Effects of feeding nutritionally balanced rations on animal productivity,feed conversion efficiency,feed nitrogen use efficiency,rumen microbial protein supply,parasitic load,immunity and enteric methane emissions of milking animals under field conditions

Milking animals produce milk commensurate with their genetic potential only when they are fed a nutritionally balanced ration in an amount that provides nutrients to express their genetic potential. As animals kept by smallholder farmers are rarely fed a balanced ration, a programme to feed balanced rations to animals of such farmers was launched in India. Based on their milk yield, the animals were categorized as: low (<8 kg/d), medium (8–12 kg/d) and high (>12 kg/d) yielders. Milk yield, milk fat and net daily income to milk producers were recorded before and after feeding a balanced ration. Nutritional status of animals showed that, for 71% of animals’, crude protein (CP) and metabolizable energy intakes were higher and, for 65% of animals’, calcium and phosphorus intakes were lower than requirements. Ration balancing improved milk yield by 2–14% and its milk fat proportion by 0.2–15%. Feed conversion efficiency, as kg of fat corrected milk (FCM)/kg of dry matter intake of buffaloes (n = 1131) before and after feeding balanced rations was 0.6 and 0.7, respectively, and in cows (n = 540) the values were 0.6 and 0.8. Dietary N secreted into milk increased from 0.16 to 0.25 and 0.16 to 0.19 in low and medium yielding cows and buffaloes, respectively. Rumen microbial CP synthesis also increased (P<0.05) by 36 and 38% in cows and buffaloes, respectively. On feeding balanced rations, levels (mg/ml) of plasma immunoglobulins IgG, IgM and IgA increased from 14.48 to 22.11, 2.69 to 3.29 and 0.48 to 0.67, and the parasitic load was reduced from 168 to 81 eggs/g of faeces. Enteric CH₄ emissions (g/kg milk yield) was reduced by 15–20% (P<0.05) in these lactating animals. Results demonstrate that feeding nutritionally balanced rations increased milk production and reduced enteric CH₄ emissions and N excretion from lactating cows and buffaloes. While implementation of a ration balancing programme under small holding systems is challenging, large scale use of this programme in tropical countries can help improve productivity of milking animals with available feed resources in an environmentally sustainable manner.     

Enhanced production of valienamine by Stenotrophomonas maltrophilia with fed-batch culture in a stirred tank bioreactor

Valienamine is an important medicinal intermediate with broad use in the synthesis of some stronger α-glucosidase inhibitors. In order to improve valienamine concentration in the fermentation broth and make the downstream treatment easy, a fed-batch process for the enhanced production of valienamine by Stenotrophomonas maltrophilia in a stirred tank bioreactor was developed. Results showed that supplementation of validamycin A in the process of cultivation could increase the valienamine concentration. One-pulse feeding was observed to be the best strategy. The maximum valienamine concentration of 2.35 g L⁻¹ was obtained at 156 h when 86.4 g of validamycin A was added to a 15-L bioreactor containing 8 L fermentation medium with one-pulse feeding. The maximum valienamine concentration had a great improvement and was increased above 100% compared to batch fermentation in the stirred tank bioreactor. The pH-controlled experiments showed that controlling the pH in the process of one-pulse feeding fermentation had not obvious effect on the production of valienamine.     

Production of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. TS1-1: Optimization of carbon and nitrogen concentration in the feed medium using central composite design

Optimisation of nutrient feeding was developed to overcome the limitation in batch fermentation and to increase the CGTase production from Bacillus sp. TS1-1 in fed batch fermentation. Optimisation of the C/N ratio in the feed stream was conducted in a 5 l fermenter, where feeding was initiated at constant rate of 0.02 h⁻¹. In our initial screening process, the addition of nitrogen source boosted the growth of the microbes, but on the other hand reduced the CGTase production. The amount of tapioca starch and yeast extract was optimised in order to obtain a sufficient growth and thus, increased the CGTase production. Results were analysed using three-dimensional response surface plot, and the optimised values of carbon and nitrogen concentration of 3.30% (w/v) and 0.13% (w/v) were obtained, respectively. CGTase activity increased up to 80.12 U/ml, which is 13.94% higher as compared to batch fermentation (70.32 U/ml). This also led to 14.54% increment of CGTase production in fed batch culture as compared to the production before the optimisation. The CGTase activity obtained was close to the predicted value, which is 78.05 U/ml.     

Use of different carbon sources in cultivation of recombinant Pichia pastoris for angiostatin production

To improve the growth of recombinant Pichia pastoris with a phenotype of Mut^S and expression of angiostatin, the effects of glycerol, sorbitol, acetate and lactic acid which were, respectively, added together with methanol in the expression phase, were studied in a 5-l fermentor. Methanol concentration was automatically controlled at 5 g/l by a methanol monitor and control system, while the feeding of the other carbon source was manually adjusted. The angiostatin production level was 108 mg/l when glycerol was added at an initial rate of 2.3 g/h and gradually increased to 9.9 g/h within an induction period of 96 h. The angiostatin concentration was 141 mg/l as sorbitol was used, while only 52 mg/l were obtained on acetate. The highest angiostatin production of 191 mg/l was achieved as lactic acid was used; whose feeding rate was gradually increased from 2.6 to 11.3 g/h. Lactic acid accumulated during the induction phase and reached 6.3 g/l at the end of fermentation. However, the accumulation of lactic acid did not interfere with angiostatin production, indicating that lactic acid to be a non-repressive carbon source. The average productivity and specific productivity of angiostatin obtained on lactic acid and methanol were, respectively, 2.96 and 0.044 mg/(g h), 1.7- and 2.5-fold of those obtained in the fermentation fed with glycerol and methanol.     

Effect of the supplementation of a high-concentrate diet with sunflower and fish oils on ruminal fermentation in sheep

This study was conducted to test the hypothesis that the supplementation of a high-concentrate diet with lipids, reportedly a good strategy for improving the nutritional value of ruminant-derived products, may not necessarily be associated with detrimental effects on ruminal fermentation in sheep. Four ruminally cannulated adult ewes were fed a high-concentrate diet, with no oil (Control diet), for a 14-day adaptation period. Afterwards, they were fed the same basal diet but supplemented with sunflower oil [20 g/kg fresh matter (FM)] and fish oil (10 g/kg FM) (SOFO diet) for a further 11 days, to investigate the impact of the addition of oils on the ruminal fermentation of the diet. On days 0 (Control), 3 and 10 of the experimental period rumen fluid was sampled at 0, 1.5, 3, 6 and 9 h after the morning feeding, for analysis of pH, and ammonia, lactate and total volatile fatty acid (VFA) concentrations. Alfalfa hay was incubated in situ, using the nylon bag technique, for 12 and 24 h to examine the effect of oil supplementation on ruminal disappearance of dry matter (DM), crude protein (CP) and neutral-detergent fibre (NDF). On days 0 and 11, rumen fluid was collected just before the morning feeding and used to incubate alfalfa hay and the Control and SOFO diets by means of the in vitro gas production technique. The mean concentrations of acetate (87.8 mmol/L vs. 73.7 mmol/L) and butyrate (21.2 mmol/L vs. 17.7 mmol/L) were reduced by oil supplementation (P < 0.05) and the total VFA showed a tendency (P = 0.098) to be lower with the SOFO diet (139.0 mmol/L vs. 122.1 mmol/L). However, none of the other in vivo ruminal fermentation parameters were affected by the treatment (P > 0.10). The oil supplementation affected neither in situ rumen disappearance of DM, CP and NDF of alfalfa hay, nor rates of gas production (P > 0.10). On the other hand, a little, but significant reduction in cumulative gas production was observed when the experimental diets were incubated with rumen fluid derived from animals fed the oil-rich diet (P < 0.05).Overall, the results suggest that the supplementation of high-concentrate diets with sunflower oil (20 g/kg FM) plus fish oil (10 g/kg FM) had little effect on ruminal fermentation and therefore its use to improve the nutritional value of ruminant-derived products cannot be precluded.     

Influence of supplemental enzymes on the performance and phosphorus excretion of broilers fed wheat-based diets to 6 weeks of age

Efficacies of phosphorolytic enzymes (phytase+acid phosphatase), and an enzymic “cocktail” (phytase+acid phosphatase+pectinase+citric acid), were investigated in broilers fed wheat-based diets from day 1 to 43. Broilers were fed the following four diets: (1) a positive control diet (7.1 g total P/kg, 4.1 g non-phytate P/kg, 9.8 g Ca/kg); (2) a low phosphorus diet (4.1 g total P/kg, 1.7 g non-phytate P/kg, 6.0 g Ca/kg) supplemented with phytase (750 units/kg) and acid phosphatase (3156 units/kg); (3), a low phosphorus diet (4.1 g total P/kg, 1.7 g non-phytate P/kg, 6.0 g Ca/kg) supplemented with phytase, acid phosphatase, pectinase (1900 units/g) and citric acid (20 g/kg); and (4) a low phosphorus diet (4.1 g total P/kg, 1.7 g non-phytate P/kg, 8.0 g Ca/kg) supplemented as in diet 3. For the grower period (22–43 days), the contents of P and Ca were lowered by 0.2 and 0.3 g/kg, respectively. The dietary treatments were fed to three floor pen replicates of 50 birds each. For the starter period, there were no differences observed among dietary treatments in terms of body weight gains or feed efficiency. Total body weight gains for the starter and grower periods did not differ among dietary treatments, but total feed efficiency was significantly enhanced in birds fed diet 2. At the completion of the experiment chickens fed phosphorolytic enzymes had the best feed efficiencies, the highest contents of ash in the toes, and the highest carcass yield. Chicken receiving the cocktail of enzymes and 8 g Ca/kg (diet 4) performed as well as birds in the control treatment, but had higher yields of carcass and excreted 56% less phosphorus.     

Mixed culture of Saccharomyces cerevisiae and Acetobacter pasteurianus for acetic acid production

Mixed culture of Saccharomyces cerevisiae and Acetobacter pasteurianus was carried out for high yield of acetic acid. Acetic acid production process was divided into three stages. The first stage was the growth of S. cerevisiae and ethanol production, fermentation temperature and aeration rate were controlled at 32 °C and 0.2 vvm, respectively. The second stage was the co-culture of S. cerevisiae and A. pasteurianus, fermentation temperature and aeration rate were maintained at 34 °C and 0.4 vvm, respectively. The third stage was the growth of A. pasteurianus and production of acetic acid, fermentation temperature and aeration rate were controlled at 32 °C and 0.2 vvm, respectively. Inoculation volume of A. pasteurianus and S. cerevisiae was 16% and 0.06%, respectively. The average acetic acid concentration was 52.51 g/L under these optimum conditions. To enhance acetic acid production, a glucose feeding strategy was subsequently employed. When initial glucose concentration was 90 g/L and 120 g/L glucose was fed twice during fermentation, acetic acid concentration reached 66.0 g/L.     

The influence of dry period feeding on liver fat and postpartum performance of dairy cows

Animal performances were monitored in 30 Friesean dry cows (18 multiparous, MP-cows and 12 primiparous, PP-cows) starting six weeks before calving to eight weeks after calving. The cows were kept indoors and fed individually with a prepartum diet containing either low, moderate or high energy (0.75, 1.00 or 1.25 of the calculated ME requirement) and supplemented with low (0.3 kg day⁻¹) or high (1.5 kg day⁻¹) rapeseed meal (RSM). The diets were consisted of 1.5 kg hay, 20–25 kg wilted grass silage and grain (barley and oat, 1 : 1 DM basis) with RSM. The average ME intake during six weeks of prepartum was 75, 97 and 123 MJ day⁻¹ on three different energy levels. After calving the cows were fed grass silage ad lib, 6.5 kg (primiparous) or 8.5 kg (multiparous) grain and 1.5 kg RSM. Liver biopsy and blood samples were taken to determine differences in metabolites due to diet and parity. Reduction of prepartum energy allowance to 0.75 of the moderate level did not affect the calf's birth weight and colostrum composition. Cows fed prepartum low energy–high rapeseed meal diet (LEHR) showed a faster increase in feed intake and milk production after parturition. Continuous low feed intake and milk production were observed in cows fed a prepartum high energy–low rapeseed meal diet (HELR). Milk yield was constantly lower for cows fed prepartum high energy diet, the difference being significant (p<0.01 and p<0.05) at six and seven weeks of lactation. Overall milk yield also showed a linear decrease with energy feeding level and an increase (p<0.10) with RSM feeding levels. Prepartum high energy feeding increased (p<0.01) milk protein content. Neither energy nor RSM feeding level affected the liver fat infiltration of the experimental cows. Cow parity however showed a significant influence on liver fat content, β-hydroxybutyrate (BHBA) and plasma glucose. A week before calving, the plasma concentration of essential amino acids (EAA) was lower for cows fed prepartum low energy diet. During the first four weeks of lactation, the concentrations of plasma non-esterified fatty acids (NEFA) and insulin were similar for all the treatment group.     

Enhancement of pilot scale production of l(+)-lactic acid by fermentation coupled with separation using membrane bioreactor

Traditional batch fermentation leads to a higher energy consumption and lower production capability because of longer culture time. In this work, a pilot scale bioreactor composed of a 3000 L fermentor and external ceramic microfiltration equipment was used to perform cell-recycle fermentation. Repeat feeding medium was also used to relieve the substrate inhibition. In such pilot system, the maximum yield and productivity of l(+)-lactic acid production reached 157.22 ± 3.42 g/L and 8.77 ± 0.15 g/L/h which were 4.23% and 315.64% higher than those of batch fermentation, respectively, when equal amount of sugar was consumed. The cost of l(+)-lactic acid production was successfully reduced about two-thirds by the increase of yield and productivity. 12 rounds of cell-recycle fermentations were successfully achieved in the pilot system. The membrane filtration productivity reached to 61.27 ± 2.74 L/m²/h which increased 172.80%, while the cell damaging rate dropped to 3.88 ± 0.18% which decreased 85.77%, compared with those of the ultrafiltration. Furthermore, the ceramic microfiltration membrane showed advantages in tolerance for the temperature, pressure and acid, compared with the organic ultrafiltration membrane. The experimental results indicated that the method could give a reference for low cost production of l(+)-lactic acid in an industrial scale.     

Fed-batch fermentation of recombinant Citrobacter freundii with expression of a violacein-synthesizing gene cluster for efficient violacein production from glycerol

The extensive prospects of violacein in the pharmaceutical industry have attracted increasing interest. However, the fermentation levels of violacein are currently inadequate to meet the demands of industrial production. This study was undertaken to develop an efficient process for the production of violacein by recombinant Citrobacter freundii. The effects of dissolved oxygen (DO) and pH on cell growth and violacein production in batch cultures were investigated first. When the DO and pH of the medium were controlled at around 25% and 7.0, respectively, the biomass and concentration of violacein were maximized. Based on the consumption of nutrients in the medium observed during batch culture, a fed-batch fermentation strategy with controlled DO and pH was implemented. By continuously feeding glycerol, NH₄Cl, and l-tryptophan at a constant feeding rate of 16 mL h⁻¹, the final concentration of violacein reached 4.13 g L⁻¹, which was 4.09-fold higher than the corresponding batch culture, and the maximal dry cell weight (DCW) and average violacein productivity obtained for the fed-batch culture were 3.34 g DCW L⁻¹ and 82.6 mg L⁻¹ h⁻¹, respectively. To date, this is the first report on the efficient production of violacein by genetically engineered strains in a fermentor.     

Xylitol production from non-detoxified corncob hemicellulose acid hydrolysate by Candida tropicalis

The interest on use of lignocellulose for producing chemicals is increasing as these feedstocks are low cost, renewable and widespread sources of sugars. Corncob is an attractive raw material for xylitol production due to its high content of xylan. In this study, hemicellulose hydrolysate from corncobs without detoxification was used for xylitol production by Candida tropicalis CCTCC M2012462. Compared with prepared xylose medium, xylitol production with dilute acid hydrolysate medium does not seem to influence specific xylose reductase activity. The decrease in xylitol productivity with dilute acid hydrolysate medium is a result of a lower biomass concentration and lag-phase time. It appears that biomass growth rate is essential for xylitol production. In xylitol fermentation with a low initial inhibitors concentration and substrate feeding strategy, a maximal xylitol concentration of 38.8 g l⁻¹ was obtained after 84 h of fermentation, giving a yield of 0.7 g g⁻¹ xylose and a productivity of 0.46 g l⁻¹ h⁻¹.     

High production of poly-β-hydroxybutyrate (PHB) by an Azotobacter vinelandii mutant altered in PHB regulation using a fed-batch fermentation process

A mixed fermentation strategy based on exponentially fed-batch cultures (EFBC) and nutrient pulses with sucrose and yeast extract was developed to achieve a high concentration of PHB by Azotobacter vinelandii OPNA, which carries a mutation on the regulatory systems PTSNtr and RsmA-RsmZ/Y, that negatively regulate the synthesis of PHB. Culture of the OPNA strain in shake flaks containing PY-sucrose medium significantly improved growth and PHB production with respect to the results obtained from the cultures with the parental strain (OP). When the OPNA strain was cultured in a batch fermentation keeping constant the DOT at 4%, the maximal growth rate (0.16 h⁻¹) and PHB yield (0.30 g_PHB g_Suc⁻¹) were reached. Later, in EFBC, the OPNA strain increased three fold the biomass and 2.2 fold the PHB concentration in relation to the values obtained from the batch cultures. Finally, using a strategy of exponential feeding coupled with nutrient pulses (with sucrose and yeast extract) the production of PHB increased 7-fold to reach a maximal PHB concentration of 27.3 ± 3.2 g L⁻¹ at 60 h of fermentation. Overall, the use of the mutant of A. vinelandii OPNA, impaired in the PHB regulatory systems, in combination with a mixed fermentation strategy could be a feasible strategy to optimize the PHB production at industrial level.     

Effect of polyethylene glycol,urea and sunflower meal on olive (Olea europaea var. europaea) leaf fermentation in continuous fermentors

A continuous culture system, inoculated with rumen liquor from goats or sheep, was used to study fermentation characteristics of olive leaves (OL). The effects of adding polyethylene glycol (PEG 4000 MW; 0, 2 or 20 g/100 g OL) and/or supplementing with urea (U) or sunflower meal (SM) (1.0 g N/100 g OM) were also studied. Olive leaf fermentation promoted low VFA production (35.2 mmol/d), predominantly of acetic acid, and low efficiency of VFA production (4.91 mol/kg digestible carbohydrates, DCHO). Both values increased with N supplementation, but effects of PEG were variable. No differences ascribed to the rumen inoculum origin were observed. The ammonia N concentration was increased only by supplementation with U. Total and amino acid N output was low and increased with N addition, but it was not affected by PEG treatment. No differences ascribed to the inoculum origin were observed concerning microbial N production rate or efficiency (g N/kg DCHO). There was no clear difference between sources of supplementary N regarding bacterial protein synthesis. On the basis of PEG results, the effect of tannins on OL fermentation was not important.     

Mycophenolic acid production in solid-state fermentation using a packed-bed bioreactor

Mycophenolic acid (MPA) was produced from Penicillium brevicompactum by solid-state fermentation (SSF) using pearl barley, and submerged fermentation (SmF) using mannitol. It was found that SSF was superior to SmF in terms of MPA concentration (1219 mg/L vs. 60 mg/L after 144 h fermentation), and the product yields were 6.1 mg/g pearl barley for SSF and 1.2 mg/g mannitol for SmF. The volumetric productivities were 8.5 and 0.42 mg/L h for SSF and SmF, respectively.The optimum solid substrate of SSF for MPA production was pearl barley, producing 5470 mg/kg compared with wheat bran (1601 mg/kg), oat (3717 mg/kg) and rice (2597 mg/kg). The optimum moisture content, incubation time and inoculum concentrations were 70%, 144 h and 6%, respectively. Neither the addition of mannitol or (NH4)₂HPO₄ nor adjustment of media pH within the range of 3–7 significantly enhanced MPA production.MPA production by SSF using a packed-bed bioreactor was performed and an increased maximum production of MPA 6.9 mg/g was achieved at 168 h incubation time. The higher volumetric productivity and concentrations makes SSF an attractive alternative to SmF for MPA production.     

Varying endophyte status and energy supplementation of fresh tall fescue in continuous culture

Eight dual-flow continuous culture vessels (700 ml) were used to compare in vitro effects of toxic, endophyte-infected (E+), endophyte-free (E−), and non-toxic, endophyte-infected (EN) Jesup tall fescue (vegetative stage) on ruminal fermentation at 4 levels (0, 150, 300, and 450 g kg⁻¹ DM) of concentrate supplementation (ground corn) for a total of 12 experimental diets in a randomized incomplete block design with 2 replicates. Each culture vessel was offered a total of 15 g DM d⁻¹. Forage was fed in four equal portions (fed at 03:00, 09:00, 15:00, and 21:00 h); and corn was fed in two equal portions (fed at 09:00 and 21:00 h). Headspace gas and liquid samples were analyzed for methane, ruminal culture pH, ammonia–N, and volatile fatty acid production. Ammonia–N output (g d⁻¹) varied by grass; EN had lower values compared to those of E+ and E−. Increasing the level of grain linearly decreased ruminal culture pH, ammonia–N, acetate production, and the acetate-to-propionate ratio, whereas propionate and butyrate production increased with higher grain supplementation. Ruminal fermentation was minimally altered by the presence of the endophyte; however, for the highest level of grain fed (450 g kg⁻¹ DM fed) the methane production pattern for all three grasses was altered. In addition to having the lowest ruminal ammonia–N accumulation, the non-toxic, endophyte-infected fescue resulted in the lowest methane production measured.     

Estimation of the phosphorus requirement of weanling pigs fed supplemental phytase

Studies were conducted with crossbred weanling pigs to determine the level of phosphorus needed to be fed when a maize–soyabean meal–whey diet was supplemented with exogenous phytase (Natuphos™). In Trial 1, phytase was added at 1200 phytase units (PTU) kg⁻¹ as phosphorus decreased. The control diet in Phase I (0–14 days) contained 7.3 g kg⁻¹ phosphorus and in Phase II (14–28 days) contained 6.5 g kg⁻¹ phosphorus. Dietary phosphorus was calculated to decrease by 0.8, 1.6 or 2.4 g kg⁻¹ when phytase was supplemented. Chromic oxide was added for estimation of apparent absorption of phosphorus. Performance was optimum when 5.7 and 4.8 g kg⁻¹ phosphorus (analysed levels) were fed with 1200 PTU kg⁻¹ phytase in Phases I and II, respectively. The lowest dietary phosphorus levels did not reduce performance for the overall 28-day period. Apparent phosphorus digestibility was increased by phytase in Phase I when 5.7 g kg⁻¹ phosphorus was fed compared to the control diet and in Phase II when 6.0 g kg⁻¹ phosphorus was fed with phytase. Faecal phosphorus excretion decreased in both phases as dietary phosphorus decreased. Faecal phosphorus excretion was minimized at the lowest phosphorus level with no decrease in performance. The estimated requirement for dietary phosphorus, as determined by the NLIN procedure, is 5.0 g kg⁻¹ in Phase I and 4.3 g kg⁻¹ in Phase II when 1200 PTU kg⁻¹ is used. In Trial 2, phytase was supplemented at 500 PTU kg⁻¹ when phosphorus was decreased in the diet. The control diet contained 6.6 and 6.0 g kg⁻¹ phosphorus in Phases I and II, respectively, and phosphorus was calculated to decrease by 0.5, 1.0, 1.5, or 2.0 g kg⁻¹ when phytase was added. Daily gain decreased when 5.0 g kg⁻¹ phosphorus was fed in Phase I and when 4.6 or 4.2 g kg⁻¹ (analysed levels) phosphorus was fed in Phase II with 500 PTU kg⁻¹. Faecal phosphorus excretion decreased as dietary phosphorus decreased, but there were no treatment effects on apparent phosphorus digestibility. The dietary phosphorus requirement was estimated to be 5.7 and 5.0 g kg⁻¹ in Phases I and II, respectively, when phytase is fed at 500 PTU kg⁻¹. At the present recommendation of 500 PTU kg⁻¹ in starter feed, phosphorus can be decreased by 0.10 g kg⁻¹. However, higher levels of phytase are needed to actually increase apparent phosphorus digestibility.     

Liquid state fermentation of apple pomace sludge for the production of ligninolytic enzymes and liberation of polyphenolic compounds

Ligninolytic enzyme production and polyphenolic compound extraction by liquid-state culture of Phanerochaete chrysosporium ATCC 24275 was investigated by employing apple pomace sludge and synthetic medium. Different physico-chemical and biological parameters namely viscosity, zeta potential and particle size, viability and enzyme production were investigated. The ligninolytic enzyme production was higher in apple pomace sludge (45 U/l of laccase, 220 U/l of MnP and 6.5 U/l of LiP) than in synthetic medium (17 U/l of laccase, 37 U/l of MnP and 6 U/l). These maximal activities were found during the stationary and decline phase. It was also found that enzyme production was strongly correlated with P. chrysoporium viability in both synthetic medium and apple pomace sludge. Moreover, physico-chemical parameters, such as particle size, zeta potential and viscosity were strongly correlated to the viability of P. chrysosporium and to the ligninolytic enzyme production. An increase in polyphenol content extracted by acetone (383–720 mg GAE/l) was observed during fermentation of apple pomace and it was found that the polyphenol content extracted by ethanol increased ～1.5 fold until 67 h of fermentation and later it decreased. It was found that antioxidant activity increased to 35% and eventually decreased based on the change in the polyphenol content.     

Effects of yeast culture (Saccharomyces cerevisiae) on ruminal digestion in non-lactating dairy cows

Six non-lactating dairy cows fitted with ruminal cannulas were used in a cross-over design, to investigate the effects of supplemental yeast culture (Saccharomyces cerevisiae) (YC) and interaction of YC by sampling time on ruminal fermentation and in situ fibre degradation. Cows were fed twice daily with a diet composed of 67% corn silage, 32% concentrate and 1% vitamin and mineral mixture, on a dry matter (DM) basis. Concentrates were not mixed with silage. YC (0.5% DM) significantly decreased rumen ammonia from 148.5 mg l⁻¹ to 103.1 mg l⁻¹ 3 h post-feeding, and significantly increased by about 20% the concentration of total volatile fatty acids before and 1 h after feeding. YC significantly increased molar percentage of propionate and decreased the acetate : propionate ratio before feeding. No significant effect was observed on ruminal pH and molar percentages of acetate or butyrate. Pattern of degradation of DM, neutral and acid detergent fibre from hay was affected, with a cubic effect of interaction of YC by incubation time. However, magnitude of degradation was not significantly different at any time. These results show that modifications of ruminal fermentation due to YC addition are time dependent when the diet is fed twice daily.     

Nutrient control for stationary phase cellulase production in Trichoderma reesei Rut C-30

This work describes the use of nutrient limitations with Trichoderma reesei Rut C-30 to obtain a prolonged stationary phase cellulase production. This period of non-growth may allow for dependable cellulase production, extended fermentation periods, and the possibility to use pellet morphology for easy product separation. Phosphorus limitation was successful in halting growth and had a corresponding specific cellulase production of 5 ± 2 FPU/g-h. Combined with the addition of Triton X-100 for fungal pellet formation and low shear conditions, a stationary phase cellulase production period in excess of 300 h was achieved, with a constant enzyme production rate of 7 ± 1 FPU/g-h. While nitrogen limitation was also effective as a growth limiter, it, however, also prevented cellulase production.     

The effect of gas double-dynamic on mass distribution in solid-state fermentation

The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5 °C and 2.48 mg/(h g) under static aeration solid-state fermentation (SASSF) and 33.9 °C and 5.38 mg/(h g) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30 ± 1 °C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products.