Buffer systems in the rumen of sheep. II. Buffering properties in relationship to composition.

1955 ◽  
Vol 6 (1) ◽  
pp. 125 ◽  
Author(s):  
AW Turner ◽  
VE Hodgetts
Keyword(s):  
Volatile Fatty Acids ◽  
Particulate Material ◽  
Ruminal Fermentation ◽  
Parotid Saliva ◽  
Bicarbonate Concentration ◽  
Ruminal Fluid ◽  
Ruminal Ph ◽  
Titration Curves ◽  
Buffer Value ◽  
Ph Range

Acid-base titration curves of ovine ruminal fluid confirmed the findings of Clark and Lombard (1951) that ruminal fluid is relatively well buffered against addition of acid, but relatively poorly against additions of alkali. However, considerable differences were observed between samples from different sheep. These were associated with differences in the interval after feeding, the nature of the diet, and the consumption of drinking water; and were correlated with differences in total and relative concentrations of bicarbonate, phosphate, and volatile fatty acids (VFA). The relative importance of the main buffering components in particular fluids was studied by examining the effects of the following procedures upon titration curves: ( a ) varying bicarbonate concentration by varying pCO2; ( b ) removing, and restoring, bicarbonate, phosphate, and VFA; and ( c ) removing particulate material. Particulate material was relatively unimportant as a buffer. Within the usual pH range of the rumen, the important buffering components were bicarbonate and phosphate. In the fasting rumen, bicarbonate was more important than phosphate, and this was found to be also true in parotid saliva. As ruminal fermentation proceeded and as VFA accumulated, bicarbonate and pH decreased and the buffer value depended more and more upon phosphate. In actively fermenting rumens, in which VFA concentration was high and the pH less than 6, VFA contributed significantly to the buffer resistance against further additions of acid. It is pointed out that, because the acids and bases generated during ruminal fermentation are relatively weak, they alter ruminal pH less, mole for mole, than the strong titrants conventionally used in titrations.

scholarly journals Comparison of Two Sampling Techniques for Evaluating Ruminal Fermentation and Microbiota in the Planktonic Phase of Rumen Digesta in Dairy Cows

2020 ◽  
Vol 11 ◽  
Author(s):  
Camila Flavia de Assis Lage ◽  
Susanna Elizabeth Räisänen ◽  
Audino Melgar ◽  
Krum Nedelkov ◽  
Xianjiang Chen ◽  
...  
Keyword(s):  
Volatile Fatty Acids ◽  
Sampling Method ◽  
Bacterial Community Composition ◽  
Sampling Technique ◽  
Standard Diet ◽  
Ruminal Fermentation ◽  
Ph Change ◽  
Ruminal Fluid ◽  
Rumen Ph ◽  
Dissolved Hydrogen

The objective of this experiment was to compare ruminal fluid samples collected through rumen cannula (RC) or using an oral stomach tube (ST) for measurement of ruminal fermentation and microbiota variables. Six ruminally cannulated lactating Holstein cows fed a standard diet were used in the study. Rumen samples were collected at 0, 2, 4, 6, 8, and 12 h after the morning feeding on two consecutive days using both RC and ST techniques. Samples were filtered through two layers of cheesecloth and the filtered ruminal fluid was used for further analysis. Compared with RC, ST samples had 7% greater pH; however, the pattern in pH change after feeding was similar between sampling methods. Total volatile fatty acids (VFA), acetate and propionate concentrations in ruminal fluid were on average 23% lower for ST compared with RC. There were no differences between RC and ST in VFA molar proportions (except for isobutyrate), ammonia and dissolved hydrogen (dH2) concentrations, or total protozoa counts, and there were no interactions between sampling technique and time of sampling. Bacterial ASV richness was higher in ST compared with RC samples; however, no differences were observed for Shannon diversity. Based on Permanova analysis, bacterial community composition was influenced by sampling method and there was an interaction between sampling method and time of sampling. A core microbiota comprised of Prevotella, S24-7, unclassified Bacteroidales and unclassified Clostridiales, Butyrivibrio, unclassified Lachnospiraceae, unclassified Ruminococcaceae, Ruminococcus, and Sharpea was present in both ST and RC samples, although their relative abundance varied and was influenced by an interaction between sampling time and sampling method. Overall, our results suggest that ruminal fluid samples collected using ST (at 180 to 200 cm depth) are not representative of rumen pH, absolute values of VFA concentrations, or bacterial communities >2 h post-feeding when compared to samples of ruminal fluid collected using RC. However, ST can be a feasible sampling technique if the purpose is to study molar proportions of VFA, protozoa counts, dH2, and ammonia concentrations.

scholarly journals Concentrate containing calcium salts of fatty acids rich in polyunsaturated fatty acids can change rumen fermentation in grazing goats

2018 ◽  
Vol 39 (6) ◽  
pp. 2621
Author(s):  
Ludmila Couto Gomes ◽  
Claudete Regina Alcalde ◽  
Julio Cesar Damasceno ◽  
Luiz Paulo Rigolon ◽  
Ana Paula Silva Possamai ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Latin Square ◽  
Rumen Fermentation ◽  
Ruminal Fermentation ◽  
Calcium Salts ◽  
Linear Effect ◽  
Concentrate Supplementation ◽  
Ruminal Ph

Feeding goats with calcium salts of fatty acids (CSFA) can supply ruminants with lipids, with minimal effects on ruminal fermentation and fiber digestibility. However, there is a shortage of information on the effect of CSFA on characteristics of rumen fermentation in grassland goats. Thus, the present study aimed to assess the addition of CSFA to concentrate on the parameters of rumen fermentation of grazing goats. Five rumen cannulated goats were distributed in a Latin square 5x5 design (treatments: 0%, 1.5%, 3.0%, 4.5% and 6.0% CSFA. The pH, ammonia N and volatile fatty acids (VFA) content were analyzed in the ruminal fluid at 0, 2, 4, 6 and 8 hours after concentrate supplementation. The pH and ammonia N concentration showed a linear effect with the addition of CSFA. There was no effect observed for the VFA molar concentration after grazing goats were fed with the experimental diet. In conclusion, further research is needed to investigate the addition of CSFA to goat diets because there is evidence that CSFA increases ruminal pH and decreases excess ruminal ammonia without changing the VFA concentration in the rumen fluid.

scholarly journals Effects of feeding urea-treated triticale and oat grain mixtures on ruminal fermentation, microbial population, and milk production performance of midlactation dairy cows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Kacper Libera ◽  
Malgorzata Szumacher-Strabel ◽  
Mina Vazirigohar ◽  
Wiktor Zieliński ◽  
Rafal Lukow ◽  
...  
Keyword(s):  
Milk Production ◽  
Soybean Meal ◽  
Starch Content ◽  
Production Performance ◽  
Ruminal Fermentation ◽  
Ruminal Fluid ◽  
Ruminal Ph ◽  
Available Energy ◽  
Branched Chain

AbstractThe starch content of triticale and oat grains provides much of their readily available energy. Synchronizing energy and nitrogen in the rumen is important in optimizing profitability; for this reason, ammonia processing of these grains was evaluated for its potential to modify ruminal fermentation and to improve milk production performance. A mixture of ground triticale and oats (CONG, in a 60:40 ratio 40 by DM) was treated with urea (5 kg/1000 kg) and urease additive (20 kg/1000 kg) containing 200 g/kg of moisture, for 2 wk (UREG). The urea treatment enhanced the pH and CP content of grains by 34% and 52%, respectively. In a batch culture study, CONG or UREG as the only substrate was incubated in a buffered ruminal fluid. Compared to CONG, UREG increased pH, total VFA concentration, total gas, and disappearance of DM, while reducing CH4 production, whereas NH3 concentration increased and entodiniomorph counts tended to increase. In the in vivo study, cows were randomly allocated to two dietary groups (n = 24) and were offered TMR based on maize and grass silage, containing either 155 g/kg of CONG and 80 g/kg of soybean meal (CONT) or 155 g/kg of UREG and 59 g/kg of soybean meal (URET) for 31 d. Ruminal fluid was collected (n = 10) using rumenocentesis. The relative abundances of Streptococcus bovis decreased, but Megasphaera elsdenii, methanogens, and ammonia-producing bacteria increased by URET. Entodiniomorph and holotrich counts were decreased by URET. Feeding with URET increased ruminal pH and concentrations of total VFA, acetate, branched-chain VFA, and NH3. Feeding with URET also increased milk yield. These results demonstrate that replacing untreated triticale and oat grains with urea-treated grains can beneficially modulate ruminal microbiota and fermentation, consequently improving production performance and profitability.

Depression of ruminal digestion in adult sheep by aureomycin.

1952 ◽  
Vol 3 (4) ◽  
pp. 453 ◽  
Author(s):  
AW Turner ◽  
VE Hodgetts
Keyword(s):  
Body Weight ◽  
Organic Acids ◽  
Yeast Extract ◽  
Ruminal Fermentation ◽  
Gram Positive ◽  
Ruminal Fluid ◽  
Adult Sheep ◽  
Low Level ◽  
Ruminal Ph ◽  
Ruminal Digestion

After the consumption by adult sheep of an amount of aureomycin hydrochloride corresponding to 23.6-27.1 mg. per kg. body weight, the ruminal flora had fallen about 75 per cent. within two hours and remained a t this low level for at least two days, the survivors being predominantly Gram-positive rods and cocci. Ruminal fermentation was greatly depressed; the yield of organic acids reached only about 30 per cent. of the normal and was insufficient to lower the ruminal pH significantly. Appetite was lessened and body weight fell, but responded favourably to administration of ruminal fluid and yeast extract.

scholarly journals Metatranscriptomic analyses reveal ruminal pH regulates fiber degradation and fermentation by shifting the microbial community and gene expression of carbohydrate-active enzymes

2020 ◽  
Author(s):  
MengMeng Li ◽  
Robin R. White ◽  
Le Luo Guan ◽  
Laura Harthan ◽  
Mark D. Hanigan
Keyword(s):  
Microbial Community ◽  
Volatile Fatty Acids ◽  
Liquid Fraction ◽  
Transcriptome Profiling ◽  
Metabolizable Energy ◽  
Ruminal Fermentation ◽  
Bacterial Phyla ◽  
Ruminal Ph ◽  
Fiber Degradation ◽  
Genes Encoding

Abstract Background Volatile fatty acids (VFA) generated from ruminal fermentation by microorganisms provide up to 75% of total metabolizable energy in ruminants. Ruminal pH is an important factor affecting the profile and production of VFA by shifting the microbial community. However, how ruminal pH affects the microbial community and its relationship with expression of genes encoding carbohydrate-active enzyme (CAZyme) for fiber degradation and fermentation are not well investigated. To fill in this knowledge gap, six cannulated Holstein heifers were subjected to a continuous 10-day intraruminal infusion of distilled water or a dilute blend of hydrochloric and phosphoric acids to achieve a pH reduction of 0.5 units in a cross-over design. RNA-seq based transcriptome profiling was performed using total RNA extracted from ruminal liquid and solid fractions collected on day 9 of each period, respectively. Results Metatranscriptomic analyses identified 19 bacterial phyla with 121 genera, 3 archaeal genera, 11 protozoal genera, and 97 CAZyme transcripts in sampled ruminal contents. Within these, 4 bacteria phyla (Proteobacteria, Firmicutes, Bacteroidetes, and Spirochaetes), 2 archaeal genera (Candidatus Methanomethylophilus and Methanobrevibacter), and 5 protozoal genera (Entodinium, Polyplastron, Isotricha, Eudiplodinium, and Eremoplastron) were considered as the core active microbes, and genes encoding for cellulase, endo-1,4-beta- xylanase, amylase, and alpha-N-arabinofuranosidase were the most abundant CAZyme transcripts distributed in the rumen. Rumen microbiota is not equally distributed throughout the liquid and solid phases of rumen contents, and ruminal pH significantly affect microbial ecosystem, especially for the liquid fraction. In general, 76 bacterial genera, 4 protozoal genera, and 48 genes encoding CAZyme were significantly correlated with metabolic pathways for fiber degradation and VFA production. Within them, 29 bacterial genera, 4 protozoal genera, and 6 genes encoding CAZyme could be regulated by ruminal pH. Conclusions The ruminal microbiome changed the expression of transcripts for biochemical pathways of fiber degradation and VFA production in response to reduced pH, and at least a portion of the shifts in enzyme transcripts was associated with altered microbial community structure.

scholarly journals Metatranscriptomic analyses reveal ruminal pH regulates fiber degradation and fermentation by shifting the microbial community and gene expression of carbohydrate-active enzymes

2020 ◽  
Author(s):  
MengMeng Li ◽  
Robin R. White ◽  
Le Luo Guan ◽  
Laura Harthan ◽  
Mark D. Hanigan
Keyword(s):  
Microbial Community ◽  
Volatile Fatty Acids ◽  
Liquid Fraction ◽  
Transcriptome Profiling ◽  
Metabolizable Energy ◽  
Ruminal Fermentation ◽  
Bacterial Phyla ◽  
Ruminal Ph ◽  
Fiber Degradation ◽  
Genes Encoding

Abstract Background: Volatile fatty acids (VFA) generated from ruminal fermentation by microorganisms provide up to 75% of total metabolizable energy in ruminants. Ruminal pH is an important factor affecting the profile and production of VFA by shifting the microbial community. However, how ruminal pH affects the microbial community and its relationship with expression of genes encoding carbohydrate-active enzyme (CAZyme) for fiber degradation and fermentation are not well investigated. To fill in this knowledge gap, six cannulated Holstein heifers were subjected to a continuous 10-day intraruminal infusion of distilled water or a dilute blend of hydrochloric and phosphoric acids to achieve a pH reduction of 0.5 units in a cross-over design. RNA-seq based transcriptome profiling was performed using total RNA extracted from ruminal liquid and solid fractions collected on day 9 of each period, respectively.Results: Metatranscriptomic analyses identified 19 bacterial phyla with 156 genera, 3 archaeal genera, 11 protozoal genera, and 97 CAZyme transcripts in sampled ruminal contents. Within these, 4 bacteria phyla (Proteobacteria, Firmicutes, Bacteroidetes, and Spirochaetes), 2 archaeal genera (Candidatus Methanomethylophilus and Methanobrevibacter), and 5 protozoal genera (Entodinium, Polyplastron, Isotricha, Eudiplodinium, and Eremoplastron) were considered as the core active microbes, and genes encoding for cellulase, endo-1,4-beta- xylanase, amylase, and alpha-N-arabinofuranosidase were the most abundant CAZyme transcripts distributed in the rumen. Rumen microbiota is not equally distributed throughout the liquid and solid phases of rumen contents, and ruminal pH significantly affect microbial ecosystem, especially for the liquid fraction. In total, 21 bacterial genera, 4 protozoal genera, and 6 genes encoding CAZyme were regulated by ruminal pH. Metabolic pathways participated in glycolysis, pyruvate fermentation to acetate, lactate, and propanoate were downregulated by low pH in the liquid fraction.Conclusions: The ruminal microbiome changed the expression of transcripts for biochemical pathways of fiber degradation and VFA production in response to reduced pH, and at least a portion of the shifts in transcripts was associated with altered microbial community structure.

Intake, ruminal fermentation parameters, and apparent total tract digestibility by beef steers consuming Pensacola bahiagrass hay treated with calcium oxide

2021 ◽  
Author(s):  
Francine M Ciriaco ◽  
Darren D Henry ◽  
Tessa M Schulmeister ◽  
Carla D Sanford ◽  
Luara B Canal ◽  
...  
Keyword(s):  
Organic Matter ◽  
Repeated Measures ◽  
Volatile Fatty Acids ◽  
Treatment Time ◽  
Neutral Detergent Fiber ◽  
Ruminal Fermentation ◽  
Plasma Urea ◽  
Ruminal Fluid ◽  
Fermentation Parameters

Abstract To determine the effect of CaO treated Pensacola bahiagrass (Paspalum notatum) hay on intake, ruminal fermentation parameters, and apparent total tract digestibility of nutrients, 9 ruminally cannulated Angus-crossbred steers were used in a triplicated 3 × 3 Latin square design. Steers had ad libitum access to either: 1) untreated dry hay (DH;  n = 8); 2) hay at 50% DM treated with 8.9% CaCO3 [dry matter (DM) basis; CC; n = 9]; or 3) hay at 50% DM treated with 5% CaO (DM basis; CO; n = 8). Water was added to reach 50% DM in the CC and CO diets. Ruminal fluid and blood samples were collected every 3 h for 24 h. Ruminal fluid was analyzed for pH, volatile fatty acids (VFA), and ammonia-nitrogen (NH3-N). Blood was analyzed for plasma urea nitrogen (PUN). Hay and fecal samples were collected for 4 d, 4 times daily for hay and twice daily for feces, to determine apparent total-tract digestibility of nutrients. The hay provided to steers during the digestibility period was analyzed for in vitro organic matter digestibility (IVOMD) for 48h. Data were analyzed as repeated measures for blood and ruminal fermentation parameters. Total DM intake was not affected (P ≥ 0.674) by treatment. A treatment effect (P < 0.001) was observed for average ruminal pH, where steers consuming CO had the greatest pH (P < 0.001). Ruminal concentration of NH3-N tended (P = 0.059) to be reduced in steers consuming CO. There was a treatment × time interaction (P = 0.023) on concentrations of PUN, where at 3 h DH and CO were lesser than CC (P ≤ 0.050) and at 21 h DH was lesser than CC (P = 0.020). Total VFA, acetate, propionate, butyrate, branched-chain VFA, and valerate concentrations were affected by treatment (P ≤ 0.035), where a reduction (P ≤ 0.034) occurred in steers consuming CO. No treatment differences were observed for total-tract digestibility of DM (P = 0.186), organic matter (P = 0.169), or crude protein (P = 0.152); however, steers consuming DH had greater neutral detergent fiber (P = 0.038) than CC and tended to be greater than CO (P = 0.082). The CO hay had greater (P = 0.005) IVOMD compared with DH and tended (P = 0.100) to be greater than CC. Bahiagrass hay treated with CaO may reduce ruminal fermentation, as indicated by decreased total VFA concentration without altering DM intake. The addition of CaO did not improve the digestibility of bahiagrass hay in vivo; however, in vitro results are contradictory and warrant further elucidation.

scholarly journals 196 Screening several phytogenic compounds for their effect on ruminal fermentation parameters in cattle fed high grain diet

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 156-157
Author(s):  
Sara Ricci ◽  
Renee M Petri ◽  
Ezequias Castillo-Lopez ◽  
Raul Rivera-Chacon ◽  
Nicole Reisinger ◽  
...  
Keyword(s):  
Volatile Fatty Acids ◽  
Low Dose ◽  
Rumen Fluid ◽  
Microbial Fermentation ◽  
Ruminal Fermentation ◽  
Beneficial Effects ◽  
Ruminal Ph ◽  
Ruminal Acidosis ◽  
Garlic Oil ◽  
Fermentation Parameters

Abstract Phytogenic compounds, e.g. secondary plant compounds and essential oils, are often used as supplements in ruminant nutrition to modulate microbial fermentation under ruminal dysbiosis associated with high grain feeding. The aim of this study was to evaluate the short-term effects of phytogenic compounds on volatile fatty acids (VFA) production and composition in cows affected by subacute ruminal acidosis (SARA). Nine substances were tested at low and high dosage (1x and 10x respectively) using nine non-lactating ruminally cannulated Holstein cows, adapted to a 65% concentrate and 35% silage (grass and corn) ration (DM basis). Feeding was restricted for nine hours before providing the substance mixed with five kg of TMR. Each substance and dosage was tested individually on four cows (n = 4/compound/dose) over a period of four hours. Rumen and reticulum fluid were collected before the treatment, and four hours after feeding. VFA were measured with gas chromatography. Ruminal pH was continuously recorded (eCow indwelling pH systems). Data were analyzed with the Proc Mixed procedure of SAS. Seven out of nine compounds showed an effect or a trend on VFA measured, both in rumen and reticulum. Acetic acid in rumen fluid decreased with garlic oil, while low dose mint oil increased its concentration (P = 0.06 and P = 0.01, respectively). Low dose mint oil (P < 0.01) and L-menthol (P = 0.03) both increased the A:P ratio, whereas garlic oil tended towards a decrease in the A:P ratio. Garlic oil and ginger showed negative correlations between total VFA and mean ruminal pH (P = 0.03 and P < 0.01, respectively). Our results suggest that phytogenic compounds can modulate microbial activity within four hours of feeding. The use of phytogenic compounds may have beneficial effects on microbial fermentation under low pH conditions associated with high grain feeding.

Effects of fibrolytic enzymes and isobutyrate on ruminal fermentation, microbial enzyme activity and cellulolytic bacteria in pre- and post-weaning dairy calves

2019 ◽  
Vol 59 (3) ◽  
pp. 471 ◽  
Author(s):  
C. Wang ◽  
Q. Liu ◽  
G. Guo ◽  
W. J. Huo ◽  
Y. X. Wang ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Volatile Fatty Acids ◽  
Dairy Calves ◽  
Ruminal Fermentation ◽  
Cellulolytic Bacteria ◽  
Fibrolytic Enzymes ◽  
Ruminal Ph ◽  
Bull Calves ◽  
Microbial Enzyme ◽  
Microbial Enzyme Activity

The objective of the present study was to evaluate the effects of fibrolytic enzymes (FE, containing 160 units of cellulase and 4000 units of xylanase) or isobutyrate (IB) supplementation on ruminal fermentation, microbial enzyme activity and cellulolytic bacteria in dairy calves. Forty-eight Holstein bull calves of 15 days of age and of 44.9 ± 0.28 kg of BW were randomly assigned to four groups in a 2 × 2 factorial arrangement. Two levels of FE (0 g (FE–) or 1.83 g per calf per day (FE+)) and IB (0 g (IB–) or 6 g per calf per day (IB+)) were added. Calves were weaned at 60-day-old and four calves were selected from each treatment at random and slaughtered at 45 and 90 days of age. There was no IB × FE interaction effect. Ruminal pH decreased with IB or FE supplementation for post-weaned calves, whereas concentrations of total volatile fatty acids and acetate increased with IB or FE supplementation for pre- and post-weaned calves. Acetate to propionate ratio increased with IB supplementation, but was unaffected by FE supplementation. Ammonia-N concentration decreased with IB or FE supplementation for pre- and post-weaned calves. For post-weaned calves, activities of CMCase increased with IB or FE supplementation, and activities of cellobiase, xylanase, pectinase, β-amylase and protease increased with IB supplementation. Populations of B. fibrisolvens and F. succinogenes for pre- and post-weaned calves and R. flavefaciens for post-weaned calves increased with IB or FE supplementation. It is suggested that ruminal fermentation and growth performance of calves was improved with IB and FE supplementation, and the combination of IB and FE has the potential to stimulate the growth of pre- and post-weaned dairy calves.

scholarly journals 413 Effect of chitosan inclusion and dietary crude protein level on rumen fermentation in beef heifers fed a total mixed ration

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 166-167
Author(s):  
Stuart Kirwan ◽  
Tommy Boland ◽  
Eleonora Serra ◽  
Gaurav Rajauria ◽  
Karina Pierce
Keyword(s):  
Crude Protein ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Rumen Fermentation ◽  
Ruminal Fermentation ◽  
Beef Heifers ◽  
Total Mixed Ration ◽  
Ruminal Ph ◽  
Dietary Crude Protein ◽  
Dietary Treatments

Abstract Chitosan (N-acetyl-D-glucosamine polymer) is a natural biopolymer, which is the second most abundant organic compound on earth, found in lower plants and some arthropods and crustaceans. Studies with ruminants have shown that supplementing with chitosan can alter ruminal fermentation, including higher propionate concentration and lower acetate to propionate ratio, improving the energy efficiency within the rumen though data on nitrogen metabolism is lacking. Therefore, the objective of this study was to evaluate the effects of chitosan with different dietary crude protein (CP) inclusion on rumen fermentation in beef heifers. Eight ruminally cannulated Belgian Blue x Holstein Friesian heifers (752 ± 52Kg BW) were allocated one of four dietary treatments in a 2 x 2 factorial Latin Square design (n = 8). Diets were offered as total mixed ration (TMR) consisting of grass silage plus concentrate. Diets were offered once daily ad libitum. Dietary treatments were as follows: high CP (16%) +/- chitosan (10g kg-1 DMI) supplementation (HP+) or (HP-) and low CP (12%) +/- chitosan supplementation (LP+) or (LP-). Experimental periods were 25d in duration (14 d dietary adaptation and 10 d sampling). Rumen fluid was collected via cannula every 2 h post feeding for analysis of ruminal pH, ammonia (NH3) and volatile fatty acids (VFA) over a 48-hour period. Data was analysed using Proc Mixed procedure in SAS. Significant differences were considered when P < 0.05. Dietary treatment had no effect on ruminal pH (P > 0.05). Chitosan supplementation had no effect on ruminal NH3 and VFA concentrations (P > 0.05), whereas, animals offered 16% CP had higher concentrations of ruminal NH3 (P < 0.001). In conclusion, supplementing a TMR diet fed to beef heifers with chitosan had no effect on rumen fermentation. However, reducing dietary CP concentration fed to beef animals resulted in lower rumen NH3 concentrations.

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