Methane production from commercial dairy rations estimated using an in vitro gas technique

Agroecological Zone-Specific Diet Optimization for Water Buffalo (Bubalus bubalis) through Nutritional and In Vitro Fermentation Studies

The water buffalo faces challenges in optimizing nutrition due to varying local feed resources. In response to this challenge, the current study introduces originality by addressing the lack of region-specific feeding strategies for water buffaloes. This is achieved through the formulation of 30 different diets based on locally available resources, offering a tailored approach to enhance nutritional optimization in diverse agroecological contexts. These diets were segmented into three groups of ten, each catering to the maintenance (MD1 to MD10), growth (GD1 to GD10), and lactation/production (PD1 to PD10) needs of buffaloes. Utilizing local feed ingredients, each diet was assessed for its chemical composition, in vitro gas and methane emissions, and dry matter (DM) disappearance using buffalo rumen liquor. The production diets (127 and 32.2 g/kg DM) had more protein and fats than the maintenance diets (82.0 and 21.0 g/kg DM). There was less (p < 0.05) fiber in the production diets compared to the maintenance ones. Different protein components (PB1, PB2) were lower (p < 0.05) in the maintenance diets compared to the growth and production ones, but other protein fractions (PB3, Pc) were higher (p < 0.05) in the maintenance diet. Furthermore, the growth diets had the highest amount of other protein components (PA), while the maintenance diets had the highest amount of soluble carbohydrates (586 g/kg DM), whereas the carbohydrate fraction (CB1) was highest (p < 0.05) in the production diets (187 g/kg DM), followed by the growth (129 g/kg DM) and maintenance diets (96.1 g/kg DM). On the contrary, the carbohydrate CA fraction was (p < 0.05) higher in the maintenance diets (107 g/kg DM) than in the growth (70.4 g/kg DM) and production diets (44.7 g/kg DM). The in vitro gas production over time (12, 24, and 48 h) was roughly the same for all the diets. Interestingly, certain components (ether extract, lignin, NDIN, ADIN, and PB3 and CC) of the diets seemed to reduce methane production, while others (OM, NPN, SP, PA and PB1, tCHO and CB2) increased it. In simple words, this study reveals that different diets affect gas production during digestion, signifying a significant step towards a promising future for buffalo farming through tailored, region-specific formulations.

Differences in Donor Animal Production Stage Affect Repeatability of In Vitro Rumen Fermentation Kinetics

In vitro gas production techniques (IVGPT) are widely used to screen feeds and feed additives to reduce the number of animals needed for experiments, which in turn, reduces costs and increases animal welfare. However, information about repeatability is scarce. The objective of this study was to evaluate the variation from in vitro gas production fermentations in the same laboratory using the same feed substrate. The source of rumen fluid used in the fermentations was from two different farms with either cannulated lactating dairy cows or cannulated fasting heifers, representing two distinct stages of production (donor types). Seventeen 24 h fermentations, undertaken during a year, were used to evaluate the variation between the following parameters: gas curve parameters, baseline-corrected total gas production (TGP (mL at Standard Temperature and Pressure (STP))/g incubated dry matter (DM)), methane concentration (%) and yield (mL gas at STP/g DM), pH and degraded dry matter (dDM). Significant differences between donor types were found for the pH of the rumen fluid from individual animals and pH of fermented fluid. However, no significant differences were observed within donor type. The means for methane concentration and yield, after 24 h of fermentation, were not significantly different between or within donor types. Rate of early gas production was significantly different between donor types, but baseline-corrected TGP was not significantly different at 24 h. No dDM differences after 24 h of fermentation between or within donor types were detected. Gas production curves were different between donor types, being either a monophasic version of the sigmoidal model or an exponential curve for the heifers and the production animals, respectively. No differences were observed within type. Repeatability of rumen fluid (CVRF), calculated as the coefficient of variation, and the associated parameters, which were investigated, was best for methane yield (CVRFALL = 0.3%) and least for TGP at 3 h (CVRFALL = 3%). Repeatability was dependent on donor type.

Phosphorus recovery as K-struvite from a waste stream: A review of influencing factors, advantages, disadvantages and challenges

Currently, the depletion of natural resources and contamination of the surrounding environment demand a paradigm shift to resource recycling and reuse. In this regard, phosphorus (P) is a model nutrient that possesses the negative traits of depletion (will be exhausted in the next 100 years) and environmental degradation (causes eutrophication and climate change), and this has prompted the scientific community to search for options to solve P-related problems. To date, P recovery in the form of struvite from wastewater is one viable solution suggested by many scholars. Struvite can be recovered either in the form of NH₄-struvite (MgNH₄PO₄•6H₂O) or K-struvite (MgKPO₄•6H₂O). From struvite, K (MgKPO₄•6H₂O) and N (MgNH₄PO₄•6H₂O) are important nutrients for plant growth, but N is more abundant in the environment than K (the soil's most limited nutrient), which requires a systematic approach during P recovery. Although K-struvite recovery is a promising approach, information related to its crystallization is deficient. Here, we present the general concept of P recovery as struvite and details about K-struvite, such as the source of nutrients, factors (pH, molar ratio, supersaturation, temperature, and seeding), advantages (environmental, economic, and social), disadvantages (heavy metals, pathogenic organisms, and antibiotic resistance genes), and challenges (scale-up and acceptance). Overall, this study provides insights into state-of-the-art K-struvite recovery from wastewater as a potential slow-release fertilizer that can be used as a macronutrient (P-K-Mg) source for plants as commercial grade-fertilizers.

Effect of Chitosan and Naringin on Enteric Methane Emissions in Crossbred Heifers Fed Tropical Grass

Simple Summary

The increase in human population and the concomitant rise in demand for animal protein have contributed to augment enteric methane emissions. It is imperative to reduce methane, increase sustainable production, avoid the use of chemical compounds, and guarantee quality products for the consumer. Chitosan and naringin possess antimicrobial properties, and they have shown their capacity to reduce methane in in vitro trials. This study investigated their effects as feed additives given to improve ruminal fermentation and nutrient utilization and decrease methane in crossbred heifers fed tropical grass. In in vitro experiments, chitosan and naringin at three levels (0, 1.5, 3.0 g/kg) showed significant methane reductions when 1.5 g/kg of chitosan was included. The in situ study did not reveal changes in rumen degradability with the inclusion of the additives. However, in in vivo assays, chitosan and naringin at 1.5 or 3.0 g/kg dry matter intake or the combination of both compounds (1.5 and 1.5 g/kg) given directly into the rumen did not induce changes in rumen fermentation, methane production, or nutrient utilization. However, given the promising evidence from other studies, more research needs to be conducted to clarify the potential effects of chitosan and naringin in animal production.

Abstract

In order to meet consumer needs, the livestock industry is increasingly seeking natural feed additives with the ability to improve the efficiency of nutrient utilization, alternatives to antibiotics, and mitigate methane emissions in ruminants. Chitosan (CHI) is a polysaccharide with antimicrobial capability against protozoa and Gram-positive and -negative bacteria, fungi, and yeasts while naringin (NA) is a flavonoid with antimicrobial and antioxidant properties. First, an in vitro gas production experiment was performed adding 0, 1.5, 3.0 g/kg of CHI and NA under a completely randomized design. The substrate containing forage and concentrate in a 70:30 ratio on a dry matter (DM) basis. Compounds increased the concentration of propionic acid, and a significant reduction in methane production was observed with the inclusion of CHI at 1.5 g/kg in in vitro experiments (p < 0.001). In a dry matter rumen degradability study for 96 h, there were no differences in potential and effective degradability. In the in vivo study, six crossbred heifers fitted with rumen cannulas were assigned to a 6 × 6 Latin square design according to the following treatments: control (CTL), no additive; chitosan (CHI1, 1.5 g/kg DMI); (CHI2, 3.0 g/kg DMI); naringin (NA1, 1.5 g/kg DMI); (NA2, 3.0 g/kg DMI) and a mixture of CHI and NA (1.5 + 1.5 g/kg DMI) given directly through the rumen cannula. Additives did not affect rumen fermentation (p > 0.05), DM intake and digestibility of (p > 0.05), and enteric methane emissions (p > 0.05). CHI at a concentration of 1.5 g/kg DM in in vitro experiments had a positive effect on fermentation pattern increasing propionate and reduced methane production. In contrast, in the in vivo studies, there was not a positive effect on rumen fermentation, nor in enteric methane production in crossbred heifers fed a basal ration of tropical grass.

Development of an on-farm model to predict flow of fecal volatile solids to the liquid and solid handling systems of commercial California dairy farms

A source of methane (CH₄) emissions from dairy farms arefecal volatile solids (VS) produced by cattle, which is impacted by herd size, cattle type, feed intake/composition and farm management practices. Where cattle deposit fecal VS in their pen is important in this regard since that deposited on concrete, which will be handled and stored in a liquid form, is a likely source of CH₄ emissions, whereas fecal VS deposited on drylot surfaces will be handled and stored in a dry form and is a minor source of CH₄ emissions. Our objective was to create a model to assist dairy farmers and regulators make informed evaluations of impacts of dairy farm management practices on potential CH₄ emissions from fecal VS. Evaluation of initial model outputs led to on-farm data collection of the model inputs which influenced predicted fecal VS entering the liquid and solid manure handling systems. A key input limitation was lack of information on cattle fecal deposition locations within pens. Data collection used four dairy farms to measure time that cattle spent on concrete surfaces within day among season, as well as other model inputs. The final model, populated with collected data, showed that lactating cattle contribute the overwhelming proportion of fecal VS, 77% in the composite dairy farms, and that a composite freestall dairy farm had 65% of total fecal VS deposited on concrete annually with the remainder on drylot surfaces. In contrast, a composite drylot dairy farm had 37% of fecal VS deposited on concrete annually.

Comparison of five methods for the estimation of methane production from vented in vitro systems

BACKGROUND

There are several methods for estimating methane production (MP) from feedstuffs in vented in vitro systems. One method (A; 'gold standard') measures methane proportions in the incubation bottle's headspace (HS) and in the vented gas collected in gas bags. Four other methods (B, C, D and E) measure methane proportion in a single gas sample from the HS. Method B assumes the same methane proportion in the vented gas as in the HS, method C assumes constant methane to carbon dioxide ratio, method D has been developed based on empirical data, and method E assumes constant individual venting volumes. This study aimed to compare the MP predictions from these methods to that of the gold standard method under different incubation scenarios, to validate these methods based on their concordance with a gold-standard method.

RESULTS

Methods C, D and E had greater concordance (0.85, 0.88 and 0.81), lower root-mean-square error (RMSE; 0.80, 0.72 and 0.85) and lower mean bias (0.20, 0.35, -0.35) with the gold standard than did method B (concordance 0.67, RMSE 1.49 and mean bias 1.26). Methods D and E were simpler to perform than method C, and method D was slightly more accurate than method E.

CONCLUSION

Based on precision, accuracy and simplicity of implementation, it is recommended that, when method A cannot be used, methods D and E are preferred to estimate MP from vented in vitro systems. © 2018 Society of Chemical Industry.

Effects of chitosan and whole raw soybeans on ruminal fermentation and bacterial populations, and milk fatty acid profile in dairy cows

The objective of this study was to evaluate whether providing chitosan (CHI) to cows fed diets supplemented with whole raw soybeans (WRS) would affect the nutrient intake and digestibility, ruminal fermentation and bacterial populations, microbial protein synthesis, N utilization, blood metabolites, and milk yield and composition of dairy cows. Twenty-four multiparous Holstein cows (141 ± 37.1 d in milk, 38.8 ± 6.42 kg/d of milk yield; mean ± SD) were enrolled to a 4 × 4 Latin square design experiment with 23-d periods. Cows were blocked within Latin squares according to milk yield, days in milk, body weight, and rumen cannula (n = 8). A 2 × 2 factorial treatment arrangement was randomly assigned to cows within blocks. Treatments were composed of diets with 2 inclusion rates of WRS (0 or 14% diet dry matter) and 2 doses of CHI (0 or 4 g/kg of dry matter, Polymar Ciência e Nutrição, Fortaleza, Brazil). In general, CHI+WRS negatively affected nutrient intake and digestibility of cows, decreasing milk yield and solids production. The CHI increased ruminal pH and decreased acetate to propionate ratio, and WRS reduced NH3-N concentration and acetate to propionate in the rumen. The CHI reduced the relative bacterial population of Butyrivibrio group, whereas WRS decreased the relative bacterial population of Butyrivibrio group, and Fibrobacter succinogenes, and increased the relative bacterial population of Streptococcus bovis. No interaction effects between CHI and WRS were observed on ruminal fermentation and bacterial populations. The CHI+WRS decreased N intake, microbial N synthesis, and N secreted in milk of cows. The WRS increased N excreted in feces and consequently decreased the N excreted in urine. The CHI had no effects on blood metabolites, but WRS decreased blood concentrations of glucose and increased blood cholesterol concentration. The CHI and WRS improved efficiency of milk yield of cows in terms of fat-corrected milk, energy-corrected milk, and net energy of lactation. The CHI increased milk concentration [g/100 g of fatty acids (FA)] of 18:1 trans-11, 18:2 cis-9,cis-12, 18:3 cis-9,cis-12,cis-15, 18:1 cis-9,trans-11, total monounsaturated FA, and total polyunsaturated FA. The WRS increased total monounsaturated FA, polyunsaturated FA, and 18:0 to unsaturated FA ratio in milk of cows. Evidence indicates that supplementing diets with unsaturated fat sources along with CHI negatively affects nutrient intake and digestibility of cows, resulting in less milk production. Diet supplementation with CHI or WRS can improve feed efficiency and increases unsaturated FA concentration in milk of dairy cows.

Nutrient composition and in vitro methane production of sub-tropical grass species in transitional rangeland of South Africa

The development of greenhouse gas mitigation strategies has become an important issue globally. Enteric methane (CH4) emissions from livestock do not only contribute substantially to the environmental footprint of livestock production but it also represents a loss of energy that could be channelled towards animal growth and production. In this study 14 sub-tropical grass species typical of transitional rangeland regions of South Africa were characterised in terms of ecological status, chemical composition, in vitro total gas and CH4 production. The aim of the study was 2-fold: to identify grass species that could be selected for low enteric CH4 production; evaluate the influence of rangeland ecological status on the methanogenic potential of a rangeland. Grass samples were collected by hand, air-dried, milled and analysed for nutrient composition, in vitro organic matter digestibility (IVOMD) and in vitro gas and CH4 production. Cenchrus ciliaris and Urelytrum agropyriodes produced the highest 48-h in vitro CH4 of 17.49 and 14.05 mL/g DM digested respectively. The lowest 48-h in vitro CH4 was produced by Andropogan gayanus and Bothriochloa bladhii with 5.98 and 6.08 mL/g DM digested respectively. The evaluated grass species were overall of poor quality with low CP concentrations ranging from 2.4% for Trachypogon spicatus to 6.7% for Digitaria eriantha and IVOMD ranging from 22.5% for Andropogon gayanus to 42.2% for Urelytrum agropyriodes. Decreaser grass species presented with higher in vitro CH4 production compared with Increaser I and Increaser II grass species in the present study. The results of the study emphasise the importance of including the nutritional potential of grass species for improved livestock production when evaluating grass species for possible greenhouse gas mitigation strategies.

In vitro evaluation of the methane mitigation potential of a range of grape marc products

Grape marc consists of the skins, seeds and stems remaining after grapes have been pressed to make wine. Interest in grape marc for use as a dietary feed additive for ruminants has grown after recent research showed that inclusion of grape marc in the diet of dairy cows reduced their enteric methane (CH4) emissions. In the present research, in vitro fermentations were conducted on 20 diverse grape marcs to evaluate their potential as ruminant feed supplements and, in particular, mitigants of enteric CH4 emissions. The grape marcs, which were sourced from vineyards in south-eastern Australia, contained a range of red and white grape varieties with different proportions of skins, seeds and stalks, and had diverse chemical compositions. For each grape marc, four replicate samples, each of 1 g DM, were incubated in vitro with ruminal fluid. The volumes of total gas and CH4 produced after 48 h of incubation were determined. Total gas production ranged from 21.8 to 146.9 mL and CH4 production from 6.8 to 30.3 mL. White grape marcs produced more (P < 0.05) total gas (81.8 mL) than did red grape marcs (61.0 mL), but had a lower (P < 0.05) percentage of CH4 (25.3% and 30.3% of total gas). Grape marcs with a higher proportion of seeds produced less (P < 0.05) total gas than did the types composed of either skin or stalks; however, the seed types produced the greatest (P < 0.05) percentage of CH4 (49.8% of total gas). It is concluded that grape marcs differ greatly in their potential as mitigants of enteric CH4 emissions for ruminal production systems.

Influence of main dietary chemical constituents on the in vitro gas and methane production in diets for dairy cows

BACKGROUND

Modification of chemical composition of diets fed to dairy cows might be a good strategy to reduce methane (CH4) production in the rumen. Notable reductions of CH4 production compared to conventional high-roughages rations were more frequently observed for very concentrated diets or when fat supplements were used. In these cases, the reduction in the gas emission was mainly a consequence of an overall impairment of rumen function with a reduction of fiber digestibility. These strategies do not always comply with feeding standards used in intensive dairy farms and they are usually not applied owing to the risks of negative health and economic consequences. Thus, the present study evaluated the effects of seven commercial diets with contents of neutral detergent fiber (NDF), protein and lipids ranging 325 to 435 g/kg DM, 115 to 194 g/kg DM, and 26 to 61 g/kg DM, respectively, on in vitro degradability, gas (GP), and CH4 production.

RESULTS

In this experiment, changes in the dietary content of NDF, crude protein (CP) and lipids were always obtained at the expense or in favor of starch. A decreased of the dietary NDF content increased NDF (NDFd) and true DM (TDMd) degradability, and increased CH4 production per g of incubated DM (P < 0.001), but not that per g of TDMd. An increase of the dietary CP level did not change in vitro NDFd and TDMd, decreased GP per g of incubated DM (P < 0.001), but CH4 production per g of TDMd was not affected. An increased dietary lipid content reduced NDFd, TDMd, and GP per g of incubated DM, but it had no consequence on CH4 production per g of TDMd.

CONCLUSIONS

It was concluded that, under commercial conditions, changes in dietary composition would produce small or negligible alterations of CH4 production per unit of TDMd, but greater differences in GP and CH4 production would be expected when these amounts are expressed per unit of DM intake. The use of TDMd as a standardizing parameter is proposed to account for possible difference in DM intake and productivity.

Methodological factors affecting gas and methane production during in vitro rumen fermentation evaluated by meta-analysis approach

Effects of some methodological factors on in vitro measures of gas production (GP, mL/g DM), CH₄ production (mL/g DM) and proportion (% CH₄ on total GP) were investigated by meta-analysis. These factors were considered: pressure in the GP equipment (0 = constant; 1 = increasing), incubation time (0 = 24; 1 = ≥ 48 h), time of rumen fluid collection (0 = before feeding; 1 = after feeding of donor animals), donor species of rumen fluid (0 = sheep; 1 = bovine), presence of N in the buffer solution (0 = presence; 1 = absence), and ratio between amount of buffered rumen fluid and feed sample (BRF/FS; 0 = ≤ 130 mL/g DM; 1 = 130–140 mL/g DM; 2 = ≥ 140 mL/g DM). The NDF content of feed sample incubated (NDF) was considered as a continuous variable. From an initial database of 105 papers, 58 were discarded because one of the above-mentioned factors was not stated. After discarding 17 papers, the final dataset comprised 30 papers (339 observations). A preliminary mixed model analysis was carried out on experimental data considering the study as random factor. Variables adjusted for study effect were analyzed using a backward stepwise analysis including the above-mentioned variables. The analysis showed that the extension of incubation time and reduction of NDF increased GP and CH₄ values. Values of GP and CH₄ also increased when rumen fluid was collected after feeding compared to before feeding (+26.4 and +9.0 mL/g DM, for GP and CH₄), from bovine compared to sheep (+32.8 and +5.2 mL/g DM, for GP and CH₄), and when the buffer solution did not contain N (+24.7 and +6.7 mL/g DM for GP and CH₄). The increase of BRF/FS ratio enhanced GP and CH₄ production (+7.7 and +3.3 mL/g DM per each class of increase, respectively). In vitro techniques for measuring GP and CH₄ production are mostly used as screening methods, thus a full standardization of such techniques is not feasible. However, a greater harmonization of analytical procedures (i.e., a reduction in the number of available protocols) would be useful to facilitate comparison between results of different experiments.

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates

BACKGROUND

In vitro techniques are used to predict ruminant feedstuff values or characterise rumen fermentation. As the results are influenced by several factors, such as the relative effects of inocula and substrates, this study aimed to examine in vitro incubation of two total mixed rations (substrates) differing in their proportion of concentrate [low (L): 350 g kg(-1) vs. high (H): 700 g kg(-1)] incubated in inocula provided by goats fed either a L or a H diet. Gas production and composition in carbon dioxide (CO2), methane (CH4 ) and hydrogen (H2), volatile fatty acids (VFAs), soluble carbohydrates (SCs) and ammonia (NH3) concentrations, and pH of the fermentation fluid were measured.

RESULTS

In comparison with the L inoculum and L substrate, the H ones produced more CO2 and CH4 gas, which led to higher SCs and VFA concentrations, and lower acetate-to-propionate ratio and NH3 concentration, with a predominant effect of the inoculum.

CONCLUSION

The effects of the inocula and of the substrates were additive using donor animals adapted to the diets.

Mathematical formulae for accurate estimation of in vitro CH4 production from vented bottles

A widely used method for the in vitro measurement of fermentation parameters, total gas and methane (CH4) production (mL/g) from feed samples employs AnkomRF Technology with vented bottles, initially flushed with carbon dioxide (CO2). The volumes of gas accumulated between ventings, and the volumes vented, are calculated from the headspace pressure data. By using these data, it is possible to infer mathematically the quantity of CH4 produced, given just a single measurement of the CH4 mixing ratio measured in the headspace at the termination of fermentation. However, this calculation requires an additional assumption. Two possibilities for this are considered. We present mathematical formulae arising from each, and describe their sensitivity to violations of their respective assumptions. Also considered is a formula based on using N2 instead of CO2 as the flushing gas. It appears that, in practice, all three formulae are suitable for estimating CH4 production, with errors less than 3%.

Technical note: In vitro total gas and methane production measurements from closed or vented rumen batch culture systems

This study compared measured gas production (GP) and computed CH4 production values provided by closed or vented bottles connected to gas collection bags. Two forages and 3 concentrates were incubated. Two incubations were conducted, where the 5 feeds were tested in 3 replicates in closed or vented bottles, plus 4 blanks, for a total of 64 bottles. Half of the bottles were not vented, and the others were vented at a fixed pressure (6.8 kPa) and gas was collected into one gas collection bag connected to each bottle. Each bottle (317 mL) was filled with 0.4000 ± 0.0010 g of feed sample and 60 mL of buffered rumen fluid (headspace volume = 257 mL) and incubated at 39.0°C for 24 h. At 24 h, gas samples were collected from the headspace of closed bottles or from headspace and bags of vented bottles and analyzed for CH4 concentration. Volumes of GP at 24 h were corrected for the gas dissolved in the fermentation fluid, according to Henry's law of gas solubility. Methane concentration (mL/100mL of GP) was measured and CH4 production (mL/g of incubated DM) was computed using corrected or uncorrected GP values. Data were analyzed for the effect of venting technique (T), feed (F), interaction between venting technique and feed (T × F), and incubation run as a random factor. Closed bottles provided lower uncorrected GP (-18%) compared with vented bottles, especially for concentrates. Correction for dissolved gas reduced but did not remove differences between techniques, and closed bottles (+25 mL of gas/g of incubated DM) had a greater magnitude of variation than did vented bottles (+1 mL of gas/g of incubated DM). Feeds differed in uncorrected and corrected GP, but the ranking was the same for the 2 techniques. The T × F interaction influenced uncorrected GP values, but this effect disappeared after correction. Closed bottles provided uncorrected CH4 concentrations 23% greater than that of vented bottles. Correction reduced but did not remove this difference. Methane concentration was influenced by feed but not by the T × F interaction. Corrected CH4 production was influenced by feed, but not by venting technique or the T × F interaction. Closed bottles provide good measurements of CH4 production but not of GP. Venting of bottles at low pressure permits a reliable evaluation of total GP and CH4 production.

Effects of a commercial blend of essential oils and monensin in a high-grain diet containing wheat distillers’ grains on in vitro fermentation

Li, Y. L., Li, C., Beauchemin, K. A. and Yang, W. Z. 2013. Effects of a commercial blend of essential oils and monensin in a high-grain diet containing wheat distillers’ grains on in vitro fermentation. Can. J. Anim. Sci. 93: 387–398. Our objective was to evaluate in vitro effects of a commercial blend of essential oils (BEO) versus monensin (MON) on fermentation of a high-grain diet containing wheat distillers’ dried grains with solubles (DDGS). Two experiments were conducted. The first experiment was designed as a short-term batch culture to determine the optimum dose of BEO (0, 45, 90 or 180 mg kg−1DM) on fermentation variables. The second experiment was a completely randomized block design with a 2×2 factorial arrangement of treatments using the rumen simulation technique. A high-grain dietary substrate containing wheat DDGS was supplemented with 0 or 28 mg MON kg−1DM combined with 0 and 90 mg BEO kg−1DM. Monensin did not affect the total volatile fatty acid (VFA) concentration or the molar proportions of individual VFA, but reduced CH4production (mL L−1gas; P=0.01) and disappearance of DM (P=0.04). Supplementation of BEO did not affect VFA concentration, but decreased (P=0.01) the molar proportion of acetate and reduced (P=0.02) the acetate to propionate concentration ratio and CH4production (mL g−1digested organic matter). The BEO increased (P=0.01) disappearance of neutral detergent fiber without affecting disappearance of other nutrients. These results indicate that supplementation of high-grain dietary substrate containing wheat DDGS with BEO improved fermentation pattern by increasing propionate concentration, reducing CH4production, and increasing fiber digestibility. This commercial BEO could be a potential substitute for MON for beef cattle fed high-grain diets containing DDGS.

Metabolisable Energy, In situ Rumen Degradation and In vitro Fermentation Characteristics of Linted Cottonseed Hulls, Delinted Cottonseed Hulls and Cottonseed Linter Residue

Dietary supplementation with conventional linted cottonseed hulls (LCSH) is a common practice in livestock production all over the world. However, supplementation with mechanically delinted cottonseed hulls (DCSH) and cottonseed linter residue (CLR) is uncommon. Cottonseed by-products, including LCSH, DCSH and CLR, were assessed by chemical analysis, an in situ nylon bag technique, an in vitro cumulative gas production technique and in vitro enzyme procedure. The crude protein (CP) content of CLR (302 g/kg dry matter (DM)) was approximately 3 times that of LCSH and 5 times that of DCSH. The crude fat content was approximately 3 times higher in CLR (269 g/kg DM) than in LCSH and 4 times higher than in DCSH. Neutral detergent fibre (311 g/kg DM) and acid detergent fibre (243 g/kg DM) contents of CLR were less than half those of DCSH or LCSH. Metabolisable energy, estimated by in vitro gas production and chemical analyses, ranked as follows: CLR (12.69 kJ/kg DM)>LCSH (7.32 kJ/kg DM)>DCSH (5.82 kJ/kg DM). The in situ degradation trial showed that the highest values of effective degradability of DM and CP were obtained for CLR (p<0.05). The in vitro disappearance of ruminal DM ranked as follows: CLR>LCSH>DCSH (p<0.05). The lowest digestibility was observed for DCSH with a two-step in vitro digestion procedure (p<0.05). The potential gas production in the batch cultures did not differ for any of the three cottonseed by-product feeds. The highest concentration of total volatile fatty acids was observed in CLR after a 72 h incubation (p<0.05). The molar portions of methane were similar between all three treatments, with an average gas production of 22% (molar). The CLR contained a higher level of CP than did LCSH and DCSH, and CLR fermentation produced more propionate. The DCSH and LCSH had more NDF and ADF, which fermented into greater amounts of acetate.

In vitro evaluation, in vivo quantification, and microbial diversity studies of nutritional strategies for reducing enteric methane production

The main objective of the present work was to study nutritive strategies for lessening the CH(4) formation associated to ruminant tropical diets. In vitro gas production technique was used for evaluating the effect of tannin-rich plants, essential oils, and biodiesel co-products on CH(4) formation in three individual studies and a small chamber system to measure CH(4) released by sheep for in vivo studies was developed. Microbial rumen population diversity from in vitro assays was studied using qPCR. In vitro studies with tanniniferous plants, herbal plant essential oils derived from thyme, fennel, ginger, black seed, and Eucalyptus oil (EuO) added to the basal diet and cakes of oleaginous plants (cotton, palm, castor plant, turnip, and lupine), which were included in the basal diet to replace soybean meal, presented significant differences regarding fermentation gas production and CH(4) formation. In vivo assays were performed according to the results of the in vitro assays. Mimosa caesalpineaefolia, when supplemented to a basal diet (Tifton-85 hay Cynodon sp, corn grain, soybean meal, cotton seed meal, and mineral mixture) fed to adult Santa Ines sheep reduced enteric CH(4) emission but the supplementation of the basal diet with EuO did not affect (P > 0.05) methane released. Regarding the microbial studies of rumen population diversity using qPCR with DNA samples collected from the in vitro trials, the results showed shifts in microbial communities of the tannin-rich plants in relation to control plant. This research demonstrated that tannin-rich M. caesepineapholia, essential oil from eucalyptus, and biodiesel co-products either in vitro or in vivo assays showed potential to mitigate CH(4) emission in ruminants. The microbial community study suggested that the reduction in CH(4) production may be attributed to a decrease in fermentable substrate rather than to a direct effect on methanogenesis.

Recovery of struvite from animal wastewater and its nutrient leaching loss in soil

Contaminants in swine wastewater were recovered in the form of struvite, a crystal of magnesium ammonium phosphate (MAP), using a newly designed process, and the leaching loss of MAP in soil was examined. The continuous flow process was operated under optimal conditions: 1.0 molar ratio of magnesium (Mg) addition with respect to orthophosphate (OP) and an aeration rate of 0.73 L/L min. Five treatments were performed with three replications for soil pH and nutrient leaching loss tests. It was found that 93% of the OP in the swine wastewater was crystallized, and the MAP crystal formation was verified by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The analyses revealed that the pattern of pH change and N leaching losses for MAP-treated soil were remarkably different from those for fused super phosphate (FSP)-urea-treated soils. The pH levels for the control and FSP-urea-treated soils after a five-week experiment were unchanged or slightly decreased, whereas an increase in pH was observed in the MAP-treated soils. Leaching loss of N was higher in FSP-urea treatments, with MAP treatments showing N losses of only 1.93 and 2.05%, respectively, while FSP-urea treatments showed N losses of 7.82 and 6.47%, respectively, during the same period. Phosphate (P) leaching was very slow in both MAP- and FSP-treated groups.

An evaluation of the methane output associated with high-moisture grains and silages using the in vitro total gas production technique

This study aimed to quantify the methane and total gas emissions associated with a range of ensiled feeds using the in vitro total gas production (TGP) technique. This suite of feeds included cereal grains (wheat, barley and triticale) and maize, whole-crop wheat and grass silages. The methane and total gas output of these feeds was then regressed on chemical composition to assess the relationship between these variables. Subsequently, the efficacy of the TGP technique was also discussed. From this analysis it was observed that 96% of the variation in methane output per unit of feed incubated was explained by variations in in vitro organic matter digestibility (IVOMD), neutral detergent fibre (NDF) and ash. Of these variables, the greatest single response was with NDF, which was negatively related to methane output. When expressed per unit of feed digested, 78% of the variation was explained by IVOMD, NDF and starch. The methane responses observed in this study contradicted expected in vivo trends in methane output, thus calling into question the reliability of the in vitro technique to accurately determine methane output of feeds differing this widely in NDF and starch contents.

Evaluation of tropical plants containing tannin on in vitro methanogenesis and fermentation parameters using rumen fluid

BACKGROUND

Methane (CH(4)) produced during ruminal fermentation represents a loss of 10-11% of gross energy intake. The use of browse species containing tannin as feed supplement for ruminants tends to increase in order to reduce CH(4) production. The present study was conducted to evaluate some tropical plants containing tannin as feed supplement (200 g kg(-1)) on in vitro CH(4) production and fermentation parameters.

RESULTS

The crude protein (CP) content ranged from 87 to 390 g kg(-1) dry matter (DM) and was highest in Sesbania grandiflora (L.) Poiret. The neutral detergent fibre (NDF) concentration was highest in Pennisetum purpureum Schumach (725 g kg(-1) DM) and lowest in S. grandiflora (330 g kg(-1) DM). The ranking order of plants based on their total tannin content was Acacia mangium Willd. > Biophytum petersianum Klotzch > Jatropa curcas Linnaeus > Psidium guajava Linnaeus > Phaleria papuana > Persea americana Mill. > S. grandiflora. Methane gas production after 48 h of incubation was significantly (P < 0.05) lower with inclusion of A. mangium (PP + AM), B. petersianum (PP + BP), J. curcas (PP + JC) or P. guajava (PP + PG) as compared to control feed (PP). There was negative correlation between total tannin content and CH(4) production at 48 h of incubation (r = - 0.76). Concentration NH(3)-N was significantly (P < 0.01) higher with inclusion of S. glandiflora. Inclusion of P. guajava significantly (P < 0.05) suppressed protozoa population by 49.7% relative to control feed (PP).

CONCLUSION

It was concluded that A. mangium, B. petersianum, J. curcas and P. guajava have potential to be used as a feed supplement to reduce CH(4) production in ruminants.