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The ruminal degradation of P bound in phytate (InsP 6) can vary between feeds, but data on ruminal degradation of InsP6 from different feedstuffs for cattle are rare. One objective of this study was to increase the data base on ruminal effective degradation of InsP6 (InsP 6 ED) and to assess if InsP6ED of compound feeds (CF) can be calculated from comprising single feeds. As a second objective, use of near-infrared spectroscopy (NIRS) to predict InsP6 concentrations was tested. Nine single feeds (maize, wheat, barley, faba beans, soybeans, soybean meal (SBM), rapeseed meal (RSM), sunflower meal (SFM), dried distillers’ grains with solubles (DDGS)) and two CF (CF1/CF2), consisting of different amounts of the examined single feeds, were incubated for 2, 4, 8, 16, 24, 48 and 72 h in the rumen of three ruminally fistulated Jersey cows. Samples of CF were examined before (CF1/CF2 Mash) and after pelleting (CF1/CF2 Pellet), and InsP6ED was calculated for all feeds at two passage rates (InsP 6 ED 5: k = 5%/h; InsP 6 ED 8: k = 8%/h). For CF1 and CF2, InsP6ED was also calculated from values of the respective single feeds. Near-infrared spectra were recorded in duplicate and used to establish calibrations to predict InsP6 concentration. Besides a global calibration, also local calibrations were evaluated by separating samples into different data sets based on their origin. The InsP6ED8 was highest for faba beans (91%), followed by maize (90%), DDGS (89%), soybeans (85%), wheat (76%) and barley (74%). Lower values were determined for oilseed meals (48% RSM, 65% SFM, 66% SBM). Calculating InsP6ED of CF from values of single feeds underestimated observed values up to 11 percentage points. The NIRS calibrations in general showed a good performance, but statistical key data suggest that local calibrations should be established. The wide variation of InsP6ED between feeds indicates that the ruminal availability of P bound in InsP6 should be evaluated individually for feeds. This requires further in situ studies with high amounts of samples for InsP6 analysis. Near-infrared spectroscopy has the potential to simplify the analytical step of InsP6 in the future, but the calibrations need to be expanded.

Single concentrate feeds are mixed together forming compound feeds for cattle. However, knowledge regarding the potential interactions (associative effects) between the feeding values of single feeds in compound feeds is lacking. The main objective of the present study was to evaluate ruminal fermentation characteristics and feeding values of eight industrially produced compound feeds in mash form from their constituent single feeds for dairy cows through in vitro assays. Additivity was given for gas production (GP), digestibility of organic matter (dOM) and utilisable CP at the duodenum (uCP). Additivity of CP fractions (determined using the Cornell Net Carbohydrate and Protein System (CNCPS)) was dependent on the fraction and compound feed type; however, the effective degradation calculated from CP fractions (EDCNCPS) showed additivity. Additivity was not given for intestinal digestibility of rumen-undegraded protein (IDRUP) for five out of eight compound feeds. Precise calculation of metabolisable energy (ME) of compound feeds from ME of single feeds was possible when using the same ME equations for all single and compound feeds. Compound feeds are often provided in pellet form; therefore, our second objective was to evaluate the effects of pelleting on ruminal fermentation characteristics and feeding values of compound feeds. Pelleting affected GP at 24 h (GP24; up to 2.4 ml/200 mg DM), dOM (up to 2.3 percentage point (pp)) and ME (up to 0.3 MJ/kg DM), but these differences were overall small. More considerable effects of pelleting were observed for uCP, which was increased in all compound feeds except the two with the highest CP concentrations. The IDRUP was lower in most compound feeds following pelleting (up to 15 pp). Pelleting also affected CP fractions in a non-systematic way. Overall, the effects of pelleting were not considerable, which could be because pelleting conditions were mild. Our third objective was to compare in situ ruminal CP degradation (EDIN_SITU) of compound feeds with ED using two prediction methods based on CP fractions. EDIN_SITU reference data were obtained from a companion study using the same feeds. Prediction accuracy of EDIN_SITU and EDCNCPS was variable and depended on the compound feed and prediction method. However, future studies are needed as to date not enough data are published to draw overall conclusions for the prediction of EDIN_SITU from CP fractions.

Phytase enzyme is used as a dietary supplement in broiler nutrition to improve phosphorous bioavailability. Phytase deliberates phosphate groups from phytic acid and produces myo-inositol after total dephosphorylation. Myo-inositol is a bioactive compound having beneficial modulatory effects on metabolism in humans. However, it is not well understood if and how phytic acid degradation products, particularly myo-inositol, can modulate metabolism in broiler chicken. The purpose of this study was to investigate effects of dietary supplements of phytase and myo-inositol on the blood plasma metabolome profile of broiler chickens. Broilers were provided a nutrient-adequate control diet or the same diet supplemented with either 3.5 g myo-inositol or 500, 1500 or 3000 units of phytase, per kilogram of feed (grower diet). Broilers were group-housed in floor pens (eight pens per diet) and provided one of the treatment diets for 22 days. Then, blood was collected from one bird per pen, resulting in eight replicated measurements per diet. A targeted metabolomics approach was applied to the heparin plasma. Body weight of the birds was not significantly affected by the treatments. Plasma myo-inositol concentrations were significantly increased by myo-inositol supplementation and phytase supplementation at 500 and 1500 units/kg. Metabolites generally affected by phytase supplementation belonged to the groups of acyl-carnitines, phosphatidylcholines, sphingomyelins, lysophosphatidylcholine, biogenic amines and amino acids. Compared to the control diet, phytase supplements had significantly higher plasma concentrations of kynurenine and creatinine, but lower concentrations of histamine and cis-4-hydroxyproline. Myo-inositol supplementation significantly increased plasma concentrations of dopamine and serotonine. While some metabolites were similarly affected by myo-inositol and phytase supplementation, others were distinctly differently affected. We conclude that myo-inositol, either as a directly added supplement or indirectly released from phytate upon phytase supplementation, can affect specific metabolic pathways. Additional effects found on phytase supplementation may be related to intermediary phytate degradation products. Results are indicative for innovative hypothesis to be tested in future experiments, for instance, with regard to relationships between phytase or myo-inositol supplements and bird immunity or behaviour.

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.

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 (R2Validation=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 (R2>0.90), but the database needs to be extended to obtain more stable calibrations for routine use.

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R2 = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

In this study, 10 samples of rapeseed meal (RSM) from 10 different oil plants in Germany were examined. In situ rumen degradation of CP was determined by incubation over 1, 2, 4, 8, 16, 32 and 72 h in duplicate per time point using three rumen fistulated dry cows. Degradation kinetics were estimated by an exponential model and effective CP degradation was calculated. Degradation was corrected for small particle loss as the difference between washing loss and water-soluble fraction. Amino acid analysis was carried out in the samples and in the residues after 8 and 16 h of incubation in situ and degradation of individual amino acids was calculated for these incubation times. In vitro pepsin-pancreatin digestibility of CP (IPD) was determined in the samples as well as in the 8 and 16 h residues. Effective CP degradation for a rumen outflow rate of 8%/h (ED8) averaged 54.3% with a considerable variation among samples ranging from 44.3% to 62.7%. A multiple regression equation containing acid detergent insoluble N, total glucosinolates and petroleum ether extract as independent variables predicted ED8 with satisfying accuracy (R 2 = 0.74; RSD = 6.4%). Degradation of amino acids was different from that of CP for most amino acids studied, especially after 8 h of incubation. Compared with CP, degradation of essential amino acids was predominantly lower while degradation of non-essential amino acids was higher in most cases. However, for lysine and methionine no distinct difference with CP degradation was found. Degradation of individual amino acids was predicted from CP degradation with high accuracy using linear regression equations. Average IPD of RSM was 79.8 ± 2.6%. IPD was lower in the incubation residues and decreased with longer incubation time and increasing rumen degradation, respectively.

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.

The objective was to investigate the effect of variation in forage source and feed particle size of a diet, including interactions, on the amount and the composition of microbial crude protein (CP) in a semi-continuous culture system (Rusitec). Different microbial CP fractions were compared. Five diets with mean forage proportion of 0.88 and different maize silage to grass silage ratios (100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100) were used. Diets were ground through sieves with a pore size of either 1 or 4 mm, matching the particle size of fine (F) and coarse (C), respectively. Diets were characterised by increasing concentrations of CP and fibre fractions, and decreasing concentrations of starch with ascending inclusion rates of grass silage. Microbial mass was isolated from feed residues after incubation from the liquid phase of the fermenter and from the liquid effluent. The amount of synthesised microbial CP was determined on the basis of 15N balance. It increased quite linearly by the stepwise replacement of maize silage by grass silage, and was higher in C treatments compared to F treatments. Efficiency of microbial CP synthesis (EMPS) was improved from 29 to 43 mg microbial N/g degraded organic matter (OM) by increasing the proportion of grass silage in the diet, but was unaffected by particle size. The N content as well as the profiles of amino acids of the three microbial fractions was affected by diet composition and particle size. The ratio of solid- to liquid-associated microbes was affected by diet composition and feed particle size. The amount and EMPS seemed to be improved by degradation of OM from grass silage and an increasing availability of N. Moreover, the results of this study indicated a shift in the composition of the microbial community caused by variation in forage composition and feed particle size.

Beet pulp contains high amounts of pectins that can reduce the risk of rumen disorders compared to using feedstuffs high in starch. The objective was to study the effects of inclusion of ensiled pressed beet pulp in total mixed rations (TMR) for high-yielding dairy cows. Two TMR containing no or about 20% (on dry matter (DM) basis) beet pulp silage were used. The beet pulp silage mainly replaced maize silage and corn cob silage. The TMR were intentionally equal in the concentrations of energy and utilisable crude protein (CP) at the duodenum. TMR were fed to 39 and 40 dairy cows, respectively, for 118 days. The average daily milk yield was about 43 kg/day. No significant differences in milk yield and milk fat or milk protein content were detected. DM intake of cows was significantly reduced by the inclusion of beet pulp silage (23.0 v. 24.5 kg/day). However, a digestibility study, separately conducted with sheep, showed a significantly higher organic matter digestibility and metabolisable energy concentration for the TMR that contained beet pulp silage. In vitro gas production kinetics indicated that the intensity of fermentation was lower in the TMR that contained beet pulp silage. In vitro production of short-chain fatty acids, studied using a Rusitec, did not differ between the TMR. However, the inclusion of beet pulp silage in the ration caused a significant reduction in the efficiency of microbial CP synthesis in vitro. The amino acid profile of microbial protein remained unchanged. It was concluded that beet pulp silage has specific effects on ruminal fermentation that may depress feed intake of cows but improve digestibility. An inclusion of beet pulp silage of up to 20% of DM in rations for high-yielding dairy cows is possible without significant effects on milk yield and milk protein or milk fat.

In a feeding trial with sheep, four animals each were fed one of the three roughages (perennial ryegrass (PR), meadow fescue (MF) and red clover (RC)) or one of the four different mixtures (g/day 250 : 250 : 250, 375 : 75 : 300, 525 : 187.5 : 37.5 and 75 : 525 : 150, respectively) of those three roughages, both with and without the inclusion of 100 g of beeswax-labelled barley. Further, four sheep received a pure lucerne diet to enlarge available data on single species faecal recoveries. All sheep except those fed single-component diets and the 250 : 250 : 250 roughage mix were administered intra-ruminal alkane controlled-release devices (CRD). The aim of the study was to investigate the effect of diet composition on faecal alkane recoveries, and to assess the accuracy of the alkane-based estimate of diet composition and intake based either upon a general set of faecal recoveries across diets or upon dietary recoveries and dietary samples more specifically attributable to individual dietary treatments. For each roughage component independently, the accuracy of diet composition estimates was assessed using linear regression across all diets. The estimates of the proportion of barley were analysed further using mean differences and mean prediction errors. Faecal alkane recovery increased with increasing chain length and was affected by diet composition. RC had a significantly higher faecal recovery for alkanes C25, C27, C29 and C31 than at least one of the other single-roughage diets. When considering mixed diets consisting of PR, MF, RC and barley, the composition of the roughage component significantly affected faecal recovery of all alkanes except C30 and C33. The inclusion of beeswax-labelled barley caused a decrease in faecal recovery of alkanes up to C29. This effect was attributable to the beeswax rather than the barley itself. By contrast, the decrease of faecal recovery of synthetic dosed alkanes from the CRD in diets containing barley, compared with the corresponding diets without barley, was attributable to the supplement itself. It was concluded that synthetic dosed alkanes behaved differently during gut transit from natural alkanes. The proportions of individual dietary components were estimated well over a wide range of proportions. Generally, the more information available, the more accurate the estimates achieved. However, a general set of faecal alkane recoveries and bulked samples of dietary components yielded estimates of diet composition sufficiently accurate for a large number of studies, especially in situations where groups of animals are of concern and not the individual animal.