Batch Culture Technique Research Articles

In vitro degradation and methane production of short-season corn hybrids harvested before or after a light frost

In western Canada, short-season corn silage production is increasing due to its potentially high nutritive value. The objective of this study was to determine variability and relationships among nutrient concentration, degradability, and methane (CH4) production of short-season whole-plant corn hybrids harvested before or after light frost (−1.5 °C). Four hybrids, based on their corn heat unit rating (≤2600, CHU rating), were grown in 2 yr in central and southern Alberta (AB) with two field replications. The batch culture and Daisy fermenter techniques were used to characterize degradability and gas production measurements. At both locations, dry matter (DM) concentration was affected by harvest and hybrid (P ≤ 0.02). However, starch and neutral detergent fiber (NDF) concentrations differed (P ≤ 0.01) or tended (P = 0.07) to differ among harvest and hybrid only in central AB. Over both locations and harvest times, CH4production was related negatively to propionate and positively to acetate proportions. In conclusion, harvesting southern AB hybrids after frost increased DM concentration and NDF degradability with no effect on CH4emissions, but the high DM concentration may negatively affect silage quality and animal performance. Harvesting central AB hybrids after frost increased DM and starch concentrations, while reducing CH4emissions but had limited effects on nutrient degradability.

Effect of Xylanase and Phytase Supplementation on Goat's Performance in Early Lactation.

Supplementing diets of dairy animals with phytase and xylanase can enhance phosphorus availability and fiber degradation in the rumen and positively affect animal's health and productivity. In vitro and in vivo trials have been conducted to define the optimal addition level of xylanase and phytase to lactating Baldi goat's rations and investigate effects of these enzymes on animal's nutrients digestibility, blood chemistry, milk production and milk composition. In vitro batch culture technique was used to evaluate the effect of phytase and xylanase supplementation at different levels (0, 1, 2 and 3 g kg-1 DM) on rumen fermentation characteristics. Eighteen early lactating Baldi goats were randomly assigned into three groups and fed 4% dry matter according to their body weight. The first group was fed control ration (35% yellow corn, 20% corn stalks, 20% berseem hay, 12.5% soybean meal and 12.5% wheat bran), the second group fed control ration+Penizyme at 2 g kg-1 DM (R1), while the third group fed control ration+Phtase-Plus® at 1 g kg-1 DM (R2). Xylanase and phytase supplementation increased the in vitro DM and OM degradability and ruminal NH3-N and total volatile fatty acids (TVFA) concentrations, with no effect on total gas production (TGP) volume. All nutrients digestibility (except CP), blood serum glucose concentration, milk production and milk components yields were increased for enzymes supplemented goats than control. Inclusion of xylanase and phytase in lactating goat's rations improved their productive performance with no deleterious effects on their health.

IN VITRO EVALUATION OF ENSILING AND /OR EXOGENOUS FIBROLYTIC ENZYME SUPPLEMENTATION OF DATE PRESS CAKE

This study was conducted to evaluate the effect of ensiling and /or exogenous fibrolytic enzyme supplementation date press cake using in vitro batch culture technique . Untreated date press cake (DPC) and ensiled DPC with exogenous fibrolytic enzymes (ZAD1 and ZAD2) and with or without adding urea compared to corn grains were in vitro evaluated using batch culture technique. DM, NDF and ADF degradation and total gas production as well as fermentation parameters of the incubated samples were determined after 24 h of fermentation. Total VFAs, proportions are not affected (P > 0.05) by any of the treatments. However, value of ammonia concentration was higher (P 0.05) with the ensiling treatments. There were no significant differences in the values of DMD and OMD between the different treatments. But, the values of NDFD and ADFD were increased (P 0.05) between the corn grain and the DPC without any treatments. While, values of metabolizable protein (MP) and efficiency of microbial biomass production (EMP) were increased (p<0.05) with DPC compared to corn grains . There was no significant difference in the rumen activity when using date press cake (DPC) or corn grains. Moreover, the ensiling process did not cause a clear improvement in rumen fermentation.

IN-VITRO EVALUATION OF PROBIOTIC BACTERIA SUPPLEMENTATION TO RUMINANT RATIONS

The aim of this study was to evaluate effect of different level of probiotic supplementation to ruminant rations, using in-vitro batch culture technique to determine degradation and fermentation parameters. In vitro experimental ration was formulated, the ration consisted of 40% alfalfa hay and 60% concentrate feed mixture. Three level of probiotic supplementation (106, 108, 1010 cfu/kg DM) were evaluated. DM and total gas production as well as fermentation parameters of the incubated samples were determined after 24 hrs. of fermentation. Slightly increases (P>0.05) in in-vitro dry matter degradability were observed for the ration supplemented with probiotics bacteria at different levels (106,108 and 1010 cfu/ kg DM) compared to control ration. Probiotics bacteria supplementation with different level (106,108 and 1010 cfu/ kg DM) led to significant (P<0.001) increases in organic matter degradability and total gas production per sample and per g DM, OM, NDF and ADF compared to the not supplemented ration (control ration), and no significant differences were observed among the different levels of probiotics supplementation. Significant increase in total volatile fatty acid concentration after 24 hours' incubation period compared to the not supplemented ration. On the other hand, the treatment supplemented with probiotic recorded lower ammonia concentration compared to the control group. It could be concluded that, adding probiotics bacteria supplementation to experimental ration resulted increase DM and OM degradability and using dose 106 CFU/kg DM feed is sufficient to induce improvement in degradability and fermentation parameters

Inoculum source and transfer of rumen contents from bison to cattle improved in vitro gas production and feed digestibility, but not the responses to exogenous enzymes supplementation

We hypothesized that inoculating the rumen of beef cattle with rumen contents of bison and supplementing with exogenous fibrolytic enzymes (FE) would improve ruminal feed digestibility by enhancing microbiome activity in the rumen. The objectives of this study were to evaluate the effects of inoculum source (cattle versus bison), inocula after transfer from bison to cattle, FE supplementation, and their interaction on in vitro fermentation of barley straw, alfalfa hay and wheat dried distillers grain with solubles (DDGS). Rumen content transfers were performed using 16 beef heifers (body weight = 461 kg) twice at a 2-week interval by replacing 0.70 of total rumen contents of heifers with an equivalent amount of mixed rumen contents collected from plains bison. Three experiments were conducted using batch culture techniques. Barley straw and alfalfa hay were ground through 1-mm screen and DDGS was incubated as-is. In Exp. 1, inocula were prepared by combining rumen fluids (vol/vol) of cattle and bison at ratios of 100:0, 67:33, 33:67 and 0:100; the substrates were incubated for 96 h for determination of gas production (GP) kinetics. In Exp. 2, inocula with the same ratios as in Exp. 1 were incubated with substrates in vitro for 24 h to determine dry matter (DM) digestibility (DMD). In Exp. 3, incubations were conducted for 6, 24 and 48 h with the same substrates in four runs to compare the before versus after inocula effect. Each batch culture was a completely randomized design without or with FE addition at a rate of 2.0 μl/g substrate DM. Three different FE products (referred to FE1, FE2 and FE3) were used, with FE1 added in Exp. 1 and 2, while all 3 FE were added and compared in Exp. 3. Asymptotic GP of barley straw and alfalfa hay was not affected, whereas that of wheat DDGS responded quadratically (P < 0.04) with increasing bison contents in inocula. Rate of GP decreased (P < 0.03) for barley straw and alfalfa hay (quadratic), and for wheat DDGS (linear) with increasing bison contents in inocula (Exp. 1). In vitro DMD of barley straw at 24 h of incubation quadratically (P < 0.02) increased with increasing bison contents in inocula, whereas DMD of alfalfa hay and DDGS linearly (P < 0.01) decreased (Exp. 2). For Exp. 3, the DMD of barley straw, alfalfa hay and DDGS were greater (P < 0.05) at 6 h of incubation with the inocula collected after, as compared to before the rumen content transfer. In contrast, the DMD of alfalfa hay at 48 h and DDGS at 24 h and 48 h were less (P < 0.04) with inocula after versus before rumen content transfer. Addition of FE improved (P < 0.05) DMD of DDGS. The results demonstrated that the ruminal inocula from bison had an advanced capacity to degrade fibrous feed in vitro as compared to those from cattle. Enrichment of the cattle rumen microbiome with that of bison could potentially improve rumen digestion of fibrous feeds in beef cattle. Moreover, the results also suggest that the improvement in feed digestibility due to supplemental FE may be independent of inoculum source.

Short communication: Ground corn steeped in citric acid modulates in vitro gas production kinetics, fermentation patterns and dry matter digestibility

This study investigated the effect of citric acid (CA) concentration and steeping time (ST) treatment of ground corn on ruminally resistant starch (RRS) contents and subsequent effects on starch resistance to rumen degradation using batch culture technique. It was hypothesized that CA concentration and ST are keys affecting the RRS in CA treated ground corn. The experiment was 3 × 3 factorial arrangement using three CA solutions combined with three ST. Ground corn (2 mm) was steeped in an equal quantity (i.e., in a ratio of 1:1, w/v) of tap water alone (Ctr), of 5 (Low) or 10 g/L (High) CA solution for 12, 24 or 48 h. Chemical composition of CA treated corn was measured, and gas production (GP), volatile fatty acids (VFA), NH3-N and dry matter (DM) disappearance (DMD) were determined at 6 and 24 h of incubation. Inocula were obtained from three ruminally cannulated beef heifers fed a diet consisting of 300 g/kg barley silage, 670 g/kg dry rolled barley and 30 g/kg vitamin and mineral supplement (DM basis). No CA × ST interaction was detected. Citric acid treated corn had greater (P < 0.05) RRS than Ctr, with no differences between Low and High CA treatments; the content of RRS was greater (P < 0.05) at 48 h ST than 12 or 24 h. At 24 h of incubation, CA treated corn had lower (P < 0.05) asymptotic cumulative GP, GP rate, DMD, total VFA and NH3-N concentrations than did Ctr. Rate of GP, DMD and NH3-N concentration were highest (P < 0.01) with 12 h, intermediate with 24 h and lowest with 48 h ST at 24 h of incubation. Total VFA concentration was also higher (P < 0.01) with 12 h ST versus 24 and 48 h ST. Production of CH4 and CO2 decreased (P < 0.05) either by CA treatment or with increasing ST. These results indicated that CA treated ground corn increased RRS content, altered fermentation pattern for more acetate production and decreased ruminal DMD in batch culture. Use of CA to treat corn grain can be an effective processing to reduce ruminal corn starch digestion, and thus potentially alleviate risk of rumen acidosis.

Effects of eucalyptus oil and anise oil supplementation on rumen fermentation characteristics, methane emission, and digestibility in sheep.

The objective of this study was to evaluate antimethanogenic activity of eucalyptus oil (EUC) and anise oil (ANI) in vitro and in vivo using sheep as a model. In vitro study was conducted using batch culture technique, each of EUC and ANI were added at 0, 50, 100, 200, or 400 mg/L of fermentation media with substrate containing 60% corn-based concentrate and 40% hay (DM basis). Total gas production (GP) linearly (P < 0.01) decreased with increasing ANI, whereas the GP was not affected with EUC addition. Supplementation of ANI and EUC linearly (P < 0.01) decreased total methane production and methane proportion in total gas. Total VFA and ammonia-nitrogen (NH3-N) concentration linearly (P < 0.01) decreased with increasing ANI supplementation. For the in vivo study, a replicated 3 × 3 Latin square design was carried out using six ruminal cannulated Du Han hybrid sheep (BW, 64.5 ± 8.56 kg) with 22 d of periods. Three treatments were control diet (consisted of 60% corn-based concentrate and 40% Chinese wildrye hay), EUC (control diet supplemented with 0.5 g EUC/d per head), and ANI (control diet supplemented with 0.5 g ANI/d per head). Each period consisted of 14 d for adaption and 8 d for sampling and data collection. Supplementation of EUC and ANI had no effects on feed intake and apparent nutrient digestibility. Ruminal NH3-N concentration was greater with EUC (P < 0.01) and ANI (P = 0.03) than control. Urinal allantoin output was less (P < 0.05) in sheep fed EUC and ANI than control animals. Methane emission was less (P = 0.03) in sheep fed ANI than sheep fed EUC, and a tendency of decrease for an eduction in this parameter was found for sheep fed with ANI (P = 0.08) compared to control. The in vitro results indicated a reduction of methane production with both EUC and ANI but in a dose-dependant manner. Supplementation of ANI tended to reduce ruminal methane production without adversely affecting rumen fermentation characteristics, nutrient intake, and digestibility, suggesting potential inhibition of ruminal methane emission in sheep supplemented with ANI.

Effect of Partial Substitution of Ration's Soybean Meal by Biologically Treated Feathers on Rumen Fermentation Characteristics (in vitro).

Feather wastes are the most abundant keratinous material in the nature and its accumulation causes multiple environmental problems. Nutritive value upgrading of such wastes through biological treatments may provide ruminant's rations with high quality and cost effective source of protein. Therefore, the main objective of this study was to investigate the potential uses of biologically treated feathers (BTF) as a feedstuff for ruminants through in vitro experiments. Keratinase production time course was performed by ten microbial isolates (3 fungal, 3 actinomyces and 4 bacterial isolates) under static and shaking conditions using turkey feather- synthetic medium. The chemical composition and amino acid analysis for the crude feathers, BTF and soybean meal were determined according to AOAC methods. Two in vitro experiments were conducted to study the effects of crude feathers, BTF and modified ruminant rations (in which soybean meal were substituted by the BTF in 10, 20 and 30%) on rumen fermentation characteristics. Ration's Dry Matter (DM), Organic Matter (OM), Neutral detergent fibre (NDF) and Acid detergent Fibre (ADF) degradability by rumen microorganisms were tested using batch culture technique. Ruminal final pH, ammonia-nitrogen, total volatile fatty acids and short chain fatty acids concentrations were determined after 24 h of incubation. The total gas production volume was determined using 100 mL glass syringes. Bacillus licheniformis ALW1 was the most potent keratinase producer strain under static condition at 37°C for four days of incubation. Feather biological treatment by Bacillus licheniformis increased its content of some of essential-sulphur amino acids. The degradability of BTF by rumen microorganisms was 4 folds higher than crude feather degradability. There were no significant differences between control and partially substituted (R10 and R20) rations in all of rumen fermentation characteristics. The utilization of BTF as substitute for costly soybean meal in ruminant's rations up to 20% had no negative effect on all rumen fermentation characteristics.

Effects of gallic acid on in vitro rumen fermentation and methane production using rumen simulation (Rusitec) and batch-culture techniques

Two experiments were conducted to investigate the effects of adding gallic acid (GA) to ruminant diets on long- and short-term in vitro rumen fermentation and methane (CH4) production, and to test possible interactions between GA and ethanol on fermentation. The first experiment was conducted using the rumen simulation technique (Rusitec), as a completely randomised block design with four replications and the following four doses of GA: 0, 5, 10 and 20 mg GA/g dry matter (DM). Ethanol was used in all treatments to increase the solubilisation of GA in rumen fluid. The experimental period lasted 16 days, of which the first 7 days were for adaptation and the subsequent 9 days were for sampling. The second experiment was a 48-h batch-culture incubation conducted as a completely randomised design with a 4 (GA dose; 0, 10, 20, and 40 mg GA/g DM) × 2 (with or without ethanol) arrangement of treatments. In the Rusitec experiment, addition of GA up to 20 mg/g DM did not affect DM disappearance (DMD), organic matter (OM) disappearance, neutral detergent-fibre disappearance (NDFD), acid detergent-fibre disappearance (ADFD) or starch disappearance (P &amp;gt; 0.05), but crude protein disappearance was linearly decreased (P = 0.04) from 78.3% to 72.0%. Daily gas production and CH4 production expressed as mL/g DM and mL/g DMD were not affected by addition of GA (P &amp;gt; 0.05). Addition of GA up to 20 mg/g DM increased butyrate and isovalerate production (P &amp;lt; 0.05) and tended to increase isobutyrate (P = 0.09) and decrease heptanoate production (P = 0.07). In the batch-culture experiment, adding GA up to 40 mg/g DM linearly increased 48-h DMD, NDFD and ADFD (P &amp;lt; 0.05) and decreased (P &amp;lt; 0.05) CH4 expressed as mL/g DMD, mL/g NDFD and mL/g ADFD. Methane production was decreased after 24 h and 48 h only when GA was added at 10 mg/g DM without ethanol. Fermentation liquid pH and concentration of ammonia-nitrogen (ammonia-N) were also reduced (P &amp;lt; 0.05) with an increasing concentration of GA. Treatments with ethanol notably enhanced 48-h DMD, NDFD, ADFD, gas production (mL/g DM, mL/g OM or mL/g DMD), CH4 production (mL/g DM, mL/g DMD or mL/g NDFD), total volatile fatty acid concentration, the acetate:propionate ratio, acetate, valerate, isovalerate and caproate molar proportions (P &amp;lt; 0.01) and decreased propionate, butyrate and isobutyrate molar proportions (P &amp;lt; 0.01). Significant dose of GA × ethanol interaction was observed only for acetate molar proportion (P = 0.03). In conclusion, our study suggests that the beneficial effects of GA on feed digestion and CH4 production may be short term, while improvements in N metabolism may be sustained over the long term. It may be useful to conduct long-term in vivo studies using a range of diets and doses to verify whether GA can be used as a feed additive to mitigate enteric CH4 production and improve N metabolism of ruminants.

Influence of rumen contents’ processing method on microbial populations in the fluid and subsequent in vitro fermentation of substrates of variable composition

The in vitro batch culture technique is being increasingly used to study rumen fermentation, but the results are affected by several factors, being the source of the inoculum one of the most relevant. This work was conducted to assess the effects of different processing methods of ruminal contents on microbial populations in the obtained fluid, and its influence on fermentation parameters when the fluid was used as inoculum for in vitro incubations. Rumen contents were obtained from four rumen-fistulated sheep fed a 2:1 alfalfa hay:concentrate diet and subjected to the following treatments: SQ: squeezed through four layers of cheesecloth; FL: SQ treatment and further filtration through a 100-μm nylon cloth; STO: blended for three min at 230revmin−1 in a Stomacher® and further filtrations as in SQ. Microbial populations’ abundance and bacterial diversity in the ruminal fluids were analysed by quantitative PCR (qPCR) and automated ribosomal intergenic spacer analysis (ARISA), respectively. Three forages (alfalfa hay, grass hay and barley straw) were incubated in vitro, either alone or mixed with concentrate (1:1), using each of the ruminal fluids as inoculum. There were no differences between SQ and FL methods in any of the microbial populations analysed, but STO increased the relative abundance of Fibrobacter succinogenes and Ruminococcus albus (P<0.05) and decreased (P<0.05) the concentration of protozoal DNA compared with SQ. Bacterial diversity was not affected (P>0.05) by the processing methods. There were no interactions (P>0.05) between the processing method and the characteristics of the substrates for any of the fermentation parameters analysed. Compared with SQ, the STO method resulted in greater (P<0.05) methane production and ammonia-N concentrations in 8h incubations. After 24h of incubation, the use of STO inoculum increased (P<0.05) methane production and dry matter degradability compared with SQ, with no differences in the rest of the parameters. No differences between SQ and FL methods were detected in any parameter. The results show that stomaching the rumen contents prior to inoculation of in vitro cultures modified some microbial populations, but had only subtle effects on fermentation parameters.

Suitability of Inland Saline Ground Water for the Growth of Marine Microalgae for Industrial Purposes

Australia enjoys large inland areas rich in saline waters with potentials to marine aquaculture. In this study, these potentials were examined. Initially 9 different species of marine micro algae from three different divisions, namely Chlorophyta, Bascillariophyta and Chrysophyta, were cultivated using batch culture techniques to examine their growth performance in inland saline ground water (ISGW) with f/2 algae culture media. Dunaliealla tertiolecta was found to have highly significant growth performance while Nitzschia closterium showed significantly negative growth. In general, the average cell densities of all species of Chlorophyta were found to be higher compared to all species of Chrysophyta and Bascillariophyta. Significant differences of lipid were found to be in the Chlorophyta group compare to other two groups. The study successfully demonstrated that the marine microalgal group of Chlorophytes can be successfully grown in ISGW. However microalgae cultivation in ISGW still has enormous potential despite the negative growth of two diatom species and comparatively slow growth of Chrysophytes algae in this study. More controlled research on different groups of microalgae would be a good investment and a synergistic approach is recommended, including water chemistry, hydro-geology, soilwater interactions of and nutritional profiles of microalgae in ISGW.

In vitro ruminal fermentation of ground and dry-rolled barley grain differing in starch content

In vitro ruminal fermentation of ground and dry-rolled barley samples differing in starch content was evaluated using a batch culture technique. The study was arranged in a 2 (low and high starch)×2 (ground and dry-rolled) factorial design. Gas production (GP), short chain fatty acids (SCFA), dry matter (DM) and starch disappearance were estimated at 3, 6, 12 and 24h of incubation using rumen fluid from 3 ruminally fistulated beef cattle. Rate of GP was greater (P<0.05) in both high starch and ground (2mm) barley samples. Kinetics of DM and starch disappearance were calculated using the equation of a+b (1−e−c(t−L)). Starch content×processing interactions were noted for the b fraction and rate of DM disappearance. Consistently, both high starch and ground barley samples had greater (P<0.05) a and b fractions, rate constant of disappearance of b fraction and effective degradability versus low starch and dry-rolled samples. Expectedly, molar proportions of individual and total SCFA were greater (P<0.05) in the ground barley samples at all incubation periods. Overall, starch content (high versus low) had significant effect on the rate of GP and constant rate of DM disappearance but no effect on the constant rate of starch disappearance.

Short Communication: Variation in response to processing, in vitro gas production and fermentation of western Canadian feed barley

Yang, W. Z., Oba, M., Swift, M. L. and McAllister, T. A. 2014. Short Communication: Variation in response to processing, in vitro gas production and fermentation of western Canadian feed barley. Can. J. Anim. Sci. 94: 725–729. Sixty feed barley samples were collected from various locations in western Canada. Samples were either ground (1 mm) or dry-rolled to a processing index of 80%, and fermentability was assessed by measuring gas production (GP) and dry matter disappearances (DMD) at 0, 4, 8, 14 and 24 h of incubation using a batch culture technique. Physical and chemical composition, and GP and DMD varied substantially among samples. There were significant correlations among test weight and nutrient content of barley with GP and DMD of ground barley. The results indicate that the impact of nutrient content on in vitro DMD is more easily detected with ground than rolled barley.

Effect of traditional leafy vegetables on the growth of lactobacilli and bifidobacteria

Traditional leafy vegetables, apart from being a staple in the diet of most of sub-Saharan Africa, are an essential part of traditional medicine and are used daily by traditional healers in the region to treat a wide variety of ailments. In this study, a batch culture technique was used to investigate whether 25 infusions from 22 traditional leafy vegetables stimulated the growth of Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus reuteri and Bifidobacterium longum in pure culture. High performance liquid chromatography was used to determine the inulin content of the infusions. Sonchus oleraceus stimulated all four strains and Taraxacum officinale stimulated three strains. In total, 18 plants stimulated at least one of the four probiotic strains. The inulin content of the infusions varied between 2.5% and 3.6%, with Asparagus sprengeri containing the highest percentage. These results indicate that traditional leafy vegetables do stimulate the growth of the selected lactobacilli and bifidobacteria in pure culture and contain inulin. These infusions can now be tested for prebiotic potential using mixed culture systems or human hosts.

Effects of bulk density, precision processing and processing index on in vitro ruminal fermentation of dry-rolled barley grain

A study using a batch culture technique was conducted to evaluate the effects of bulk density (BD, g/L), processing method (PM; control vs. precision processing [PP]: sieving grains into large versus small kernels and rolling based on kernel size), and processing index (PI; BD after rolling/BD before rolling) on kinetics of gas production, dry matter degradability (DMD), molar proportions and total short chain fatty acids (SCFA) of dry rolled barley grain. The study was arranged in a 2×2×2 factorial design. Gas production and DMD were measured at 3, 6, 12 and 24h of incubation using rumen fluid from 3 fistulated beef heifers fed diet containing 700g barley silage and 300g of a barley grain-based concentrate. We hypothesized that incorporating other factors with PI would help improve prediction of the feeding value of processed barley grain. Barley samples were collected monthly from ten different feedlots in Southern Alberta for one year. Samples were ranked according to their BD into low (580g/L) and high (680g/L) BD which were subjected to different processing (control vs. PP) before being dry-rolled with extent of processing expressed as PI of 0.75 or 0.85±0.03. The dry-rolled samples used in the study were not subjected to further grinding. Cumulative gas production (GP; mL/g organic matter) was fitted to an exponential model GP=B(1−exp−c×[t−lag]). Processing method×PI interactions (P<0.01) were observed for asymptotic gas volume, rate, lag time and absolute initial gas produced during the first hour. In addition, a PM×BD interaction (P<0.05) was noted for asymptotic gas volume. Data from DMD at different times of incubation were fitted to a model DMD=a+b(1−e−c(t−L)). Effective degradability coefficients ranged from 0.18 to 0.26. Only PI had an effect (P<0.05) on the rate of DMD. Total SCFA values ranged from 30.2 to 40.1mmol/L. Apart from PM and PI interaction (P<0.05) on C2:C3, no other interaction was observed after 24h of incubation. Regression results showed that BD and PM were better for predicting rate of DMD than PI. This is consistent with our hypothesis that using only PI as a measurement for extensity of grain processing may not be reliable when barley grain kernels are highly variable in size.

Microbial Community Structure of Three Traditional Zambian Fermented Products: Mabisi, Chibwantu and Munkoyo

Around the world, raw materials are converted into fermented food products through microbial and enzymatic activity. Products are typically produced using a process known as batch culture, where small volumes of an old culture are used to initiate a fresh culture. Repeated over many years, and provided samples are not shared among producers, batch culture techniques allow for the natural evolution of independent microbial ecosystems. While these products form an important part of the diets of many people because of their nutritional, organoleptic and food safety properties, for many traditional African fermented products the microbial communities responsible for fermentation are largely unknown. Here we describe the microbial composition of three traditional fermented non-alcoholic beverages that are widely consumed across Zambia: the milk based product Mabisi and the cereal based products Munkoyo and Chibwantu. Using culture and non-culture based techniques, we found that six to eight lactic acid bacteria predominate in all products. We then used this data to investigate in more detail the factors affecting community structure. We found that products made from similar raw materials do not harbor microbial communities that are more similar to each other than those made from different raw materials. We also found that samples from the same product taken at the same location were as different from each other in terms of microbial community structure and composition, as those from geographically very distant locations. These results suggest that microbial community structure in these products is neither a simple consequence of the raw materials used, nor the particular suite of microbes available in the environment but that anthropogenic variables (e.g., competition among sellers or organoleptic preferences by different tribes) are important in shaping the microbial community structures.

Effects of vitamin E on the concentration of conjugated linoleic acids and accumulation of intermediates of ruminal biohydrogenation in vitro

The aim of this study was to investigate effects of vitamin E (Vit. E) addition to high soybean oil diets on the concentration of conjugated linoleic acids (CLA) and accumulation of biohydrogenation intermediates in mature goat rumen fluid using an in vitro batch culture technique. Rumen fluid collected from six fistulated mature goats was incubated for 24h with addition of Vit. E at different concentrations [0 (control), 0.5, 1.0 and 2.0mg/80ml] in triplicate. Results indicate that acetate, total volatile fatty acid (VFA), as well as the ratio of acetate to propionate, increased at a decreasing rate (linearly P<0.01 and quadratic P<0.05) with increased Vit. E supplementation, whereas the concentration of butyrate linearly (P<0.001) decreased. Vit. E had no effect on pH, ammonia-N, and total gas production. However, Vit. E linearly (P<0.001) decreased cis-9, trans-11 CLA concentration, linearly (P=0.002) increased trans-11 C18:1 and concentration of trans-10 C18:1 was the lowest at intermediate addition levels of Vit. E (quadratic P<0.001). Concentrations of linoleic acid and linolenic acid were both linearly (P<0.05) decreased at a decreasing rate with increased Vit. E addition. Vit. E linearly (P=0.001) decreased the oleic acid concentration, whereas that of stearic acid was linearly (P<0.001) increased. Results demonstrate that Vit. E supplementation affected ruminal fermentation parameters, particularly the concentration of conjugated linoleic acids and accumulation of intermediates of ruminal biohydrogenation in the ruminal fluid. The mechanism by which Vit. E may alter biohydrogenation is unclear, but the modification of rumen microbial populations/dynamics and consequent fatty acid hydration might be involved.

Effect of gap size between tooth and restorative materials on microbiolism based caries in vitro

To evaluate the effect of gap size between tooth and restorative materials on microbiolism based caries in vitro. Tooth blocks made of human molars without caries and the same size composite resin blocks were selected and prepared. Tooth-resin matrix was mounted on resin base with a gap size of 0, 25, 50, 100, 190, 250 µm and a control group was dealed with adhesive system. Six experimental groups and one control group were included, with 8 samples in one group and a total of 56 samples. The samples were cultured by a 14-day sequential batch culture technique. The development of outer surface lesion and wall lesion was assessed with confocal laser scanning microscope (CLSM) by measuring the maximum lesion depth, fluorescence areas and average fluorescence value. The data were collected and statistically analyzed. The deposits of the tooth-restoration interface and the development of the carious lesion were observed by scanning electron microscope (SEM). Most groups showed outer surface lesion and wall surface lesions observed by CLSM and SEM except 2 samples in control group. There was no significant difference on the outer surface lesion (P > 0.05). The maximum lesion depth [(1145.37 ± 198.98), (1190.12 ± 290.80) µm respectively], the maximum lesion length, fluorescence areas and average fluorescence value of 190 and 250 µm groups' wall lesions were significantly higher than the 0, 25, 50 and 100 µm groups [the maximum lesion depth was (205.25 ± 122.61), (303.87 ± 118.80), (437.75 ± 154.88), (602.87 ± 269.13) µm respectively], P < 0.01. With the increase of the gap size, the demineralization developed more seriously. While the maximum lesion depth, the maximum lesion length and fluorescence areas of 0, 25, 50 µm groups' wall lesions were of no significant difference. There was close relationship between gap size and wall lesion when the gap was above 100 µm at tooth-composite resin interface. The existence of gap was the main influencing factor on the development of microbiolism based caries lesion.

Fermentation of animal components in strict carnivores: A comparative study with cheetah fecal inoculum1,2

The natural diet of felids contains highly digestible animal tissues but also fractions resistant to small intestinal digestion, which enter the large intestine where they may be fermented by the resident microbial population. Little information exists on the microbial degradability of animal tissues in the large intestine of felids consuming a natural diet. This study aimed to rank animal substrates in their microbial degradability by means of an in vitro study using captive cheetahs fed a strict carnivorous diet as fecal donors. Fresh cheetah fecal samples were collected, pooled, and incubated with various raw animal substrates (chicken cartilage, collagen, glucosamine-chondroitin, glucosamine, rabbit bone, rabbit hair, and rabbit skin; 4 replicates per substrate) for cumulative gas production measurement in a batch culture technique. Negative (cellulose) and positive (casein and fructo-oligosaccharides; FOS) controls were incorporated in the study. Additionally, after 72 h of incubation, short-chain fatty acids (SCFA), including branched-chain fatty acids (BCFA), and ammonia concentrations were determined for each substrate. Glucosamine and glucosamine-chondroitin yielded the greatest organic matter cumulative gas volume (OMCV) among animal substrates (P < 0.05), whereas total SCFA production was greatest for collagen (P < 0.05). Collagen induced an acetate production comparable with FOS and a markedly high acetate-to-propionate ratio (8.41:1) compared with all other substrates (1.67:1 to 2.97:1). Chicken cartilage was rapidly fermentable, indicated by a greater maximal rate of gas production (R(max)) compared with all other substrates (P < 0.05). In general, animal substrates showed an earlier occurrence for maximal gas production rate compared with FOS. Rabbit hair, skin, and bone were poorly fermentable substrates, indicated by the least amount of OMCV and total SCFA among animal substrates (P < 0.05). The greatest amount of ammonia production among animal substrates was measured after incubation of collagen and rabbit bone (P < 0.05). This study provides the first insight into the potential of animal tissues to influence large intestinal fermentation in a strict carnivore, and indicates that animal tissues have potentially similar functions as soluble or insoluble plant fibers in vitro. Further research is warranted to assess the impact of fermentation of each type of animal tissue on gastro-intestinal function and health in the cheetah and other felid species.

In vitro rumen methane output of perennial ryegrass varieties and perennial grass species harvested throughout the growing season

AbstractThe selection and feeding of perennial ryegrass (Lolium perenne L.) varieties (PRV) or perennial grass species (PGS) may affect enteric methane (CH4) output because of changes in the fermentation dynamics in the rumen as a result of differences in herbage chemical composition. The objective of this study was to determine the effects of PRV and PGS harvested throughout the growing season on herbage chemical composition, and in vitro rumen fermentation variables and CH4 output per unit of feed using a batch culture technique. Seven PRV (Experiment 1: Alto, Arrow, Bealey, Dunluce, Greengold, Malone, Tyrella) and six perennial grasses [Experiment 2: perennial ryegrass (Navan), perennial ryegrass (Portstewart), cocksfoot, meadow fescue, tall fescue, timothy; defined as PGS], managed under a simulated grazing regime, were incubated for 24 h with buffered rumen fluid in two separate experiments. The CH4 output per unit of feed dry‐matter (DM) incubated was not affected (P &gt; 0·05) by PRV (range of mean values across PRV of 23·9–25·3 (SEM 0·41) mL g−1 DM) or by PGS (25·6–26·6 (SEM 0·37) mL g−1 DM). The CH4 output per unit feed DM disappearing during the in vitro rumen incubation was not affected by PRV (33·9–35·1 (SEM 0·70) mL g−1 DM), and although there was an overall PGS effect (P &lt; 0·05; 37·2–40·3 (SEM 0·71) mL g−1 DM), none of the paired contrasts between PGS were significant when analysed using Tukey adjusted comparisons. This outcome reflected either small‐scale or a lack of treatment effects on individual herbage chemical composition (e.g. 454–483 g NDF kg−1 DM, 215–224 g CP kg−1 DM and 94–122 g water‐soluble carbohydrate (WSC) kg−1 DM across PRV; 452–506 g NDF kg−1 DM, 208–243 g CP kg−1 DM and 73–131 g WSC kg−1 DM across PGS) and in vitro rumen fermentation variables. Hence, these results provide no encouragement that choices among the grasses examined, produced within the management regimes operated, would reduce enteric CH4 output per unit of feed in vivo. However, the technique utilized did not take account of animal × PRV or PGS interactions, such as potential differences in intake between animals, that may occur under farm conditions.