Digestion by ruminant lambs of a diet containing formaldehyde-treated casein

1971 ◽  
Vol 22 (3) ◽  
pp. 461 ◽  
Author(s):  
GJ Faichney ◽  
RH Weston
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Plasma Levels ◽  
Volatile Fatty Acids ◽  
Amino Nitrogen ◽  
Ammonia Nitrogen ◽  
Casein Diet ◽  
Plasma Urea ◽  
Urea Level

Digestion of a diet containing 10% casein, either untreated or treated with formaldehyde, was studied in crossbred wether lambs. The treatment prevented breakdown of the casein in rumen liquor in vitro. There was a highly significant decrease in organic matter digestion in the rumen when the treated casein diet was given to the lambs. This was accounted for by increases in the amounts of protein and starch passing to the intestines. There was a 60 % increase in the amount of non-ammonia nitrogen and a 55 % increase in the amount of starch digested in the intestines. The concentrations of volatile fatty acids and ammonia in the rumen were significantly lower. There were increases in the plasma levels of insulin and �-amino nitrogen and a decrease in the plasma urea level in response to the treatment.

scholarly journals Multiple-factor associative effects of peanut shell combined with alfalfa and concentrate determined by in vitro gas production method

2019 ◽  
Vol 64 (No. 8) ◽  
pp. 352-360
Author(s):  
Jiu Yuan ◽  
Xinjie Wan
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Production Method ◽  
Ammonia Nitrogen ◽  
Gas Production ◽  
Peanut Shell ◽  
Dry Matter Digestibility ◽  
In Vitro Gas Production

The associative effects (AE) between concentrate (C), peanut shell (P) and alfalfa (A) were investigated by means of an automated gas production (GP) system. The C, P and A were incubated alone or as 40 : 60 : 0, 40 : 45 : 15, 40 : 30 : 30, 40 : 15 : 45, 40 : 0 : 60 and 30 : 70 : 0, 30 : 55 : 15, 30 : 40 : 30, 30 : 25 : 45, 30 : 10 : 60, 30 : 0 : 70 mixtures where the C : roughage (R) ratios were 40 : 60 and 30 : 70. Samples (0.2000 ± 0.0010 g) of single feeds or mixtures were incubated for 96 h in individual bottles (100 ml) with 30 ml of buffered rumen fluid. GP parameters were analysed using a single exponential equation. After incubation, the residues were used to determine pH, dry matter digestibility (DMD), organic matter digestibility (OMD), volatile fatty acids (VFA) and ammonia nitrogen (NH<sub>3</sub>-N) of the incubation fluid, and their single factor AE indices (SFAEI) and multiple-factors AE indices (MFAEI) were determined. The results showed that group of 30 peanut shell had higher SFAEI of GP<sub>48 h</sub>, DMD, OMD and total volatile fatty acids (p &lt; 0.05) and MFAEI (p &lt; 0.05) than groups 60, 45 and 0 when C : R was 40 : 60. The group of 10 peanut shell showed higher SFAEI of GP<sub>48 h</sub>, DMD and OMD (p &lt; 0.05) than groups 70, 55 and 40 and MFAEI (p &lt; 0.01) when C : R was 30 : 70. It is concluded that optimal SFAEI and MFAEI were obtained when the C : P : A ratios were 40 : 30 : 30 and 30 : 10 : 60.

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 &lt; 0.001) was observed for average ruminal pH, where steers consuming CO had the greatest pH (P &lt; 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.

Optimalisasi Penggunaan Level Sabun Kalsium Minyak Kedelai dalam Ransum Terhadap Karakteristik Fermentasi, Populasi Mikroba dan Kecernaan Nutrien Secara In Vitro Menggunakan Cairan Rumen Sapi Bali

2018 ◽  
Vol 5 (2) ◽  
pp. 11
Author(s):  
Ali Bain ◽  
Komang G. Wiryawan ◽  
Dewi Apri Astuti ◽  
Chairrusyuhur Arman ◽  
Sri Suharti
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Microbial Population ◽  
Total Volatile ◽  
Calcium Soap ◽  
Total Bacteria ◽  
Range Test

ABSTRAKPenelitian ini bertujuan untuk mengevaluasi optimalisasi penggunaan level sabun kalsium yang berbeda dalam ransum secara in vitro terhadap karakteristik fermentasi, populasi mikroba dan kecernaan nutrien ransum, menggunakan sumber inokulum cairan rumen sapi Bali. Penelitian dilaksanakan menggunakan rancangan acak kelompok dengan 4 jenis perlakuan dalam 3 ulangan.  Ransum penelitian terdiri atas : R1, 40% rumput lapang (RL) + 60% konsentrat (K), R2 (40% RL + 60% K, mengandungn 2.5% SCa-kedelai), R3 (40%  RL + 60% K, mengandung 5% SCa-kedelai), R4 (40%  RL + 60% K, mengandung 7.5% SCa-kedelai). Variabel yang diukur terdiri atas karakteristik fermentasi in vitro (pH, N-NH3, produksi total volatile fatty acids), populasi mikroorganisme (total bakteri dan total protozoa), dan kecernaan nutrien (kecernaan bahan kering dan kecernaan bahan organik). Data dianalisis menggunakan analysis of varians  (ANOVA) dan perbedaan antara perlakuan diuji dengan Duncan’s Multiple Range Test.  Hasil penelitian menunjukkan, penambahan SCa-kedelai pada level yang berbeda dalam konsentrat tidak mempengaruhi pH, konsentrasi amonia, populasi mikroba, kecernaan bahan kering dan kecernaan bahan organik fermentasi tetapi berpengaruh sangat nyata (P<0.002) terhadap produksi total VFA. Produksi total VFA tertinggi diperoleh pada ransum perlakuan R4 (konsentrat yang mengandung 7.5% SCa-kedelai). Produksi total VFA tertinggi diperoleh pada perlakuan R4 dan produksi total VFA paling rendah terjadi pada perlakuan ransum R1 (kontrol).  Produksi total VFA  ransum R1 dan R2 dan ransum R2 dan R3 tidak berbeda nyata namun produksi total VFA ransum R3 lebih tinggi dibanding ransum kontrol. Penambahan SCa-kedelai dalam konsentrat menghasilkan produksi total VFA tetinggi namun mulai menekan populasi total bakteri. Mempertimbangkan hasil peubah fermentasi dan populasi mikroba serta biaya pembuatan produk sabun kalsium, SCa-kedelai pada level 5% merupakan level penggunaan SCa-kedelai yang terbaik dalam ransum.Kata kunci: sabun kalsium, fermentasi, in vitro, kecernaanABSTRACTThe study to evaluate the optimalization the different level of soybean oil calcium soap (CaS-soybean) in ration on in vitro fermentation using Bali cattle rumen fluid. The experiment was arranged in a complete randomized block design with 4 different ration treatments and 3 replicates. Ration treatments were R1: 40% native grass (NG) + 60% concentrate (C), R2 : 40% NG + 60% C, supplemented with 2.5% soybean oil calcium soap (CaS-soybean), and R3 (40% NG + 60% C, supplemented with 5.0% CaS-soybean and R4 (40% NG + 60% C, supplemented with 7.5% CaS-soybean). Variables measured were fermentation characteristics (pH, NH3-N, total volatile fatty acids), microbial population (total bacteria and total protozoa), and nutrient digestibility (dry matter and organic matter digestibility). Data were analyzed using analysis of variance (ANOVA) and the differences between treatments means were examined by Duncan Multiple Range Test. Results of the study  showed that the four different level of CaS-soybean in ration did not have any significant effect (P>0,05) on pH, NH3-N, total bacteria, total protozoa, dry matter and organic matter digestibility. The treatments significantly increased (P<0.05) the production of total volatile fatty acids.  The highest production of total VFA was obtained from ration R4 (concentrate containing 7.5% CaS-soybean) and the lowest was obtained from treatment R1 (control). There were no significant differences between R1 and  R2, and between R2 and R3 on the total VFA production. However, the total productions of VFA in ration R3 were higher than that of the control ration. The addition of CaS-soybean in the concentrate had increased the total production of VFA, but at the same time, it began pressing the total population of bacteria. Considering the results of the fermentation variables and microbial population as well as the cost of making calcium soap products, CaS-soybean at 5% level was selected as the best level of CaS-soybean in ration.Keywords : calcium soap, fermentation, in vitro, digestibility

The digestion of pasture plants by sheep. IV*. The digestion of Phalaris tuberosa at different stages of maturity

1969 ◽  
Vol 20 (5) ◽  
pp. 925 ◽  
Author(s):  
JP Hogan ◽  
RH Weston ◽  
JR Lindsay
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Organic Matter ◽  
Plasma Levels ◽  
Crude Protein ◽  
Volatile Fatty Acids ◽  
Essential Amino Acids ◽  
Digestible Organic Matter ◽  
Time And Energy ◽  
Dietary Origin

A study was made of the composition, intake, and digestion of dried Phalaris tuberosa forage that had been harvested at three stages of maturity. Advancing maturity was associated with: (i) decreased food intake; (ii) increased expenditure of time and energy in chewing activities; (iii) decline in the rate of flow of digesta from the abomasum though not from the rumen; (iv) decline in digestibility in the whole tract of organic matter, nitrogen, and the structural carbohydrates; (v) decline in the digestion of fibre in the rumen relative to that occurring in the whole tract; (vi) decline in the quantities of volatile fatty acids and amino acids made available to the animal. By contrast only small differences attributable to maturity were observed in: (i) the distribution of digestion of organic matter between stomach and intestines; (ii) the digestibility of nitrogen other than ammonia in the intestines; (iii) the proportions of digestible organic matter derived from volatile fatty acids and amino acids; (iv) the proportions of individual amino acids in the digesta passing to the intestine. It was calculated that microbial piotcin contributed 33, 38, and 47% of the protein passing from the stomach to the intestincs with the diets of advancing maturity. Most of the remaining protein was presumably of dietary origin. About 80% of the crude protein in the digesta was present in the form of amino acids, and the quantities of amino acids released in the intestines were calculated to be equivalent to 64–66 g/100 g crude protein intake. With advancing maturity of the diets the plasma levels of the essential ammo acids except lysine, histidine, and arginine declined; there was little effect of diet on the plasma levels 01 non-essential amino acids. However, relative to total essential amino acids, the ratios of valine and leucine decreased with advancing maturity of the diet while those of lysine, histidine, glutamate, glycine, alanine, and serine increased. * Part 111, Aust. J. Agric. Res., 1969, 20, 347.

scholarly journals Insects as Novel Ruminant Feed and a Potential Mitigation Strategy for Methane Emissions

Animals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2648
Author(s):  
Eslam Ahmed ◽  
Naoki Fukuma ◽  
Masaaki Hanada ◽  
Takehiro Nishida
Keyword(s):  
Fatty Acids ◽  
Methane Production ◽  
Volatile Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Ammonia Nitrogen ◽  
Nutrient Digestibility ◽  
Acheta Domesticus ◽  
Environmental Benefit ◽  
Grass Hay

This study is the first to evaluate the chemical composition and impacts of four different edible insects, Acheta domesticus (A.d), Brachytrupes portentosus (B.p), Gryllus bimaculatus (G.b), and Bombyx mori (B.m), on the digestibility, rumen fermentation, and methane production when used as a substitute for 25% of the soybean meal (SBM) in a ruminant diet through in vitro incubation. The dietary treatments were 100% grass hay, 60% grass hay + 40% SBM, 60% grass hay + 30% SBM + 10% A.d, 60% grass hay + 30% SBM + 10% B.p, 60% grass hay + 30% SBM + 10% G.b, and 60% grass hay + 30% SBM + 10% B.m. The experiment was conducted as a short-term batch culture for 24 h at 39 °C, and the incubation was repeated in 3 consecutive runs. Chemical analysis of the insects showed that they were rich in fat (14–26%) with a high proportion of unsaturated fatty acids (60–70%). Additionally, the insects were rich in protein (48–61%) containing all essential amino acids and the amino acid profiles of the insects were almost the same as that of SBM. The inclusion of insects did not affect nutrient digestibility or the production of volatile fatty acids but did increase the production of ammonia-nitrogen. The addition of G.b and B.m led to decrease in methane production by up to 18% and 16%, respectively. These results reveal that substitution of 25% SBM in the diet with the tested insects had no negative impacts, and their potential to reduce methane production is an environmental benefit.

scholarly journals Effects of garlic supplementation on in vitro nutrient digestibility, rumen fermentation, and gas production

2021 ◽  
Vol 51 (2) ◽  
pp. 271-279
Author(s):  
M.R. Kekana ◽  
D. Luseba ◽  
M.C. Muyu
Keyword(s):  
Fatty Acids ◽  
Crude Protein ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Ammonia Nitrogen ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Nutrient Digestibility ◽  
Garlic Powder

Garlic contains secondary metabolites with antimicrobial properties that can alter nutrient digestibility and rumen fermentation, similar to other antimicrobial products. The objectives of the study were to evaluate the effects of garlic powder and garlic juice on in vitro nutrient digestibility, rumen fermentation, and gas production. The treatments consisted of control with no additives, garlic powder, and garlic juice at 0.5 ml and 1 ml. The digestibility of dry matter, crude protein and neutral detergent fibre were determined after 48 hours incubation. Rumen ammonia nitrogen and volatile fatty acids were determined at 12 hours and 24 hours incubation. The cumulative gas production was recorded periodically over 48 hours. The in vitro dry matter disappearance decreased with 1 ml of garlic juice compared with control. The crude protein degradability in garlic powder and garlic juice was lower than in control. Volatile fatty acids increased in all treatments. Individual volatile fatty acids were significantly different, especially propionate, whereas the acetate to propionate ratio was reduced by garlic juice, and ammonia nitrogen was reduced by garlic powder and 0.5 ml of garlic juice. The cumulative gas production increased significantly with both levels of garlic juice. The addition of garlic juice at 0.5 mL/100 ml could enhance the production of propionate, and reduce the acetate to propionate ratio, implying that the supply of hydrogen for methanogens was limited.

scholarly journals In vitro assessment of ruminal fermentation, digestibility and methane production of three species of Desmanthus for application in northern Australian grazing systems

2018 ◽  
Vol 69 (8) ◽  
pp. 797 ◽  
Author(s):  
Sophie Vandermeulen ◽  
Sultan Singh ◽  
Carlos Alberto Ramírez-Restrepo ◽  
Robert D. Kinley ◽  
Christopher P. Gardiner ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Volatile Fatty Acids ◽  
Nutritive Value ◽  
Rumen Fluid ◽  
Northern Australia ◽  
Rhodes Grass ◽  
Ch4 Production ◽  
Grass Hay

Three species of Desmanthus adapted to the heavy clay soils of northern Australia were studied to determine their nutritive value and effects on in vitro fermentation with rumen fluid, compared with Rhodes grass (Chloris gayana) hay. Leaves and stems of D. leptophyllus cv. JCU 1, D. virgatus cv. JCU 2 and D. bicornutus cv. JCU 4 were collected in summer, winter and spring of 2014 and analysed for chemical composition. Apparent digestibility as in vitro organic matter digestibility (IVD-OM) and fermentation parameters including methane (CH4) production were measured during 72-h fermentations using rumen fluid from steer donors grazing tropical grasses and legumes. Desmanthus bicornutus was on average more digestible than both D. leptophyllus and D. virgatus at 24, 48 and 72 h of incubation. This species also demonstrated an anti-methanogenic potential, in particular when harvested in summer with a reduction in CH4 production of 26% compared with Rhodes grass hay after 72 h of incubation. At this time point, D. leptophyllus produced higher volatile fatty acids (VFA per g of organic matter fermented) compared with the other forages. This legume also reduced the CH4 production up to 36% compared with the Rhodes grass hay reference. However, D. leptophyllus showed lower IVD-OM. Overall, Desmanthus species produced lower in vitro CH4 and lower volatile fatty acids concentration compared with the reference grass hay. These effects may be due to presence of secondary compounds such as hydrolysable tannins, condensed tannins and/or their combination in Desmanthus species. The IVD-OM was influenced by the season after 72 h of incubation; the digestibility was higher in plants collected in spring. This study suggests that contrasting fermentative profiles in Desmanthus cultivars may offer the opportunity to reduce the greenhouse gas contribution of the beef industry. The next step in demonstration of these promising in vitro results is demonstration of Desmanthus in vivo as proof of concept confirming the productivity and CH4 reduction ability of these legumes in the pastoral systems of northern Australia.

Effect of inoculum source (Sheep or Goat) on in vitro gas production and rumen fermentation parameters of some fodder shrubs in northern Tunisia

2015 ◽  
Vol 3 (3) ◽  
pp. 260-266
Author(s):  
H. Selmi ◽  
Z. Abdelwahed ◽  
A. Rouissi ◽  
M. Hanene ◽  
G. Tibaoui ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Ammonia Nitrogen ◽  
Gas Production ◽  
Opuntia Ficus Indica ◽  
Atriplex Halimus ◽  
Medicago Arborea ◽  
Acacia Cyanophylla ◽  
Fodder Shrubs

In order to ensure nutritional characterization of some fodder shrubs and test the effect of inoculum source (sheep and goats) on their digestibility. Four shrubs “Acacia cyanophylla, Atriplex halimus, Opuntia ficus-indica. Var.inermis(cactus) and Medicago arborea” were tested in vitro by incubating them firstly into the rumen fluid of sheep then into goat’s inoculums. The evaluation included chemical composition, total gas production (CO2 and CH4), the prediction of organic matter digestibility (OMD), metabolizable energy (ME), the concentration of total volatile fatty acids (SCFA) and metering ammonia nitrogen (NH3-N). Ruminal fermentation of Opuntia ficus-indica and Medicago arborea have identified more total gas amonts than Atriplex halimus and Acacia cyanophylla. Digestibility of organic matter, metabolisable energy and the concentration of total volatil fatty acids were higher in the case of Opuntia ficus-indica compared to other shrubs. The lowest values were recorded in the Atriplex halimus. The concentration of ammonia nitrogen (NH3-N), it turned out that Opuntia ficus-indica is the food with less protein concentration (140 and 270.66 mmol/syringe) respectively for sheep and goats. In against part, the Medicago arborea is presented as a good protein source recording of ammonia nitrogen concentration (214.67 mmol/syringe) into the sheep’s rumen and (494.67 mmol/syringe) into the goats inoculum. The source of the inoculum showed a highly significant effect (p > 0.05).

Factors limiting the intake of feed by sheep. 11. The effect of pregnancy and early lactation on the digestion of a medium-quality roughage

1988 ◽  
Vol 39 (4) ◽  
pp. 659 ◽  
Author(s):  
RH Weston
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Volatile Fatty Acids ◽  
Late Pregnancy ◽  
Ammonia Nitrogen ◽  
Hormonal Changes ◽  
Early Lactation ◽  
Nitrogen Flow ◽  
Sodium And Potassium ◽  
In Pregnancy

Various aspects of digestion were studied at a constant level of roughage feeding in ewes bearing single or twin foetuses during pregnancy, and in ewes suckling a single lamb during early lactation. In pregnancy, ewes with twins responded similarly to those with singles, except that they drank more water. The responses to pregnancy generally increased in magnitude as pregnancy progressed. Late pregnancy was associated with increases in (i) digesta flows through the stomach, (ii) marker clearance rates through the alimentary tract, (iii) absorption rate of volatile fatty acids, (iv) non-ammonia nitrogen flow into the intestines, and (v) faecal water output, and decreases in (i) reticulo-rumen liquor volume, (ii) reticulorumen pools of volatile fatty acids, ammonia, sodium and potassium, and (iii) organic matter digestion. Lactation was associated with increases in (i) digesta flows through the stomach, (ii) marker clearance rate from the reticula-rumen, (iii) non-ammonia nitrogen flow into the intestines, (iv) rumen digesta pH and (v) flow of sodium and potassium from the reticulo-rumen, and decreases in (i) reticula-rumen pools of volatile fatty acids, ammonia, sodium and potassium, (ii) organic matter digestion and (iii) blood urea concentration. It was concluded that (i) the digestion responses were large enough to influence the interpretation of various nutrition studies in pregnancy and lactation, and (ii) the relative contributions of physical and hormonal changes to the altered digestion transactions need elucidation.

Effects of forage neutral detergent fibre and time after feeding on medial and ventral rumen pH and volatile fatty acids concentration in heifers fed highly digestible grass/clover silages

2017 ◽  
Vol 57 (1) ◽  
pp. 129 ◽  
Author(s):  
A. K. S. Schulze ◽  
A. C. Storm ◽  
M. R. Weisbjerg ◽  
P. Nørgaard
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Latin Square ◽  
Growth Stages ◽  
Neutral Detergent Fibre ◽  
Rumen Epithelium ◽  
Rumen Ph

The major microbial fermentation of forages and production of volatile fatty acids (VFA) takes place in the medial part of the rumen, whereas the absorption of VFA occurs through the rumen epithelium, for example the ventral sac. The objective was to study effects of forage neutral detergent fibre (NDF) content and time after feeding on the medial to ventral VFA and pH gradient as well as rumen motility in the rumen of heifers fed grass/clover silages. Four silages were harvested at different growth stages with NDF contents of 31–45% of DM and in vitro organic matter digestibilities of 75–82% and fed to four rumen-fistulated Jersey heifers at 90% of ad libitum level in a Latin square design, with half the ration fed at 0800 hours and 1530 hours. Rumen fluid was sampled hourly from 0730 hours to 1530 hours in the medial and ventral rumen, and analysed for pH and concentrations of VFA, L-lactic acid, and ammonia to assess ruminal chemical gradient. Reticular contractions were continuously recorded by a pressure transducer. Time relative to feeding affected rumen parameters as pH was generally lower and VFA content greater in medial compared with ventral rumen fluid. Greater NDF content of the silage caused lower VFA concentration and higher pH in the rumen mat, and therefore the gradient diminished at greater NDF content in the silages; an effect probably caused by reduced organic matter digestibility rather than digesta NDF properties. This study therefore suggests that VFA production decreased with greater NDF content of forages, whereas intra-ruminal equilibration increased.

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