corn at 15.5% moisture. Th is diff ers with previous research in which 15.8 lb of leaf and husk were produced per bu of corn (2016 Nebraska Beef Cattle Report, pg 71- 73). Grain yield averaged 217 bu/acre and was not infl uenced by any treatments.No signifi cant diff erence was observed for corn residue IVOMD or DOM between the corn- soybean rotation and corn- corn rotation (P- value ≥ 0.95; Table 2). Previous treatment (fall, spring, or non- grazed) also did not aff ect IVOMD or DOM of corn res-idue harvested prior to grazing (P ≥ 0.97). Plant parts did diff er in IVOMD and DOM (P < 0.01; Table 3). Th e IVOMD and DOM Table 2.  In vitro organic matter digestibility and digestible organic matter of corn plant samples by areaAreaItem C- SB1 C- C2 SEM P- valueIVOMD3, % 44.3 44.0 3.0 0.96DOM4, % 40.8 40.5 3.2 0.951Area that was in a corn- soybean rotation2Area that was in a corn- corn rotation3In vitro organic matter digestibility4Digestible organic matter (as a % of dry matter); calculated as OM content (%) × IVOMD (%)Table 3. In vitro organic matter digestibility and digestible organic matter of corn plant partsHusk Leaf Blade Leaf Sheath SEM P- valueIVOMD1, % 60.0a 39.7b 32.7c 0.6 <0.01DOM2, % 58.1a 33.7b 30.2c 0.6 <0.011In vitro organic matter digestibility2Digestible organic matter (as a % of dry matter); calculated as OM content (%) × IVOMD (%)abcMeans within a row with unique superscripts diff er (P < 0.05)Table 4.  In vitro organic matter digestibility and digestible organic matter of corn residue diet samples by treatment and time1Fall Spring P- value2Item Beginning End Beginning End SEM Trt Time Int.IVOMD 3, %62.1 a 48.9 b 58.6 a 29.0 c 3.0 <0.01 <0.01 <0.01DOM4, % 58.5 a 40.0 c 53.5 b 25.7 d 2.9 <0.01 <0.01  0.041Treatments are due to timing of grazing (fall or spring) and timing of sample collection (at the beginning or end of grazing).2Trt= fi xed eff ect of treatment; Time= fi xed eff ect of time; Int. = treatment × time interaction3In vitro organic matter digestibility4Digestible organic matter (as a % of DM); calculated as OM content (%) × IVOMD (%); adjusted for ash content of salivaabcdMeans within a row with unique superscripts diff er (P < 0.05)

Corn Residue Quality throughout the Grazing Season

UNL | Libraries

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Nebraska Beef Cattle Reports Animal Science Department
2017
Corn Residue Quality throughout the Grazing
Season
Shelby E. Gardine
University of Nebraska-Lincoln, sgardine2@unl.edu
Gavin L. Harsh
University of Nebraska - Lincoln, gharsh_20@hotmail.com
Robert G. Bondurant Bondurant
University of Nebraska-Lincoln, robby.bondurant@unl.edu
Jana L. Gramkow
University of Nebraska - Lincoln
Andrea K. Watson
University of Nebraska-Lincoln, awatson3@unl.edu
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.
Gardine, Shelby E.; Harsh, Gavin L.; Bondurant, Robert G. Bondurant; Gramkow, Jana L.; Watson, Andrea K.; and Klopfenstein,
Terry J., "Corn Residue Quality throughout the Grazing Season" (2017). Nebraska Beef Cattle Reports. 944.
http://digitalcommons.unl.edu/animalscinbcr/944
Authors
Shelby E. Gardine, Gavin L. Harsh, Robert G. Bondurant Bondurant, Jana L. Gramkow, Andrea K. Watson,
and Terry J. Klopfenstein
This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/animalscinbcr/944
60 · 2017 Nebraska Beef Cattle Report
©  Th e Board Regents of the University of 
Nebraska. All rights reserved.
spectively. To determine changes in forage 
quality throughout each grazing period, 6 
ruminally fi stualed steers were allowed to 
graze the fi eld replications at the initiation 
and completion of each grazing season. 
Prior to sampling, rumen contents were 
removed from each steer. Fistulated steers 
were then transferred to the corn residue 
fi eld where 3 steers per replication were 
allowed to graze. Aft er approximately 30 
minutes of grazing, freshly consumed feed 
was collected from each steer’s rumen and 
placed in a cooler for later analysis. Former 
rumen contents were returned to the 
rumen. Collected samples were analyzed 
for in vitro organic matter digestibility 
(IVOMD) using the Tilley and Terry meth-
od, which was modifi ed with the inclusion 
of 1 gram of urea to the buff er. Th e IVOMD 
values were also adjusted using in vivo corn 
residue and grass hay standards. Digestible 
organic matter (DOM) was then calculated 
by multiplying the IVOMD and percent or-
ganic matter of the original residue sample. 
A starch analysis (Megazyme Total Starch 
Assay, Megazyme International Ireland Ltd., 
Ireland) was conducted to determine the 
percentage of grain within diet samples.
All data were analyzed using the mixed 
procedure of SAS. Corn plant data included 
treatment (spring and fall grazed), crop ro-
tation, and plant part (husk, leaf blade, and 
leaf sheath) as fi xed eff ects. Data from corn 
residue diet samples included treatment 
(spring and fall) and time (beginning and 
end of grazing season) as fi xed eff ects.
Th erefore, the direct objective of this study 
was to determine diet quality of a corn 
residue fi eld throughout fall and spring 
grazing periods. A secondary objective was 
to evaluate the eff ects of crop rotation on 
subsequent corn residue quality.
Procedures
Corn plant samples
An irrigated cornfi eld located at the 
Eastern Nebraska Research and Exten-
sion Center (ENREC) was utilized in the 
study. Th e fi eld consisted of 2 sections with 
diff erent crop rotations: 1) corn- corn rota-
tion and 2) corn- soybean rotation. Th ree 
treatments (fall grazed, spring grazed, and 
non- grazed) with four replications of each 
treatment have been applied to the fi eld 
annually. Ten consecutive whole corn plant 
samples harvested above the anchor root 
were collected from each fi eld replica-
tion prior to grain harvest. Plant samples 
were separated into individual plant parts 
(leaf, sheath, husk) and weighed for DM. 
Plant parts were then composited within 
replication and analyzed for in vitro organic 
matter digestibility (IVOMD), digestible 
organic matter (DOM), and starch.
Corn residue diet samples
Following grain harvest of the corn 
fi eld, cow- calf pairs grazed the fall grazed 
(November to February) and the spring 
(March) fi eld replications at a stocking rate 
of 1.4 and 0.5 acres per cow- calf pair, re-
Shelby E. Gardine
Gavin L. Harsh
Robert G. Bondurant
Jana L. Gramkow
Andrea K. Watson
Terry J. Klopfenstein
Summary with Implications
Changes in in vitro organic matter digest-
ibility and digestible organic matter of corn 
residue were evaluated throughout the fall 
grazing and spring grazing seasons. In vitro 
organic matter digestibility and digestible 
organic matter were greatest at the beginning 
of fall grazing and declined over time. Slight 
weathering resulted in lower quality corn 
residue available at the beginning of spring 
grazing compared to the beginning of fall 
grazing. Th e in vitro organic matter digest-
ibility of available residue declined 21% over 
the fall grazing season and 51% throughout 
the spring grazing season. As the availability 
of nutrients declines over time, adjustments 
in feeding management or rotational grazing 
may be necessary to meet energy require-
ments of grazing cattle.
Introduction
With the conversion of much grassland 
to cropland, supply of traditional forage 
resources has been challenged. However, 
an increase in acres being planted for corn 
production has resulted in greater availabil-
ity of corn residue, which can be a valuable 
feed resource for grazing situations. Over 
time, corn residue quality will vary due 
to selective grazing of the higher quality 
plant parts (husk and leaves) and weath-
ering. Characterizing a corn residue fi eld 
for nutrient quality throughout a grazing 
period is important because adjustments in 
feeding management or rotational grazing 
may be necessary to meet the nutrient 
requirements of animals grazing the fi eld. 
 Corn Residue Quality throughout the Grazing Season
Table 1. Yield of residue measured by clipping individual corn plants (% of grain)
Treatment1
Fall grazed Spring grazed Non- grazed SEM P- value
Husk 5.8 6.1 5.3 0.32 0.22
Leaf 17.6 18.2 16.9 1.04 0.68
Sheath 8.6 8.7 8.2 0.49 0.77
Cob 9.1 9.4 8.5 0.39 0.31
1 Treatments were due to timing of cattle grazing residue 2 years prior to these samples being collected. Ten plants were collected 
from each of 4 replications per treatment.
2017 Nebraska Beef Cattle Report · 61 
decline in quality over time was greater for 
spring grazing, 51 and 52% for IVOMD and 
DOM, respectively.
Starch in the diet samples ranged from 
0.04% to 6.44% (average of 1.6%) at the be-
ginning of both grazing seasons. Th e broad 
range in starch content indicates signifi cant 
variability expressed in grazing selection 
among steers. Given that corn consists of 
70% starch, approximately 2.2 % of the 
steer’s diet contained corn at the start of the 
grazing season.
Th e higher DOM of the corn residue 
diet samples observed at the beginning of 
both grazing seasons would suggest that 
cattle are selectively eating the husk and 
grain within the fi eld. Th e diff erence in 
DOM observed between the beginning and 
end of both grazing seasons is evident that 
as the availability of husk and grain de-
creases, cattle begin to consume the leaves. 
Leaves are lower in IVOMD than husks and 
even lower in DOM because they have a 
high ash content (approximately 15% ash). 
In addition, the lower DOM observed at the 
beginning of the spring grazing compared 
to the beginning of the fall grazing would 
indicate that weathering may be responsible 
for a portion of DOM reduction.
Conclusion
Th e energy content that a corn residue 
fi eld provides to grazing cattle is greatest 
at the beginning of the fall grazing season. 
However, as cattle selectively consume the 
higher digestible plant parts and weather-
ing deteriorates the corn residue, the fi eld 
provides less and less energy to the cattle. 
Characterizing a fi eld for its nutrient profi le 
is important during the grazing season. As 
the availability of nutrients declines over 
time, adjusting feeding management or uti-
lizing rotational grazing may be necessary 
to continue to meet energy requirements of 
the grazing cattle.
Shelby E. Gardine, graduate student
Gavin L. Harsh, undergraduate student
Robby G. Bondurant, research technician
Jana L. Gramkow, research technician
Andrea K. Watson, research assistant 
professor
Terry J. Klopfenstein, professor, University 
of Nebraska- Lincoln Department of Animal 
Science, Lincoln, NE
were greatest for the husk, intermediate for 
leaf blade, and least for leaf sheath.
A treatment by time interaction was ob-
served for IVOMD of the corn residue diet 
samples (P < 0.01; Table 4). Th e IVOMD 
was greatest at the beginning of the fall and 
spring grazing seasons, intermediate at the 
end of the fall grazing, and least for the end 
of the spring grazing season.
A treatment by time interaction was also 
observed for DOM of the corn residue (P 
= 0.01). Th e beginning of the fall grazing 
season had the greatest DOM compared to 
all other time points within both grazing 
seasons. Th e beginning of spring grazing 
had greater DOM than the end of fall 
grazing. Digestible OM was least for the 
end of the spring grazing compared to all 
other grazing time points. From initiation 
of grazing to the end of the grazing season, 
IVOMD declined 21% while DOM declined 
32% for the fall grazed treatment. Th e 
Results
Amount of residue (as a percentage 
of grain) per plant is shown by treatment 
(Table 1). Th e average amount of leaf blade, 
leaf sheath, and husk was 31.8 % of the 
grain. Th at is 21 lb of residue dry matter/
bu of corn at 15.5% moisture. Th is diff ers 
with previous research in which 15.8 lb of 
leaf and husk were produced per bu of corn 
(2016 Nebraska Beef Cattle Report, pg 71- 
73). Grain yield averaged 217 bu/acre and 
was not infl uenced by any treatments.
No signifi cant diff erence was observed 
for corn residue IVOMD or DOM between 
the corn- soybean rotation and corn- corn 
rotation (P- value ≥ 0.95; Table 2). Previous 
treatment (fall, spring, or non- grazed) also 
did not aff ect IVOMD or DOM of corn res-
idue harvested prior to grazing (P ≥ 0.97). 
Plant parts did diff er in IVOMD and DOM 
(P < 0.01; Table 3). Th e IVOMD and DOM 
Table 2.  In vitro organic matter digestibility and digestible organic matter of 
corn plant samples by area
Area
Item C- SB1 C- C2 SEM P- value
IVOMD3, % 44.3 44.0 3.0 0.96
DOM4, % 40.8 40.5 3.2 0.95
1Area that was in a corn- soybean rotation
2Area that was in a corn- corn rotation
3In vitro organic matter digestibility
4Digestible organic matter (as a % of dry matter); calculated as OM content (%) × IVOMD (%)
Table 3. In vitro organic matter digestibility and digestible organic matter of corn plant parts
Husk Leaf Blade Leaf Sheath SEM P- value
IVOMD1, % 60.0a 39.7b 32.7c 0.6 <0.01
DOM2, % 58.1a 33.7b 30.2c 0.6 <0.01
1In vitro organic matter digestibility
2Digestible organic matter (as a % of dry matter); calculated as OM content (%) × IVOMD (%)
abcMeans within a row with unique superscripts diff er (P < 0.05)
Table 4.  In vitro organic matter digestibility and digestible organic matter of corn residue 
diet samples by treatment and time1
Fall Spring P- value2
Item Beginning End Beginning End SEM Trt Time Int.
IVOMD 
3, %
62.1 a 48.9 b 58.6 a 29.0 c 3.0 <0.01 <0.01 <0.01
DOM4, % 58.5 a 40.0 c 53.5 b 25.7 d 2.9 <0.01 <0.01  0.04
1Treatments are due to timing of grazing (fall or spring) and timing of sample collection (at the beginning or end of grazing).
2Trt= fi xed eff ect of treatment; Time= fi xed eff ect of time; Int. = treatment × time interaction
3In vitro organic matter digestibility
4Digestible organic matter (as a % of DM); calculated as OM content (%) × IVOMD (%); adjusted for ash content of saliva
abcdMeans within a row with unique superscripts diff er (P < 0.05)


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Corn Residue Quality throughout the Grazing Season

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