Effects of grain or hay supplementation on the chewing behaviour and stability of rumen fermentation of dairy cows grazing perennial ryegrass-based pasture in spring

2005 ◽  
Vol 45 (12) ◽  
pp. 1519 ◽  
Author(s):  
Y. J. Williams ◽  
W. J. Wales ◽  
P. T. Doyle ◽  
A. R. Egan ◽  
C. R. Stockdale
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Rumen Fermentation ◽  
Total Volatile ◽  
Neutral Detergent Fibre ◽  
Degradation Rates ◽  
Cereal Grain ◽  
Chewing Behaviour

Cows grazing highly digestible pasture in early spring can have very low rumen fluid pH that can negatively impact on the efficiency of microbial digestion. In this experiment, cows in early lactation grazed perennial ryegrass (Lolium perenne L.)-based pasture alone at low or high allowances, or at a low allowance supplemented with either a cereal grain pellet, a chopped hay cube or a cube containing cereal grain and chopped hay to determine the effects of the addition of neutral detergent fibre as hay on chewing behaviour and stability of rumen fermentation. The hypotheses tested were that: (i) supplementing high digestibility ryegrass pasture with pelleted cereal grain would increase the proportion of the day that the pH of rumen fluid was below 6.0 and would decrease the rate of degradation of neutral detergent fibre in pasture and hay; and (ii) the inclusion of chopped hay with the cereal grain supplement in cubes would reduce the proportion of the day that the rumen fluid pH was below 6.0 and restore the rate of degradation of neutral detergent fibre in pasture and hay to that in unsupplemented cows. Rumen fluid pH was highest (P<0.05) in cows fed a chopped hay cube and lowest (P<0.05) in cows fed a cube containing cereal grain and chopped hay, with no significant (P>0.05) difference between those fed pasture only or cereal grain pellets. The introduction of grain, with or without hay, did not substantially alter the pattern or magnitude of changes in rumen fluid pH, but did reduce (P<0.05) the rate of degradation of neutral detergent fibre in pasture (5.3 v. 7.6%/h) and hay (2.7 v. 5.0%/h) in the rumen. Rumen degradation rates of pasture dry matter and neutral detergent fibre were not improved by adding chopped hay. Total volatile fatty acid concentrations in rumen fluid were highest (P<0.05) on the high pasture allowance treatment and lowest (P<0.05) on the low pasture allowance and the chopped hay cube treatments. Supplementation with grain reduced (P<0.05) the proportion of acetate and increased (P<0.05) the proportion of propionate in total volatile fatty acids. There were no significant (P>0.05) effects of dietary treatment on time spent grazing or on rate of biting while grazing. Cows in treatments receiving grain supplements (532 min) and those in the high pasture allowance treatment (566 min) spent more (P<0.05) time ruminating than those in the low pasture allowance (415 min) and chopped hay cube (465 min) treatments. The relative contributions of low pH and of starch to the reduction in rates of dry matter and neutral detergent fibre degradation in the rumen cannot be determined from this experiment, however, it is likely that both factors contribute to a relative increase in the metabolic activity of non-cellulolytic microorganisms.

Digestion, rumen fermentation and chewing behaviour of red deer fed fresh chicory and perennial ryegrass

1995 ◽  
Vol 124 (2) ◽  
pp. 289-295 ◽  
Author(s):  
S. O. Hoskin ◽  
K. J. Stafford ◽  
T. N. Barry
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Red Deer ◽  
Rumen Fluid ◽  
Apparent Digestibility ◽  
Eating Time ◽  
Outflow Rate ◽  
Structural Carbohydrate ◽  
Chewing Behaviour

SUMMARYPure chicory (Cichorium intybus) and perennial ryegrass (Lolium perenne) forages were cut and fed fresh at Palmerston North, New Zealand, during March 1993 to castrated male red deer kept indoors in metabolism crates. Chicory contained lower levels of dry matter, higher levels of ash, and had a higher ratio of readily fermentable: structural carbohydrate than perennial ryegrass. Apparent digestibility of organic matter was highest for chicory (0·81 v. 0·72), but cellulose apparent digestibility was highest for perennial ryegrass (0·71 v. 0·59). Relative to perennial ryegrass, the rumen fluid of deer fed chicory contained higher concentrations of protozoa, ammonia and total volatile fatty acids (VFA) but had a lower pH at 15.00 h. Chicory-fed deer had higher rumen VFA molar proportions of n-butyrate and a higher acetate: propionate ratio. Total eating time and chews during feeding/g dry matter intake were similar for deer fed the two forages, but deer fed chicory spent much less time ruminating (33 v. 270 min/day) and had fewer rumination boluses (38 v. 305/day). It was concluded that the low rumination time may indicate rapid disintegration of chicory in the rumen to < 1 mm critical particle size, and that particle breakdown and rumen fractional outflow rate should be measured in future experiments with deer fed on chicory.

Rumen fermentation characteristics of dairy cows grazing different allowances of Persian clover- or perennial ryegrass-dominant swards in spring

2005 ◽  
Vol 45 (6) ◽  
pp. 665 ◽  
Author(s):  
Y. J. Williams ◽  
G. P. Walker ◽  
P. T. Doyle ◽  
A. R. Egan ◽  
C. R. Stockdale
Keyword(s):  
Fatty Acid ◽  
Dairy Cows ◽  
Perennial Ryegrass ◽  
Volatile Fatty Acid ◽  
Dry Matter ◽  
Rumen Fluid ◽  
Rumen Fermentation ◽  
Total Volatile ◽  
Persian Clover ◽  
Grazing Dairy Cows

An experiment was conducted in which cows in early lactation grazed Persian clover (Trifolium resupinatum L.) or perennial ryegrass (Lolium perenne L.)-dominant pastures at low or high pasture allowances in order to determine the effects of pasture type and level of feeding on rumen fermentation patterns. The hypotheses for grazing dairy cows were: (i) the consumption of Persian clover would result in a more rapid rate of degradation and less stable rumen fermentation patterns compared with perennial ryegrass; and (ii) the greater intake of cows grazing at high compared with low pasture allowances would also cause less stable rumen fermentation patterns. Stability of rumen fermentation refers to the level to which rumen fluid pH declines, especially for long periods of a day, indicating that the rumen is not coping with neutralising and/or removing acids. Cows grazing Persian clover had lower (P<0.05) average daily rumen fluid pH (5.7 v. 5.9), molar proportions of acetic acid (68.3 v. 70.6%) and ratios of lipogenic to glucogenic volatile fatty acid (4.6 v. 5.1) in the rumen than those grazing perennial ryegrass. They had higher (P<0.05) rumen fluid ammonia-N (26.3 v. 13.0 mg/100 mL) and total volatile fatty acid (165 v. 134 mmol/L) concentrations and molar proportions of butyric (11.3 v. 10.7%) and propionic (17.2 v. 16.1%) acids than cows grazing perennial ryegrass. Cows grazing at low pasture allowances had a higher (P<0.05) average daily rumen fluid pH (5.9 v. 5.7) and lower rumen fluid ammonia-N (18.6 v. 20.7 mg/100 mL) and total volatile fatty acid (143 v. 156 mmol/L) concentrations than cows grazing at high pasture allowances. Cows given Persian clover at the high allowance had a rumen fluid pH less than 6.0 for the entire day while rumen fluid pH was below 6.0 for at least 15 h of the day on all the other treatments. There was no effect (P>0.05) of pasture allowance on the degradation rate of perennial ryegrass dry matter, but the higher allowance of Persian clover resulted in the highest (P<0.05) rate of degradation of dry matter compared with either ryegrass treatment or the low allowance of Persian clover. The effective dry matter degradability of Persian clover was greater (P<0.05) than that of perennial ryegrass, and the effective dry matter degradability of herbage in cows grazing at low allowances was greater (P<0.05) than at higher allowances. However, future research should consider neutral detergent fibre degradation in grazing dairy cows with low rumen fluid pH levels.

scholarly journals Effects of Geraniol and Camphene on in Vitro Rumen Fermentation and Methane Production

2017 ◽  
Vol 48 (2) ◽  
pp. 63-69
Author(s):  
M. Joch ◽  
V. Kudrna ◽  
B. Hučko
Keyword(s):  
Methane Emission ◽  
Methane Production ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Positive Control ◽  
Rumen Fermentation ◽  
Dry Matter Digestibility

AbstractThe objective of this study was to determine the effects of geraniol and camphene at three dosages (300, 600, and 900 mg l-1) on rumen microbial fermentation and methane emission in in vitro batch culture of rumen fluid supplied with a 60 : 40 forage : concentrate substrate (16.2% crude protein, 33.1% neutral detergent fibre). The ionophore antibiotic monensin (8 mg/l) was used as positive control. Compared to control, geraniol significantly (P < 0.05) reduced methane production with increasing doses, with reductions by 10.2, 66.9, and 97.9%. However, total volatile fatty acids (VFA) production and in vitro dry matter digestibility were also reduced (P < 0.05) by all doses of geraniol. Camphene demonstrated weak and unpromising effects on rumen fermentation. Camphene did not decrease (P > 0.05) methane production and slightly decreased (P < 0.05) VFA production. Due to the strong antimethanogenic effect of geraniol a careful selection of dose and combination with other antimethanogenic compounds may be effective in mitigating methane emission from ruminants. However, if a reduction in total VFA production and dry matter digestibility persisted in vivo, geraniol would have a negative effect on animal productivity.

scholarly journals Dose-response effects of sage (Salvia officinalis) and yarrow (Achillea millefolium) essential oils on rumen fermentation in vitro

2018 ◽  
Vol 18 (1) ◽  
pp. 125-142
Author(s):  
Mina Kahvand ◽  
Mostafa Malecky
Keyword(s):  
Essential Oil ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Dose Range ◽  
Ammonia Concentration ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Total Volatile ◽  
Alpha Pinene

Abstract This study aimed at determining the chemical composition of sage essential oil (SEO) and yarrow essential oil (YEO), and investigate in vitro their impacts on gas production kinetics, ruminal digestibility and fermentation, and rumen methanogenesis at different dosages (0, 250, 500 and 750 mg L-1 for SEO; and 0, 250, 500, 750 and 1000 mg L−1 for YEO). Alpha-pinene and 1,8 cineol were two major constituents of both SEO and YEO. Both SEO and YEO had a linear and quadratic effect on asymptotic gas production (P<0.05). The gas production rate increased linearly with SEO and curve-linearly with YEO dosages (P<0.05). In vitro degradability of dry matter and organic matter decreased only by YEO. The partitioning factor (PF) and the microbial biomass (MB) decreased and increased linearly with YEO and SEO dosages, respectively (P<0.05). Total volatile fatty acids (VFA ) were not affected by SEO, but decreased in a linear and quadratic manner with YEO dosage (P<0.05). The VFA pattern was modified in a linear and quadratic manner by both SEO and YEO (P<0.05). Ammonia concentration increased linearly only with YEO increasing doses. The methane to total gas (TG) ratio decreased quadratically only by SEO with reductions of 6.7, 13 and 4.2% at the doses of 250, 500 and 750 mg L−1, respectively. These results revealed that SEO modifies the rumen fermentation positively towards producing more MB and less methane in the dose range of 0-750 mg L−1, however, YEO adversely affected the rumen fermentation at all the tested doses.

EFFECT OF ACCLIMATION TO HIGH NITRATE INTAKES ON SOME RUMEN FERMENTATION PARAMETERS IN SHEEP

1985 ◽  
Vol 65 (4) ◽  
pp. 841-849 ◽  
Author(s):  
A. R. ALABOUDI ◽  
G. A. JONES
Keyword(s):  
Nitrate Reduction ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Residual Effect ◽  
Basal Diet ◽  
Rumen Fermentation ◽  
Nitrite Reduction ◽  
Rumen Bacteria ◽  
Cereal Grain ◽  
Nitrate And Nitrite

Four sheep, fed a basal diet which included 44% cereal grain and 50% hay and which was supplemented with KNO3, were progressively acclimated to a KNO3 intake of 2.5 g∙kg body wt−1∙day−1. Nitrate and nitrite reducing activity in strained rumen fluid (SRF) collected 2 h after feeding showed maximum values of 45.3 μg N∙mL−1∙h−1 and 39.4 μg N∙mL−1∙h−1, respectively, at an intake of 1.5 g∙kg body wt−1∙day−1. The rate of nitrate reduction was threefold higher (P < 0.01), and that of nitrite reduction fivefold higher (P < 0.01), than in SRF from sheep not receiving KNO3. When the KNO3 supplement was withdrawn the reducing activities fell to their initial levels within 3 wk. In a second experiment, nitrate, nitrite and volatile fatty acids in SRF, and methemoglobin in peripheral blood, were estimated at 30-min intervals after feeding in four sheep, two of which received 1.5 g KNO3∙kg body wt−1∙day−1. In the animals fed KNO3 the peak concentration of nitrate in SRF (13.30 μg NO3−–N∙mL−1) was reached 30 min after feeding, and that of nitrite (2.90 μg NO2−–N∙mL−1) 60 min after feeding; the presence of nitrate in SRF was associated with an increase in the molar proportion of acetate (P < 0.01) and a decrease in the proportion of n-butyrate (P < 0.01). The blood methemoglobin concentration did not exceed 2% (wt/wt) of total hemoglobin at any sampling time. In these animals 30–35 g KNO3 cleared the rumen within 3 h after feeding with no symptoms of nitrate toxicity. Enumeration of rumen bacteria by a direct isolation procedure indicated that the proportion of nitrate reducers in SRF was threefold higher (P < 0.01) in acclimated animals than in control animals. It was concluded that safe acclimation of sheep to high levels of dietary nitrate involved an increase in the rates of nitrate and nitrite reduction in the rumen, a narrowing of the ratio of these activities, and an increase in the proportion of nitrate reducing rumen bacteria. The residual effect of nitrate on the fermentation following clearance from the rumen was short-lived. Key words: Rumen fermentation, sheep, nitrate toxicity, nitrate reduction, nitrite reduction, rumen bacteria

Increasing the intake of highly digestible Persian clover herbage reduces rumen fluid pH and the rate of degradation of neutral detergent fibre in grazing dairy cows

2005 ◽  
Vol 45 (12) ◽  
pp. 1529 ◽  
Author(s):  
Y. J. Williams ◽  
P. T. Doyle ◽  
A. R. Egan ◽  
C. R. Stockdale
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Daily Intake ◽  
Total Volatile ◽  
Neutral Detergent Fibre ◽  
Persian Clover ◽  
Grazing Dairy Cows ◽  
Fibre Loss ◽  
Plot Design

An experiment was conducted to investigate the hypothesis that increasing the intake of Persian clover (Trifolium resupinatum L.) would decrease rumen fluid pH and the rate of loss of neutral detergent fibre from nylon bags. It was further hypothesised that the reduction in the rate of disappearance of neutral detergent fibre with increased intake would be less in highly digestible clover than in highly digestible ryegrass or pasture hay. Sixteen rumen fistulated cows, in late lactation, were used in a completely randomised, split-plot design for 33 days. There were 4 pasture allowance treatments (9, 16, 32 and 53 kg dry matter (DM)/cow.day of Persian clover) with 4 cows per treatment. Cows grazed in individual plots, pasture intakes were measured, and rumen fluid and in sacco measurements were undertaken. Pasture DM intake increased asymptotically as pasture allowance increased from 9 to 53 kg DM. Cows grazing at the 9 kg pasture allowance spent less time grazing than cows at higher allowances (294 v. 368, 421 and 414 min, P<0.05). Cows grazing at the 2 lower allowances spent less time grazing at night than cows at the 2 higher allowances. There was no effect (P>0.05) of pasture allowance on time spent ruminating, which averaged 236 min. Estimated rates of intake increased (P<0.05) with pasture allowance. Average daily rumen fluid pH decreased linearly (P<0.05) with pasture intake, with the averages for the pasture allowance treatments being 6.03, 5.95, 5.83 and 5.79 as pasture allowance increased. The patterns of rumen fluid pH over 24 h indicated that it was only late in the night that treatment differences were detected, with the lower pasture allowance treatments recording higher rumen fluid pH values than the higher pasture allowance treatments. There was no effect of pasture allowance on average daily rumen fluid ammonia-N concentrations (25 mg/100 mL). Total volatile fatty acids concentrations averaged 139, 152, 163 and 168 mmol/L as pasture allowance increased from 9 to 53 kg DM/cow.day. The proportion of acetate in total volatile fatty acids generally declined (71.4, 70.4, 67.4 and 69.2%; s.e.d. = 1.14) and the proportion of propionate generally increased (15.2, 15.5, 17.6 and 17.0%; s.e.d. = 0.77) as pasture allowance increased from 9 to 53 kg DM/cow, respectively. Rate of neutral detergent fibre loss from nylon bags was highest in clover, and lowest in hay, and was higher in cows grazing at 9 and 16 kg allowances compared with cows at 32 and 53 kg (P<0.05). There was a linear relationship (P<0.05) between rate of neutral detergent fibre loss and rumen fluid pH for clover and ryegrass, but not hay (P>0.05). There were no differences (P>0.05) in total rumen contents (75.6 kg; s.e.d. = 6.95), or DM (7.3 kg; s.e.d. = 0.73) and neutral detergent fibre (2.7 kg; s.e.d. = 0.32) pools, of cows grazing at different allowances. Offering cows increasing allowances of Persian clover pasture reduced rumen digesta retention times, as rumen pool sizes did not change. Average daily pH fell with increasing allowance due to differences in daily intake and pH patterns, and increasing pasture allowance decreased the rate of disappearance of neutral detergent fibre. It is suggested that increased outflow rates, driven by differences in daily pH patterns and changes in substrate composition, were responsible for the decline in disappearance of neutral detergent fibre from nylon bags, but the effects of the factors cannot be separated.

scholarly journals The effect of different physical forms of starter feed on rumen fermentation indicators and weight gain in calves after weaning

2017 ◽  
Vol 86 (3) ◽  
pp. 285-291 ◽  
Author(s):  
Leoš Pavlata ◽  
Ondřej Šťastník ◽  
Štěpánka Křivová ◽  
Hana Dočkalová ◽  
Lenka Sedláková ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Weight Gain ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Average Daily Gain ◽  
Rumen Fermentation ◽  
Total Volatile ◽  
Ruminal Acidosis ◽  
Molar Proportion ◽  
Rumen Ph

The aim of the study was to determine the effect of different physical forms of starter feed on rumen fermentation indicators of calves after weaning and their weight gain. The experiment was performed with Czech Fleckvieh calves after weaning. The calves were fed ad libitum completely pelleted starter feed or texturized starter feed with chopped straw. The rumen fluid samples were collected after a month of feeding the starter feeds. The calves were weighed monthly. The pH, total acidity, total volatile fatty acids, acetate, propionate, butyrate, lactic acid, ammonia and the number of rumen ciliate protozoa were determined in the rumen fluid samples. The calves receiving the starter feed with straw showed significantly higher rumen pH (6.24 ± 0.51 vs. 5.58 ± 0.30), total volatile fatty acids (98.02 ± 20.46 vs. 61.40 ± 26.51 mmol/l), molar proportion of acetate (61.20 ± 4.87 vs. 50.53 ± 4.66%), and the acetate:propionate ratio (2.38 ± 0.53 vs. 1.34 ± 0.18) and lower molar proportion of propionate (26.55 ± 4.48 vs. 37.92 ± 3.58%) compared with the calves receiving pelleted starter feed. Average daily gain of the calves did not differ significantly. The feeding of starter feed with chopped straw compared with the pelleted starter feed led to better development of the rumen fermentation evaluated by rumen pH, by total volatile fatty acids production, and by the proportion and ratio of acetic and propionic acids. The feeding of starter feed with chopped straw reduced the occurrence of subacute ruminal acidosis in the weaned calves.

EFFECT OF FEEDING A CONCENTRATED WHEY-CANOLA MEAL MIXTURE AS THE MAJOR COMPONENT OF STARTER RATIONS FOR CALVES

1985 ◽  
Vol 65 (3) ◽  
pp. 683-691 ◽  
Author(s):  
L. J. FISHER ◽  
W. T. BUCKLEY
Keyword(s):  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Dry Matter Intake ◽  
Canola Meal ◽  
Total Volatile ◽  
Plasma Urea ◽  
Holstein Calves ◽  
Sodium And Potassium ◽  
Effect Of Feeding

Thirty-two male Holstein calves were subdivided into four groups at 35 days of age and used to evaluate the feeding of an evaporated whey-canola meal feedstuff (EWC) fed in combination with either a grain-based starter ration or chopped hay. Over a feeding period of 7 wk, dry matter intake of EWC increased to 84 and 90% of total dry matter intake for the grain-based and hay-based starter rations, respectively. Rumen fluid butyrate and valerate levels increased to 40% and 15%, respectively, of total volatile fatty acids produced. Plasma urea levels were lower and phosphorus, potassium and copper levels were higher when EWC was fed. The digestibility of EWC-based diets was higher than either grain or hay diets without EWC. Nitrogen, calcium, sodium and potassium balances were substantially increased by the EWC-based diet. Bloat was a problem when the EWC was fed in conjunction with a grain-based starter ration. This problem was prevented by feeding small amounts of chopped hay. It was concluded from the results of this study that EWC could be fed in combination with chopped hay at up to 90% of the total dry matter intake of young calves without causing acidosis or digestive upsets. Key words: Whey, canola meal, starter rations, calves

Effect of dietary monensin and tetronasin on rumen fermentation in sheep

1990 ◽  
Vol 1990 ◽  
pp. 31-31
Author(s):  
C. J. Newbold ◽  
R. J. Wallace
Keyword(s):  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Control Diet ◽  
Latin Square ◽  
Rumen Fermentation ◽  
Mixed Diet ◽  
Feed Conversion ◽  
Nutritional Effects

Tetronasin is an ionophore which improves feed conversion efficiency in ruminants (Bartleet al, 1988). Its nutritional effects are at least partly derived from its influence on nitrogen and energy metabolism in the rumen. The mode of action of tetronasin is therefore similar to monensin and although it is more potent than monensin, it has a similar spectrum of antimicrobial activity (Newboldet al, 1988). The aim of the present study was to compare the effects of the inclusion of tetronasin or monensin in the diet on the rumen fermentation.Three mature sheep weighing approximately 50 kg and fitted with rumen cannulae were fed 1 kg/d of a mixed diet of hay, barley, molasses, fishmeal and vitamins/minerals (500, 299.5, 100, 91 and 9.5 g/kg dry matter respectively) in two equal meals. A control diet (no addition, C), tetronasin (10 ppm in the diet, T) or monensin (33 ppm, M) were compared in a 3 x 3 Latin square. Periods were 28 days long with samples taken on two consecutive days during the last 5 days. Samples of rumen fluid were withdrawn at 0, 1, 2, 4 and 6 h after the morning feed for the determination of pH, volatile fatty acids (VFA) L-lactic acid and ammonia concentrations.

Rumen fermentation patterns in sheep receiving silages of different chemical composition supplemented with concentrates rich in starch or in digestible fibre

1994 ◽  
Vol 122 (1) ◽  
pp. 145-150 ◽  
Author(s):  
P. A. Martin ◽  
D. G. Chamberlain ◽  
S. Robertson ◽  
D. Hirst
Keyword(s):  
Lactic Acid ◽  
Chemical Composition ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Microbial Population ◽  
Strong Relationship ◽  
Rumen Fermentation ◽  
Total Volatile ◽  
Rumen Ph ◽  
Fermentation Pattern

SUMMARYIn each of two experiments, eight silages supplemented with concentrates containing a high proportion of either starch or digestible fibre were given to rumen-cannulated sheep. The silages constituted c. 65% of the total dry matter and differed widely in chemical composition, reflecting differences in the extent of fermentation in the silo.Rumen pH was lower (P < 0·01 and P < 0·001 for Expts 1 and 2 respectively) and the concentration of total volatile fatty acids (VFA) in the rumen was higher (P < 0·001 for Expt 2) for the starchy concentrate. Silages differed in their effects on ruminal proportions of acetate (P < 0·001 and P < 0·01 for Expts 1 and 2 respectively) and, inversely, of propionate (P < 0·001 for Expt 1). There was evidence of a strong relationship between the molar proportion of propionate in the rumen and the concentration of lactic acid in the silage. The results indicate that the production of propionate during the metabolism of silage lactic acid by the rumen microbial population was the predominant influence on rumen fermentation pattern.It is suggested that this relationship is the basis of some of the differences in milk production reported for silages showing restricted as opposed to extensive fermentation.

Sign in / Sign up

Export Citation Format

Share Document