Lucerne (Medicago sativa L.), grass and whole-crop maize silages were offered to lactating dairy cows in various combinations and feed intake, milk yield and milk composition were determined. Cows were fed total mixed rations (TMR) with an average forage to concentrate ratio of 55:45 (dry matter (DM) basis). The forage component of the control (CON) ration was a 50:50 mixture of grass and maize silages (DM basis). The forage component of the three lucerne-based diets comprised (DM basis) either lucerne and grass silage (50:50), lucerne and maize silage (50:50) or equal proportions of the three silage types. The TMR were formulated to have the same protein content, expressed as utilisable crude protein at the duodenum (uCP) but rations differed with regard to energy, fibre and starch concentrations and physically effective neutral detergent fibre (NDF). In a digestibility study in sheep, lucerne silage was found to be less digestible in terms of organic matter, crude lipid and gross energy than grass or maize silages; the fibre fractions were also less digestible than those of grass silage. A seven-phase feeding trial was conducted with a herd of 60 lactating cows. The whole herd received each diet ad libitum for six weeks; data were collected over the last four weeks and then the diet was changed. The CON diet was fed during phases 1, 3, 5 and 7. Daily DM intake (DMI) ranged from 20.8 kg to 22.3 kg and was greater (P < 0.05) when cows were fed the lucerne silage diets. Cows were only able to compensate for the lower energy density of the lucerne diets when they were fed the combination of maize and lucerne silages; the greater DMI of the maize and lucerne diets relative to the CON diet allowed them to achieve the same net energy intake per day. The average energy-corrected milk yield ranged from 31.7 and 33.6 kg/day across treatments. Including lucerne silage in the TMR reduced milk yield, milk protein concentration and milk protein yield. Only the combination of lucerne and grass silage increased milk fat content relative to the CON diet (4.31 vs. 3.89%). In this study lucerne silage did not improve dairy cow performance although there was an improvement in DMI; this indicates that the maturity of lucerne at harvest is critical to the nutritional value of lucerne silage and its potential contribution to improving the protein and fibre supplied to dairy cows.

A feeding trial was conducted to determine the response by dairy cows to total mixed rations (TMR) in which distillers dried grains with solubles (DDGS, Protigrain (R)) replaced solvent-extracted rapeseed meal (RSM). A third TMR contained DDGS and was supplemented with the rumen-protected amino acids (AA) lysine and methionine. Fifty eight lactating dairy cows were assigned to a 3 x 3 Latin square design experiment over six-week periods. Rations were formulated such that DDGS (> 4 kg dry matter [DM]/day) was 100% of the supplemental crude protein (CP) replacing the CP from RSM. All rations averaging (DM basis) 17.9% CP and 17.9% utilisable CP at the duodenum consisted of (DM basis) 62% forage and 38% concentrate. The aim of the study was to investigate how cows would respond when fed with DDGS as the sole supplemental protein source in the diet. Dry matter intake was lower in the DDGS group (p < 0.05). Milk production was similar for cows on the three rations. Milk fat content and milk fat yield were also the same in all rations. Milk protein content (p < 0.01) and milk protein yield (p < 0.05) was lower in the DDGS and the DDGS + AA groups in contrast to the RSM group. If data of cows were separated according to 'high' or 'low' milk yield, higher DM intake was observed in the RSM and the DDGS + AS groups compared with the DDGS group (p < 0.01). Based on economic and nutritional considerations, the supplementation of rumen-protected AA (lysine and methionine) should be further evaluated in rations for high-yielding dairy cows in early lactation.

Daniellia Oliveri was examined as a potential fodder for small ruminant, using nine castrated and ruminally fistulated West African Dwarf sheep (29 kg BW) to determine rumen ammonia and nutrient digestibility. Dried leaves of Daniellia oliveri were offered at two levels (25% and 50% of DMI) as supplement to a basal hay diet. A digestibility trial of 8 days was conducted after 10 days of adaptation period. Rumen liquor was sampled one hour before, and one, three and five hours after the morning feeding for three consecutive days. Diet D50% showed a higher (P<0.05) pH than both the control and D25% diets, respectively. Diet D25% had an inferior (P<0.05) pH than the controls. The ruminal ammonia concentration of D25% was superior (P<0.05) to D50% and the controls, respectively. Similarly, diet D50% had a superior (P<0.05) ruminal ammonia concentration than the controls. There were significant increases (P<0.05) in the OM, CP, NDF, ADF, ADL and cellulose intake of D50% diet compared with the controls. Similarly, inclusion level of 50% Daniellia oliveri resulted in a reduction (P<0.05) in digestibility of DMI, OM, NDF, ADF and ADL, in comparison to sheep fed the control diet. Cellulose and hemi-cellulose digestibility of diet D50% was superior (P<0.05) to that of the controls. It would appear that condensed tannins had inhibitory effect on organic matter and detergent fibre digestibility. It was concluded that Daniellia oliveri with a high CP and GE (165 g/kg and 20.3 kJ/g DM) respectively, could serve as a fodder tree for small ruminant in spite of its relatively high content of condensed tannin (48 g/kg DM). An inclusion range of 25 to 50% was recommended during period of scarcity.

The main objective of this study was to evaluate the variability in in situ CP degradation characteristics of 15 batches lupin grains from nine genotypes in a standardised approach. This study also investigated whether differences in CP degradation can be described by protein fractionation using the Cornell Net Carbohydrate and Protein System (CNCPS) and also whether thermal processing of lupins has an effect on CP degradation in the rumen and analysed protein fractions. The rising political and consumer demand for milk products from dairy production systems based on domestic protein sources and the wide range of lupin types and varieties that can be chosen as protein feed in dairy nutrition requires research to determine the variability in CP degradation characteristics in the rumen. For CP degradation measurements, ground grains were incubated in the rumen of three lactating Jersey cows fitted with a ruminal cannula for different times from 2 to 48 h, and the washing loss of non-incubated samples was also measured. Protein fractions were analysed according to CNCPS and used for the estimation of ruminally degraded protein. In situ CP degradation parameters varied widely between untreated samples. The mean value for the washout fraction was 29.3% (from 16.4% to 43.6%). The potentially degradable fraction averaged 70.5% (from 55.6% to 83.7%), hence maximal degradation of CP was close to completeness. Mean degradation rate was 16.6%/h (from 12.6 to 21.0%/h). Variation in estimated parameters led to variation in the effective degradation (ED) averaging 76.6% (from 67.3% to 83.0%) when calculated assuming a ruminal outflow of 8%/h. Thermal treatment of lupins induced changes in degradation characteristics, primarily by lowering degradation rates, and also led to a significant reduction in ED. The ED calculated from analysed protein fractions averaged 10 percentage points higher than ED calculated from in situ parameters for untreated grains. The ED based on protein fractionation was also reduced by heat treatment, but the correlation with in situ based ED was poor. It can be concluded that the variation in ED indicates a potential to increase the amount of rumen undegraded protein without additional chemical or physical treatment and the effect of genetic factors and agronomic practices on ED of lupin grains should be investigated in systematic studies in the future.

A screening study was conducted to investigate the nutrient composition, anti-nutritional factors, in vitro gas (GP) and methane (CH 4 ) production of leaves and whole pods in tropical multipurpose trees (MPTs). The results indicated that the highest CP (296 g/kg DM) was found in Moringa stenopetala leaves followed by Acacia abysinica (277 g/kg DM), Millettia ferruginea (264 g/kg DM), Prosopis juliflora (261 g/kg DM) and Moringa oleifera (256 g/kg DM). In whole pods, the CP ranged from 172 in M. ferruginea to 191 g/kg DM in M. stenopetala . The starch in M. stenopetala , P. juliflora and Chamaecytisus palmensis leaves was 44.2, 28.8 and 24.4 g/kg DM, respectively. Leaves of Cajanus cajan had the highest concentrations of valine, isoleucine, leucine, phenylalanine, lysine and threonine. The highest concentration of total and tannin phenols were observed in leaves of A. nilotica while P. juliflora leaves had the lowest. Leaves of M. oleifera had higher total phenols and soluble condensed tannins than those of M. stenopetala . The in vitro GP were (P < 0.05) higher in leaves of Moringa species, Sesbania sesban , C. palmensis and Leucaena leucocephala than other MPTs. The CH 4 production in A. nilotica , P. juliflora and C. cajan leaves was 1.05, −1.16 and 1.79 ml/200 mg DM, respectively and were lower (P < 0.05) than other MPTs. The lowest CH 4 was observed in M. ferruginea pods (2.64 ml/200 mg DM) being (P < 0.05) different from other species. In conclusion, leaves of A. nilotica , P. juliflora , C. cajan and pods of M. ferruginea were identified as potential candidates in mitigating CH 4 production and might be used as feed additives or supplementary feed for grazing ruminants.

Ruminal in situ incubations are widely used to assess the nutritional value of feedstuffs for ruminants. In in situ methods, feed samples are ruminally incubated in indigestible bags over a predefined timespan and the disappearance of nutrients from the bags is recorded. To describe the degradation of specific nutrients, information on the concentration of feed samples and undegraded feed after in situ incubation ('bag residues') is needed. For cereal and pea grains, CP and starch (ST) analyses are of interest. The numerous analyses of residues following ruminal incubation contribute greatly to the substantial investments in labour and money, and faster methods would be beneficial. Therefore, calibrations were developed to estimate CP and ST concentrations in grains and bag residues following in situ incubations by using their near-infrared spectra recorded from 680 to 2500 nm. The samples comprised rye, triticale, barley, wheat, and maize grains (20 genotypes each), and 15 durum wheat and 13 pea grains. In addition, residues after ruminal incubation were included (at least from four samples per species for various incubation times). To establish CP and ST calibrations, 620 and 610 samples (grains and bag residues after incubation, respectively) were chemically analysed for their CP and ST concentration. Calibrations using wavelengths from 1250 to 2450 nm and the first derivative of the spectra produced the best results (R 2 Validation=0.99 for CP and ST; standard error of prediction=0.47 and 2.10% DM for CP and ST, respectively). Hence, CP and ST concentration in cereal grains and peas and their bag residues could be predicted with high precision by NIRS for use in in situ studies. No differences were found between the effective ruminal degradation calculated from NIRS estimations and those calculated from chemical analyses (P>0.70). Calibrations were also calculated to predict ruminal degradation kinetics of cereal grains from the spectra of ground grains. Estimation of the effective ruminal degradation of CP and ST from the near-infrared spectra of cereal grains showed promising results (R 2>0.90), but the database needs to be extended to obtain more stable calibrations for routine use.

The current study was conducted to evaluate the component composition, anti-nutritional factors, in vitro gas production (GP) and methane (CH4) production profiles of fruit by-products (pineapple pulp, mango seed kernels, banana and papaya peel, Moringa stenopetala and Moringa oleifera seeds) and leaves of root crops (sweet potato [Ipomoea batatas], cassava [Manihot esculenta], yam [Dioscorea abyssinica], enset [Ensete ventricosum] and samma [Urtica simensis]). Root crop leaves had high crude protein (CP) ranging from 211 to 318 g/kg dry matter (DM) in yam and samma, respectively. M. stenopetala seeds contained the highest CP (450 g/kg DM). Samma leaves were rich in calcium (58.6 g/kg DM) and iron (1186 mg/kg DM). Leaves of root crops had similar concentrations of essential amino acids with appreciable values. Total phenols were highest in mango seed kernels (158 g/kg DM). The asymptotic GP at 96 h incubation of pineapple pulp, papaya and banana peel was 397, 358 and 279 ml/g DM, respectively, and differed significantly from each other. Sweet potato and yam leaves produced 238 and 225 ml/g DM GP, respectively, being significantly higher than those of other root crops. CH4 production was significantly lowest in Moringa seeds, mango seed kernels and sweet potato leaves. In conclusion, fruit by-products have the potential as energy sources and root crop leaves as protein supplements for ruminant and non-ruminant animals. Moringa seeds, mango seed kernels and sweet potato leaves were identified as potential candidates in mitigating CH4 emissions in tropical livestock with animal-based experiments recommended to validate the in vitro findings.

In recent years, advances in plant breeding were achieved, which potentially led to modified nutritional values of cereal grains. The present study was conducted in order to obtain a broad overview of ruminal digestion kinetics of rye, triticale and barley grains, and to highlight differences between the grain species. In total, 20 genotypes of each grain species were investigated using in situ and in vitro methods. Samples were ground (2 mm), weighed into polyester bags, and incubated in situ 1 to 48 h in three ruminally cannulated lactating dairy cows. The in vitro gas production of ground samples (1 mm) was measured according to the 'Hohenheim Gas Test', and cumulative gas production was recorded over different time spans for up to 72 h. There were significant differences (P<0.05) between the species for most parameters used to describe the in situ degradation of starch (ST) and dry matter (DM). The in situ degradation rate (c) and effective degradability (assuming a passage rate of 8%/h; ED8) of ST differed significantly between all grains and was highest for rye (rye: 116.5%/h and 96.2%; triticale: 85.1%/h and 95.0%; barley: 36.2%/h and 90.0% for c and ED8, respectively). With respect to DM degradation, the ranking of the species was similar, and predicted c values exhibited the highest variation within species. The in vitro gas production rate was significantly higher (P<0.05) for rye than for triticale and barley (rye: 12.5%/h; triticale: 11.5%/h; barley: 11.1%/h). A positive relationship between the potential gas production in vitro and the maximal degradable DM fraction in situ was found using all samples (r=0.84; P<0.001) as well as rye (P=0.002) and barley (P<0.001) alone, but not for triticale. Variation in ruminal in situ degradation parameters within the grain species resulted from the high c values, but was not reflected in the ED estimates. Therefore, the usage of mean values for the ED of DM and ST for each species appears reasonable. Estimated metabolisable energy concentrations (ME, MJ/kg DM) and the estimated digestibility of organic matter (dOM, %) were significantly lower (P<0.05) for barley than for rye and triticale. Rye and triticale dOM and ME values were not significantly different (P=0.386 and 0.485).

Rations for dairy cows are comprised of high proportions of cereal grains. Thus, despite their low crude protein (CP) content, grains can contribute considerably to the CP intake of dairy cows. This study was conducted to describe and compare ruminal CP degradation of a broad range of barley, rye and triticale genotypes in situ and in vitro and different methods to estimate the utilisable CP at the duodenum (uCP). Twenty samples each of rye, barley and triticale were incubated in situ and in vitro. Exponential regression analyses were used to estimate in situ degradation parameters. Further, the effective degradability (ED), ruminal undegraded CP (UDP) and uCP for ruminal passage rates of 5% and 8% per hr were estimated. The uCP was estimated in vitro and based on two different approaches using in situ UDP data and estimates of microbial synthesised protein (based on fermented organic matter [fOM] or equations of the Gesellschaft für Ernährungsphysiologie). The degradation rate declined from rye (43% per hr) to triticale (27% per hr) to barley (20% per hr), and it exhibited remarkable variation between the genotypes of a single species. The maximal degradable CP fraction also differed between the species, but was overall very high (94%-99%). The lowest washout fraction (26%) and the highest variation in ED (77%-86% and 69%-80% for a passage rate of 5% and 8% per hr, respectively) were found in barley. The in situ uCP content (estimated using fOM) was lower for barley than for rye and triticale at ruminal passage rates of 5% and 8% per hr (barley: 157 g/kg DM at both passage rates; rye and triticale: 168 (at 5% per hr) and 169 (at 8% per hr) g/kg DM). In vitro estimations of uCP did not differ between the grain species and uCP estimated according to GfE was higher for triticale than for barley and rye, which did not differ. The low variation within a single grain species and the weak correlations between ruminal CP degradation and nutrient concentrations suggested that differentiation of ED and uCP between the genotypes of a single grain species is not necessary.

The first objective of this study was to determine the influence of dietary composition on the in situ disappearance of phytate (InsP6) from wheat, corn, soybean meal, and rapeseed meal [solvent-extracted, without (RSM) or with (hRSM) heat treatment] in the rumen of dairy cows. The second objective was to assess the primary degradation products of InsP6 in the rumen. Three diets differing in phosphorus and InsP6 concentration (basal diet = 0.38% P in dry matter; high-P diet = 0.56% P; high-InsP6 diet = 0.39% P) were fed to 3 ruminally fistulated lactating Jersey cows in a 3 × 3 Latin square. Ground concentrates (sieve size = 2 mm) were incubated in polyester bags in the rumen for 2, 4, 8, 16, and 24 h. The bag residues were analyzed for P, InsP6, isomers of lower inositol phosphates (InsP5, InsP4, InsP3), and crude protein. The InsP6 disappeared more rapidly from cereal grains than from oilseed meals; however, after 24 h of incubation ≥95% InsP6 had disappeared from all concentrates except hRSM (57%; diet average). Feeding the high-InsP6 diet increased InsP6 disappearance for oilseed meals, but not for corn and wheat. The predominant InsP5 isomer in all bag residues was Ins(1,2,4,5,6)P5 followed by Ins(1,2,3,4,5)P5 and Ins(1,2,3,4,6)P5. A further InsP5 isomer [Ins(1,3,4,5,6)P5] was detected in both rapeseed meal bag residues. Feeding the high-InsP6 diet led to lower concentrations of Ins(1,2,4,5,6)P5 and Ins(1,2,3,4,5)P5, whereas an interaction between diet, concentrate, and time occurred for Ins(1,2,3,4,6)P5 and Ins(1,3,4,5,6)P5. The results confirm the high potential of rumen microorganisms to hydrolyze InsP6; however, increasing the amount of InsP6 in the diet can further enhance InsP6 hydrolysis, which may be relevant when concentrates with slowly degradable InsP6, such as RSM or heat-treated concentrates, are fed to dairy cows. Based on the concentrations of InsP5 isomers, 3 and 6 phytases appear to play a major role in the rumen. Conversely, intrinsic plant phytase activity appears to be less relevant as the percentage of its primary hydrolysis product, Ins(1,2,3,4,5)P5, changed only slightly upon using wheat known for high intrinsic phytase activity instead of the other concentrates. Additional information regarding the factors influencing the extent of ruminal InsP6 disappearance will require further studies to determine the phytase activity of rumen microorganisms and the characteristics of their respective phytases.

The ruminal disappearance of phytate phosphorus (InsP6 -P) from maize grain and rapeseed meal (RSM) was determined in two in vitro studies. In experiment 1, two diets differing in phosphorus (P) and InsP6 -P concentration were fed to the donor animals of rumen fluid (diet HP: 0.49% P in dry matter, diet LP: 0.29% P). Maize grain and RSM were incubated in a rumen fluid/saliva mixture for 3, 6, 12 and 24 h. In experiment 2, a diet similar to diet HP was fed, and the rumen fluid was mixed with artificial saliva containing 120 mg inorganic P/l (Pi) or no inorganic P (P0). Maize grain and RSM were incubated with either buffer for 3, 6, 12 and 24 h. Total P (tP) and InsP6 concentration were analysed in the fermenter fluids and feed residues. The disappearance of InsP6 -P from maize was completed after 12 h of incubation in both experiments. From RSM, 93% (diet LP) and 99% (diet HP) of the InsP6 -P in experiment 1 and 80% (Pi) and 89% (P0) in experiment 2 had disappeared after 24 h of incubation. InsP6 -P disappearance was higher when diet HP was fed (maize: 3 and 6 h; RSM: 6 and 24 h of incubation) and when rumen fluid was mixed with buffer P0 (maize: 6 h; RSM: 12 and 24 h of incubation). InsP6 -P concentration in the fermenter fluids was higher for maize, but no accumulation of InsP6 -P occurred, indicating a prompt degradation of soluble InsP6 . These results confirmed the capability of rumen micro-organisms to efficiently degrade InsP6 . However, differences between the feedstuffs and diet composition as well as the presence of inorganic P in the in vitro system influenced the degradation process. Further studies are required to understand how these factors affect InsP6 degradation and their respective relevance in vivo.

The objective of this study was to determine the variation of in situ ruminal degradation characteristics of dry matter (DM), crude protein (CP) and starch (ST), and to determine the effective degradation (ED) of wheat genotypes. Further, multivariate associations of these in situ values with their corresponding in vitro gas production (GP) kinetics and laboratory measurements were evaluated using correlation and multiple linear regression analyses. Grains of 20 genotypes of wheat were characterized by proximate constituents, amino acid (AA) composition and physical characteristics. Ruminal degradation kinetics were determined by in situ degradation of DM, CP and ST, and subsequent evaluation of in vitro GP relative to time courses. In situ and GP measurements were fitted to an exponential equation, and ED was calculated using passage rates in the rumen of 5%/h (ED5) and 8%/h (ED8). To predict ED8 of CP (EDCP8) and ST (EDST8), correlations were evaluated and stepwise multiple linear regression analyses were applied. Estimated degradation parameters varied considerably between wheat genotypes irrespective of the nutrient tested. Variance in a, b and c was not reflected in the variation of the ED, due to high degradation rates (c). The assumed passage rate also impacted estimation of the ED minimally. Estimated GP parameters varied only slightly among wheat genotypes. Nevertheless, regression models explained up to 80 and 99% of the variance in EDCP8 and EDST8, respectively, and associations between EDST8 and EDCP8 and chemical and physical characteristics of grains were detected. As ST is the primary nutrient in wheat grains and can comprise substantial portions of dairy rations, the total amount of ST as well as its ED in the rumen should be taken into account when wheat is incorporated into dairy rations. Conversely, variance in wheat grain CP degradation was very low and can largely be neglected in practical ration formulation for ruminants.

To investigate the effect of the change from a concentrate and silage-based ration (total mixed ration, TMR) to a pasture-based ration, a 10-wk trial (wk 1-10) was performed, including 10 rumen- and duodenum-fistulated German Holstein dairy cows (182±24 d in milk, 23.5±3.5kg of milk/d; mean ± standard deviation). The cows were divided in either a pasture group (PG, n=5) or a confinement group (CG, n=5). The CG stayed on a TMR-based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG was gradually transitioned from a TMR to a pasture-based ration (wk 1: TMR only; wk 2: 3 h/d on pasture wk 3 and 4: 12 h/d on pasture wk 5-10: pasture only). Ruminal pH, volatile fatty acids (VFA), NH3-N, and lipopolysaccharide (LPS) concentrations were measured in rumen fluid samples collected medially and ventrally on a weekly basis. Ruminal pH was continuously recorded during 1 to 4 consecutive days each week using ruminal pH measuring devices. In wk 1, 5, and 10, rumen contents were evacuated and weighed, papillae were collected from 3 locations in the rumen, and subsequently a VFA absorption test was performed. In the PG, mean rumen pH and molar acetate proportions decreased, and molar butyrate proportions increased continuously over the course of the trial, which can most likely be ascribed to an increased intake of rapidly fermentable carbohydrates. During the first weeks on a full grazing ration (wk 5-7), variation of rumen pH decreased, and in wk 5 a lower rumen content, papillae surface area, and potential for VFA absorption were observed. In wk 8 to 10, variation of rumen pH and total VFA concentrations increased again, and acetate/propionate ratio decreased. In wk-10 rumen content, papillae area and VFA absorption characteristics similar to initial levels were observed. Although continuous rumen pH assessments and LPS concentrations did not reveal an increased risk for subacute rumen acidosis (SARA) during the adaption period, histopathology of rumen papillae and potential for VFA absorption indicated a possible risk for rumen health. An increased risk for SARA was observed in wk 9 and 10 in the PG, but rumen LPS concentrations and histopathology were not adversely affected. Results of the present study suggest that after behavioral and metabolic adaptation to the transition from a TMR to a pasture-based ration, no adverse effects on rumen morphology and absorption capacity occurred, although rumen pH after adaptation to pasture indicated increased risk of SARA.

The effect of crushed full fat rapeseed or its free oil on milk yield and milk fatty acid composition was assed using three groups of mid-lactating Holstein dairy cows, assigned to a randomized 3×3 Latin square design. Dietary treatments included a control (CTL, ether extract 2.3% of dry matter, DM) and two experimental treatments (ether extract 4.2% of DM) supplemented with the same amount of fat either supplied as 4.9% of DM crushed full fat rapeseed, RCor2.2% of DM free rapeseed oil RO. Both experimental treatments increased DM intake (P<0.005) and daily milk yield (P<0.001). Milk fat and protein concentration was decreased in the supplemented diets (p<0.001). A reduced (p<0.001) yield of saturated fatty acids (FA) and an increased yield of long chain and unsaturated FA (p<0.001 for mono unsaturated FA and p<0.05 for poly unsaturated FA) in milk fat was observed for both experimental treatments. The results confirmed a reduced de novo synthesis and an increased carry-over of dietary FA upon feeding dairy cow diets supplemented with long chain and unsaturated FA. The lower degree of saturation in milk fat from cows fed RC compared to RO indicates a partial protection of the crushed rapeseed against ruminal hydrogenation.

Three experiments were conducted to study the loss of secondary starch particles from bags used for the in situ incubation of different cereal grains. Two in vitro and one in situ study were combined. Ruminally cannulated Jersey cows were used for rumen fluid collection and in situ degradation studies in randomly assigned repeated measures designs, each including three replicates per treatment. An in vitro time course study was conducted to determine whether secondary starch particle losses occur during ruminal incubation. Ground wheat was weighed and placed in bags with a pore size of 50 pm, then washed, dried, and incubated for 0.5, 1, 2, 3, 5, 8, 16, and 32h in a modified RUSITEC-system. Bag residues and samples of freeze-dried fermenter fluids were enzymatically analyzed for starch content. Using the same technique used for the first in vitro experiment, but with an incubation time of only 8 h, ground wheat, barley, and corn grains were incubated in bags with pore sizes of 50,30 (with the exception of corn), 20, and 6 mu m. In the in situ experiment, ground wheat, barley, corn, and oats were rumen-incubated in bags with pore sizes of 50, 20, and 6 mu m for different time periods. Then, the grains and bag residues were enzymatically analyzed to determine their starch content, and the degradation characteristics of the materials were calculated. The in vitro trials showed that incubating wheat and barley in bags with pore sizes of 50 and 30 mu m leads to a substantial degree of secondary starch particle loss during incubation. These losses were not detectable when the samples were placed in bags with pore sizes of 20 and 6 mu m. No secondary starch particle losses occurred in corn, regardless of pore size; thus, corn can be studied in situ even when using bags with 50 mu m pore size. Due to the high washout losses the in situ method is not suitable for the measurement of starch degradation in oats using the pore sizes tested in the present study. Because of the methodological problems associated with pore sizes <50 mu m, no recommendations can be provided for the evaluation of wheat and barley. Thus, caution must be taken when the in situ technique is used for ruminal grain starch degradation measurements, as there are substrate-related errors possible that must be taken into account. (C) 2015 Elsevier B.V. All rights reserved.

Dietary unsaturated fatty acids (FA) are intensively hydrogenated in the rumen, resulting in reduced amount of poly-unsaturated fatty acids (PUFA) and accumulation of several biohydrogenation (BH) products. In this study, BH of PUFA originating from different oilseeds (linseed, soya beans, sunflower seed and rapeseed) present in crushed oilseeds or their free oils were assessed in vitro. The assay substrates were incubated in buffered rumen fluid for 0, 6, 12 and 24 h. After incubation, the FA pattern of the incubated samples was analysed using gas chromatography. Biohydrogenation is defined as disappearance of double bonds (DB) calculated from the contents of unsaturated FA. After 24-h incubation, the DB contents of all oilseeds were reduced (p < 0.001) by 40-60%. The reduction was higher (p < 0.001) for the crushed form compared with the oil form. In addition, linseed and sunflower seed known as oilseeds with high contents of linolenic acid C18:3 c9,12,15 (LNA) and linoleic acid C18:2 c9,12 (LA), respectively, showed a higher (p < 0.001) accumulation of the BH intermediates conjugated linoleic acid (CLA, isomer C18:2 c9t11) and vaccenic acid (C18:1 t11) for the crushed form, when compared with the oil. These results suggest an inherent effect of the physical form of the assay oilseeds on in vitro BH. Changes in FA pattern during BH in vitro can be attributed to both source and physical form of the assay oilseeds. However, further investigations are warranted to ensure whether the observed in vitro effects on ruminal BH can be confirmed in vivo.

The aim of the present study was to determine the effects of some plant extracts on rumen fermentation and protozoal counts by using Hohenheim in vitro gas production technique in cattle. In this study in vitro gas productions at varying doses of thymol, oregano, zingiber and syzygium essence oils were determined at 2, 4, 8, 12, 24, 36 and 48 (h), respectively. For all feed types, high doses (50 ppm) of thymol and oregano supplementations significantly decreased gas production at later hours of incubation (p<0.05). On the other hand, for all feed types, all doses of zingiber and syzygium supplementations significantly increased gas production at later hours of incubation (p<0.05). High total gas production quantity indicates that most of the substrates are converted to gas which results in decreased concentrations of volatile fatty acids and other beneficial end products. Varying doses of all essence oils were assessed within the same incubation periods and it was found that high doses of thymol and oregano supplementations resulted significant decrease in gas production (p<0.05). For all feed types, the highest protozoal counts were identified in Z. officinale 200 pmm group compared to positive and negative control groups, while the lowest protozoal count for TMR was recorded in T. vulgaris, O. vulgare and S. aromaticium groups. These essence oils can be utilized as rumen regulators. Similar effects are anticipated with the supplementation of these oils to ruminant rations (in vivo), which, therefore, will lead to improved ruminant performance.

The long-term effects of adding chestnut (CHE; Castanea sativa) and valonea (VAL; Quercus valonea) tannin-rich extracts to sheep feed were investigated. In Experiment 1, sheep (65 kg BW) were fed 842 g/day of a ryegrass-based hay. The control-treated animals (CON) received 464 g/day of concentrate, and tannin-treated animals received the same amount of concentrate additionally containing 20 g of the respective tannin-rich extract. Hay and concentrates were offered together in one meal. After the onset of treatment, methane release was measured in respiration chambers for 23.5-h intervals (nine times) in a 190-days period. Faeces and urine were collected three times (including once before the onset of the tannin treatment) to assess digestibility and urinary excretion of purine derivatives. Based on the results obtained from Experiment 1, a second experiment (Experiment 2) was initiated, in which the daily tannin dosage was almost doubled (from 0.9 (Experiment 1) to 1.7 g/kg BW0.75). With the exception of the dosage and duration of the treatment (85 days), Experiment 2 followed the same design as Experiment 1, with the same measurements. In an attempt to compare in vitro and in vivo effects of tannin supplementation, the same substrates and tannin treatments were examined in the Hohenheim gas test. In vitro methane production was not significantly different between treatments. None of the tannin-rich extract doses induced a reduction in methane in the sheep experiments. On the 1st day of tannin feeding in both experiments, tannin inclusion tended to decrease methane release, but this trend disappeared by day 14 in both experiments. In balance period 3 of Experiment 1, lower dry matter and organic matter digestibility was noted for tannin treatments. The digestibility of CP, but not NDF or ADF, was reduced in both experiments. A significant shift in N excretion from urine to faeces was observed for both tannin-rich extracts in both experiments, particularly in Experiment 2. In balance period 2 of Experiment 2, an increased intake of metabolisable energy for VAL was observed. The urinary excretion of purine derivatives was not significantly different between treatments, indicating that microbial protein synthesis was equal for all treatments. Thus, we concluded that both tannin-rich extracts temporary affect processes in the rumen but did not alter methane release over a longer period.

We evaluated the effect of three sources of dried distillers' grains with solubles (DDGS) in diets of mid-lactating dairy cows on milk production and milk composition and on digestibility in sheep. DDGS from wheat, corn and barley (DDGS1 ), wheat and corn (DDGS2 ) and wheat (DDGS3 ) were studied and compared with a rapeseed meal (RSM). RSM and DDGS were characterized through in situ crude protein (CP) degradability. Nutrient digestibility was determined in sheep. Twenty-four multiparous cows were used in a 4 × 4 Latin square design with 28-day periods. Treatments included total mixed rations containing as primary protein sources RSM (control), DDGS1 (D1), DDGS2 (D2) or DDGS3 (D3). RSM contained less rapidly degradable CP (fraction a), more potentially degradable CP (fraction b) and more rumen undegradable CP (UDP) than the three DDGS. In vivo digestibility of RSM organic matter was similar to DDGS. Calculated net energy for lactation (NEL ) was lower for RSM (7.4 MJ/kg DM) than for DDGS, which averaged 7.7 MJ/kg DM. Cows' dry matter intake did not differ between diets (21.7 kg/day). Cows fed D1 yielded more milk than those fed D3 (31.7 vs. 30.4 kg/day); no differences were found between control and DDGS diets (31.3 vs. 31.1 kg/day). Energy-corrected milk was similar among diets (31.2 kg/day). Diets affected neither milk fat concentration (4.0%) nor milk fat yield (1.24 kg/day). Milk protein yield of control (1.12 kg/day) was significantly higher than D3 (1.06 kg/day) but not different form D1 and D2 (1.08 kg/day each). Feeding DDGS significantly increased milk lactose concentration (4.91%) in relation to control (4.81%). DDGS can be a suitable feed in relation to RSM and can be fed up to 4 kg dry matter per day in rations of dairy cows in mid-lactation. However, high variation of protein and energy values of DDGS should be considered when included in diets of dairy cows.

Tannins, polyphenolic compounds found in plants, are known to complex with proteins of feed and rumen bacteria. This group of substances has the potential to reduce methane production either with or without negative effects on digestibility and microbial yield. In the first step of this study, 10 tannin-rich extracts from chestnut, mimosa, myrabolan, quebracho, sumach, tara, valonea, oak, cocoa and grape seed, and four rapeseed tannin monomers (pelargonidin, catechin, cyanidin and sinapinic acid) were used in a series of in vitro trials using the Hohenheim gas test, with grass silage as substrate. The objective was to screen the potential of various tannin-rich extracts to reduce methane production without a significant effect on total gas production (GP). Supplementation with pelargonidin and cyanidin did not reduce methane production; however, catechin and sinapinic acid reduced methane production without altering GP. All tannin-rich extracts, except for tara extract, significantly reduced methane production by 8% to 28% without altering GP. On the basis of these results, five tannin-rich extracts were selected and further investigated in a second step using a Rusitec system. Each tannin-rich extract (1.5 g) was supplemented to grass silage (15 g). In this experiment, nutrient degradation, microbial protein synthesis and volatile fatty acid production were used as additional response criteria. Chestnut extract caused the greatest reduction in methane production followed by valonea, grape seed and sumach, whereas myrabolan extract did not reduce methane production. Whereas chestnut extract reduced acetate production by 19%, supplementation with grape seed or myrabolan extract increased acetate production. However, degradation of fibre fractions was reduced in all tannin treatments. Degradation of dry matter and organic matter was also reduced by tannin supplementation, and no differences were found between the tannin-rich extracts. CP degradation and ammonia-N accumulation in the Rusitec were reduced by tannin treatment. The amount and efficiency of microbial protein synthesis were not significantly affected by tannin supplementation. The results of this study indicated that some tannin-rich extracts are able to reduce methane production without altering microbial protein synthesis. We hypothesized that chestnut and valonea extract have the greatest potential to reduce methane production without negative side effects.