Ruminally fistulated steers with wireless pH probes were utilized to quantify ruminal pH plus hydrogen sulfide (H2S) levels produced at different times post feeding and to determine the effect of roughage level in high byproducts diets on hydrogen sulfide production. Because of variation in H2S levels, ruminal pH was not related to high H2S levels. When treatment means were used, pH and H2S levels were highly correlated. We observed lower H2S levels in diets with 7.5% or 15% grass hay compared with no roughage

Erickson, Galen E.

Klopfenstein, Terry J.

Meyer, Nathan

Vanness, Sarah

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department 2009 Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage Levels Sarah Vanness University of Nebraska-Lincoln Nathan Meyer University of Nebraska-Lincoln, nmeyer2@unl.edu Terry J. Klopfenstein University of Nebraska-Lincoln, tklopfenstein1@unl.edu Galen E. Erickson University of Nebraska-Lincoln, gerickson4@unl.edu Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Vanness, Sarah; Meyer, Nathan; Klopfenstein, Terry J.; and Erickson, Galen E., "Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage Levels" (2009). Nebraska Beef Cattle Reports. 540. https://digitalcommons.unl.edu/animalscinbcr/540 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. 2009 Nebraska Beef Report  — Page 81 Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage LevelsSarah J. VannessNathan F. MeyerTerry J. KlopfensteinGalen E. Erickson1SummaryRuminally fistulated steers with wire-less pH probes were utilized to quantify ruminal pH plus hydrogen sulfide (H2S) levels produced at different times post feeding and to determine the effect of roughage level in high byproducts diets on hydrogen sulfide production. Because of variation in H2S levels, ruminal pH was not related to high H2S levels. When treatment means were used, pH and H2S levels were highly correlated. We observed lower H2S levels in diets with 7.5% or 15% grass hay compared with no roughage.IntroductionIn a recent finishing study (Wilken et al., 2009 Nebraska Beef Report, pp. 76-78), steers fed 66% wet distill-ers grains plus solubles (WDGS) with a higher roughage level (29.4% DM) did not experience polio (sul-fur level 0.55%), whereas cattle fed a diet with a somewhat lower level of sulfur (0.48%) and low roughage (7.5% DM) did experience some polio cases. Based on a recent summary of University of Nebraska–Lincoln byproduct research (Vanness et al., 2009 Nebraska Beef Report, pp. 79-80), cattle can tolerate up to 0.46% sulfur with little risk (0.1%) of polio. The National Research Council (2003) suggests cattle fed corn-based diets can tolerate only 0.30% sulfur in the diet. It is believed that hydrogen sulfide (H2S) production by rumen micro-organisms is the direct cause of polio-encephalomalacia with high dietary S levels. An objective of the current study was to determine the effect of roughage level in high byproduct diets on H2S levels in the rumen. An added objective was to determine the relationship between ruminal pH and hydrogen sulfide concentration.ProcedureIn Experiment 1, seven ruminally fistulated steers were fed during a 4-week adaptation period. Steers were housed in individual pens with bunks suspended from load cells. Cattle were fed twice daily at 0700 and 1600 with 50% of the feed at each time. Bunks were evaluated and residual feed weighed before the 0700 feeding. All steers were stepped up on the same diet. Each grain adaptation diet was fed for seven days with a common finisher being fed in week 4 (Table 1). Steers were fed decreasing amounts of alfalfa hay and increasing amounts of dry-rolled corn (DRC) for three weeks, with wet distillers grains plus solubles (WDGS) held constant at 50% diet DM. Wireless pH probes were inserted to measure ruminal pH. Measurements were taken every minute and recorded onto a data log-ger. Loggers were downloaded prior to feeding on the first day of each adap-tation diet.The finishing diet included 50% WDGS (received from Abengoa Bioenergy, York, Neb.), 37.5% DRC, 7.5% alfalfa and 5% supplement. The dietary S level was 0.44%. Gas samples were collected on the last day of each step. Gas collection devices were inserted through the ruminal cannula prior to feeding on day 7 and samples were collected at 1500 that day and 0600 (prior to feed-ing) on the next day (day 1 of the next adaptation diet). Four gas samples were taken from each steer at each time point.In Experiment 2, seven ruminally fistulated steers were used in a 6 x 6 Latin square design. Two steers con-sumed the same diet throughout the trial. A 3 x 2 factorial treatment design was used. The first factor was three different inclusion levels of grass hay (0%, 7.5% or 15%, DM basis), while the second factor was two different byproduct inclusion levels and sources (Table 2). One of the diets tested by Wilken and others (2009 Nebraska Beef Report, pp. 76-78) consisted of a 50:50 blend of wet corn gluten feed (WCGF) and WDGS. That diet was replicated in this experiment . Each period was seven days (six days of adaptation and one day of collection). Steers were housed in individual pens with bunks suspended from load cells. Bunk measurements were taken every minute. Steers were fed twice daily with equal amounts at 0700 and 1600. Feed amounts were determined and feed refusal weighed if present before the 0700 feeding. Rumen gas samples were collected on day 7 of each period as described above. Data were analyzed as a 6 x 6 Latin square using the MIXED procedure Table 1. Diet compositions and nutrient analysis of adaptation diets in Experiment 1.Items Diet 1 Diet 2 Diet 3 FinisherWDGS1 50.0 50.0 50.0 50.0Alfalfa 35.0 25.0 15.0 7.5DRC2 10.0 20.0 30.0 37.5Supplement 5.00 5.0 5.0 5.00CP, % DM 24.96 23.89 22.82 22.02Fat, % DM 6.66 6.90 7.13 7.31NDF, % DM 29.48 27.32 25.16 23.54Sulfur, % DM 0.50 0.48 0.46 0.441WDGS = wet distillers grains plus solubles.2DRC = dry-rolled corn.(Continued on next page)Page 82 — 2009 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.and P = 0.05, respectively; Table 3). We hypothesized that H2S levels would increase as roughage level decreased during grain adaptation. The increased H2S production could be a result of reduced dietary fiber or increased dietary starch concentra-tion. Intake increased (P < 0.01) as the cattle were adapted over the 21 days prior to the finishing diet.Average pH, maximum pH and minimum pH decreased (P < 0.01) as the cattle were stepped up to the fin-isher diet. The area under pH 5.6 and 5.3 increased (P < 0.01) as cattle were adapted to the finisher diet.In Experiment 2, there were no by-product x grass hay level interactions; therefore, main effects are presented (Table 4). Cattle fed the combination byproduct diet had greater dry matter intake (DMI; P = 0.07); however, average, maximum and minimum ruminal pH levels also were higher (P < 0.01) than in those who received the diet with lower byproduct inclu-sion. The H2S levels were not different between the two diets. No differences were observed between byproduct diets for area under pH 5.6, pH change (maximum-minimum ), or pH variance (P > 0.10).With increasing grass hay levels in the diets (Table 5), DMI and average, maximum and minimum ruminal pH increased linearly (P < 0.03). No differences were observed for area under pH 5.6, 5.3 or 5.0. At 8 hours post-feeding, H2S levels declined lin-early as grass hay levels in the diets increased (P < 0.01). At 23 hours post feeding, a numerical decrease in H2S was observed with increasing grass hay levels. Because of the relatively high ruminal pH levels with the com-bination byproduct diet, it might be tempting to remove the roughage from the diet to improve feed effi-ciency. These data illustrate that the H2S level of the diet with 7.5% hay was 44% of the H2S level in the no rough-age diet. Therefore, the risk of polio is expected to be much greater for cattle fed the no roughage diet; diets should contain at least 6-7% roughage.The 7.5% hay diet is probably typi-cal of most commercial feedlot diets. Table 2. Diet compositions and nutrient analysis of byproduct combination diets with varying amounts of grass hay in Experiment 2.  50% WDGS   37.5% WDGS /37.5%WCGFRoughage level: 0 7.5 15 0 7.5 15WDGS1 50.0 50.0 50.0 37.5 37.5 37.5WCGF2 0.0 0.0 0.0 37.5 37.5 37.5Grass hay 0.0 7.5 15.0 0.0 7.5 15.0DRC3 45.0 37.5 30.0 20.0 13.5 6.0Supplement 5.0 5.0 5.0 5.0 5.0 5.0Nutrient compositionCP, % DM 21.9 21.8 21.7 25.4 25.3 25.2NDF, % DM 21.8 26.3 30.8 28.4 32.9 37.4Fat, % DM 7.2 7.2 7.1 6.2 6.2 6.1Sulfur, % DM 0.43 0.42 0.41 0.47 0.46 0.451WDGS = wet distillers grains plus solubles.2WCGF = wet corn gluten feed.3DRC = dry-rolled corn.Table 3. Effects of adaptation diet on pH and H2S values in Experiment 1. Diet 1 Diet 2 Diet 3 Finisher P-ValueDMI, (lb/d) 14.70 16.70 19.49 20.62 < 0.01Average pH 6.05 5.51 5.49 5.51 < 0.01Max pH 6.65 6.27 6.08 6.19 < 0.01Min pH 5.54 5.10 5.14 5.15 < 0.01pH change 1.14 1.17 0.94 1.05 < 0.01Area < 5.61 0.38 335.39 285.18 1438.79 < 0.01Area < 5.31 6.51 150.95 91.07 73.09 0.02H2S 8 h2 8.90 8.30 47.70 121.50 < 0.01H2S 23 h3 6.20 4.50 21.20 33.30 0.051Area is magnitude of pH under respective pH by minute.2H2S values are μmol hydrogen sulfide gas per mL of rumen gas collected 8 hours post feeding.3H2S values are μmol hydrogen sulfide gas per mL of rumen gas collected 23 hours post feeding.Table 4. Main effects of byproduct for intake, ruminal pH and H2S in Experiment 2.Item WDGS WDGS/WCGF1 SE P-valueDMI (lb/day) 20.6 21.1 0.3 0.15Average pH 5.69 5.87 0.0 <0.01Max. pH 6.31 6.47 0.0 <0.01Min. pH 5.26 5.45 0.0 <0.01Area < 5.62 253.5 168.2 60.5 0.26pH change 1.04 1.01 0.0 0.71pH variance 0.06 0.05 0.0 0.20H2S 8 h3 53.1 87.9 15.7 0.13H2S 23 h4 88.2 65.0 20.0 0.281WDGS = wet distillers grains plus solubles, WCGF = wet corn gluten feed.2Area under curve is magnitude of pH < 5.6 by minute.3Values are μmol hydrogen sulfide/mL rumen gas collected 8 hours post feeding.4Values are μmol hydrogen sulfide/mL rumen gas collected 23 hours post feeding.of SAS (SAS Inst. Inc.). Treatment was included in the model as a fixed effect with animal being the random effect. No byproduct x grass hay level interac-tions were observed (P > 0.23); there-fore, only main effects of byproduct or grass hay levels were reported. The correlation procedure of SAS was used to determine correlations between pH and H2S values. With the high variability in individual data, treat-ment means also were used for correla-tion calculations.ResultsIn Experiment 1, H2S levels increased as roughage decreased (grain adaptation) at both 8 and 23 hours post feeding, (P < 0.01 © The Board of Regents of the University of Nebraska.  All rights reserved. 2009 Nebraska Beef Report  — Page 83 Doubling the hay level to 15% reduced H2S levels in the rumen. Approxi-mately 55% less H2S was produced in the 15% hay diet compared to the 7.5% hay diet at 8 hours post feeding.At this time, we have not devel-oped a cause-and-effect relationship between ruminal H2S levels and polio. However, we assume the risk of polio is decreased if ruminal H2S levels are decreased. Feeding additional rough-age with high byproduct diets appears to reduce H2S levels and therefore the risk of polio.We hypothesized pH to be posi-tively correlated with the level of H2S concentration in the rumen. There were no significant correla-tions using individual animal data at 8 or 23 hours post feeding in either experiment (Table 6). The lack of significant correlations appears to be due to the large variability in H2S concentrations; therefore, treatment mean correlations were calculated. In Experiment 1, area below pH 5.6 on the same day was correlated to H2S levels at both 8 (r = 0.94, P = 0.06) and 23 hours (r = 0.85, P = 0.15) post feeding. In Experiment 2, there was a tendency for the 23-hour H2S level to increase as average pH decreased  (r = -0.92, P = 0.13). There also was a tendency for the 8-hour H2S level to increase as the amount of time below pH 5.6 the previous day increased (r = 0.98, P = 0.12) At 23 hours post feeding, H2S levels increased as the area below pH 5.6 of the same day increased (r = 0.98, P = 0.13). We conclude that average ruminal pH is negatively correlated with ruminal H2S levels. Roughage level in the diet appears to be very important. In these experiments, dietary sulfur levels ranged from 0.47% to 0.41%; the H2S levels ranged from 125.9 to 29.7μmol/mL of rumen gas. In another study (Vanness et al. 2009 Nebraska Beef Report pp. 84-85), H2S levels at 12 hours post feeding ranged from 19.3μmol/mL when dietary S levels were 0.53%, to 13.7μmol/mL when dietary S levels were 0.34%. This does not show a clear relationship between dietary S levels and ruminal H2S levels. However, this comparison is across experiments and a conclusion Table 5. Main effect of grass hay level in Experiment 2 for intake, ruminal pH and H2S.  Grass hay levelItem 0 7.5 15.0 SE Lin. Quad.DMI, lb/day 20.6 20.4 21.5 0.3 < 0.03 0.08Average pH 5.62 5.75 5.96 0.0 < 0.01 0.42Max pH 6.22 6.32 6.62 0.0 < 0.01 0.03Min pH 5.25 5.37 5.44 0.0 < 0.01 0.58Area < 5.61 306.0 176.8 149.7 72.0 0.08 0.54Area < 5.31 73.4 29.6 39.2 20.0 0.19 0.27Area < 5.01 4.3 2.4 2.4 1.6 0.33 0.59pH change 1.0 1.0 1.2 0.0 < 0.01 < 0.01H2S 8 h2 125.9 55.9 29.7 19.0 < 0.01 0.37H2S 23 h3 91.5 84.1 54.2 30.0 0.45 0.671Area is magnitude of pH under respective pH by minute.2Values are μmol hydrogen sulfide mL of rumen gas collected 8 hours post feeding.3Values are μmol of hydrogen sulfide mL of rumen gas collected 23 hours after first feeding.Table 6. Correlation of ruminal pH to H2S levels at 8 and 23 hours post feeding.Item 8 hour P-value 23 hour P-valueExperiment 1    Individual1 Average pH 0.12 0.95 -0.05 0.79 Area < 5.6 -0.21 0.29 -0.03 0.86 Previous day time < 5.62 -0.05 0.80 0.06 0.73 Time < 5.6 -0.01 0.95 0.01 0.95Treatment mean3 Average pH -0.47 0.53 -0.50 0.50 Area < 5.6 0.94 0.06 0.85 0.15 Previous day time < 5.6 0.37 0.63 0.42 0.58 Time < 5.6 0.45 0.55 0.50 0.50Experiment 2Individual1 Average pH -0.05 0.76 -0.16 0.41 Area < 5.6 -0.06 0.70 0.02 0.90 Previous day time <5.6 -0.00 0.98 0.30 0.11 Time < 5.6 -0.05 0.73 0.23 0.23Treatment mean2 Average pH -0.92 0.25 -0.98 0.13 Area < 5.6 0.99 0.07 0.77 0.44Previous day time < 5.6 0.98 0.12 0.92 0.26 Time < 5.6 0.93 0.25 0.98 0.131Correlations based on individual animal values for pH and H2S.2This value is the amount of time ruminal pH was below 5.6 one day prior to H2S collection.3Correlations based on treatment mean.cannot be drawn until dietary S levels are compared within an experiment.1Sarah J. Vanness, research technician; Nathan F. Meyer, research technician; Terry J. Klopfenstein, professor; and Galen E. Erickson, associate professor, Animal Science, Lincoln, Neb.

Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage Levels

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
2009 
Ruminal Sulfide Levels in Corn Byproduct Diets with Varying 
Roughage Levels 
Sarah Vanness 
University of Nebraska-Lincoln 
Nathan Meyer 
University of Nebraska-Lincoln, nmeyer2@unl.edu 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
Galen E. Erickson 
University of Nebraska-Lincoln, gerickson4@unl.edu 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Vanness, Sarah; Meyer, Nathan; Klopfenstein, Terry J.; and Erickson, Galen E., "Ruminal Sulfide Levels in 
Corn Byproduct Diets with Varying Roughage Levels" (2009). Nebraska Beef Cattle Reports. 540. 
https://digitalcommons.unl.edu/animalscinbcr/540 
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. 2009 Nebraska Beef Report  — Page 81 
Ruminal Sulfide Levels in Corn Byproduct Diets 
with Varying Roughage Levels
Sarah J. Vanness
Nathan F. Meyer
Terry J. Klopfenstein
Galen E. Erickson1
Summary
Ruminally fistulated steers with wire-
less pH probes were utilized to quantify 
ruminal pH plus hydrogen sulfide (H
2
S) 
levels produced at different times post 
feeding and to determine the effect of 
roughage level in high byproducts diets 
on hydrogen sulfide production. Because 
of variation in H
2
S levels, ruminal pH 
was not related to high H
2
S levels. When 
treatment means were used, pH and 
H
2
S levels were highly correlated. We 
observed lower H
2
S
 
levels in diets with 
7.5% or 15% grass hay compared with 
no roughage.
Introduction
In a recent finishing study (Wilken 
et al., 2009 Nebraska Beef Report, pp. 
76-78), steers fed 66% wet distill-
ers grains plus solubles (WDGS) 
with a higher roughage level (29.4% 
DM) did not experience polio (sul-
fur level 0.55%), whereas cattle fed 
a diet with a somewhat lower level 
of sulfur (0.48%) and low roughage 
(7.5% DM) did experience some polio 
cases. Based on a recent summary 
of University of Nebraska–Lincoln 
byproduct research (Vanness et al., 
2009 Nebraska Beef Report, pp. 79-80), 
cattle can tolerate up to 0.46% sulfur 
with little risk (0.1%) of polio. The 
National Research Council (2003) 
suggests cattle fed corn-based diets 
can tolerate only 0.30% sulfur in the 
diet. 
It is believed that hydrogen sulfide 
(H
2
S) production by rumen micro-
organisms is the direct cause of polio-
encephalomalacia with high dietary 
S levels. An objective of the current 
study was to determine the effect 
of roughage level in high byproduct 
diets on H
2
S levels in the rumen. An 
added objective was to determine the 
relationship between ruminal pH and 
hydrogen sulfide concentration.
Procedure
In Experiment 1, seven ruminally 
fistulated steers were fed during a 
4-week adaptation period. Steers were 
housed in individual pens with bunks 
suspended from load cells. Cattle were 
fed twice daily at 0700 and 1600 with 
50% of the feed at each time. Bunks 
were evaluated and residual feed 
weighed before the 0700 feeding. All 
steers were stepped up on the same 
diet. Each grain adaptation diet was 
fed for seven days with a common 
finisher being fed in week 4 (Table 1). 
Steers were fed decreasing amounts 
of alfalfa hay and increasing amounts 
of dry-rolled corn (DRC) for three 
weeks, with wet distillers grains plus 
solubles (WDGS) held constant at 
50% diet DM. Wireless pH probes 
were inserted to measure ruminal 
pH. Measurements were taken every 
minute and recorded onto a data log-
ger. Loggers were downloaded prior to 
feeding on the first day of each adap-
tation diet.
The finishing diet included 50% 
WDGS (received from Abengoa 
Bioenergy, York, Neb.), 37.5% DRC, 
7.5% alfalfa and 5% supplement. The 
dietary S level was 0.44%. 
Gas samples were collected on the 
last day of each step. Gas collection 
devices were inserted through the 
ruminal cannula prior to feeding on 
day 7 and samples were collected at 
1500 that day and 0600 (prior to feed-
ing) on the next day (day 1 of the next 
adaptation diet). Four gas samples 
were taken from each steer at each 
time point.
In Experiment 2, seven ruminally 
fistulated steers were used in a 6 x 6 
Latin square design. Two steers con-
sumed the same diet throughout the 
trial. A 3 x 2 factorial treatment design 
was used. The first factor was three 
different inclusion levels of grass hay 
(0%, 7.5% or 15%, DM basis), while 
the second factor was two different 
byproduct inclusion levels and sources 
(Table 2). One of the diets tested by 
Wilken and others (2009 Nebraska Beef 
Report, pp. 76-78) consisted of a 50:50 
blend of wet corn gluten feed (WCGF) 
and WDGS. That diet was replicated in 
this experiment . Each period was seven 
days (six days of adaptation and one 
day of collection). 
Steers were housed in individual 
pens with bunks suspended from load 
cells. Bunk measurements were taken 
every minute. Steers were fed twice 
daily with equal amounts at 0700 and 
1600. Feed amounts were determined 
and feed refusal weighed if present 
before the 0700 feeding. Rumen gas 
samples were collected on day 7 of 
each period as described above. 
Data were analyzed as a 6 x 6 Latin 
square using the MIXED procedure 
Table 1. Diet compositions and nutrient analysis of adaptation diets in Experiment 1.
Items Diet 1 Diet 2 Diet 3 Finisher
WDGS1 50.0 50.0 50.0 50.0
Alfalfa 35.0 25.0 15.0 7.5
DRC2 10.0 20.0 30.0 37.5
Supplement 5.00 5.0 5.0 5.00
CP, % DM 24.96 23.89 22.82 22.02
Fat, % DM 6.66 6.90 7.13 7.31
NDF, % DM 29.48 27.32 25.16 23.54
Sulfur, % DM 0.50 0.48 0.46 0.44
1WDGS = wet distillers grains plus solubles.
2DRC = dry-rolled corn.
(Continued on next page)
Page 82 — 2009 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
and P = 0.05, respectively; Table 3). 
We hypothesized that H
2
S levels 
would increase as roughage level 
decreased during grain adaptation. 
The increased H
2
S production could 
be a result of reduced dietary fiber or 
increased dietary starch concentra-
tion. Intake increased (P < 0.01) as the 
cattle were adapted over the 21 days 
prior to the finishing diet.
Average pH, maximum pH and 
minimum pH decreased (P < 0.01) as 
the cattle were stepped up to the fin-
isher diet. The area under pH 5.6 and 
5.3 increased (P < 0.01) as cattle were 
adapted to the finisher diet.
In Experiment 2, there were no by-
product x grass hay level interactions; 
therefore, main effects are presented 
(Table 4). Cattle fed the combination 
byproduct diet had greater dry matter 
intake (DMI; P = 0.07); however, 
average, maximum and minimum 
ruminal pH levels also were higher 
(P < 0.01) than in those who received 
the diet with lower byproduct inclu-
sion. The H
2
S levels were not different 
between the two diets. No differences 
were observed between byproduct 
diets for area under pH 5.6, pH 
change (maximum-minimum ), or pH 
variance (P > 0.10).
With increasing grass hay levels in 
the diets (Table 5), DMI and average, 
maximum and minimum ruminal 
pH increased linearly (P < 0.03). No 
differences were observed for area 
under pH 5.6, 5.3 or 5.0. At 8 hours 
post-feeding, H
2
S levels declined lin-
early as grass hay levels in the diets 
increased (P < 0.01). At 23 hours post 
feeding, a numerical decrease in H
2
S 
was observed with increasing grass 
hay levels. Because of the relatively 
high ruminal pH levels with the com-
bination byproduct diet, it might be 
tempting to remove the roughage 
from the diet to improve feed effi-
ciency. These data illustrate that the 
H
2
S level of the diet with 7.5% hay was 
44% of the H
2
S level in the no rough-
age diet. Therefore, the risk of polio is 
expected to be much greater for cattle 
fed the no roughage diet; diets should 
contain at least 6-7% roughage.
The 7.5% hay diet is probably typi-
cal of most commercial feedlot diets. 
Table 2. Diet compositions and nutrient analysis of byproduct combination diets with varying amounts 
of grass hay in Experiment 2.
  50% WDGS   37.5% WDGS /37.5%WCGF
Roughage level: 0 7.5 15 0 7.5 15
WDGS1 50.0 50.0 50.0 37.5 37.5 37.5
WCGF2 0.0 0.0 0.0 37.5 37.5 37.5
Grass hay 0.0 7.5 15.0 0.0 7.5 15.0
DRC3 45.0 37.5 30.0 20.0 13.5 6.0
Supplement 5.0 5.0 5.0 5.0 5.0 5.0
Nutrient composition
CP, % DM 21.9 21.8 21.7 25.4 25.3 25.2
NDF, % DM 21.8 26.3 30.8 28.4 32.9 37.4
Fat, % DM 7.2 7.2 7.1 6.2 6.2 6.1
Sulfur, % DM 0.43 0.42 0.41 0.47 0.46 0.45
1WDGS = wet distillers grains plus solubles.
2WCGF = wet corn gluten feed.
3DRC = dry-rolled corn.
Table 3. Effects of adaptation diet on pH and H
2
S values in Experiment 1.
 Diet 1 Diet 2 Diet 3 Finisher P-Value
DMI, (lb/d) 14.70 16.70 19.49 20.62 < 0.01
Average pH 6.05 5.51 5.49 5.51 < 0.01
Max pH 6.65 6.27 6.08 6.19 < 0.01
Min pH 5.54 5.10 5.14 5.15 < 0.01
pH change 1.14 1.17 0.94 1.05 < 0.01
Area < 5.61 0.38 335.39 285.18 1438.79 < 0.01
Area < 5.31 6.51 150.95 91.07 73.09 0.02
H
2
S 8 h2 8.90 8.30 47.70 121.50 < 0.01
H
2
S 23 h3 6.20 4.50 21.20 33.30 0.05
1Area is magnitude of pH under respective pH by minute.
2H
2
S values are μmol hydrogen sulfide gas per mL of rumen gas collected 8 hours post feeding.
3H
2
S values are μmol hydrogen sulfide gas per mL of rumen gas collected 23 hours post feeding.
Table 4. Main effects of byproduct for intake, ruminal pH and H
2
S in Experiment 2.
Item WDGS WDGS/WCGF1 SE P-value
DMI (lb/day) 20.6 21.1 0.3 0.15
Average pH 5.69 5.87 0.0 <0.01
Max. pH 6.31 6.47 0.0 <0.01
Min. pH 5.26 5.45 0.0 <0.01
Area < 5.62 253.5 168.2 60.5 0.26
pH change 1.04 1.01 0.0 0.71
pH variance 0.06 0.05 0.0 0.20
H
2
S 8 h3 53.1 87.9 15.7 0.13
H
2
S 23 h4 88.2 65.0 20.0 0.28
1WDGS = wet distillers grains plus solubles, WCGF = wet corn gluten feed.
2Area under curve is magnitude of pH < 5.6 by minute.
3Values are μmol hydrogen sulfide/mL rumen gas collected 8 hours post feeding.
4Values are μmol hydrogen sulfide/mL rumen gas collected 23 hours post feeding.
of SAS (SAS Inst. Inc.). Treatment was 
included in the model as a fixed effect 
with animal being the random effect. 
No byproduct x grass hay level interac-
tions were observed (P > 0.23); there-
fore, only main effects of byproduct 
or grass hay levels were reported. The 
correlation procedure of SAS was used 
to determine correlations between 
pH and H
2
S values. With the high 
variability in individual data, treat-
ment means also were used for correla-
tion calculations.
Results
In Experiment 1, H
2
S levels 
increased as roughage decreased 
(grain adaptation) at both 8 and 
23 hours post feeding, (P < 0.01 
© The Board of Regents of the University of Nebraska.  All rights reserved. 2009 Nebraska Beef Report  — Page 83 
Doubling the hay level to 15% reduced 
H
2
S levels in the rumen. Approxi-
mately 55% less H
2
S was produced 
in the 15% hay diet compared to the 
7.5% hay diet at 8 hours post feeding.
At this time, we have not devel-
oped a cause-and-effect relationship 
between ruminal H
2
S levels and polio. 
However, we assume the risk of polio 
is decreased if ruminal H
2
S levels are 
decreased. Feeding additional rough-
age with high byproduct diets appears 
to reduce H
2
S levels and therefore the 
risk of polio.
We hypothesized pH to be posi-
tively correlated with the level of 
H
2
S concentration in the rumen. 
There were no significant correla-
tions using individual animal data at 
8 or 23 hours post feeding in either 
experiment (Table 6). The lack of 
significant correlations appears to 
be due to the large variability in H
2
S 
concentrations; therefore, treatment 
mean correlations were calculated. In 
Experiment 1, area below pH 5.6 on 
the same day was correlated to H
2
S 
levels at both 8 (r = 0.94, P = 0.06) 
and 23 hours (r = 0.85, P = 0.15) post 
feeding. In Experiment 2, there was a 
tendency for the 23-hour H
2
S level to 
increase as average pH decreased  
(r = -0.92, P = 0.13). There also was a 
tendency for the 8-hour H
2
S level to 
increase as the amount of time below 
pH 5.6 the previous day increased 
(r = 0.98, P = 0.12) At 23 hours post 
feeding, H
2
S levels increased as the 
area below pH 5.6 of the same day 
increased (r = 0.98, P = 0.13). We 
conclude that average ruminal pH is 
negatively correlated with ruminal 
H
2
S levels. Roughage level in the diet 
appears to be very important. In these 
experiments, dietary sulfur levels 
ranged from 0.47% to 0.41%; the H
2
S 
levels ranged from 125.9 to 29.7μmol/
mL of rumen gas. In another study 
(Vanness et al. 2009 Nebraska Beef 
Report pp. 84-85), H
2
S levels at 12 
hours post feeding ranged from 
19.3μmol/mL when dietary S levels 
were 0.53%, to 13.7μmol/mL when 
dietary S levels were 0.34%. This does 
not show a clear relationship between 
dietary S levels and ruminal H
2
S 
levels. However, this comparison is 
across experiments and a conclusion 
Table 5. Main effect of grass hay level in Experiment 2 for intake, ruminal pH and H
2
S.
  Grass hay level
Item 0 7.5 15.0 SE Lin. Quad.
DMI, lb/day 20.6 20.4 21.5 0.3 < 0.03 0.08
Average pH 5.62 5.75 5.96 0.0 < 0.01 0.42
Max pH 6.22 6.32 6.62 0.0 < 0.01 0.03
Min pH 5.25 5.37 5.44 0.0 < 0.01 0.58
Area < 5.61 306.0 176.8 149.7 72.0 0.08 0.54
Area < 5.31 73.4 29.6 39.2 20.0 0.19 0.27
Area < 5.01 4.3 2.4 2.4 1.6 0.33 0.59
pH change 1.0 1.0 1.2 0.0 < 0.01 < 0.01
H
2
S 8 h2 125.9 55.9 29.7 19.0 < 0.01 0.37
H
2
S 23 h3 91.5 84.1 54.2 30.0 0.45 0.67
1Area is magnitude of pH under respective pH by minute.
2Values are μmol hydrogen sulfide mL of rumen gas collected 8 hours post feeding.
3Values are μmol of hydrogen sulfide mL of rumen gas collected 23 hours after first feeding.
Table 6. Correlation of ruminal pH to H
2
S levels at 8 and 23 hours post feeding.
Item 8 hour P-value 23 hour P-value
Experiment 1    
Individual1
 Average pH 0.12 0.95 -0.05 0.79
 Area < 5.6 -0.21 0.29 -0.03 0.86
 Previous day time < 5.62 -0.05 0.80 0.06 0.73
 Time < 5.6 -0.01 0.95 0.01 0.95
Treatment mean3
 Average pH -0.47 0.53 -0.50 0.50
 Area < 5.6 0.94 0.06 0.85 0.15
 Previous day time < 5.6 0.37 0.63 0.42 0.58
 Time < 5.6 0.45 0.55 0.50 0.50
Experiment 2
Individual1
 Average pH -0.05 0.76 -0.16 0.41
 Area < 5.6 -0.06 0.70 0.02 0.90
 Previous day time <5.6 -0.00 0.98 0.30 0.11
 Time < 5.6 -0.05 0.73 0.23 0.23
Treatment mean2
 Average pH -0.92 0.25 -0.98 0.13
 Area < 5.6 0.99 0.07 0.77 0.44
Previous day time < 5.6 0.98 0.12 0.92 0.26
 Time < 5.6 0.93 0.25 0.98 0.13
1Correlations based on individual animal values for pH and H
2
S.
2This value is the amount of time ruminal pH was below 5.6 one day prior to H
2
S collection.
3Correlations based on treatment mean.
cannot be drawn until dietary S levels 
are compared within an experiment.
1Sarah J. Vanness, research technician; 
Nathan F. Meyer, research technician; Terry J. 
Klopfenstein, professor; and Galen E. Erickson, 
associate professor, Animal Science, Lincoln, 
Neb.


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Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage Levels

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