Rumen Fluid Volume Research Articles

Rumen fermentation of meal-fed sheep in response to diets formulated to vary in fiber and protein degradability.

The concentration of volatile fatty acid (VFA) provides an imprecise view of VFA dynamics due to the confounding effects of fluid pool size and dynamics. Determination of VFA flux using isotope is expensive and a complex methodology. Therefore, a rapid and affordable approach to explore VFA dynamics may allow comprehensive characterization of VFA availability. The objective of this study was to explore the use of VFA dynamics generated by meal feeding to derive time-series rates of VFA apparent appearance and disappearance driven by different protein and fiber sources. Six ruminally cannulated wethers were fed diets containing timothy hay or beet pulp (TH and BP) and soybean meal (SBM) or heated soybean meal (HSBM). Diets were, TH + HSBM; TH + SBM; BP + HSBM; and BP + SBM and the experimental design was a partially replicated 4 × 4 Latin Square. Concentrations of VFA and polyethylene glycol (PEG) in rumen fluid samples were estimated. Concentrations of PEG were used to estimate fluid passage and volume to calculate VFA mass, and fluid-mediated exit. Maximum apparent appearance rate (mmol/h), the rate of apparent appearance decline (mmol/mmol/h), mean apparent appearance flux (mmol/h), mean apparent disappearance (mmol/h), and apparent disappearance rate (mmol/mmol/h) were estimated by deriving a 1 pool model for each VFA on a mass basis where appearance was assumed to follow an exponential decay pattern and disappearance followed mass-action kinetics. Statistical analyses were conducted using a linear mixed effect regression with fixed effects for fiber source, protein source, and their interaction, as well as random effects for animal and period. Rumen fluid volume (L) was greater in HSBM diets (P = 0.033) and fluid passage (%/h) was greater in SBM diets (P = 0.048). Concentrations (higher acetate and butyrate, P = 0.002 and 0.004, respectively) and molar proportions (higher valerate, P = 0.035) of VFA were affected only by fiber source; however, protein source and fiber source interacted to significantly influence apparent appearance rates and absorption rates of many major VFA. On a flux basis, HSBM supported significantly elevated mean disappearance of propionate (P = 0.033). This data demonstrates that time-series evaluation of fermentation dynamics, including fluid dynamics and VFA concentrations can be used to estimate apparent appearance and disappearance of VFA. Although further work is needed to confirm the alignment of these estimates with measurements of VFA supplies to the animal, this modeling approach may provide a simpler way to better understand the kinetics of rumen.

Recovery of the fibrolytic microorganisms from rumen fluid by flocculation for simultaneous treatment of lignocellulosic biomass and volatile fatty acid production

Large volumes of rumen fluid are continuously discharged from slaughterhouses, which are typically transported to facilities for treatments of lignocellulosic biomass. Recovery of fibrolytic microorganisms from the rumen fluid enables to reduce the load for wastewater treatment and transportation of rumen fluid. However, there is no standardized method for recovering ruminal microorganisms. Here, we established a flocculation-based method with an optimized flocculant concentration required to recover ruminal microorganisms with fibrolytic activity. Rumen fluid was flocculated with poly-ferric sulfate at 0.4%, 0.7%, 1.0%, and 2.0% and with an inorganic neutral flocculant at 13.0%. Poly-ferric sulfate at 0.4%, 0.7%, and 1.0% effectively recovered ruminal microorganisms, which resulted in an 85.6%, 77.3%, and 75.6% reduction in rumen fluid volume, respectively. These recovered microorganisms retained the endoglucanase activity at 52 kDa and 53 kDa in size. In addition, recovery of ruminal microorganisms allowed for substantial reductions in the solids and organic compound concentrations of the filtrates after the flocculation. As a practical demonstration of this method, tomato leaves were treated with the flocculated rumen fluid at 37 °C for 48 h. Hydrolysis of the tomato leaves using the rumen fluid flocculated with 0.7% poly-ferric sulfate demonstrated elevated endoglucanase activity at 37 kDa, 46 kDa, 57 kDa, 61 kDa, and 66 kDa in size during treatment. Therefore, 0.7% poly-ferric sulfate is the optimal concentration for recovering ruminal microorganisms while maintaining their fibrolytic activity. This is the first study which suggest a novel method to efficiently recover ruminal microorganisms from huge amounts of rumen fluid offers a practical and sustainable solution to reduce the load for wastewater treatment at slaughterhouses and in the transportation of rumen fluid.

Is rumenocentesis a safe technique to collect rumen fluid in dairy cows?

Subacute ruminal acidosis is a major issue in dairy cattle and a definite diagnosis is only established by measuring the rumen fluid pH, most credibly collected by rumenocentesis. However, due to its invasive nature, there is still some debate whether it is a safe method or poses risks for cows’ health and welfare. The aim of the study was to retrospectively evaluate the safety of rumenocentesis as a technique to obtain rumen fluid in dairy cows. Results were derived from 2 studies. In study 1, rumenocentesis was performed in 153 Holstein cows from 12 herds, once, between 10 and 90 days in milk (DIM). In study 2, 83 Holstein cows from a dairy farm were repeatedly subjected to rumenocentesisat 30, 90 and 150 DIM. From the 83 cows that were initially enrolled, 8 were culled before the end of the study for reasons irrelative to rumenocentesis; therefore, 236 rumenocenteses were actually performed in study 2 (3 times in 75 cows, twice in 3 cows and once in 5 cows). All cows were monitored for 10 days after rumenocentesis for presence of complications. In addition, daily milk yield was automatically recorded for each cow in study 2 to detect any possiblepost-rumenocentesis short-term reduction of milk yield. Minor only complications were recorded in 7 cases: in 4/153 (2.61%) and 3/236 (1.27%) rumenocenteses in studies 1 and 2, respectively. Small diameter abscesses in 6 cows (3 in study 1 and 3 in study 2) and a larger one in 1 cow in study 1 were observed. The 3 small abscesses in study 2 were all recorded after the 1st rumenocentesis, at DIM 30. All 7 cases were resolved spontaneously within two weeks. Moreover, short-term daily milk yield of study 2 cows was not affected by rumenocentesis. The conclusion is that rumenocentesis is a safe technique to collect small volume of rumen fluid for SARA diagnosis, which does not compromise cows’ health and welfare when appropriately performed.

Isolation, characterization and strain selection of a Paenibacillus species for use as a probiotic to aid in ruminal methane mitigation, nitrate/nitrite detoxification and food safety

The effects of dietary nitrate and Paenibacillus 79R4 (79R4), a denitrifying bacterium, when co-administered as a probiotic, on methane emissions, nitrate and nitrite-metabolizing capacity and fermentation characteristics were studied in vitro. Mixed populations of rumen microbes inoculated with 79R4 metabolized all levels of nitrite studied after 24 h in vitro incubation. Results from in vitro simulations resulted in up to 2 log10 colony forming unit reductions in E. coli O157:H7 and Campylobacter jejuni when these were co-cultured with 79R4. Nitrogen gas was the predominant final product of nitrite reduction by 79R4. When tested with nitrate-treated incubations of rumen microbes, 79R4 inoculation (provided to achieve 106 cells/mL rumen fluid volume) complemented the ruminal methane-decreasing potential of nitrate (P < 0.05) while concurrently increasing fermentation efficiency and enhancing ruminal nitrate and nitrite-metabolizing activity (P < 0.05) compared to untreated and nitrate only-treated incubations.

Test of conditions that affect in vitro production of volatile fatty acids and gases.

In vitro methods have been developed to measure digestibility, but such methods may not accurately reflect gas production or volatile fatty acid (VFA) profiles. The objective of this study was to determine the effect of different in vitro conditions on VFA and gas production. The experimental design was a 4 × 2 × 2 factorial CRD with four replicates. Treatments were four ratios of medium to rumen fluid by volume (5:95, 25:75, 50:50, and 75:25), two concentrations (w/v) of added timothy hay (0.5% or 1%), with or without added sodium acetate (increased initial concentration by 50 mM). Total volume of medium and rumen fluid was 10 mL per tube. Measurements of gas production and VFA were recorded at 0, 4, 16, 24, and 48 h. Statistical analyses used a mixed model including all fixed effects and interactions with tube as a random effect, and time nested within tube. Total gas production increased (P < 0.001) with higher medium proportion. The final pH increased (P < 0.0001) as medium proportion increased. Medium proportion positively affected (P < 0.05) overall average concentration of both acetate production and propionate production. Higher hay concentration increased (P < 0.0001) total gas produced from 0 to 48 h, increased total acetate production (P < 0.01), propionate production (P < 0.001), and decreased pH between 24 and 48 h (P < 0.0001). Sodium acetate addition increased (P < 0.0001) pH between 24 and 48 h. Acetate:propionate (A:P) concentration decreased over time (P < 0.0001). Initial rumen fluid A:P ratio was 3.7 but average A:P ratio of produced VFA started at 2.2 and increased to 2.50 (SE = ±0.51). The A:P ratio differed for VFA produced in vitro compared to initial rumen fluid, but no tested treatments were found to change A:P ratio.

Phosphorus net absorption in dairy cows subjected to abomasal infusion of inorganic phosphorus – a pilot study

In this pilot study, the effects of phosphorus (P) supply on inorganic phosphorus (Pi ) net absorption in dairy cows were investigated. Three non-lactating, non-pregnant, rumen-fistulated Swedish Red breed dairy cows were studied in a 3 × 3 Latin square design. Monosodium dihydrogen orthophosphate dihydrate (NaH2 PO4 *2H2 O) was continuously infused into the abomasum for 4 days. The solutions provided 0, 14.4 or 28.8 g Pi /day. Rumen fluid volume and outflow rate were estimated at day four of each experimental period using cobalt-lithium EDTA as an external marker. Acid insoluble ash in feeds and faecal samples was used to quantify P faecal excretion. Concentrations of Pi in collected samples of rumen fluid, blood, faeces and urine were determined. Pi flow into the small intestine increased (p < 0.05) with Pi infusion. Pi net absorption tended to increase (p = 0.08) but proportion of absorbed Pi tended to decrease (p = 0.08). Urinary Pi excretion was negligible and did not affect P homoeostasis (p = 0.50). There was no change in plasma Pi concentration (p = 0.45) in response to Pi infusion. The increase in total faecal P excretion (p < 0.05) with increasing level of infused Pi was solely because of increased soluble faecal Pi (p < 0.05). It is suggested that at P overfeeding, intestinal Pi net absorption is saturable in dairy cows.

Regulation of rumen fermentation during seasonal fluctuations in food intake of muskoxen

We studied rumen fermentation of castrated adult muskoxen (Ovibos moschatus; n=4) during periods of low (May) and high (August) food intake. Turnover time (17+/-1.8 h) and volume (26+/-3.9 L) of rumen fluid were consistent between May and August and among days within each season. Rumen temperature did not vary significantly during the day (38.8+/-0.29 degrees C) in either season. Rumen osmolality (271.9+/-16.4 vs. 245.9+/-11.4 mOsm kg(-1)) and pH (6.81+/-0.31 vs. 6.39+/-0.15) were higher in May than in August indicating a shift in the allostatic set point. Rumen fluid pH was more variable in May than in August both before and after a single meal of fermentable substrate even though fermentation acids were lower in May than in August (101.0+/-11.0 vs. 126.0+/-8.74 mM). Changing proportions of minor fermentation acids indicated a shift in metabolic pathways even though bacterial numbers were similar between seasons (6.4+/-5.8x10(9) mL(-1)). Allostatic set points probably alter the homeostatic range of conditions and the microbial diversity of fermentations in herbivores from highly seasonal environments.

Effect of different planes of nutrition on urea molasses mineral block intake, nutrient utilization, rumen fermentation pattern and blood profile in Murrah buffaloes ( Bubalus bubalis)

In order to investigate the effect of plane of nutrition on intake and nutrient utilization from urea molasses mineral block (UMMB), rumen fermentation pattern and blood biochemical constituents, 20 intact and 12 rumen fistulated male Murrah buffaloes aged about 3 years and weighing 320.3±13.11 kg were randomly distributed into four groups of eight animals in each, thus each group having five intact and three rumen fistulated buffaloes. All the animals were fed individually for 40 days. Animals in group I (control) were fed ad libitum wheat straw alone along with mineral mixture and common salt, group II, III and IV were given ad libitum wheat straw alongwith increasing levels of energy from UMMB alone (group II), UMMB+700 g concentrate mixture (group III) and UMMB+1400 g concentrate mixture (group IV). Crushed barley fortified with mineral mixture and common salt was the concentrate mixture used. At the end of feeding trial, a metabolism trial of 7 days duration was conducted on intact animals to determine the digestibility of nutrients. Rumen fermentation study was carried out on 12 rumen fistulated animals following the metabolism trial, blood was collected from intact animals to estimate the nitrogenous constituents in blood serum of animals fed on different planes of nutrition. The intake of total dry matter (DM) and total digestible nutrients (TDN) was non-significantly and intake of digestible crude protein (DCP) was significantly ( p<0.01) higher in treatment groups over control group. Apparent digestibility of DM, organic matter (OM), and crude protein (CP) increased significantly ( p<0.01) in group II to IV over group I, whereas, the digestibility of neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose and hemicellulose tended to be higher in UMMB fed groups. Nitrogen intake and its balance increased significantly ( p<0.01) with the increase in plane of nutrition. Significantly ( p<0.01) higher concentration of total volatile fatty acids (TVFA), total nitrogen (TN) and its fractions were observed due to increased plane of nutrition. The rumen pH reduced significantly ( p<0.01) due to concentrate feeding in group III and IV, but rumen fluid volume and digesta flow rate were unaffected. The concentration of blood serum urea increased significantly ( p<0.01) in experimental groups as compared to control but ammonia–N and total protein concentrations were unaffected due to feeding of animals on different plane of nutrition. Results indicated that additional energy supplied through concentrate in group III and IV, respectively, resulted in higher intake of protein and energy than the maintenance requirement (Kearl, L.C., 1982. Nutrient Requirements of Ruminants in Developing Countries. International Feed Stuffs Institute, Utah State University, Logan, UT, 82 pp), whereas wheat straw supplemented with UMMB was sufficient to meet the maintenance requirements of adult buffaloes. Higher plane of nutrition did not have any positive effect on intake of wheat straw and UMMB.

粗飼料を単体給与したメンヨウにおける反芻胃内容液通過速度と微生物態タンパク質合成量との関連

Three rumen cannulated sheep offered corn silage (CS) and chopped timothy hay (TH) ad lib. were used to examine the effect of an altered rumen fluid outflow rate on microbial nitrogen (MN) yield. Four levels (0, 1, 2 and 3l/d) of artificial saliva was infused into the rumen of sheep offered the two diets. The intraruminal infusion level had little effect on the rate constant of rumen fluid outflow and rumen fluid volume in sheep offered the two diets. The rate constant of rumen fluid outflow tended to be higher in TH group than CS, while rumen fluid volume was higher (P<0.05) in CS than TH group. Rumen fluid outflow (l/d) did not differ (P>0.05) across the treatments. The MN yield was markedly greater (P<0.05) in TH than CS group. The effect of saliva infusion level on MN was not detected. Available energy and N supply were higher for TH compared with CS feeding, this resulted in an increase in MN yield.

Effects of experimentally-impaired reticular contractions on digesta passage in sheep.

The aim of the study was to evaluate the functional role of reticular contractions for digesta passage in sheep. Feed intake, mean retention time of fluid and plastic particles in the reticulo-rumen, rumen fluid volume, forestomach motility and particle size distribution in the faeces were determined in five rumen-fistulated sheep fed on hay ad libitum (Expt 1). The same variables were determined when reticular movements were impaired for 10 d by introducing a silicone-covered lead weight (500 g) into the reticulum (Expt 2). As feed intake dropped in Expt 2 by 27% compared with Expt 1, the sheep received in an additional experiment exactly the amount of feed which had been consumed during Expt 2 and measurements were repeated without impairing reticular movements (Expt 3). The introduction of the weight did not affect the frequency of A- or B-cycles, but elevation of the reticular floor in a cranio-dorsal direction during the biphasic contraction was markedly reduced. The pattern of marker excretion indicated a drastically changed composition of reticular outflow in Expt 2 compared with Expts 1 and 3. During Expt 2, rumen fluid volume was similar to that in Expt 1 but about 25% higher than that in Expt 3; the amount of large feed particles in the faeces was increased compared with Expt 1 (+49%) and Expt 3 (+76%). In at least two sheep, abomasal emptying was inhibited during Expt 2, as indicated by an enlarged impacted abomasum. In conclusion, the results emphasize the central role of reticular motility for the separation of particles in the forestomach, the outflow of digesta from the reticulo-rumen and transpyloric digesta flow.

Nutrient utilization and rumen fermentation pattern in crossbred cattle fed different planes of nutrition supplemented with urea molasses mineral block

In order to investigate the effect of the plane of nutrition on intake and nutrient utilization from urea molasses mineral blocks (UMMB) and rumen fermentation pattern, sixteen adult crossbred cattle were divided into four equal groups following a completely randomised design and fed individually for 60 days ad libitum with either wheat straw alone (Group I) or with wheat straw with UMMB (Group II) or with wheat straw and UMMB with 50% of energy requirements provided by crushed barley fortified with mineral mixture and common salt (Group III) or with wheat straw and UMMB with 100% of energy requirements provided by fortified crushed barley (Group IV). At the termination of the feeding trial, a metabolism trial of six days duration was also conducted. A fermentation study was carried out on four rumen fistulated adult cattle following a 4 × 4 latin square design. Results showed that intake (except for ether extract) and digestibility of all the nutrients increased significantly ( P < 0.01) in the block-fed groups which was further enhanced by energy (barley) supplementation except for digestibility of neutral detergent fibre (NDF) and acid detergent fibre (ADF) which decreased owing to concentrate supplementation. Total digestible nutrients and digestible protein contents of UMMB were 56.6 and 42.5%, respectively. Significantly increased ( P < 0.01) concentrations of total nitrogen and its fractions, except TCA-precipitable-N owing to block feeding were observed. However, it did not influence the TVFA concentration in rumen liquor of fistulated animals. Rumen pH, rumen fluid volume and digesta flow rate were also unaffected. This clearly indicated that supplementing 50% of energy requirements through concentrate on a straw based diet along with UMMB resulted in increased intake of UMMB and better utilization of dietary nutrients in adult crossbred cattle.

Changes in factors affecting the rate of digesta passage during pregnancy and lactation in sheep fed on hay.

The objective of this study was to assess feed intake and digesta passage characteristics in five Blackhead ewes fed hay ad libitum during pregnancy [I: d 60-80 post conceptionem (p conc); II: d 105-125 p conc; III: d 128-148 p conc] and lactation [IV: d 10-30 post partum (pp); V: d 35-55 pp]. During pregnancy, feed intake and rumination activity increased. The rumen fluid volume and the daily number of A-cycles did not change significantly. The mean retention time (MRT) of the fluid and particle markers in the reticulorumen (RR) and distal to the RR decreased by 14-32%. During lactation, the rumen fluid volume increased as compared to pregnancy by about 15%. Daily feed intake peaked during period V (83.7 g DM/kg BW0.75). The MRT of particle markers in the RR increased as compared with late pregnancy. Both during pregnancy and lactation, the increased passage rate of digesta was achieved predominantly by an increased amount of digesta passing through the reticulo-omasal orifice during each opening. Sieving of forestomach contents and faeces revealed that the breakdown rate of large feed particles did not limit digesta passage.

Effects of underfeeding and of fish meal supplementation on forage digestion in sheep

SUMMARYThe effects of severe food restriction and of protein supplementation on the apparent digestibility of a forage were studied on 12 wethers in 1992 at INRA, Theix. Ruminal digestion of the forage cell walls was studied in a second experiment carried out on four ewes fitted with rumen and duodenal cannulas, receiving the same diets as the wethers. The animals were fed on two different hay-based diets: hay only (58 or 25 g/kg BW0·75 per day) or hay supplemented with fish meal (48 or 20 g hay with 6·5 and 3·0 g fish meal respectively per kg BW0·75). The effects of fish meal supplementation on apparent digestibility of the hay cell walls were small, + 1·8 and + 2·3 units for neutral detergent fibre (NDF) and acid detergent fibre (ADF) respectively. In contrast, NDF and ADF digestibility was respectively 4·0 and 4·7 units higher at low than at high intake. Rumen fluid volume decreased by 2·4 1 with decreasing intake, while water concentration in rumen content increased slightly from 89·8 to 91·8%. The mean retention time of the hay particles in the foreguts increased concomitantly from 39·5 to 55·1 h. This was achieved by a higher retention time to a similar extent in both slow and fast compartments. The calculated in situ degradability of NDF and ADF increased respectively by 12·1 and 13·1 units with decreasing intake. This reflected the lower fractional outflow rate recorded at low intake. If a fractional outflow rate value of 4·1%/h (as measured in high intake diets) was applied to all dietary treatments, NDF and ADF in situ degradability would be greater at low than at high intake (31·7 v. 26·6% for NDF; 27·9 v. 22·1 % for ADF), indicating a higher microbial activity in restricted diets. Interactions between intake and fish meal supply were detected for in situ degradation parameters, indicating principally a reduction of the cell wall undegraded fraction in supplemented diets when intake declined. Ruminal fermentation was modified by the dietary treatments, the acetate: propionate ratio being higher at low intake. Fish meal increased concentrations of ammonia and of isoacids in rumen liquid. The relationship between apparent digestibility and in situ degradability of plant particles is discussed.

Food and snow intake, body mass and rumen function in reindeer fed lichen and subsequently starved for 4 days

Food and snow intake, body mass, rumen fluid volume, rumen fluid turnover time and ruminal dry matter content were examined in four female rumen fistulated reindeer which were first fed lichen ad libitum in 14 days and then starved for 4 days in March. When the animals were eating lichen median daily dry matter food intake was 15.7 g/kg (range 12.2-19.9 g/kg), while median daily snow intake only amounted to 0.6 g/kg (range 0-3.3 g/kg). The median body mass decreased from 67.5 kg (range 62.5-69.5 kg) to 63.5 kg (range 60.5-68.5 kg) during this period, and dropped further to 62.5 kg (range 57.5-66.0 kg) after four days of starvation. Rumen fluid volume and fluid turnover time were fairly constant in individual animals, but varied between animals fed lichen ad libitum. Neither of these parameters changed significantly (P&amp;gt;0.05), but ruminal dry matter decreased, while snow intake rose conspicuously in reponse to starvation. Thus, aside from the latter, which mitigate the reduction of total rumen volume, we have failed to expose any special adaptions aimed at the maintenance of ruminal integrity in starving reindeer.

Indirect measurement of saliva secretion in sheep fed diets of different structures and the effect of such diets on ruminal fluid kinetics and fermentation pattern

Four Suffolk x Dorset sheep were allocated in a 4 x 4 Latin square design and received a hay-barley-molasses diet in one of four different physical structures: (1) pelleted; (2) pelleted:chopped (60:40); (3) chopped:pelleted (60:40); or (4) chopped. The animals were penned individually and the diet was restricted to provide 20 g of dry matter (DM) per kilogram live weight daily. The effects of the diets on rumen fluid kinetics, fermentation pattern and microbial nitrogen (MN) supply were examined. Saliva secretion was estimated using an indirect method based on water balance in the rumen. When the animals were fed the chopped diet, the salivation rate, rumen fluid volume and rumen liquid outflow were all increased significantly (P < 0.05 to P < 0.01). No consistent effect of dietary structure on rumen fluid dilution rate, purine derivative (PD) excretion or MN supply was observed. Dietary structure had no effect on the rumen fermentation pattern, digestibility of DM or nitrogen.

Studies in fibre digestion and passage rate of liquid and solid in cattle and buffaloes

Rumen liquor characteristics and disappearance rate of dry matter were studied in Kedah-Kelantan cattle and swamp buffaloes fed grass of rice straw-based diet. Cobalt-EDTA and chromium mordented fibres prepared from the faecal material were used to determine the liquid and solid particles movement in both animal species fed with rice straw. Swamp buffaloes showed a more intense rumen fermentation activity than Kedah-Kelantan cattle when both species were fed straw-based diet. The buffaloes also demonstrated faster rates of grass and straw degradation in situ. The fluid outflow rate from the rumen of buffalo (1.06 0.19 1/h) was observed to be slower than that of cattle (1.55 0.01 1/h). No significant differences between cattle and buffaloes were observed in rumen fluid volume and passage rate of small particles from the rumen.

Effect of soya oil hydrolysate on rumen digestion in defaunated and refaunated sheep

The effects of soya oil hydrolysate (SOH) supplementation on the kinetics of rumen contents and on in sacco rumen degradabilities of various feeds were studied using two defaunated and refaunated sheep. This allowed us to investigate the relative importance of protozoa depletion in the overall effect of oil feeding on rumen metabolism. The addition of 7% SOH to the diet lowered protozoal numbers from 1.6 10 6 ml −1 to 6 10 5 ml −1. SOH supplementation significantly enhanced rumen fluid volume and rumen dry matter, and this effect was partly connected with protozoa depletion. The addition of SOH did not modify the amount of volatile fatty acids in the rumen, but shifted the fermentation patterns to a greater proportion of propionate, while decreases in butyrate and acetate were observed. SOH supplementation did not affect in sacco degradabilities of maize grains and soya-bean meal in the rumen of refaunated animals, but strongly enhanced them in defaunated sheep (respectively, 57% DM vs. 37% and 64% DM vs. 48% after 8 h incubation). SOH lowered in sacco degradabilities of straw (25% DM vs. 46% after 48 h) and cellulose (43% DM vs. 65% after 24 h) in refaunated animals, but only in sacco degradability of straw in defaunated animals (31% DM vs. 44% after 48 h). Coating of cellulose by SOH did not affect its in sacco degradability in the rumen. An estimation of SOH fatty acid kinetics in the rumen seemed to indicate that the variation of rumen content kinetics during the adaptation period to SOH favoured a decrease by 25% in the concentration of SOH fatty acids in the rumen.

Water movements after an intraruminal water load in pregnant and lactating Sardi sheep

The effects of an intraruminal load of 3 litres of water on body water movements was compared in Sardi sheep during the last month of pregnancy, lactation and a non-pregnant, non-lactating control period. Before the water load, rumen fluid volume, estimated by polyethylene glycol was similar in pregnant, compared to control, animals and 27% higher in lactating sheep. After the water load, rumen volume returned to pre-hydration level in 1 h during pregnancy, after 3 h during lactation and in the control period. Rumen osmolality decreased by 40% and remained at this low level for 3 h after the water load in all physiological periods. When the water load was tritiated water (TOH), the rate of TOH transfer into plasma was faster during the last month of pregnancy than during the control period. Plasma osmolality and proteins decreased in response to the water load. No differences in these responses were observed between pregnancy, lactation and the control period. Water diuresis began in the first 30 min following the water load in pregnant ewes and in the second 30 min in lactating and control ewes. The diuresis was also more pronounced in pregnant, than in non-pregnant, states. These results indicate that water is more rapidly absorbed from the gastrointestinal tract in pregnant, rather than in non-pregnant, sheep. This may partly explain the increased water turnover seen during pregnancy.

Einfluß der Trächtigkeit und der Laktation auf Verdauungsvorgänge beim Schaf

The average passage time, the rumen fluid volume and the digestibility of the organic matter were determined in addition to 3 individual feeding experiments with fertility oriented crossbreed ewes, which received pelleted straw-concentrate mixtures. The average passage time of the feed particles through the digestive tract is shorter in pregnant animals than in lactating ones. It is longest in non-pregnant sheep. High quotas of straw and coarse particles prolong the passage time, increasing feed intake and supplements of long straw shorten it. The volume of rumen fluid is lower in ewes fed ad libitum in the stage of late pregnancy and after lactation than during lactation. The rumen fluid volume is also lower in restrictively fed animals during the stage of late pregnancy than during lactation. In animals in the stage of late pregnancy it correlates negatively with the weight of the litter. On an average of all experiments at maintenance level the digestibility of the organic matter in ewes in the 4th month of pregnancy gravidity amounted to 56.6%, in the 2nd month of lactation to 59.8% and in wethers to 59.5% Due to an increase of energy intake from maintenance to 2. maintenance digestibility of the straw-concentrate mixture with 40% straw decreased by 5.5 units and of that with 60% straw by 17.8 units in the period before delivery. Pregnancy in the 4th month resulted in a digestion depression of between 3.0 and 5.8 units.

Ruminal Degradation and Outflow of Amino Acids in Cows

Two rumen- and duodenum-cannulated cows were used to study the disappearance rate, degradation in, and outflow from the rumen of four amino acids administered individually into the rumen at the following dose levels (mmol): lysine 273-547-820, tyrosine 276-496-828, isoleucine 381-762-1143 methionine 335. Calculations were based on the use of PEG (polyethylene glycol, 4000) as liquid marker for determination of the volume and dilution rate of rumen fluid. At the same dry matter intake a comparison was made between the influence of a high-forage and a low-forage diet. At the lowest dose level, the initial rates of disappearance (mmol/l per h) were 0.52 for lysine, 0.48 for tyrosine, 0.55 for isoleucine and 0.58 for methionine. The rates increased with increasing dose levels. The fractions of administered amino acids flowing out of the rumen and the fractions degraded in the rumen were studied over an 11 h period. At the lowest dose level, outflow (mmol/11 h) amounted to 42 and 54 for lysine, 36 and 29 for tyrosine, 93 and 48 for isoleucine, 104 and 75 for methionine on the high and low forage diet, respectively. The corresponding figures for degradation were 232 and 209, 239 and 247, 287 and 333, 226 and 259 mmol/11 h. The fractions of an administered amino acid flowing intact out of the rumen increased, and the fractions degraded in the rumen decreased, with increasing doses.