Two experiments evaluated effects of straw bedding (in sheltered and unsheltered facilities) and pen density (in unsheltered facilities) on cattle performance during winter/spring (mid-December to late March) seasons. Bedding had no effect on overall performance in the sheltered facilities, but performance improvements were noted from December through February in unsheltered facilities. Lowering pen density(increasing pen space per animal) improved performance and lowered mud condition scores on the animal and in the feedlot

Colgan, Sheryl L.

Mader, Terry L.

English

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University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 2007 
Pen Density and Straw Bedding During Feedlot Finishing 
Terry L. Mader 
University of Nebraska-Lincoln, tmader1@unl.edu 
Sheryl L. Colgan 
Haskell Agricultural Laboratory/Northeast Research and Extension Center, Concord 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Mader, Terry L. and Colgan, Sheryl L., "Pen Density and Straw Bedding During Feedlot Finishing" (2007). 
Nebraska Beef Cattle Reports. 70. 
https://digitalcommons.unl.edu/animalscinbcr/70 
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. 
© The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 4 
Pen Density and Straw Bedding During Feedlot Finishing
Terry L. Mader
Sheryl L. Colgan1
Summary
Two experiments evaluated effects 
of straw bedding (in sheltered and 
unsheltered facilities) and pen density 
(in unsheltered facilities) on cattle 
performance during winter/spring 
(mid-December to late March) sea-
sons. Bedding had no effect on overall 
performance in the sheltered facilities, 
but performance improvements were 
noted from December through February 
in unsheltered facilities. Lowering pen 
density (increasing pen space per ani-
mal) improved performance and low-
ered mud condition scores on the animal 
and in the feedlot.
Introduction
Managing cattle in periods of 
adverse weather can be challenging. 
Winter cold and wind, combined with 
precipitation, can increase the main-
tenance requirement of feedlot cattle 
and decrease performance. While 
cold stress alone can reduce profits, it 
is most detrimental when combined 
with mud. Cattle in mud have a ten-
dency to eat less frequently and the 
muddy hair coat reduces insulation. 
Shelter belts and windbreaks have 
been shown to be effective at reducing 
cold stress, however, more knowledge 
regarding how to reduce mud and 
mud effects in feedlots is needed.
While feedlot surface mainte-
nance, such as removing manure and 
rebuilding mounds, can help reduce 
mud in the winter and spring time, 
more can be done to further mini-
mize the problems associated with 
mud. The objectives of our trials were 
to evaluate the effects of adding straw 
bedding and reducing pen density to 
reduce mud and cold stress in feedlot 
cattle.
Procedure
One-hundred eighty (Trial 1) 
and two-hundred thirty-four (Trial 
2) crossbred steers were received at 
Haskell Agricultural Laboratory, 
Concord, Neb. Following receiving, 
all cattle were vaccinated (Vision 7 
and Titanium 5 PHM Bac 1; Inter-
vet, Millsboro, Del.). Additionally, in 
Trial 1, cattle were implanted (Ralgro; 
Schering-Plough Animal Health, 
Kenilworth N.J.) following receiving. 
At trial initiation (d-1), steers in both 
trials were revaccinated (Vision 7 and 
Titanium 5; Intervet, Millsboro, Del.), 
treated for external parasites (Saber; 
Schering-Plough Animal Health, 
Kenilworth, N.J.), and weighed. In 
Trial 2, cattle were implanted with 
Ralgro at trial initiation. On day 0 
(Dec. 18, 200, and Dec. 16, 2004, 
respectively) of each trial, steers were 
weighed and randomly assigned to 
20 pens (Trial 1) or 24 pens (Trial 2) 
based on the weight from the previ-
ous day (day-1). Average body weight 
for the two consecutive days was used 
as the initial weight (Trial 1 mean 
BW=824 lb; Trial 2 mean BW=885 lb). 
In both trials, cattle were treated for 
external parasites (Saber) and reim-
planted (Revalor-S; Intervet, Mills-
boro, Del.) on day 5 (Trial 1) or d 4 
(Trial 2). Throughout both trials, all 
cattle were fed a 65.2 NEg mcal/cwt 
finishing diet which contained (DM 
Basis) 8.1% dry rolled corn, 6.0% 
corn silage, 5.0% alfalfa, .7% liquid 
protein supplement, and 2.2% dry 
Rumensin-Tylan (Elanco; Indianapo-
lis, Ind.) supplement. 
In Trial 1, pens were randomly 
assigned to the following treatments: 
1) Low pen density, oat straw bedding, 
sheltered (overhead shelter, enclosed 
on north side, and open to dirt lot on 
south side) feeding area; 2) Low pen 
density, no bedding, sheltered feeding 
area; ) Low pen density, no bedding, 
unsheltered feeding area; or 4) high 
pen density, no bedding, unsheltered 
feeding area. The treatments (Trt) 
were chosen to exemplify a range of 
environmental conditions from most 
comfortable (Trt 1) to least comfort-
able (Trt 4). For Trial 2, treatments 
were assigned to pens using a 2 x 2 
factorial design, which consisted of 
pen density (High vs Low) and oat 
straw bedding (provided vs not pro-
vided).
In both trials, pen density was 
obtained by adjusting the number 
of head per pen in two different pen 
sizes. The low pen density treat-
ment consisted of 6 or 7 head/pen 
for a stocking rate of approximately 
500 ft2/head. The high pen density 
treatment had 12 or 14 head/pen for 
a stocking rate of approximately 250 
ft2/head. All cattle had a minimum of 
18 inches of bunk space/head.
In both trials, pens receiving the 
bedding treatment were bedded at 
the rate of 5 lb/head/day the first day 
of the trial. Thereafter, bedding was 
applied at the rate of approximately 
2 lb/head/day based on the following 
two primary thresholds: 1) air tem-
perature was below 14oF; and/or 2) 
precipitation of at least 0.10 inch rain 
or 1 inch snow was received. When 
more than 0.10 inch rain or 1 inch 
snow was received, cattle were bed-
ded on subsequent days for each 0.10 
inch rain or 1 inch snow. Additionally, 
when there was melting snow or mud 
in the pen, even if thresholds were 
not met, cattle received 2 lb/head/day 
of bedding every day or every other 
day, respectively, until the snow and 
mud were gone. Slight alternations 
in the bedding schedules were made 
to maintain a minimal amount of 
bedding in the pens at all times, 
however, in Trial 2, no bedding was 
added from day 98 to the end of the 
trial due to warmer temperatures and 
greater windspeeds, which allowed 
for improved conditions in the pens. 
Bedding was added to pens a total 
of 65 and 59 days in Trial 1 and 2, 
respectively.
(Continued on next page)
Page 44 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
Feed intakes were recorded daily. 
Body weights were obtained on days 
0, 5, and 110 in Trial 1 and on days 0, 
4, 71, and 98 in Trial 2. Cattle were 
fed 110 and 124 d in Trials 1 and 2, 
respectively. In Trial 1 (after thawing) 
and Trial 2 (trial duration), animal 
and lot mud condition scores were 
recorded twice per week. Animal mud 
condition scores were defined as: 0) 
clean, no mud; 1) small lumps of mud 
on the hide in limited areas of the leg 
and underbelly; 2) small and large 
lumps of mud covering larger areas of 
the legs, side, and underbelly; ) small 
and large lumps of mud covering 
the hide in even areas that included 
the hind quarter, stomach, and front 
shoulder; or 4) lumps of mud con-
tinuously covering the underbelly 
and side of the animal from brisket 
to rear quarter. Lot mud condition 
scores were defined as: 0) no mud or 
mud less than  inches deep; 1) mild 
mud,  to 7 inches deep; or 2) severe 
mud, more than 7 inches deep. Ad-
ditionally, in Trial 2, lot condition was 
denoted as frozen ground or thawed. 
At slaughter (day 110, Trial 1; and day 
124, Trial 2) final weight, hot carcass 
weight, liver score, USDA marbling 
score, and USDA yield grades were 
obtained.
Statistical analysis of performance 
data, marbling scores, and yield 
grade was done using General Linear 
Models procedures of SAS. In Trial 
1, the model included Trt. Contrasts 
were used to compare density in the 
unsheltered feed area treatments and 
bedding in the sheltered feed area 
treatments. In Trial 2, the model 
included density, bedding, and the 
density by bedding interaction. Liver 
and mud condition scores (animal 
and lot) were analyzed using fre-
quency procedures of SAS. The  
P-value reported is the Mantel-
Haenszel Chi-Square.
Table 1. Weather conditions for trials.a
  Mean Ta, ºF Max Ta, ºF Min Ta, ºF RH, % WSPD, mph Precip, in  
Trial 1
 day 0 to 5 25.44 6.4 1.97 75.0 5.29 0.16
 day 6 to 110 5.78 47.26 24.9 7.96 6.46 .75
 day 0 to 110 2.58 4.90 21.16 74.8 6.10 .91
Trial 2
 day 0 to  16.55 25.8 5.82 75.0 5.8 0.1
 day 4 to 70 0.85 40.46 20.47 82.5 5.99 1.21
 day 71 to 98 .28 46.11 20.06 67.5 6.79  0.0
 day 99 to 124 49.77 60.57 8.25 68.0 8.4 1.98
 day 0 to 124 1.56 42.06 20.21 74.1 6.62 .5
aTa = Ambient temperature; RH = relative humidity; WSPD = wind speed; Precip = precipitation, as 
rain or melted snow.
Table 2. Performance and carcass data (Trial 1). 
 Facilities
  Sheltered Unsheltered
Pen Density: Low Low Low High
Bedding: Yes No No No    Contrasts
Treatment No: 1 2  4 SEM P-Value 1 v 2  v 4 1 v 4
Weight, lb
 day 0 82 822 824 827 2.0 0.48 0.89 0.46 0.21
 day 5 968 967 969 967 8.2 1.00 0.99 0.89 0.99
 day 110 1281 1272 1277 1245 14. 0.1 0.68 0.1 0.10
 day 110 (adjusted)a 129 128 1247 1216 1.2 0.42 0.9 0.12 0.24
ADG, lb
 day 0 to 5 4.14 4.15 4.14 4.02 0.2 0.98 0.98 0.72 0.7
 day 6 to 110 4.12 4.01 4.05 .65 0.16 0.18 0.60 0.09 0.05
 day 0 to 110 4.1 4.05 4.08 .77 0.12 0.20 0.66 0.09 0.06
 day 0 to 110 (adjusted)a .75 .74 .81 .51 0.11 0.0 0.94 0.08 0.15
DMI, lb
 day 0 to 5 20.57 21.1 20.80 20.64 0.47 0.84 0.41 0.82 0.92
 day 6 to 110 22.94 22.99 2.22 22.80 0.60 0.97 0.95 0.62 0.88
 day 0 to 110 22.19 22.40 22.46 22.12 0.5 0.96 0.78 0.66 0.9
Feed/gain
 day 0 to 5 5.01 5.12 5.11 5.21 0.26 0.97 0.79 0.80 0.61
 day 6 to 110 5.58 5.80 5.75 6.26 0.2 0.22 0.50 0.1 0.05
 day 0 to 110 5.9 5.57 5.50 5.88 0.18 0.27 0.49 0.15 0.07
 day 0 to 110 (adjusted)a 5.94 6.0 5.90 6.2 0.22 0.54 0.78 0.19 0.24
Carcass data
 HCW, lb 769 767 77 754 8.2 0.4 0.92 0.1 0.24
 Marbling scoreb 48 460 495 481 11. 0.22 0.18 0.9 0.91
 Yield grade 2.45 2.26 2.9 2.4 0.11 0.65 0.2 0.7 0.47
 Dressing % 60.0 60. 60.6 60.6 .0 0.57 0.45 0.96 0.22
 Liver scorec 0 . 2.86 5.71 — — 0.1 0.52 —
aBased on hot carcass weight adjusted to a 62% dressing percentage.
bMarbling score: 400 = slight0 (select), 500 = small0 (low choice). 
cPercentage condemned, due to abscesses based on Chi-Square analysis.
© The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 45 
Results
In Trial 1 (Table 2), there were no 
differences for bedding versus no bed-
ding (Trt 1 vs Trt 2) in the sheltered 
cattle. In the unsheltered groups, 
low pen density tended to increase 
(P<0.10) ADG from days 5 to 110, 
and day 0 to 110, when based on 
unadjusted full weights. Cattle with 
bedding and the most pen space (Trt 
1) had improved ADG and lower F/G 
from days 6 to 110 (P<0.05) when 
compared with nonbedded cattle 
with the least pen space (Trt 4). Over-
all performance was similar among 
groups when comparisons were based 
on a common dressing percentage, 
however, in the unsheltered group, in-
creased cattle density tended (P<0.10) 
to reduce overall gain. In Trial 2 
(Table ), the addition of bedding 
increased (P<0.05) day 4 weight, day 
71 weight, ADG from days 0 to 4 and 
ADG from days 0 to 71, and improved 
feed efficiency from days 0 to 71. The 
low density group had lower (P<0.05) 
DMI and F/G from day 0 through 
day 98 when compared with the high 
density group. The low density group 
tended (P=0.07) to have lower overall 
F/G and a greater (P=0.001) marbling 
score when compared with the high 
density group. Bedding improved 
(P=0.0) F/G through day 71 only, 
however, it did result in a greater 
(P=0.02) percentage of condemned 
livers. There were no pen density by 
bedding interactions for performance 
or carcass data. 
In Trial 1, bedding did not 
(P=0.02) result in lowering animal 
mud condition scores, but did lower 
(P<0.001) lot mud condition scores. 
However, animal and lot mud condi-
tion scores were lower (P<0.005) in 
the low density treatment when com-
pared with the high density treatment. 
Data suggest cattle with bedding were 
dirtier (P<0.05) than cattle without 
bedding, even though pens with 
bedding were less muddy (P<0.05). 
In Trial 2 (Table 5), no differences 
(P>0.05) in animal or lot mud condi-
tion were observed for bedded versus 
Table 3. Performance and carcass data (Trial 2).
  Pen density (Den)a Bedding (Bed) P-values
  Low High No Yes SEM Den Bed Den*Bed
No. pens 12 12 12 12
Weight, lb
 Initial 879 882 878 884 2.5 0. 0.11 0.19
 day 4 1048 1054 104 1059 4. 0.4 0.01 0.09
 day 71 116 1160 1150 1172 5.8 0.76 0.02 0.25
 day 98 1252 1248 124 1257 7.2 0.64 0.20 0.7
 Finalb 128 127 120 16 8.5 0.95 0.41 0.45
ADG, lb
 day 0 to 4 4.84 4.91 4.7 5.02 0.09 0.61 0.04 0.2
 day 0 to 71 4.00 .91 .85 4.07 0.06 0. 0.02 0.46
 day 0 to 98 .82 .74 .74 .82 0.06 0. 0.41 0.70
 day 0 to 124b .6 .59 .57 .65 0.04 0.57 0.6 0.50
DMI, lb
 day 0 to 4 22.87 24.96 2.81 24.01 0.9 <0.01 0.7 0.57
 day 0 to 71 22.42 24.02 2.25 2.18 0.8 0.01 0.90 0.8
 day 0 to 98 21.8 2.41 22.64 22.60 0.5 0.00 0.9 0.27
 day 0 to 124 22.11 2.87 2.04 22.94 0.9 0.19 0.89 0.20
F/G
 day 0 to 4 4.74 5.10 5.05 4.80 0.11 0.0 0.12 0.6
 day 0 to 71 5.62 6.15 6.05 5.72 0.10 <0.01 0.0 0.75
 day 0 to 98 5.72 6.28 6.05 5.94 0.11 <0.01 0.46 0.45
 day 0 to 124b 6.11 6.66 6.46 6.1 0.05 0.07 0.25 0.45
Carcass datac
 Dressing % 6.9 64.0 6.5 64. 0.19 0.65 0.21 0.40
 HCW 82 82 818 828 6.8 0.94 0.2 0.46
 Marblingd 56 527 57 552 7.6 0.00 0.16 0.59
 Yield Grade 2.8 2.7 2.40 2.4 0.07 0.92 0.56 0.4
 Liver Scoree 10.56 5.6 2.5 6.57 — 0.2 0.02  —
aLow = 500 ft2/animal; High = 250 ft2/animal.
bFinal weight (d 124) calculated as hot carcass weight (HCW) divided by a 62% dressing percentage.
cCarcass data was analyzed using the individual animal as experimental unit.
dMarbling score: 500 = Small0 (Low Choice), 600 = Modest0 (Average Choice)
ePercentage condemned, due to abscesses; based on Chi-Square analysis.
Table 4. Animal and lot mud condition scores (Trial 1).
Feeding area: Sheltered Unsheltered
Pen density: Low Low  Low High
Bedding: Yes No  No No
Treatment no.: 1 2 P-value  4 P-value
Animal conditionb   0.020   0.00
 Score 0, %a 20.00 46.67  50.00 16.67
 Score 1, %a 4. 6.67  26.67 4.
 Score 2, %a 6.67 16.67  20.00 .
 Score , %a 0.00 0.00  . 1.67 
Lot conditionc   0.001   0.002
 Score 0, %a 50.00 0.00  26.67 0.00
 Score 1, %a 50.00 100.00  7. 96.67
 Score 2, %a 0.00 0.00  0.00 .
aPercentage of pens observed at given score.
bAnimal condition: 0 = clean, no mud; 1 = small lumps of mud on the hide in limited areas of the leg 
and underbelly; 2 = small and large lumps of mud covering larger areas of the legs, side, and under-
belly;  = small and large lumps of mud covering the hide in areas along the hind quarter, stomach, and 
front shoulder.
cLot condition: 0 = no mud or mud less than  inches deep; 1 = mild mud,  to 7 inches deep; 2 = se-
vere mud, more than 7 inches deep.
(Continued on next page)
Page 46 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
nonbedded treatments. Lower cattle 
density resulted in lower (P<0.05) 
mud condition scores on cattle day 
6 to day 71, and lower (P<0.05) mud 
condition scores in the lot for days 6 
to 71, and days 72 to 98. These results 
indicate a lower stocking density can 
potentially improve comfort and per-
formance during winter (cold) and 
spring (rainy) weather patterns.
In both trials, positive responses 
to providing more pen space per ani-
mal and to providing bedding were 
observed. However, responses were 
not always maintained for the dura-
tion of the trials. Lowering pen den-
sity tended (P=0.08) to enhance ADG 
over the entire trial in Trial 1, while 
F/G tended (P=0.07) to improve and 
marbling score increased (P=0.001) 
in Trial 2. Benefits of bedding were 
not sustained. Bedding did increase 
the percentage of condemned livers in 
Trial 2, however trends in the percent-
age of condemned livers as a result 
of providing bedding or changing 
pen density were opposite for the two 
trials. For both trials, decreasing pen 
density lowered lot mud condition 
scores; however, the use of bedding 
did not consistently improve animal 
or lot mud condition scores.
The use of straw bedding may 
improve cattle performance dur-
ing periods of cold stress in feedlots 
that are not sheltered. However, in 
sheltered feedlots or times of no cold 
stress, bedding has little effect on 
ADG or F/G. It was more effective to 
reduce mud in feedlots by reducing 
the pen density versus using bedding 
during typical winter/spring weather 
patterns.
1Terry Mader, professor; and Sheryl Colgan, 
research technologist, Animal Science, Haskell 
Agricultural Laboratory/Northeast Research and 
Extension Center, Concord.
Table 5. Animal and lot mud condition scores (Trial 2).
 Bedding Density
  None  Bedded P-Value Low High P-Value
Animal conditionb
 Score, day 0 to 5   1.00   0.1
  0, %a 57.41 58.  60.19 55.56
  1, % a 24.07 26.85  26.85 24.07
  2, % a 12.96 4.6  12.04 5.56
  , % a 5.56 10.19  8. 7.41 
 Score, day 6 to 71   0.92   0.001
  0, %a 0 0  0 0   
  1, %a  1.82 0.0  52.27 9.85
  2, %a  56.06 58.  7.88 76.52
  , %a 12.12 11.6  9.85 1.64 
 Score, day 72 to 98   1.00   1.000
  0, %a 0 0  0 0
  1, %a 100.00 100.00  100.00 100.00
  2, %a 0 0  0 0
  , %a 0 0  0 0 
Lot conditionc
 Score, day 0 to 5d   1.00   1.000
  0, % a 1 . .  . .
  1, % a 1 66.67 66.67  66.67 66.67
  2, % a 1 0 0  0 0 
 Score, day 6 to 71e   0.557   0.001
  0, %a 10.61 11.6  15.15 6.82
  1, %a 75.00 69.70  77.27 67.42
  2, %a 14.9 18.94  7.58 25.76 
 Score, day 72 to 98f   0.641   0.001
  0, %a 75.00 71.88  84.40 62.50
  1, %a 17.71 19.79  12.50  25.00
  2, %a 7.29 8.  .10 12.50
aPercentage of animals or pens observed at given score over all days in given period.
bAnimal Condition: 0 = clean, no mud; 1 = small lumps of mud o the hide in limited area of the leg 
and underbelly; 2 = small and large lumps of mud covering larger areas of the legs, side, and under-
belly;  = small and large lumps of mud covering the hide in areas along the hind quarter, stomach, and 
front shoulder; 4 = lumps of mud continuously covering the underbelly and side of the animal from 
brisket to rear quarter.
cLot condition: 0 = no mud or mud less than ” deep; 1 = mild mud  to 7” deep; 2 = severe mud, more 
than 7” deep.
dn = 216; 144 frozen, 72 thawed.
en = 264; 168 frozen, 96 thawed.
fn = 192; 24 frozen, 168 thawed.
n = number of pen observations.


Pen Density and Straw Bedding During Feedlot Finishing

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2007 Pen Density and Straw Bedding During Feedlot Finishing Terry L. Mader University of Nebraska-Lincoln, tmader1@unl.edu Sheryl L. Colgan Haskell Agricultural Laboratory/Northeast Research and Extension Center, Concord Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Mader, Terry L. and Colgan, Sheryl L., "Pen Density and Straw Bedding During Feedlot Finishing" (2007). Nebraska Beef Cattle Reports. 70. https://digitalcommons.unl.edu/animalscinbcr/70 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. © The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 4 Pen Density and Straw Bedding During Feedlot FinishingTerry L. MaderSheryl L. Colgan1SummaryTwo experiments evaluated effects of straw bedding (in sheltered and unsheltered facilities) and pen density (in unsheltered facilities) on cattle performance during winter/spring (mid-December to late March) sea-sons. Bedding had no effect on overall performance in the sheltered facilities, but performance improvements were noted from December through February in unsheltered facilities. Lowering pen density (increasing pen space per ani-mal) improved performance and low-ered mud condition scores on the animal and in the feedlot.IntroductionManaging cattle in periods of adverse weather can be challenging. Winter cold and wind, combined with precipitation, can increase the main-tenance requirement of feedlot cattle and decrease performance. While cold stress alone can reduce profits, it is most detrimental when combined with mud. Cattle in mud have a ten-dency to eat less frequently and the muddy hair coat reduces insulation. Shelter belts and windbreaks have been shown to be effective at reducing cold stress, however, more knowledge regarding how to reduce mud and mud effects in feedlots is needed.While feedlot surface mainte-nance, such as removing manure and rebuilding mounds, can help reduce mud in the winter and spring time, more can be done to further mini-mize the problems associated with mud. The objectives of our trials were to evaluate the effects of adding straw bedding and reducing pen density to reduce mud and cold stress in feedlot cattle.ProcedureOne-hundred eighty (Trial 1) and two-hundred thirty-four (Trial 2) crossbred steers were received at Haskell Agricultural Laboratory, Concord, Neb. Following receiving, all cattle were vaccinated (Vision 7 and Titanium 5 PHM Bac 1; Inter-vet, Millsboro, Del.). Additionally, in Trial 1, cattle were implanted (Ralgro; Schering-Plough Animal Health, Kenilworth N.J.) following receiving. At trial initiation (d-1), steers in both trials were revaccinated (Vision 7 and Titanium 5; Intervet, Millsboro, Del.), treated for external parasites (Saber; Schering-Plough Animal Health, Kenilworth, N.J.), and weighed. In Trial 2, cattle were implanted with Ralgro at trial initiation. On day 0 (Dec. 18, 200, and Dec. 16, 2004, respectively) of each trial, steers were weighed and randomly assigned to 20 pens (Trial 1) or 24 pens (Trial 2) based on the weight from the previ-ous day (day-1). Average body weight for the two consecutive days was used as the initial weight (Trial 1 mean BW=824 lb; Trial 2 mean BW=885 lb). In both trials, cattle were treated for external parasites (Saber) and reim-planted (Revalor-S; Intervet, Mills-boro, Del.) on day 5 (Trial 1) or d 4 (Trial 2). Throughout both trials, all cattle were fed a 65.2 NEg mcal/cwt finishing diet which contained (DM Basis) 8.1% dry rolled corn, 6.0% corn silage, 5.0% alfalfa, .7% liquid protein supplement, and 2.2% dry Rumensin-Tylan (Elanco; Indianapo-lis, Ind.) supplement. In Trial 1, pens were randomly assigned to the following treatments: 1) Low pen density, oat straw bedding, sheltered (overhead shelter, enclosed on north side, and open to dirt lot on south side) feeding area; 2) Low pen density, no bedding, sheltered feeding area; ) Low pen density, no bedding, unsheltered feeding area; or 4) high pen density, no bedding, unsheltered feeding area. The treatments (Trt) were chosen to exemplify a range of environmental conditions from most comfortable (Trt 1) to least comfort-able (Trt 4). For Trial 2, treatments were assigned to pens using a 2 x 2 factorial design, which consisted of pen density (High vs Low) and oat straw bedding (provided vs not pro-vided).In both trials, pen density was obtained by adjusting the number of head per pen in two different pen sizes. The low pen density treat-ment consisted of 6 or 7 head/pen for a stocking rate of approximately 500 ft2/head. The high pen density treatment had 12 or 14 head/pen for a stocking rate of approximately 250 ft2/head. All cattle had a minimum of 18 inches of bunk space/head.In both trials, pens receiving the bedding treatment were bedded at the rate of 5 lb/head/day the first day of the trial. Thereafter, bedding was applied at the rate of approximately 2 lb/head/day based on the following two primary thresholds: 1) air tem-perature was below 14oF; and/or 2) precipitation of at least 0.10 inch rain or 1 inch snow was received. When more than 0.10 inch rain or 1 inch snow was received, cattle were bed-ded on subsequent days for each 0.10 inch rain or 1 inch snow. Additionally, when there was melting snow or mud in the pen, even if thresholds were not met, cattle received 2 lb/head/day of bedding every day or every other day, respectively, until the snow and mud were gone. Slight alternations in the bedding schedules were made to maintain a minimal amount of bedding in the pens at all times, however, in Trial 2, no bedding was added from day 98 to the end of the trial due to warmer temperatures and greater windspeeds, which allowed for improved conditions in the pens. Bedding was added to pens a total of 65 and 59 days in Trial 1 and 2, respectively.(Continued on next page)Page 44 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.Feed intakes were recorded daily. Body weights were obtained on days 0, 5, and 110 in Trial 1 and on days 0, 4, 71, and 98 in Trial 2. Cattle were fed 110 and 124 d in Trials 1 and 2, respectively. In Trial 1 (after thawing) and Trial 2 (trial duration), animal and lot mud condition scores were recorded twice per week. Animal mud condition scores were defined as: 0) clean, no mud; 1) small lumps of mud on the hide in limited areas of the leg and underbelly; 2) small and large lumps of mud covering larger areas of the legs, side, and underbelly; ) small and large lumps of mud covering the hide in even areas that included the hind quarter, stomach, and front shoulder; or 4) lumps of mud con-tinuously covering the underbelly and side of the animal from brisket to rear quarter. Lot mud condition scores were defined as: 0) no mud or mud less than  inches deep; 1) mild mud,  to 7 inches deep; or 2) severe mud, more than 7 inches deep. Ad-ditionally, in Trial 2, lot condition was denoted as frozen ground or thawed. At slaughter (day 110, Trial 1; and day 124, Trial 2) final weight, hot carcass weight, liver score, USDA marbling score, and USDA yield grades were obtained.Statistical analysis of performance data, marbling scores, and yield grade was done using General Linear Models procedures of SAS. In Trial 1, the model included Trt. Contrasts were used to compare density in the unsheltered feed area treatments and bedding in the sheltered feed area treatments. In Trial 2, the model included density, bedding, and the density by bedding interaction. Liver and mud condition scores (animal and lot) were analyzed using fre-quency procedures of SAS. The  P-value reported is the Mantel-Haenszel Chi-Square.Table 1. Weather conditions for trials.a  Mean Ta, ºF Max Ta, ºF Min Ta, ºF RH, % WSPD, mph Precip, in  Trial 1 day 0 to 5 25.44 6.4 1.97 75.0 5.29 0.16 day 6 to 110 5.78 47.26 24.9 7.96 6.46 .75 day 0 to 110 2.58 4.90 21.16 74.8 6.10 .91Trial 2 day 0 to  16.55 25.8 5.82 75.0 5.8 0.1 day 4 to 70 0.85 40.46 20.47 82.5 5.99 1.21 day 71 to 98 .28 46.11 20.06 67.5 6.79  0.0 day 99 to 124 49.77 60.57 8.25 68.0 8.4 1.98 day 0 to 124 1.56 42.06 20.21 74.1 6.62 .5aTa = Ambient temperature; RH = relative humidity; WSPD = wind speed; Precip = precipitation, as rain or melted snow.Table 2. Performance and carcass data (Trial 1).  Facilities  Sheltered UnshelteredPen Density: Low Low Low HighBedding: Yes No No No    ContrastsTreatment No: 1 2  4 SEM P-Value 1 v 2  v 4 1 v 4Weight, lb day 0 82 822 824 827 2.0 0.48 0.89 0.46 0.21 day 5 968 967 969 967 8.2 1.00 0.99 0.89 0.99 day 110 1281 1272 1277 1245 14. 0.1 0.68 0.1 0.10 day 110 (adjusted)a 129 128 1247 1216 1.2 0.42 0.9 0.12 0.24ADG, lb day 0 to 5 4.14 4.15 4.14 4.02 0.2 0.98 0.98 0.72 0.7 day 6 to 110 4.12 4.01 4.05 .65 0.16 0.18 0.60 0.09 0.05 day 0 to 110 4.1 4.05 4.08 .77 0.12 0.20 0.66 0.09 0.06 day 0 to 110 (adjusted)a .75 .74 .81 .51 0.11 0.0 0.94 0.08 0.15DMI, lb day 0 to 5 20.57 21.1 20.80 20.64 0.47 0.84 0.41 0.82 0.92 day 6 to 110 22.94 22.99 2.22 22.80 0.60 0.97 0.95 0.62 0.88 day 0 to 110 22.19 22.40 22.46 22.12 0.5 0.96 0.78 0.66 0.9Feed/gain day 0 to 5 5.01 5.12 5.11 5.21 0.26 0.97 0.79 0.80 0.61 day 6 to 110 5.58 5.80 5.75 6.26 0.2 0.22 0.50 0.1 0.05 day 0 to 110 5.9 5.57 5.50 5.88 0.18 0.27 0.49 0.15 0.07 day 0 to 110 (adjusted)a 5.94 6.0 5.90 6.2 0.22 0.54 0.78 0.19 0.24Carcass data HCW, lb 769 767 77 754 8.2 0.4 0.92 0.1 0.24 Marbling scoreb 48 460 495 481 11. 0.22 0.18 0.9 0.91 Yield grade 2.45 2.26 2.9 2.4 0.11 0.65 0.2 0.7 0.47 Dressing % 60.0 60. 60.6 60.6 .0 0.57 0.45 0.96 0.22 Liver scorec 0 . 2.86 5.71 — — 0.1 0.52 —aBased on hot carcass weight adjusted to a 62% dressing percentage.bMarbling score: 400 = slight0 (select), 500 = small0 (low choice). cPercentage condemned, due to abscesses based on Chi-Square analysis.© The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 45 ResultsIn Trial 1 (Table 2), there were no differences for bedding versus no bed-ding (Trt 1 vs Trt 2) in the sheltered cattle. In the unsheltered groups, low pen density tended to increase (P<0.10) ADG from days 5 to 110, and day 0 to 110, when based on unadjusted full weights. Cattle with bedding and the most pen space (Trt 1) had improved ADG and lower F/G from days 6 to 110 (P<0.05) when compared with nonbedded cattle with the least pen space (Trt 4). Over-all performance was similar among groups when comparisons were based on a common dressing percentage, however, in the unsheltered group, in-creased cattle density tended (P<0.10) to reduce overall gain. In Trial 2 (Table ), the addition of bedding increased (P<0.05) day 4 weight, day 71 weight, ADG from days 0 to 4 and ADG from days 0 to 71, and improved feed efficiency from days 0 to 71. The low density group had lower (P<0.05) DMI and F/G from day 0 through day 98 when compared with the high density group. The low density group tended (P=0.07) to have lower overall F/G and a greater (P=0.001) marbling score when compared with the high density group. Bedding improved (P=0.0) F/G through day 71 only, however, it did result in a greater (P=0.02) percentage of condemned livers. There were no pen density by bedding interactions for performance or carcass data. In Trial 1, bedding did not (P=0.02) result in lowering animal mud condition scores, but did lower (P<0.001) lot mud condition scores. However, animal and lot mud condi-tion scores were lower (P<0.005) in the low density treatment when com-pared with the high density treatment. Data suggest cattle with bedding were dirtier (P<0.05) than cattle without bedding, even though pens with bedding were less muddy (P<0.05). In Trial 2 (Table 5), no differences (P>0.05) in animal or lot mud condi-tion were observed for bedded versus Table 3. Performance and carcass data (Trial 2).  Pen density (Den)a Bedding (Bed) P-values  Low High No Yes SEM Den Bed Den*BedNo. pens 12 12 12 12Weight, lb Initial 879 882 878 884 2.5 0. 0.11 0.19 day 4 1048 1054 104 1059 4. 0.4 0.01 0.09 day 71 116 1160 1150 1172 5.8 0.76 0.02 0.25 day 98 1252 1248 124 1257 7.2 0.64 0.20 0.7 Finalb 128 127 120 16 8.5 0.95 0.41 0.45ADG, lb day 0 to 4 4.84 4.91 4.7 5.02 0.09 0.61 0.04 0.2 day 0 to 71 4.00 .91 .85 4.07 0.06 0. 0.02 0.46 day 0 to 98 .82 .74 .74 .82 0.06 0. 0.41 0.70 day 0 to 124b .6 .59 .57 .65 0.04 0.57 0.6 0.50DMI, lb day 0 to 4 22.87 24.96 2.81 24.01 0.9 <0.01 0.7 0.57 day 0 to 71 22.42 24.02 2.25 2.18 0.8 0.01 0.90 0.8 day 0 to 98 21.8 2.41 22.64 22.60 0.5 0.00 0.9 0.27 day 0 to 124 22.11 2.87 2.04 22.94 0.9 0.19 0.89 0.20F/G day 0 to 4 4.74 5.10 5.05 4.80 0.11 0.0 0.12 0.6 day 0 to 71 5.62 6.15 6.05 5.72 0.10 <0.01 0.0 0.75 day 0 to 98 5.72 6.28 6.05 5.94 0.11 <0.01 0.46 0.45 day 0 to 124b 6.11 6.66 6.46 6.1 0.05 0.07 0.25 0.45Carcass datac Dressing % 6.9 64.0 6.5 64. 0.19 0.65 0.21 0.40 HCW 82 82 818 828 6.8 0.94 0.2 0.46 Marblingd 56 527 57 552 7.6 0.00 0.16 0.59 Yield Grade 2.8 2.7 2.40 2.4 0.07 0.92 0.56 0.4 Liver Scoree 10.56 5.6 2.5 6.57 — 0.2 0.02  —aLow = 500 ft2/animal; High = 250 ft2/animal.bFinal weight (d 124) calculated as hot carcass weight (HCW) divided by a 62% dressing percentage.cCarcass data was analyzed using the individual animal as experimental unit.dMarbling score: 500 = Small0 (Low Choice), 600 = Modest0 (Average Choice)ePercentage condemned, due to abscesses; based on Chi-Square analysis.Table 4. Animal and lot mud condition scores (Trial 1).Feeding area: Sheltered UnshelteredPen density: Low Low  Low HighBedding: Yes No  No NoTreatment no.: 1 2 P-value  4 P-valueAnimal conditionb   0.020   0.00 Score 0, %a 20.00 46.67  50.00 16.67 Score 1, %a 4. 6.67  26.67 4. Score 2, %a 6.67 16.67  20.00 . Score , %a 0.00 0.00  . 1.67 Lot conditionc   0.001   0.002 Score 0, %a 50.00 0.00  26.67 0.00 Score 1, %a 50.00 100.00  7. 96.67 Score 2, %a 0.00 0.00  0.00 .aPercentage of pens observed at given score.bAnimal condition: 0 = clean, no mud; 1 = small lumps of mud on the hide in limited areas of the leg and underbelly; 2 = small and large lumps of mud covering larger areas of the legs, side, and under-belly;  = small and large lumps of mud covering the hide in areas along the hind quarter, stomach, and front shoulder.cLot condition: 0 = no mud or mud less than  inches deep; 1 = mild mud,  to 7 inches deep; 2 = se-vere mud, more than 7 inches deep.(Continued on next page)Page 46 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.nonbedded treatments. Lower cattle density resulted in lower (P<0.05) mud condition scores on cattle day 6 to day 71, and lower (P<0.05) mud condition scores in the lot for days 6 to 71, and days 72 to 98. These results indicate a lower stocking density can potentially improve comfort and per-formance during winter (cold) and spring (rainy) weather patterns.In both trials, positive responses to providing more pen space per ani-mal and to providing bedding were observed. However, responses were not always maintained for the dura-tion of the trials. Lowering pen den-sity tended (P=0.08) to enhance ADG over the entire trial in Trial 1, while F/G tended (P=0.07) to improve and marbling score increased (P=0.001) in Trial 2. Benefits of bedding were not sustained. Bedding did increase the percentage of condemned livers in Trial 2, however trends in the percent-age of condemned livers as a result of providing bedding or changing pen density were opposite for the two trials. For both trials, decreasing pen density lowered lot mud condition scores; however, the use of bedding did not consistently improve animal or lot mud condition scores.The use of straw bedding may improve cattle performance dur-ing periods of cold stress in feedlots that are not sheltered. However, in sheltered feedlots or times of no cold stress, bedding has little effect on ADG or F/G. It was more effective to reduce mud in feedlots by reducing the pen density versus using bedding during typical winter/spring weather patterns.1Terry Mader, professor; and Sheryl Colgan, research technologist, Animal Science, Haskell Agricultural Laboratory/Northeast Research and Extension Center, Concord.Table 5. Animal and lot mud condition scores (Trial 2). Bedding Density  None  Bedded P-Value Low High P-ValueAnimal conditionb Score, day 0 to 5   1.00   0.1  0, %a 57.41 58.  60.19 55.56  1, % a 24.07 26.85  26.85 24.07  2, % a 12.96 4.6  12.04 5.56  , % a 5.56 10.19  8. 7.41  Score, day 6 to 71   0.92   0.001  0, %a 0 0  0 0     1, %a  1.82 0.0  52.27 9.85  2, %a  56.06 58.  7.88 76.52  , %a 12.12 11.6  9.85 1.64  Score, day 72 to 98   1.00   1.000  0, %a 0 0  0 0  1, %a 100.00 100.00  100.00 100.00  2, %a 0 0  0 0  , %a 0 0  0 0 Lot conditionc Score, day 0 to 5d   1.00   1.000  0, % a 1 . .  . .  1, % a 1 66.67 66.67  66.67 66.67  2, % a 1 0 0  0 0  Score, day 6 to 71e   0.557   0.001  0, %a 10.61 11.6  15.15 6.82  1, %a 75.00 69.70  77.27 67.42  2, %a 14.9 18.94  7.58 25.76  Score, day 72 to 98f   0.641   0.001  0, %a 75.00 71.88  84.40 62.50  1, %a 17.71 19.79  12.50  25.00  2, %a 7.29 8.  .10 12.50aPercentage of animals or pens observed at given score over all days in given period.bAnimal Condition: 0 = clean, no mud; 1 = small lumps of mud o the hide in limited area of the leg and underbelly; 2 = small and large lumps of mud covering larger areas of the legs, side, and under-belly;  = small and large lumps of mud covering the hide in areas along the hind quarter, stomach, and front shoulder; 4 = lumps of mud continuously covering the underbelly and side of the animal from brisket to rear quarter.cLot condition: 0 = no mud or mud less than ” deep; 1 = mild mud  to 7” deep; 2 = severe mud, more than 7” deep.dn = 216; 144 frozen, 72 thawed.en = 264; 168 frozen, 96 thawed.fn = 192; 24 frozen, 168 thawed.n = number of pen observations.

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Pen Density and Straw Bedding During Feedlot Finishing

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