The effect of nitrogen and protein supplementation on feed intake, growth and digestive function of steers with different Bos indicus, Bos taurus genotypes when fed a low quality grass hay

1995 ◽  
Vol 46 (6) ◽  
pp. 1121 ◽  
Author(s):  
DW Hennessy ◽  
PJ Kohun ◽  
PJ Williamson ◽  
DA Brown ◽  
JV Nolan
Keyword(s):  
Feed Intake ◽  
Rumen Fluid ◽  
Bos Indicus ◽  
Basal Diet ◽  
Ammonia Concentration ◽  
Protein Supplementation ◽  
Hybrid Vigour ◽  
Protein Nitrogen ◽  
Plasma Urea ◽  
Significant Difference

Two studies were undertaken at Grafton, NSW, to determine the effects of supplementing a subtropical hay diet with a mixture of non-protein nitrogen (urea) and protein (protected casein), on the feed intake and growth of 20 steers of four genotypes (Study I), and on the digestive and metabolic functions of 16 of the steers that were fistulated in the rumen (Study 2). All steers were reared in the one subtropical environment. They consisted of backcross Hereford (H) (H x BH), backcross F1 (BH x BH) and backcross Brahman (B x BH), all of 50% heterosis, and a first-cross F1 of 100% heterosis (BxH). Steers in both studies were confined in pens and offered a basal diet of chaffed pasture hay (digestibility 52f 1.4% and nitrogen [N] content of 6.1 � 0.2 g/kg dry matter [DM]) supplemented with minerals only (low N diet; 8 steers) or with urea or formaldehyde-treated casein and cottonseed meal (high N diet; 12 steers) for 49 days. There were eight steers, for each of the two diets in Study 2, which were fed for 30 days. There was a diet x genotype interaction (P < 0-05) in the daily DM intake (DMI) of hay by steers in Study 1. The mixed N supplement increased ( P < 0.05) DM1 (per kg liveweight) by 14% in HxBH and by 13% in BxBH steers, but there was no significant effect of the supplement on the DM1 of BxH and BHxBH steers. Daily liveweight change was increased (P < 0.05) by the supplement from -30 to 250 (s.e.d � 40) g/steer and there was no significant difference between genotypes. N supplementation increased ( P < 0.05) rumen volume (63 to 87 � 7.6 L) and fluid residence time (491 to 822 � 76.9 min) (P < 0.05) in BHxBH steers, but the increases in other genotypes were not significant. Rumen ammonia concentration (30 to 61 � 3 7 mg N/L) and plasma urea concentration (56 to 94 � 6-0 g N/L) were increased (P < 0.05) by supplementation. Total protozoa density in rumen fluid was greater (P < 0.05) in BxBH than HxBH steers but did not differ significantly between supplemented and unsupplemented steers. The HxBH steers had the lowest density of small entodiniomorph protozoa when N-supplemented, which was less (P < 0.05) than that in BxBH steers which had the greatest density. Supplementation increased (P < 0.05) N retention but only B x BH steers had a positive N balance. These experiments indicated that there are some physiological differences between genotypes. The BxH genotype with the high hybrid vigour had a high DM1 on the low digestibility hay diet without the N supplements and it transferred more urea from the plasma pool to the gut. The backcross steers (HxBH and BxBH) had low DM1 which increased when supplemented. The high content B. indicus steers (BxBH) had positive net retentions of N, but the results indicated that rumen protected proteins may be more usefully fed to steers with a lower B. indicus content.

Effects of intraruminal infusions of urea, sucrose or urea plus sucrose on plasma urea and glucose kinetics in sheep fed chopped lucerne hay

1993 ◽  
Vol 121 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Y. Obara ◽  
D. W. Dellow
Keyword(s):  
Plasma Glucose ◽  
Rumen Fluid ◽  
Glucose Production ◽  
Ammonia Concentration ◽  
Irreversible Loss ◽  
Glucose Kinetics ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Urea Kinetics ◽  
Plasma Urea Concentration

SUMMARYThe effect of rumen fermentation on the relationship between urea and glucose kinetics was examined in sheep fed chopped lucerne hay with intraruminal infusions of water, urea, sucrose, or urea plus sucrose at Palmerston North, New Zealand in 1986. Sheep were fed hourly and infused intraruminally with water (1200 m1/day), or a similar volume containing either urea alone (13·7g/day), sucrose alone (178·2 g/day) or urea (14·6 g/day) plus sucrose (175·0 g/day). The added sucrose resulted in a lower rumen ammonia concentration (P< 0·05), lower plasma urea concentration (P< 0·05) and reduced urinary urea excretion (P< 0·05). Urea recycled to the gut tended to increase with the sucrose, urea or sucrose plus urea treatments compared with the water treatment. The fermentation of sucrose in the rumen resulted in decreases in ruminal pH (P< 0·05) and in the ratio of acetate to propionate (A:P) (P< 0·05). The infusion of sucrose also increased the concentration of propionate in rumen fluid (P< 0·05), tended to increase the plasma glucose level and increased plasma glucose irreversible loss (P< 0·05). The infusion of urea resulted in an increase in the plasma urea level (P< 0·05), urea pool size (P< 0·05) and urea irreversible loss (P< 0·01). However, urea infusion did not affect glucose metabolism or volatile fatty acid (VFA) fermentation. The effects of sucrose infusion on glucose and urea kinetics were broadly similar when given alone or with urea, apart from changes in the urea degradation rate. It was concluded that the additional fermentative activity resulting from sucrose increased propionate production which, in turn, was available for glucose production, thus ‘sparing’ amino acids for tissue protein utilization and reducing urea excretion.

scholarly journals High Level of Energy and Protein Supplementation Effect on Feed Intake and Liveweight Gain of Bali Bulls Fed Elephant Grass

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 91
Author(s):  
Sulendre ◽  
Marsetyo ◽  
Takdir ◽  
Harper ◽  
Poppi
Keyword(s):  
Feed Intake ◽  
Palm Kernel ◽  
Basal Diet ◽  
Protein Supplementation ◽  
Elephant Grass ◽  
Kernel Meal ◽  
Palm Kernel Meal ◽  
High Level ◽  
On Farm ◽  
Faecal Ph

This research was carried out on-farm at Malonas village, Central Sulawesi, Indonesia to examine the effect of high level supplementation of by-products formulated for high ME and CP. Feed intake, faecal pH and liveweight gain of Bali bulls was observed. The basal diet was elephant grass, and supplements were rice bran (RB), cassava (C), palm kernel meal (PKM), gliricidia (G) and urea. Fifty Bali bulls (weight 168±4.48 kg) were housed in individual pens for 18 weeks (2 introductory and 16 experimental) and allocated into five treatments: A= elephant grass (EG) ad libitum, B= EG offered at 1%W/d, plus 2.5%W/d mixed RB:G, (1:1), C = EG offered at 1%W/d plus 2.5%W/d mixed RB:PKM(1:1), D = EG offered at 1%W/d plus 2.5%W/d mixed C:G (1:1), E = EG offered at 1%W/d plus 2.5%W/d mixed C+ urea: PKM (1:1). Faecal pH was measured at weeks 3, 9 and 15. Bali bulls fed B, C, D and E, consumed supplement at the rate of 2.15, 2.19, 2.09 and 2.29 %W/d, respectively. Total feed intake was 2.47, 2.98, 2.99, 2.93, 3.13%W/d, liveweight gain was 0.30, 0.57, 0.60, 0.66, 0.69 g/d and faecal pH was 6.93, 6.76, 6.65, 6.45, 6.33 for treatment A, B, C, D, and E, respectively. Supplementation increased significantly (P<0.05) total feed intake, liveweight gain, but reduced faecal pH. The highest total feed intake and liveweight gain was achieved by treatment E. It is concluded that cassava can be provided at 1.15%W/d in combination with protein supplement for high liveweight gain of Bali bulls.

Substitution of sorghum grain for molasses increases the liveweight gain of steers given molasses-based diets

1998 ◽  
Vol 130 (2) ◽  
pp. 199-204 ◽  
Author(s):  
H. PEIRIS ◽  
R. ELLIOTT ◽  
B. W. NORTON
Keyword(s):  
Fatty Acid ◽  
Treatment Group ◽  
Feed Intake ◽  
Volatile Fatty Acid ◽  
Dry Matter ◽  
Rumen Fluid ◽  
Basal Diet ◽  
Feed Consumption ◽  
Sunflower Meal ◽  
Sorghum Grain

Sorghum grain was included in a basal diet of molasses (molasses 505, urea 21, sunflower meal 191, pangola grass hay 250, minerals 31 g/kg as fed) at rates of 0, 202, 391 and 707 g/kg, generating diets in which grain replaced 0 (diet A), 33 (diet B), 66 (diet C) and 100% (diet D) of the molasses and hay. The four diets were fed to groups of four Hereford steers (293–334 kg liveweight) over a 96-day period. One half of each treatment group was implanted with a growth promotant (zeranol), and all were slaughtered at a commercial abattoir at the end of the trial. The inclusion of 33% grain increased voluntary feed consumption, digestible dry matter (DM) intake (from 57·6 to 82·0 g digestible DM/kg0·75 per day and significantly increased liveweight gain from 592 to 900 g/day. Zeranol implantation also increased liveweight gain but not feed intake. Steers given only grain (diet D) had the highest liveweight gains (1127 g/day). The addition of grain to molasses diets decreased urinary N excretion and increased ammonia and volatile fatty acid (VFA) concentrations in rumen fluid. Molar proportions of propionic acid in total VFA increased from 0·15 to 0·20, and butyric acid decreased from 0·36 to 0·29 when 33% of the molasses was replaced by sorghum grain. The fat content (depth at sacral position) of the carcasses of steers given grain only (diet D) was significantly greater (14 mm) than that of steers given the basal diet of molasses (4 mm), and carcass fat contents were intermediate (10 and 11 mm) for steers given diets B and C respectively. It was concluded that the inclusion of small amounts of grain in molasses-based diets increased cattle growth principally by increasing digestible energy intake without decreasing molasses intake, thus improving the efficiency of utilization of molasses in molasses-based diets.

NUTRITIVE VALUE OF FORMALDEHYDE-TREATED RAPESEED MEAL FOR DAIRY CALVES

1972 ◽  
Vol 52 (2) ◽  
pp. 363-371 ◽  
Author(s):  
H. R. SHARMA ◽  
J. R. INGALLS ◽  
J. A. McKIRDY
Keyword(s):  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Nutritive Value ◽  
Rumen Fluid ◽  
Protein Digestibility ◽  
Rapeseed Meal ◽  
Dairy Calves ◽  
Plasma Urea ◽  
Significant Difference ◽  
Daily Gain

Treatment of oilseed meals with formaldehyde (FA) and glutaraldehyde (GA) significantly (P < 0.01) reduced the solubility of protein in 0.02 N NaOH and the production of NH3 in the artificial rumen. Ten Holstein and Holstein × Brown Swiss calves of both sexes were fed two test rations containing either 26% untreated or formaldehyde-treated (5.6 g FA per 100 g protein) rapeseed meal (FA-treated RSM) for 14 weeks. Plasma urea nitrogen (N) and rumen NH3 levels were significantly (P < 0.01) lower in the FA-treated RSM calves compared with the control calves during the first 8 weeks of the growth trial. No significant difference (P > 0.05) in dry matter consumption, daily gain, or feed efficiency was observed. Total volatile fatty acids (VFA) (mmoles/100 ml) concentration was significantly higher (P < 0.05) in rumen fluid from the control calves compared with those receiving treated RSM. Molar percentages of the VFA’s were not significantly different (P > 0.05) between the two groups. In the N balance and digestibility trial, dry matter consumption did not differ significantly (P > 0.05); however, the FA-treated RSM resulted in decreased (P < 0.05) dry matter and crude protein digestibility. Calves receiving the treated RSM had reduced (P < 0.01) urinary N excretion; however, there was no significant effect (P > 0.05) on N consumption and retention.

Effect of condensed tannins on the production of wool and on its processing characteristics in sheep grazing Lotus corniculatus

1998 ◽  
Vol 49 (4) ◽  
pp. 597 ◽  
Author(s):  
B. R. Min ◽  
W. C. McNabb ◽  
P. D. Kemp ◽  
T. N. Barry
Keyword(s):  
Blood Plasma ◽  
Feed Intake ◽  
Condensed Tannins ◽  
Rumen Fluid ◽  
Fibre Diameter ◽  
Lotus Corniculatus ◽  
Plasma Metabolites ◽  
Plasma Urea ◽  
Wool Production ◽  
Wool Processing

The effect of condensed tannins (CT) in Lotus corniculatus upon voluntary feed intake (VFI), concentration of rumen and plasma metabolites, production of wool, and wool processing characteristics was measured in grazing ewes restricted to maintenance feeding for 125 days during summer. A rotational grazing system with restricted feed allowance with 40 mixed aged dry ewes (54±1·0 kg) was used. Half of the ewes were selected randomly for twice-daily oral polyethylene glycol (PEG; MW 3500) supplementation (CT-inactivated), with the remainder being CT-acting animals. Measurements of the diet selected, VFI, wool production, and wool processing characteristics were made. The concentration of ammonia in rumen fluid and the concentrations of methionine, cysteine, and urea in blood plasma were also measured. The diet selected contained 32 g total nitrogen (N) and 28 g total CT/kg dry matter (DM) and had an in vitro organic matter digestibility of 0·70. Action of CT reduced rumen ammonia concentration (256 v. 302 mg N/L), reduced blood plasma urea concentration (7·3 v. 8·9 µM), and increased blood plasma cysteine concentration (30 v. 27 µM) compared with sheep receiving PEG supplementation. CT had no effect on VFI but increased clean fleece weight (2·53 v. 2·28 kg/ewe) and staple length (7·7 v. 6·9 cm), but did not affect liveweight gain (54 v 67 g/day). The CT reduced dag weight and tended to reduce wool yellowness relative to sheep receiving PEG. There were no signifiant effects of CT on fibre diameter, staple strength, bulk density, and wool resilience. It was concluded that action of CT in sheep fed L. corniculatus reduced the degradation of forage protein in the rumen and the principal effect of this was to increase the efficiency of wool production, with more wool being produced at the same feed intake and the wool being of reduced yellowness.

Effect of Stylosanthes guianensis supplementation on intake and nitrogen metabolism of Bos indicus cattle offered a basal diet of mixed rice straw and tropical grass

2013 ◽  
Vol 53 (5) ◽  
pp. 453 ◽  
Author(s):  
Miranda Pen ◽  
Darryl B. Savage ◽  
John V. Nolan ◽  
Mom Seng
Keyword(s):  
Rice Straw ◽  
Protein Production ◽  
Oryza Sativa L ◽  
Bos Indicus ◽  
Basal Diet ◽  
Ammonia Concentration ◽  
Microbial Protein ◽  
Total N ◽  
Stylosanthes Guianensis ◽  
Tropical Grass

The effect of supplementing a mixed rice straw and tropical grass diet with legume as a nitrogen (N) source on intake, digestibility, rumen ammonia and microbial protein production was evaluated in Bos indicus cattle. Four rumen-cannulated steers were used in a crossover design with two diets and two periods. The diets were T1 = 40% rice (Oryza sativa L.) straw + 60% grass (Brachiaria spp. cv. Mulato II hybrid) and T2 = 40% rice straw + 30% grass + 30% legume (Stylosanthes guianensis cv. CIAT 184) on DM basis. Supplementation with legume doubled (P < 0.01) rice straw and total N intake, and increased total DM intake by 32%. It did not affect the DM, organic matter, neutral detergent fibre and acid detergent fibre digestibility (P > 0.05) but did increase (P < 0.05) N digestibility. Faecal N and total N outputs from T2 cattle were higher (P < 0.05) than T1 cattle, but urinary N output did not differ between diets (P > 0.05). N retention in T2 cattle was improved by 83% (P < 0.05) compared with T1 cattle. Rumen ammonia concentration, microbial protein production and efficiency of microbial protein production were improved (P < 0.05) when the legume forage was included in the straw–grass diet. We conclude that when a mixed rice straw and fresh grass diet is supplemented with ~30% legume (DM basis), significant improvements in DM and N intake can be achieved.

scholarly journals Utilization of low-quality roughage byBos taurusandBos indicuscattle

1985 ◽  
Vol 53 (3) ◽  
pp. 649-656 ◽  
Author(s):  
R. A. Hunter ◽  
B. D. Siebert
Keyword(s):  
Dry Matter ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Dietary Factors ◽  
Plasma Urea ◽  
Mean Retention Time ◽  
Digitaria Decumbens ◽  
Breed Difference ◽  
Significant Difference ◽  
The Mean

1. In a number of experiments voluntary food intake of three low-quality roughages, either alone or supplemented with rumen-degradable nitrogen and sulphur and minerals, was measured in Brahman (Bos indicus) and Hereford (Bos taurus) steers. The chaffed hays were Spear grass (Heteropogon conform) (6.2 g N/kg organic matter (OM)), Pangola grass (Digitaria decumbens) (7.9 g N/kg OM), and Pangola grass (12.0 g N/kg OM). Rumen characteristics relating to rate of fluid outflow from the rumen were also determined.2. There was no significant difference between breeds in the dry-matter intakes of the unsupplemented diets which ranged from 11.3 to 17.8 g/kg body-weight (BW) by Herefords and from 11.8 to 16.1 g/kg BW by Brahmans.3. Supplementation of Spear grass with N and S significantly (P < 0.05) increased intake by Herefords (24%) but not by Brahmans. When the lower-N Pangola grass was supplemented there was a significant increase in intake by both breeds with the magnitude of the response in Herefords (42%) (P < 0.001) being greater than that in Brahmans (15%) (P < 0.05). The intakes of both the supplemented Spear grass and the lower-N Pangola diets were significantly (P < 0.05) greater by Herefords than Brahmans. There was no breed difference in intake when the higher-N Pangola grass was supplemented. Both breeds recorded an 8% intake response to supplementation, although the increase was only significant (P < 0.05) in Herefords.4. The mean retention time of fluid in the rumen on the unsupplemented Pangola grass diet of lower N content was 12.7 h in Brahmans compared with 17.5 h in Herefords (P < 0.01). When the higher-N Pangola was fed, both alone and supplemented, the mean retention times were similar on both diets (10.5 and 9.9 h for Herefords; 9.5 and 8.1 h for Brahmans for unsupplemented and supplemented diets respectively).5. Plasma urea concentrations were higher in Brahmans than in Herefords on all diets. Rumen ammonia concentrations were significantly (P < 0.001) higher in Brahmans than Herefords when the lower-N Pangola grass diet was unsupplemented.6. The intakes and the variable intake responses to supplementation between breeds and diets are discussed in relation to a number of animal and dietary factors.

scholarly journals Evaluation of cassava foliage as a protein supplement for sheep

2021 ◽  
Vol 30 (1) ◽  
pp. 37-46
Author(s):  
J. K. Alli-Balogun ◽  
C. A. M. Lakpini ◽  
J. P. Alawa ◽  
A. Mohammed ◽  
J. A. Nwanta
Keyword(s):  
Rumen Fluid ◽  
Control Diet ◽  
Nitrogen Retention ◽  
Live Weight ◽  
Basal Diet ◽  
Average Weight ◽  
Protein Supplement ◽  
Metabolic Study ◽  
Significant Difference ◽  
Weight Gains

Three trials were conducted to evaluate the potential of cassava (Manihot esculenta) foliage (leaves and petioles) as a protein supplement for sheep. In the first trial, nylon bag degradability of cassava foliage was studied. Proximate analysis of cassava foliage was conducted before and after the incubation. Rumen Ammonia Concentration (RAC) and pH were determined at 0, 4 and 8 hours after feeding cassava foliage diet (30%). Proximate composition of sundried cassava foliage was (%) DM 91.25, CP 18.55, NDF, 31.41, ADF, 29.2, EE, 6.6, Ash, 12.95. Nylon-bag dry matter disappearance (DMD) increased significantly (P<0.05) from 15.75% to 75.5% RAC values increased significantly from 8.20mg NH3/100ml at zero hour to 11.41mg NH3/100ml at 8 hours post feeding. Rumen fluid pH was not significantly changed by the 30% cassava foliage diet. In the second trial lasting 56 days, twenty-eight Yankasa/ WAD yearling rams of initial average weight of 18kg were balanced for weight and randomly allotted to seven treatments. All rams except those on control diet were fed cassava foliage or groundnut haulms or both at 1.0% or 1.5% of body weight (BW) as supplements to a basal diet of Gamba hay. Feeding Gamba hay alone (control) resulted in weight loss (-30.5g/day) but with cassava foliage or groundnut haulms supplementation at 1.0% BW, significantly higher gains of 39.2 and 44.6g/day were achieved respectively. At 1.5%BW level of supplementation with cassava foliage or groundnut haulms higher weight gains of 41.2 and 51.7g/day were achieved while feeding the (50.50) combined supplements at 1.0 and 1.50% BW resulted in live weight gains of 65.1 and 69.3g/day respectively. The third trial consisted of a four week grazing trial followed by a metabolic study. Twenty-one Yankasa/WAD yearling rams were randomly allotted to seven treatments and were balanced for live weight. All rams were allowed to graze standing digitaria hay as basal diet, except the rams on control diet. Those on treatment were fed cassava foliage or groundnut haulms or a (50:50) combination of both at 0.5% and 1.0% (BW). The metabolic study consisted of a seven day adjustment period and a seven day total collection period. There was no significant difference (P>0.05) in the live weight gains of rams on the control diet compared with those supplemented except for those supplemented with cassava foliage and groundnut haulms combined at 1% level where the weight gain was significantly higher (P<0.05). Feed intake was not significantly (P>0.05) affected by feeding either supplement. Supplementing digitaria hay with cassava foliage at both 0.5% and 1.0% BW did not significantly increase the nitrogen retention values, but groundnut haulms supplemented at 1.0% BW significantly (P<0.05) increased the nitrogen retention values.

Feed intake and liveweight of cattle on subtropical native pasture hays. 1. The effect of urea

1990 ◽  
Vol 41 (6) ◽  
pp. 1169 ◽  
Author(s):  
DW Hennessy ◽  
PJ Williamson
Keyword(s):  
Organic Matter ◽  
Experimental Design ◽  
Feed Intake ◽  
Rumen Fluid ◽  
Ammonia Concentration ◽  
Low Concentrations ◽  
Hereford Cattle ◽  
Native Pasture ◽  
Nitrogen Concentrations ◽  
Native Pastures

Twenty Hereford weaner steers and heifers, 9-months-old and of mean liveweight (� s.e.) 152 � 6 kg, were stratified according to sex and liveweight into four groups and assigned to cells in an experimental design which aimed at studying the effects of an increased urea intake on their rumen ammonia concentration, their intake of a low N native pasture hay and on their liveweight change over 49 days. The cattle on the basal hay diet maintained low concentrations of ammonia in rumen fluid (8 mg N/L) during the study and lost weight (at 50 g/day). Urea (as 15, 23, 42 and 53 g head.day) increased significantly (P< 0.01) rumen ammonia concentration (to 152 t 10.9 mg N/L), hay intake in the final 7 days (from 2633 to 3738 � 72 g organic matter/head.day) and liveweight change (to 273 � 33 g/head.day). Hay intake of the cattle increased within 14 days of supplementation with urea which was sprayed onto portions of the hay. Urinary N content, but not faeces, was increased by the urea diets. Urea intakes also increased urea nitrogen concentrations in plasma and saliva which were correlated (r=0.87). Liveweight change was maximized at daily urea intakes of 23 g/head and these gains are discussed in terms of the suitability of urea for Hereford cattle which are fed only low N native pastures

scholarly journals RUMEN FERMENTATION AND DIGESTIBILITY IN STEERS AS INFLUENCED BY LEVEL OF INTAKE AND MONENSIN

1983 ◽  
Vol 63 (4) ◽  
pp. 855-860
Author(s):  
G. M. J. HORTON ◽  
M. J. FARMER ◽  
K. A. BASSENDOWSKI ◽  
G. M. STEACY
Keyword(s):  
Feed Intake ◽  
Crude Protein ◽  
Dry Matter ◽  
Rumen Fluid ◽  
Control Diet ◽  
Protein Digestibility ◽  
Rumen Fermentation ◽  
Feed Consumption ◽  
Plasma Urea ◽  
Four Levels

The effects of level of feed intake and monensin on rumen fermentation and digestibility in steers were evaluated. The four levels of feed intake were 30, 50, 70 and 90 g of dry matter per kilogram body weight raised to the 0.75 power (g/kg0.75). Monensin was included at 0 and 33 mg/kg diet. The diet contained 60% rolled barley and 36.5% alfalfa pellets. Organic matter digestibility decreased (P < 0.05) with increasing levels of intake when the control diet was fed but was not affected by intake when monensin was included in the feed. Crude protein digestibility was consistently higher (P < 0.05) in monensin than control-fed steers at all four intake levels and decreased with increasing feed consumption in steers fed both control and monensin diets. Rumen fluid pH and ammonia and plasma urea nitrogen were not affected by monensin, and decreased (P < 0.05) as feed intake increased. Both higher feed intake and monensin caused an increase in the molar proportion of ruminal propionic acid and a decrease in the proportion of acetic acid. Key words: Intake monensin, digestibility, PUN, VFA, cattle

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