In vitro fermentation characteristics and effective utilisable crude protein in leaves and green pods of Moringa stenopetala and Moringa oleifera cultivated at low and mid-altitudes

This study was conducted to assess the in vitro nutrient digestibility and utilisation of leaves and green pods of two Moringa species in supplementing the feed of ruminant animals during the dry season. Samples were analysed for proximate nutrients using official methods. The metabolisable energy (ME), organic matter digestibility (OMD) and effective utilisable crude protein (uCP) were estimated using the Hohenheim in vitro gas test method. Gas volume in Moringa stenopetala leaves and green pods was generally higher than those of Moringa oleifera. Gas volume for leaves was similar between low and mid-altitudes but was higher for green pods at mid-altitude. M. stenopetala leaves contained significantly higher ME (9.8 MJ/kg DM) and OMD (75%) than those of M. oleifera. Similarly, M. stenopetala green pods had higher ME and OMD values than those of M. oleifera. For green pods, the ME and OMD values were significantly higher at mid-altitude than those at low altitude although these values for leaves were similar between both altitudes. Moringa oleifera leaves had higher effective uCP than those of M. stenopetala. Nevertheless, the effective uCP was higher for green pods of M. stenopetala than those of M. oleifera. The effective uCP for leaves cultivated at mid-altitude was slightly higher than those at low altitude. This study suggested that leaves and green pods could be used as alternative energy and protein supplements for tropical ruminants, particularly during dry periods. It was further concluded that leaves were generally better in nutrient compositions and in vitro nutrient digestibility characteristics than green pods.

Effect of donor animals and their diet on in vitro nutrient degradation and microbial protein synthesis using grass and corn silages

Two nonlactating cows and two wether sheep, all fitted with a permanent cannula into the rumen, were fed either hay plus concentrate, grass silage or corn silage to study the effect of the donor animal and its diet on in vitro fermentation and microbial protein synthesis. Rumen inoculum was obtained before the morning feeding. Grass silage or corn silage was incubated in a semi-continuous rumen simulation system for 14 days. Four replicated vessels were used per treatment. Degradation of crude nutrients and detergent fibre fractions as well as microbial protein synthesis and the production of volatile fatty acids were studied. Additionally, total gas and methane production was measured with a standard in vitro gas test. Gas production and methane concentration was higher when the inoculum used was from sheep than that from cows. The donor animal also affected the degradation of organic matter and ether extract as well as the amount of propionate and butyrate, and the acetate-to-propionate ratio. The effect of the diet fed to the donor animal on fermentation was much greater than the effect of the donor animal itself. Feeding hay plus concentrate resulted in higher gas production and degradation of acid detergent fibre, but in lower degradation of ether extract and reduced microbial protein synthesis. Additionally, the pattern of volatile fatty acids changed significantly when the diet of the donor animals was hay plus concentrate or one of the silages. These results show that in vitro fermentation and microbial protein synthesis is different when based on inoculum from either cattle or sheep. The diet fed to the donor animal is more important than the animal species and is probably mediated by an adjusted microbial activity. With regard to standardized feed evaluations, these results further support the need to harmonize in vitro approaches used in different laboratories.

Effect of Fusarium toxin-contaminated triticale and forage-to-concentrate ratio on fermentation and microbial protein synthesis in the rumen

In this study, the effect of Fusarium toxin-contaminated triticale (FUS) at high (60%) and low (30%) concentrate proportion in ruminant rations on ruminal fermentation, microbial protein synthesis and digestibility was investigated, using in vivo and in vitro methods. Significant effects of the forage-to-concentrate ratio on ruminal degradation and digestibility of crude nutrients and detergent fibre fractions as well as on the pH value and the concentration of short chain fatty acids (SCFA) in rumen fluid were found. The production of SCFA was affected, and the degradation of crude fibre and neutral detergent fibre in the rumen was reduced by the inclusion of FUS at high concentrate proportion. The efficiency of microbial crude protein synthesis was higher in diets with 60% than in diets with 30% concentrates, but was impaired in the presence of FUS in vitro at the high concentrate level. Marginal effects of FUS on the amino acid pattern of microbial protein were detected. It was concluded that the use of FUS in high concentrate diets can influence ruminal fermentation and microbial protein synthesis at a dietary deoxynivalenol concentration below 5 mg/kg dry matter.

Influence of the maize silage to grass silage ratio and feed particle size of rations for ruminants on the community structure of ruminal Firmicutes in vitro

AIMS

To investigate the effect of the forage source and feed particle size (FPS) in ruminant rations on the composition of the ruminal Firmicutes community in vitro.

METHODS AND RESULTS

Three diets, varying in maize silage to grass silage ratio and FPS, were incubated in a rumen simulation system. Microbial samples were taken from the liquid fermenter effluents. Microbial community analysis was performed by 16S rRNA-based techniques. Clostridia-specific single-strand conformation polymorphism profiles revealed changes of the community structure in dependence on both factors tested. The coarse grass silage-containing diets seemed to enhance the occurrence of different Roseburia species. As detected by real-time quantitative PCR, Ruminococcus albus showed a higher abundance with decreasing FPS. A slightly lower proportion of Bacilli was found with increasing grass silage to maize silage ratio by fluorescence in situ hybridization (FISH). In contrast, a slightly higher proportion of bacterial species belonging to the Clostridium-clusters XIV a and b was detected by FISH with increasing grass silage contents in the diet.

CONCLUSIONS

The ruminal Firmicutes community is affected by the choice of the forage source and FPS.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study supplies fundamental knowledge about the response of ruminal microbial communities to changing diets. Moreover, the data suggest a standardization of grinding of feeds for in vitro studies to facilitate the comparison of results of different laboratories.

Effect of the corn silage to grass silage ratio and feed particle size of diets for ruminants on the ruminal Bacteroides-Prevotella community in vitro

This study examined whether different corn silage to grass silage ratios in ruminant rations and different grinding levels of the feed affect the composition of the ruminal Bacteroides-Prevotella community in vitro. Three diets, composed of 10% soybean meal as well as of different corn silage and grass silage proportions, were ground through 1mm or 4mm screened sieves and incubated in a semi-continuous rumen simulation system. On day 14 of the incubation microbes were harvested by centrifugation from the liquid effluent of fermenter vessels. Microbial DNA was extracted for single strand conformation polymorphism (SSCP) analysis of 16S rRNA genes followed by sequencing of single SSCP bands. Fluorescence in situ hybridization (FISH) and real-time quantitative (q) PCR were used to quantify differences in the relative abundance of Bacteroides-Prevotella and Prevotella bryantii. SSCP profiles revealed a significant influence of the forage source as well as of the feed particle size on the community structure of the Bacteroides-Prevotella group. Different, phylogenetically distinct, so far uncultured Prevotella species were detected by sequence analysis of several treatment-dependent occurring SSCP bands indicating different nutritional requirements of these organisms for growth. No quantitative differences in the occurrence of Bacteroides-Prevotella-related species were detected between diets by FISH with probe BAC303. However, real-time qPCR data revealed a higher abundance of P. bryantii with increasing grass silage to corn silage ratio, thus again indicating changes within the community composition of the Bacteroides-Prevotella group. As P. bryantii possesses high proteolytic activity its higher abundance may have been caused by the higher contents of crude protein in the grass silage containing diets. To conclude, results of this study show an influence of the forage source on the ruminal community of Bacteroides-Prevotella. Furthermore, they suggest an effect of the feed particle size on this bacterial group.

Ileal microbiota of growing pigs fed different dietary calcium phosphate levels and phytase content and subjected to ileal pectin infusion

Two experiments with growing pigs were conducted to determine the effects of dietary P and Ca levels, phytase supplementation, and ileal pectin infusion on changes in bacterial populations in the ileum and on ileal and fecal fermentation patterns. Growing pigs (BW 30.1 +/- 1.3 kg) were fitted with simple T-cannulas at the distal ileum and were fed a low-P corn-soybean meal control diet (3 g of P/kg), or the control diet supplemented with either 15 g of monocalcium phosphate (MCP)/kg (Exp. 1) or 1,000 phytase units of phytase/kg (Exp. 2). Daily infusion treatments consisted of either 60 g of pectin dissolved in 1.8 L of demineralized water or 1.8 L of demineralized water as a control infusion, infused via the ileal cannula. In each experiment, 8 barrows were assigned to 4 dietary treatments according to a double incomplete 4 x 2 Latin square design. The dietary treatments in Exp. 1 were the control diet with water infusion, the control diet with pectin infusion, the MCP diet with water infusion, or the MCP diet with pectin infusion. In Exp. 2, the pigs received the same control treatments as in Exp. 1 and the phytase diet in combination with water or pectin infusion. Gene copy numbers of total bacteria, Lactobacillus spp., Lactobacillus reuteri, Lactobacillus amylovorus/Lactobacillus sobrius, Lactobacillus mucosae, Enterococcus spp., Enterococcus faecium, Enterococcus faecalis, bifidobacteria, the Clostridium coccoides cluster, the Clostridium leptum cluster, the Bacteroides-Prevotella-Porphyrmonas group, and Enterobacteriaceae were determined by quantitative PCR in DNA extracts of ileal digesta. In Exp. 1, addition of MCP reduced ileal gene copy numbers of Enterococcus spp. (P = 0.048), E. faecium (P = 0.015), and the C. leptum cluster (P = 0.028), whereas pectin infusion enhanced (P = 0.008) ileal d-lactate concentration. In Exp. 2, supplemental phytase led to greater ileal gene copy numbers of the C. coccoides (P = 0.041) and C. leptum (P = 0.048) clusters and the Bacteroides-Prevotella-Porphyrmonas group (P = 0.033), whereas it reduced (P = 0.027) fecal n-butyrate concentration. Pectin infusion reduced (P = 0.005) ileal gene copy number of the C. leptum cluster. In conclusion, ileal bacterial populations and fermentation patterns are susceptible to changes in the intestinal availability of Ca and P as well as to the supply of pectin as a fermentable substrate. Greater intestinal Ca availability decreased the numbers of some gram-positive bacteria, whereas greater P availability in the small intestine caused by phytase activity enhanced the growth of strictly anaerobic bacteria.

Effects of fermentable carbohydrates and low dietary phosphorus supply on the chemical composition of faecal bacteria and microbial metabolites in the gastrointestinal tract of pigs

The objective was to determine the effects of fermentable carbohydrates on phosphorus (P) metabolism, the chemical composition of the faecal mixed bacterial mass (MBM) and the microbial activity in the large intestine (LI) of pigs. Eight barrows (mean BW 35.9 +/- 0.9 kg), fitted with simple T-cannulas at the terminal ileum, were either fed a low-P corn-soybean meal-based control diet or 75% of the control diet supplemented with 25% cellulose, starch or pectin according to a 4 x 3 Latin Square design. Both pectin and cellulose caused higher faecal than ileal P recoveries. Ileal volatile fatty acids (VFA) levels were more pronounced for the starch (p < 0.05) rather than the cellulose and pectin treatments, whereas pectin resulted in a higher faecal VFA concentration in comparison to starch and cellulose (p < 0.05). The differences in faecal VFA concentrations corresponded to the pH values obtained in faeces. The N content of MBM was higher (p < 0.05) when cellulose was supplemented. Pectin caused a decrease in the P content of the MBM compared to the control (p < 0.05). As a result, the N:P ratio was significantly higher for the pectin (N:P = 4.33) than for the control treatment (N:P = 2.63), while the Ca:P ratio remained constant for all treatments, suggesting changes in the accumulation of N, P and Ca in MBM, probably due to changes in the species composition and activity of the microflora.

Effects of using thermally treated lupins instead of soybean meal and rapeseed meal in total mixed rations on in vitro microbial yield and performance of dairy cows

The objective was to study whether thermally treated lupins (TTL) can replace solvent-extracted soybean meal (SBM) and rapeseed meal (RSM) in dairy cow rations. Three total mixed rations (TMR) were used. They differed in the inclusion of the main protein feeds (TTL alone, TTL + RSM and RSM + SBM) but were equal in organic matter digestibility and metabolizable energy content. In vitro organic matter fermentation was not significantly different between the TMR. Efficiency of microbial crude protein (MCP) synthesis was significantly higher for TMR RSM + SBM than for TTL. In vitro gas production potential was similar for the three TMR. The maximal rate of gas production was achieved later in TMR TTL than in RSM + SBM. Feed intake of dairy cows was significantly lower when TMR TTL was fed than when TMR TTL + RSM or RSM + SBM were fed. Milk yield was significantly lower with the high inclusion rate of TTL in comparison with the other TMR. The contents of milk protein and milk fat were significantly lower when the two TTL containing TMR were fed in comparison with the RSM + SBM ration. Effects of TTL inclusion on MCP synthesis may affect the amino acid supply to the duodenum of cows to a greater extent than differences in the degradability of feed proteins.

Comparison of amino acid digestibility determined prececally or based on total excretion of cecectomized laying hens

This study investigated the possibility of using cecectomized laying hens for the determination of amino acid (AA) digestibility of protein sources as an alternative to measurements made at the terminal ileum. Toasted soybeans and corn gluten meal were used as test protein sources. A low-protein basal diet was based mainly on corn, wheat gluten, and cornstarch. In 4 other diets toasted soybeans or corn gluten meal were included each at 15% or 30% at the expense of cornstarch, so that the changes in the AA concentrations of the diets resulted from the protein sources only. Titanium dioxide was used as the indigestible marker. In experiment 1, two hundred ten 18-wk-old pullets were used. Digesta from the posterior 2-thirds of the intestine between Meckel's diverticulum and 2 cm anterior to the ileo-ceca-colonic junction was obtained from killed hens. In experiment 2, fourteen cecectomized hens were used. They were kept individually, and excreta were quantitatively collected. The apparent digestibility of AA was calculated for each diet. Linear regression analysis was used to calculate AA digestibility for the 2 protein sources. Across all diets, apparent AA digestibility was significantly higher in experiment 2 than in experiment 1. However, AA digestibilities of the 2 protein sources were not different between both experiments. Differences in AA digestibility between the protein sources were not significant in experiment 1, but in experiment 2 significant differences between the protein sources were detected for some AA due to a lower standard error of estimate. It was concluded that AA digestibility of protein sources for laying hens can be evaluated based on quantitative excreta collection with cecectomized hens using the regression approach. This needs fewer animals than the determination of digestibility at the terminal ileum. Differences between protein sources are easier to detect because of the lower standard error of estimate.

The effect of dietary phosphorus and calcium level, phytase supplementation, and ileal infusion of pectin on the chemical composition and carbohydrase activity of fecal bacteria and the level of microbial metabolites in the gastrointestinal tract of pigs

Two experiments with growing pigs were conducted to determine the effects of dietary P and Ca level, phytase supplementation, and ileal pectin infusion on ileal and fecal P and Ca balance, chemical composition of fecal mixed bacterial mass (MBM), and bacterial metabolic activity. Pigs (initial BW = 30 kg) were fitted with simple T-cannulas at the distal ileum. They were fed a low-P corn-soybean meal control diet (3 g of P/kg) or the control diet supplemented with monocalcium phosphate (MCP; 7 g of P/kg; Exp. 1) or 1,000 FTU phytase/kg (Exp. 2). The daily infusion treatments consisted of 60 g of pectin dissolved in 1.8 L of demineralized water or 1.8 L of demineralized water as the control infusion, infused via the ileal cannula. In each experiment, 8 barrows were assigned to 4 dietary treatments according to a double, incomplete 4 x 2 Latin square. The dietary treatments in Exp. 1 were the control (Con-) diet with water infusion; the control (Con+) diet with pectin infusion; the MCP diet with water infusion; and the MCP diet with pectin infusion. In Exp. 2, the pigs received the same Con- and Con+ treatments as in Exp. 1 and, in addition, the phytase-supplemented diet in combination with water or pectin infusion. After a 15-d adaptation period, feces were collected for 5 d followed by ileal digesta collection for 24 h. In Exp. 1, supplemental MCP increased (P </= 0.003) ileal and fecal P and Ca recovery as well as P and Ca content of the MBM. Pectin infusion increased the N content of the MBM (P = 0.054) and polygalacturonase activity (P = 0.032) in feces. In addition, pectin decreased (P = 0.049) ileal and tended (P < 0. 079) to increase fecal VFA concentrations. In Exp. 2, phytase decreased ileal and fecal P recovery (P < 0.001) and the P content of the MBM (P = 0.045), whereas the N content of the MBM (P = 0.094) and fecal cellulase activity (P = 0.089) tended to decrease. Similarly, pectin infusion decreased (P = 0.036) fecal cellulase activity but increased (P < 0.001) polygalacturonase activity. In conclusion, these data indicate that bacterial P and Ca assimilation and metabolic activity depend on P and Ca availability in the large intestine and on the availability of fermentable substrate, such as pectin. Thus, increasing dietary P and Ca levels increases bacterial P and Ca assimilation due to greater intestinal P and Ca availability, whereas decreasing intestinal P availability for bacteria through phytase addition to low-P diets reduces bacterial P incorporation and seems to decrease bacterial activity.

Effect of ileum segment and protein sources on net disappearance of crude protein and amino acids in laying hens

1. This study investigated the net disappearance of crude protein (CP) and amino acids (AA) from soybean meal and rapeseed meal in different sub-sections of the ileum of hens. A basal diet was used and in another 4 diets, maize starch contained in the basal diet was replaced with soybean meal or rapeseed meal at 140 and 280 g/kg so that changes in dietary AA concentrations resulted from the oilseed meals only. 2. A total of 250 Lohmann Brown pullets were used for this experiment at 20 weeks old and given one of the 5 diets for 7 d. The section between Meckel's diverticulum and 2 cm anterior to the ileo-caecal-colonic junction was taken after slaughtering the hens and cut into three sub-sections of equal length. Digesta were taken separately from each sub-section and then frozen. Net disappearance of AA and CP for the diets and the two protein sources was calculated based on standard equations and using a multiple linear regression approach. 3. Net disappearances of CP and all AA were significantly lower in the proximal sub-section than in the central and terminal sub-sections. Also, the net disappearance of CP and all AA from rapeseed meal was significantly lower in the proximal sub-section than in the central or terminal sub-sections. For soybean meal, only the net disappearances of arginine, aspartic acid, glutamic acid and phenylalanine were significantly lower in the proximal than in the terminal sub-section. No significant differences in the net disappearance of CP and AA were detected between protein sources within the central and terminal sub-sections or between the central and terminal sub-section within each protein source. Soybean meal had a significantly higher net disappearance of CP and AA (with the exception of cystine and methionine) than rapeseed meal in the proximal sub-section but these differences were not statistically significant in the central and terminal sub-sections. 4. Amino acids disappeared from the proximal region of the ileum. This needs consideration in standard approaches that are used for measuring AA digestibility. There is a variation in AA digestibility between soybean meal and rapeseed meal. The ranking of individual AA regarding their digestibility is different between the two oilseed meals.

Adaptation of epithelial sodium-dependent phosphate transport in jejunum and kidney of hens to variations in dietary phosphorus intake

The objective of this study was to explore the homeostatic response of jejunal and renal epithelia regarding the inorganic phosphate (P(i)) transport capacities to variations in dietary total phosphorus (tP) supply in hens. Adaptive processes were determined by quantitative measures of intake and excretion, P(i) transport studies across brush border membranes, and semiquantitative detection of sodium-dependent phosphate transporters (NaPi II) based on mRNA expression in the jejunum and kidney. Twelve hens (4/group) were adapted to 3 tP feeding levels in a pair-fed manner (60 g/d): low P diet with 0.073% tP, medium P diet with 0.204% tP, and high P diet with 0.343% tP. Excretion was measured during the last 5 d of a 16-d feeding period. After slaughtering, jejunal mucosa and renal cortex were removed. Tissues were used for (32)P uptake studies in brush-border membrane vesicles by rapid filtration technique and NaPi II mRNA expression studies by northern analyses. Plasma P(i) concentrations were additionally measured. The NaPi II transporter mRNA could specifically be detected in chicken jejunum and kidney. Functional parameters of Na(+)-dependent P(i) transport indicated that these transporters were involved in chicken P(i) transport across the apical membranes of jejunal and renal epithelia. Increased tP intake resulted in an increased overall tP excretion. Correlating individual data from all animals by linear regression highlighted that the adaptive decrease of renal P(i) transport capacity and NaPi IIa mRNA expression was associated with an increase in plasma P(i) levels and resulted in a higher tP excretion. Jejunal P(i) transport capacity and NaPi IIb mRNA expression did not react to variations in dietary tP supply. In conclusion, the homeostatic response was mainly based on the adaptive capacity of the kidney in hens.

Comparison of Amino Acid Digestibility in Broiler Chickens, Turkeys, and Pekin Ducks

The objective of this study was to compare prececal amino acid (AA) digestibilities in broilers, turkeys, and Pekin ducks that were 3 wk old. Five diets were used: a basal diet and diets that contained either soybean meal (SBM) or rapeseed meal (RSM) at the expense of starch each at either 150 or 300 g/kg. The differences in dietary CP and AA concentrations resulted only from the inclusion of SBM or RSM. Titanium dioxide was used as an indigestible marker. Each diet was allocated to 6 pens of 12 birds from each species and provided ad libitum for 1 wk starting at 14 d of age. Digesta were sampled on a pen basis from the distal two-thirds of the section between Meckel's diverticulum and 2 cm anterior to the ileocecocolonic junction. Ingested and digested amounts of AA were determined for each pen. Digestibilities for the 2 meals were then determined by a multiple linear regression analysis, which makes a correction for basal endogenous AA losses unnecessary. Digestibilities for essential AA from the meals varied between 92% (Met, RSM, broilers) and 62% (Val, RSM, ducks). Digestibilities were not significantly different between SBM and RSM for broilers and turkeys, but the average digestibility across all AA was slightly higher for SBM and lower for RSM in turkeys than in broilers. Digestibilities were lower in ducks than in the 2 other species, and significant differences between SBM and RSM were detected for some AA in ducks. Amino acid digestibility ranking was very similar between broilers and turkeys but different for the 2 meals. It was concluded that differences among species cannot be explained by differences in basal endogenous AA losses among species. Amino acid digestibilities determined with broilers should not be used in formulating feed for ducks.

Phytase effects on the efficiency of utilisation and blood concentrations of phosphorus and calcium in Pekin ducks

1. The objective was to study the effects of a supplementation of a 6-phytase derived from the Peniophora lycii gene in the White Pekin duck. 2. In two balance studies, low-phosphorus (P) diets consisting mainly of maize, solvent extracted soybean meal and solvent extracted sunflower meal were supplemented with phytase up to concentrations of 1500 U/kg (Study 1) or 2000 U/kg (Study 2). Each diet (phytase level) was fed to 8 to 10 individually penned ducks. The intake and excretion of each animal was measured for 5 consecutive days when ducks were in their third week of life. Responses were described by nonlinear regression. 3. Although the basal diets from the two studies were similar in ingredient composition, efficiencies of P utilisation (P accretion/P intake x 100) for the unsupplemented basal diets were 39% in Study 1 and 30% in Study 2. Phytase supplementation significantly improved P utilisation up to levels of about 55% in both studies. A plateau in P utilisation with an increase in phytase supplementation was achieved in Study 2, but not in Study 1. The enzyme was more efficient in Study 2 than in Study 1 at low rates of supplementation. Utilisation of calcium (Ca) was significantly improved by phytase supplementation. Accretions of P and Ca increased at a constant ratio. 4. In a 5-week growth study, diets with an intentionally marginal P level were used. Diets were fed either unsupplemented or supplemented with 1000 or 10,000 U/kg of phytase. Eight pens of 10 sex-separated ducks each (4 pens per sex) were allocated to each dietary treatment. 5. Phytase significantly improved the growth of ducks of both sexes between d 1 and 21, but not between d 22 and 35. Feed conversion rate was not affected by treatment. Blood serum phosphate concentrations, but not calcium, were significantly increased by phytase supplementation. Blood concentrations of creatinine, aspartate aminotransferase and lactate dehydrogenase remained unaffected while alanine aminotransferase was significantly reduced by phytase supplementation. 6. It was concluded that the efficacy of a microbial phytase varies even under similar experimental conditions. Differences in intrinsic phytase activity of maize/soybean meal-based diets may be responsible for this. The 6-phytase used has the potential to improve the utilisation of plant P in duck feeding. A plateau in response was reached above 1500 U/kg.

On the effects of Fusarium toxin contaminated wheat and wheat chaff on nutrient utilisation and turnover of deoxynivalenol and zearalenone in vitro (Rusitec)

The objective of the present study was to investigate the effects of Fusarium toxin contaminated wheat and wheat chaff (mycotoxin diet) on nutrient degradability and the metabolism of the mycotoxins deoxynivalenol (DON) and zearalenone (ZON) using the rumen simulations technique (Rusitec). A 6 day application period with control wheat and wheat chaff (control diet) was followed by an 8 day sampling phase. During this time three fermenters received the mycotoxin diet (64.9 mg DON/kg dry matter (DM) and 500 microg ZON/kg DM) and the remaining fermenters served as the controls (1.0mg DON/kg DM and 6 microg ZON/kg DM). Feed residues of the bags and samples of the effluent liquids were pooled per fermenter during the last 8 days of the experiment. Additionally, effluents of the mycotoxin fermenters were taken 6, 12 and 24h after the morning feeding on the first day of the sampling phase. The degradation of organic matter (OM; P<0.05), neutral detergent fibre (NDF; P<0.01) and protein (P<0.001) were increased by administration the Fusarium contaminated diet which was accompanied by an increased ammonia concentration (P<0.01) and increased butyrate (P<0.01), isobutyrate (P<0.01) and isovalerate (P<0.05) values of the mycotoxin effluents in relation to the controls. High proportions of ingested DON of 90% (85-93%) and ingested ZON of 93% (80-104%) were recovered at the pooled feed residues and effluents in form of DON and de-epoxy DON, and ZON and alpha-ZOL after administering the Fusarium toxin contaminated feed. While adsorption of DON as DON and de-epoxy DON in the feed particles was only minor (5%), a higher amount of 38% of ingested ZON was recovered as ZON and alpha-ZOL at the feed residues. The total recovery of DON plus de-epoxy DON in effluents as a percentage of DON intake reached 8%, 9% and 22% of ingested DON at 6, 12 and 24h after application of the contaminated diet the first time, whereby the recovery of de-epoxy DON as percentage of DON intake was only 5% at 24h. Concentrations of ZON and metabolites were lower than detection limits in the time dependent effluent samples.

Effect of total mixed ration composition on fermentation and efficiency of ruminal microbial crude protein synthesis in vitro

The goal of this study was to identify dietary factors that affect fermentation and efficiency of microbial crude protein (CP(M)) synthesis in the rumen in vitro. We used 16 total mixed, dairy cow rations with known digestibilities that varied in ingredient composition and nutrient content. Each ration was incubated in a Rusitec (n = 3) for 15 d, and fermentation of different fractions was assessed. Observed extents of fermentation in 24 h were 35 to 47% for organic matter, 25 to 60% for crude protein, 3 to 28% for neutral detergent fiber, and 31 to 45% for gross energy. Organic matter fermentation depended on the content of crude protein and neutral detergent fiber in the ration. We studied net synthesis of CP(M) using an 15N dilution technique and found that 7 d of continuous 15N application are needed to achieve an 15N enrichment plateau in the N of isolated microbes in this type of study. The efficiency of CP(M) synthesis was 141 to 286 g/kg of fermented organic matter or 4.9 to 11.1 g/MJ of metabolizable energy, and these ranges agree with those found in the literature. Multiple regressions to predict the efficiency of CP(M) synthesis by diet data showed that crude protein was the only dietary chemical fraction that had a significant effect. Fat content and the inclusion rate of corn silage in the ration also tended to improve efficiency. We suggest that microbial need for preformed amino acids may explain the crude protein effect. A large part of the variation in efficiency of microbial activity still remains unexplained.