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Abstract: Isoflavones are a group of phytoestrogens found in many plants, and daidzein is one of their major metabolites. Previous studies have shown that daidzein affects growth of rumen bacteria and intestinal microflora. This study investigated effects of daidzein on rumen microbial fermentation. Substrate containing ground Chinese wildrye hay (7g/L), corn grain powder (2.1g/L) and soybean meal (0.9g/L) was fermented in vitro by mixed rumen microorganisms and substrate containing rice straw (8g/L) by rumen anaerobic fungi from four rumen fistulated male goats. Results with mixed rumen microorganisms showed that daidzein treatment had no effect on the total VFA, but maximized propionate at about 10mg/L (quadratic P<0.01). As a result, the ratio of acetate to propionate was minimized at 10mg/L (quadratic P<0.05). Daidzein treatment also minimized NH3-N at 10mg/L (quadratic P<0.01), but had no effect on microbial crude protein. The fermentation time-course study showed that the effect of daidzein at 10mg/L on production of acetate and propionate became significant after 1h of fermentation, while the effect on NH3-N content became evident after 5h. In a culture of the rumen anaerobic fungus Neocallimastix sp., daidzein maximized cumulative gas production and specific growth rate to half of the gas pool at 10–50mg/L, but had no effect on dry matter loss. Results indicate potential regulating effects of daidzein on rumen microorganisms that could be useful in the rumen function. [Copyright &y& Elsevier]

Abstract: In 24h in vitro incubations with 25ml of buffered rumen fluid, four doses (0, 20.8, 41.6 and 83.3mg) of a DHA-edible algae product, Aquagrow-DHA, were examined in combination with sunflower (20mg) or linseed oil (20mg). One treatment contained no Aquagrow-DHA, linseed or sunflower oil and one was supplemented with Aquagrow-DHA (166.6mg) only. Addition of lard ensured that total fat content was constant among incubations. Increasing amounts of Aquagrow-DHA progressively inhibited CH4 to a maximum of 80% (P<0.001). Increased CH4 inhibition was accompanied by decreased acetate (P<0.001) and butyrate (P<0.001), and increased propionate (P<0.001) proportions, but also by depression of the short chain fatty acid (SCFA) production by 30% at the highest Aquagrow-DHA level (P<0.001). However, SCFA inhibition only occurred when the Aquagrow-DHA dose exceeded 41.6mg and CH4 production was reduced by about 30% (P<0.05) at this dose. Inhibitory effects were linked to the amount of unesterified polyunsaturated fatty acids, particularly docosahexaenoic acid. Incubations under partial H2 atmosphere suggested that a direct toxic effect to rumen methanogens was caused by higher amounts of unesterified DHA (>41.6mgAquagrow-DHA/incubation) only, whereas suppression of rumen methanogenesis at lower doses seemed to be indirect through a lack of substrate. This indicates bacteria providing H2 to the rumen methanogens to be more sensitive to unesterified DHA than rumen methanogens. [Copyright &y& Elsevier]

Abstract: The aim of this study was to continuously monitor rumen pH of loose-housed dairy cattle as affected by feeding pattern and live yeast supplementation. Three multiparous lactating rumen-cannulated cows receiving the same basal ration once daily were supplemented with 5g/d (equivalent to 1010 CFU/d) of Saccharomyces cerevisiae strain CNCM I-1077 (Levucell SC2, Lallemand, Toulouse, France) alternately for periods of 2 weeks following a cross-over design. The three cows were maintained in loose-house conditions and milked with a robotic milking system. Cows consumed a fraction of their ration in the feed bunk as a mixed ration and about 3kg/d of concentrate during milking at the robotic milking unit. During the last 8d of each period, rumen pH was monitored every 15min. However, the rumen was accessed only once every 3 days. These pH measurements were recorded with a pH meter capable of storing pH values automatically that was placed inside a custom-made polyvinyl cylinder with about 300g of lead to ensure that the device remained in the ventral part of the rumen throughout all readings. Individual feed intake and feeding patterns were also recorded. The data were analyzed using a mixed-effects model with repeated measures. Average rumen pH was greater (P<0.01) when yeast was supplemented than when no yeast was provided. Ruminal pH decreased (P<0.001) as time since last basal ration bout increased, and this decrease was more (P<0.05) pronounced when no yeast was supplemented. Yeast-supplemented cows had a greater (P<0.05) meal frequency than the unsupplemented cows. The results indicate that live yeasts have a beneficial effect on ruminal pH of cows kept in loose-house conditions. Furthermore, yeast effects on rumen pH may be evident starting 1 week after supplementation. [Copyright &y& Elsevier]

Abstract: Previously, combining docosahexaenoic acid (DHA) with linoleic acid in rumen cultures enhanced vaccenic acid (VA) and conjugated linoleic acid (CLA) accumulations. The objective of this experiment was to examine the effect of two pH levels and two polyunsaturated C18 fatty acid (FA) sources on VA and CLA accumulations in rumen cultures incubated with DHA. High pH culture treatments consisted of 10mg DHA+20mg linoleic acid (LOH), or 10mg DHA+20mg linolenic acid (LNH). Low pH culture treatments consisted of 10mg DHA+20mg linoleic acid (LOL), or 10mg DHA+20mg linolenic acid (LNL). Treatments were incubated in triplicate in 125ml flasks containing 500mg finely ground TMR, 10ml strained ruminal fluid, 40ml media, and 2ml reducing solution. Ruminal fluid was collected from fermenters fed high forage (pH 6.7) or high grain diets (pH 5.4). A 5-ml sample of culture contents was taken at 0 and 24h for fatty acid analysis by gas liquid chromatography. After 24h of incubation, VA was the predominant trans C18:1 FA isomer in the high pH cultures and its concentration was greater with LOH (20.9mg/culture) than with LNH (9.3mg/culture). Similarly, t10 C18:1 was the predominant trans C18:1 FA isomer in the low pH cultures and its concentration was greater with LOL (12.8mg/culture) than with LNL (4.5mg/culture). The c9t11 CLA (0.74mg/culture) and tt CLA (0.67mg/culture) were the predominant CLA isomers in the LOH cultures, while t10c12 CLA (1.47mg/culture) and tt CLA (1.27mg/culture) were the predominant CLA isomers in the LOL cultures. The t11t13 CLA increased in linolenic acid cultures, particularly when linolenic acid incubated under low pH condition (0.95mg/culture). Additions of linolenic acid to rumen cultures caused a dramatic increase in the concentration of t11c15 C18:2 (9.84 and 8.45mg/culture, for treatments LNH and LNL, respectively). The concentrations of VA and c9t11 CLA in rumen cultures were greatest when DHA was incubated with linoleic acid at high pH. In contrast, t10 C18:1 replaced VA and c9t11 CLA disappeared when linoleic and linolenic acids were incubated under the low pH condition. This study shows that the best approach to increase ruminal VA production, and potentially c9t11 CLA levels in ruminant food products, is by combining a DHA source (such as fish oil or algae) and linoleic acid source under high ruminal pH condition. [Copyright &y& Elsevier]

Abstract: Effects of ethanol treatment on ruminal in situ degradation kinetics of dry matter (DM) and crude protein (CP) of soybean meal (SBM) were determined. Soybean meal samples were soaked in 500, 600 or 700ml/l ethanol solutions for 2h. Duplicate nylon bags of untreated or treated SBM were suspended in the rumen of four non-lactating Holstein cows for up to 48h, and resulting data were fitted to non-linear degradation model to calculate degradation parameters of DM and CP. Intestinal CP digestibility was measured using the mobile nylon bag technique. Proteins of untreated and treated bag residues were fractionated by gel electrophoresis. There were differences (P<0.05) for DM and CP degradation parameters between untreated and ethanol treated SBM. Regardless of the concentration, ethanol treatments applied to SBM decreased the washout fraction, the estimated rate of CP degradation, and the effective protein degradation (EPD) compared to untreated SBM. The lowest estimated rate of CP degradation and the calculated EPD were observed when SBM was treated with 600ml/l ethanol solution. Extending the ethanol concentration over 600ml/l to SBM was considered excessive. Ethanol treatments increased (P<0.05) the intestinal mobile bag digestibility of ruminally undegraded CP. At concentration of 500, 600 and 700ml/l, digestibility of CP increased by 4, 12 and 13% compared to untreated SBM, respectively. Electrophoretic analyses of untreated, 500, 600 and 700ml/l ethanol treated SBM revealed that two of the subunits of β-conglycinin (ά and α) had been degraded completely after 2, 6, 8 and 8h, whereas the β subunit of this protein has been degraded after 4, 8, 12 and 12h, respectively. In untreated SBM, the acidic and basic subunits of glycinin had been degraded in 8 and 12h of incubation, but in treated SBM had not been degraded even after 48h of incubation. Based upon these results, treatment of SBM with 600ml/l ethanol solution had the greatest potential to increase rumen undegradable protein. [Copyright &y& Elsevier]

Abstract: This study investigated the potential of the goat''s ruminal adaptation to reduce the negative effect of tannins on in vitro fermentation. Rumen fluid was obtained from goats fed a mixture of tannin-containing tree fruits (adapted rumen fluid) or tannin-free commercial protein supplements (unadapted rumen fluid) for 85 days. Dry, mature fruits of Acacia nilotica, Acacia erubescens, Acacia erioloba, Dichrostachys cinerea and Piliostigma thonningii were used as substrates for the in vitro fermentation. The effectiveness of adapted rumen fluid to ferment tannin-containing substrates was compared to the extent of fermentation when tannins were inactivated with polyethylene glycol (PEG), a known tannin-binding agent. Adapted rumen fluid (P<0.05) increased gas production from all five substrates between 15.8% and 73.7%. In A. nilotica, D. cinerea and P. thonningii, this increase was less than that obtained through PEG treatment. When PEG was added to adapted rumen fluid a further improvement in extent of fermentation was observed in four out of the five fruit samples. The largest PEG effect when incubated with adapted rumen fluid was observed in A. nilotica (43.1%) and D. cinerea (42.9%) fruits. It is concluded that some tannin-rich feedstuffs may still benefit from treatment even when these are offered to adapted animals. [Copyright &y& Elsevier]

Abstract: Due to its favorable agronomic traits, Acacia saligna has the potential to be used as a perennial forage crop in the agricultural regions of southern Australia. The feed quality of populations from across the natural range of A. saligna was examined using in vitro and spectroscopic methods. The mean feed quality of A. saligna was found to be low in comparison to other forage species commonly used in southern Australia, this was due primarily to low dry matter digestibility (DMD) and high protein precipitable tannin (PPT) levels. The content of crude protein (CP) and fibre were both moderate, and the content of essential minerals was found to meet the basic requirements for sheep, with the exception of phosphorus. There was a significant level of variation in fodder quality between the sampled populations. The feed qualities of some populations were found to approach or exceed what is desirable for a livestock feed. The results showed that A. saligna has the potential to produce feed of an acceptable quality. Further development of the species as a crop requires the detailed characterisation of the variation. Some of the variation in feed quality was correlated with genetic variation in the species, and was poorly correlated with known environmental variation. It may therefore be genetically controlled, suggesting that the feed quality of A. saligna could be improved through selection and breeding. [Copyright &y& Elsevier]

Abstract: Different levels of sodium hydroxide (NaOH) or ammonia bicarbonate (NH4HCO3) were applied to rice straws to investigate the effects on histological dynamic change of stem epidermis before and after in sacco degradation using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The papillae, wart-like structures and micro-hairs on the cuticle layer of stem epidermis were crimped by treatment with NaOH above 30g/kg straw dry matter, but were not crimped in NH4HCO3-treated stems. A part of the cuticle wax and silica layer was breached at high dosages of NH4HCO3. Epidermis was degraded in NaOH-treated stem, but was still observed in untreated or NH4HCO3-treated stems, even after rumen incubation for 48h. Degradation was observed more clearly under TEM than under SEM. Micro-hairs of both untreated and treated stems were not degraded or detached from the epidermis earlier than other epidermal structures. Results indicate that the cuticle wax silica layer of rice stem epidermis is an important barrier to rumen degradation, but pretreatment with NaOH or NH4HCO3 may dissolve (NaOH) or crack off (NH4HCO3) this layer, and that changes increase in a dose-dependent manner. With the dissolving of the cuticle wax layer, the epidermis in the NaOH-treated stems could be degraded by rumen microorganisms, whereas only the breach of the cuticle layer in NH4HCO3-treated stems did not result in degradation of epidermis leading to a lesser positive improvement on rumen digestion versus NaOH treatment. [Copyright &y& Elsevier]

Abstract: A feeding trial was conducted for 60 days to determine the effect of dietary tannin on growth and health status of Labeo rohita fingerlings. One hundred and eighty fingerlings (average weight 3.2g) were randomly distributed into six treatment groups with three replicates each. Six isonitrogenous (crude protein 339.8–351.1g/kgfeed) and isocaloric (16.51–16.65MJDE/kg) practical diets were prepared with graded levels of tannin, viz. control, T1 (2.5g/kg), T2 (5g/kg), T3 (10g/kg), T4 (15g/kg) and T5 (20g/kg). Addition of tannin up to 20g/kg did not affect the weight gain (%), specific growth rate, feed conversion ratio, protein efficiency ratio, and apparent net protein utilization of fingerings significantly (P>0.05). The hepato somatic index value of control group was lowest than the other experimental groups. The muscle cholesterol level and haemoglobin count in the different treatments was significantly increased compared with the control. The immunological parameters like total leucocyte count and respiratory burst activity was significantly increased in tannin-fed groups. Based on the results of the present study, it is concluded that short-term feeding for 60 days of hydrolysable tannin has no adverse effect on growth of L. rohita fingerlings. Hence feeding of hydrolysable tannin on a long-term basis needs further study. [Copyright &y& Elsevier]

Abstract: The effective degradability (ED) and the intestinal effective digestibility (IED) of dry matter (DM) and crude protein (CP) of a green Italian rye-grass (GRG) crop and its silage (ERG) were determined using in situ and particle passage techniques on three wethers, cannulated in rumen and duodenum. Two rumen incubations with duplicate bags filled with 3g of freeze-dried samples were performed for each feed at times of 0, 2, 4, 8, 16, 24, 48 and 72h. On each incubation, one series of bags was used to determine rumen degradation and the other was freeze-dried and pooled for each incubation time. Then two sub-samples (0.2g) were incubated into mobile nylon bags through the entire intestine of each animal. The microbial contamination of rumen incubated residues (determined with 15N techniques) was fitted to an exponential function. The asymptotic values (m) for DM contamination showed that silage particle reached a greater colonisation (P=0.006) but with a slower rate of microbe accumulation (P=0.03). Values of m for CP also showed that the undegradable CP fraction was mainly of microbial origin (0.745 and 0.870 for GRG and ERG, respectively). Two different ED estimates were established: EDp, considering the particle rumen outflow rate (k p) of the ERG, and EDc,p, considering additionally the fractional rate of conminution and mixing (k c) of these particles. Mean values (and S.E.) of both rates were: 0.0497±0.0113 and 0.181±0.0165 (h−1), respectively. The microbial contamination implied an under-evaluation of EDp and EDc,p for CP: 12.7 and 13.5% in GRG and 11.0 and 12.4% in ERG, respectively. These errors were higher for the associated values of undegraded CP. Thus, a proportion of 0.380 and 0.490 in GRG and 0.429 and 0.538 in ERG of these estimates will be really of microbial origin. No differences for EDp or EDc,p values were shown between CP and total analysed amino acids (assumed as representative of true protein). The interference of microbial contamination of feeds in the rumen was also evident in intestinal disappearance values, which showed an irregular and inconsistent evolution with the increase of the rumen residence time. Ensiling reduced the ED and IED of DM as well as the protein undegraded fraction and its IED. [Copyright &y& Elsevier]

Abstract: Effects of a docosahexaenoic acid (DHA)-edible algae product, Aquagrow-DHA, on lipolysis and biohydrogenation of linoleic acid (C18:2 n-6) was studied in 24h in vitro incubations with buffer (20ml), sheep rumen contents (5ml), hay (0.4g) and sunflower oil (20mg). Four Aquagrow-DHA levels (0, 20.8, 41.6, 83.3mg) were tested and addition of lard ensured that the total fat content was constant. Increasing Aquagrow-DHA proportionally inhibited hydrogenation of C18:2 n-6, provoking an accumulation of C18:1 trans fatty acids (mainly C18:1 t10+t11). Analogous incubations for 6 and 24h with linseed oil (20mg) instead of sunflower oil, resulted in the accumulation of C18:2 t11c15 and, to a lower extent, C18:1 t10+t11 and showed that Aquagrow-DHA reduced the rate of lipolysis of linolenic acid (C18:3 n-3). Comparison of these results with incubations with the individual constituents of Aquagrow-DHA and whole algae biomass revealed that the observed effects were related to the presence of DHA. Finally, incubations under a 50:50 H2:CO2 atmosphere suggested a direct inhibitory effect of unesterified DHA on hydrogenating bacteria involved in the conversion of C18:2 t11c15 and C18:1 trans isomers, rather than on H2 availability. [Copyright &y& Elsevier]

Abstract: In arid zones of North Africa, hays formerly harvested from native range forages such as Alfa (Stipa tenacissima), can provide alternative diets for livestock during periods of forage scarcity. However, they usually constitute low-quality forages. Soaking Alfa hay in alkaline solutions prepared from dung ash, with the addition of urea, was evaluated as a potential economic treatment for improving rumen digestibility. A digestion trial was conducted using 3-year-old male goats to compare digestibility of untreated Alfa hay with a treatment containing a 200g/L solution of dung ash from dromedary, and 30g/kg urea. A second experiment was conducted in order to evaluate the effectiveness of dung ash source (dromedary or goat), concentration of dung ash solution (0, 100, 200 or 300g/L) and urea (0 or 30g/kg) on in vitro digestibility of Alfa amongst goats. Results of digestion trials showed that treated Alfa hay had higher (P<0.01) digestion coefficients for dry matter (0.483 versus 0.420), organic matter (0.558 versus 0.487), neutral detergent fiber (0.664 versus 0.531) and acid detergent fiber (0.620 versus 0.545) than untreated hay. Crude protein apparent digestibility presented no significant different values (P>0.05) between untreated and treated hay (0.356 versus 0.402). Daily dry matter intake ranged from 40.8 to 46.2g/kgBW0.75 for untreated and treated hay, respectively (P<0.05). This resulted in an increase of the daily digestible dry matter intake of about 31% for treated hay as compared with the untreated hay. Results of the second experiment showed that in vitro organic matter digestibility coefficient (IVOMD) raised from 0.271 for untreated hay to 0.499 for Alfa hay treated with a 300g/L solution of dung ash from goats and with 30g/kg urea. Dung ash from goats appeared to have a higher effect than those from dromedary. Meanwhile, IVOMD of Alfa hay only treated with 30g/L urea was intermediary (0.403). It is concluded that treating Alfa hay with a 200g/L solution of dung ashes and 30g/kg urea can provide an average quality forage which meets the nutritional maintenance requirements of livestock. The significance of these findings is discussed in relation to feeding management strategies for low-input livestock systems. [Copyright &y& Elsevier]

Abstract: Changes in the ruminal environment of cattle supplemented with corn silage (CS) before alfalfa grazing, in relation to the occurrence of frothy bloat, were evaluated. Six ruminally fistulated heifers were used in a crossover design experiment for in situ determinations and as a source of rumen fluid for in vitro measurements. Alfalfa pasture was grazed at the vegetative stage in a rotational grazing system. Treatments were—C: no supplement; CS: 0.5kg of CS dry matter/100kg body weight. CS supplementation reduced (P<0.05) the frequency and severity of frothy bloat. From the sixth hour until the end of the incubation at 12h, in vitro microbial gas production using alfalfa leaflets as substrate was lower in rumen fluids from CS supplemented heifers. Bacterial mass in the liquid phase of ruminal contents, and in situ microbial colonization of particles entering the rumen did not differ. Only at 4h post-grazing was proteolysis reduced (P<0.05) for both treatments. The anti-bloat mechanisms of CS were not completely identified, however we confirmed that CS supplementation before alfalfa grazing is a reliable management practice to reduce frothy bloat. [Copyright &y& Elsevier]