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.     

Effect of rare earth elements on in vitro rumen microbial fermentation and feed digestion

The objectives of this study were to investigate the effects of rare earth elements (REEs) on in vitro rumen fermentation, gas production, microbial protein synthesis and nutrient digestion using in vitro batch culture and continuous culture technique. A mixture of REE containing (g/kg) 380 g of LaCI₃·6H₂O, 521 g of CeCI₃·6H₂O, 30 g of PrCI₃·6H₂O and 69 g chlorides of other light REEs. The experimental diet consisted of 885 g/kg barley grain, 84 g/kg barley silage and 31 g/kg supplement (dry matter (DM) basis). Diet supplemented with different dosages of REE (control, no additional REE; low, 400 mg/kg REE; and high, 800 mg/kg REE, DM basis) were incubated for 4, 8, 14 and 24 h in diluted rumen fluid. At the end of 24 h of incubation, gas production and concentration of volatile fatty acid (VFA) linearly increased with increasing REE supplementation; whereas, influence of REE supplementation on VFA profile was marginal. Dry matter disappearance was not affected (P>0.10). Six dual-flow continuous culture fermenters were used in a replicated 3 × 3 Latin square with same treatments and same diet used in the batch culture. Mean ruminal pH (5.71) and total VFA (93.6 mM) concentration were not affected by supplementation of REE. The molar proportion (mol/100 mol) of acetate (39.1) and propionate (50.5) was similar among the treatments. However, the proportion (mol/100 mol) of butyrate was higher with the high REE (6.6) than with low REE (5.3) or the control (5.8). Ruminal true digestibilities of organic matter (OM) (0.785, 0.811 and 0.828), acid detergent fibre (0.360, 0.431 and 0.432) and crude protein (0.496, 0.590 and 0.589) for control, low and high REE, respectively, linearly increased with increasing REE supplementation, whereas, the increase in ruminal digestibility from low to high dosage of REE was minimal. Microbial nitrogen (N) production (g/day) and microbial efficiency (g N/kg of truly fermented OM) were not affected by treatments. Improvement of ruminal digestibility of OM due to REE supplementation was attributed to the increase in digestibility of fibre and degradability of protein. The results suggest that REE supplementation improved ruminal fibrolytic and proteolytic activities.     

Effect of by-product gypsum application rate to grass pasture,grass hay,and corn silage on fermentation by rumen microorganisms in continuous culture

A dual-flow continuous culture fermenter system was used to investigate ruminal fermentation in response to increased by-product gypsum application rate of three forages. The treatments included 0, 22, 45, and 90 tonnes/ha by-product gypsum applied to grass plots and 0, 22, and 45 tonnes/ha by-product gypsum applied to corn plots. Forage was harvested to represent grass pasture (GP), grass hay (GH), and corn silage (CS), dried, ground, and fed to fermenters at a rate of 60 g dry matter (DM)/day. Organic matter (OM) and neutral detergent fiber (aNDF) digestibilities, rumen pH, total volatile fatty acid (VFA) production, and N metabolism were not affected by gypsum application rate for all forage types. The GH had greater sulfur content than recommended as the maximum tolerable level by the National Research Council (NRC). The results of this study indicate that ruminal fermentation was not compromised when by-product gypsum was applied to GP, GH, or CS at rates up to 90 tonnes/ha. By-product gypsum application to pastures and crops shows promise as an economical soil amendment to reduce dissolved phosphorus loss in runoff, although potential animal health issues should be further evaluated.     

Lactobacillus plantarum effects on silage fermentation and in vitro microbial yield

In four parallel experiments, herbage [three harvests of alfalfa (308 to 379 g dry matter (DM)/kg), one of whole-plant corn (331 g DM/kg)] was ensiled with three different treatments: no inoculant (control), Lactobacillus plantarum (LP) or formic acid (FA), in 1-L mini-silos and fermented for 60 d at room temperature (22 °C). Mini-silos were opened and analyzed for fermentation characteristics and soluble N fractions. A subsample of wet silage from each mini-silo was ground to 4 mm and stored at ?20 °C. Silages were thawed and subjected to 9 h ruminal in vitro incubations to measure gas production and volatile fatty acid (VFA) production as well as microbial biomass yield (MBY) and microbial non-ammonia N (MNAN) formation using ¹⁵N as a marker. In all four experiments, silage fermentation products and pH indicated good preservation across all treatments. Analysis of data showed that FA- and LP-treated silages had lower concentrations of ammonia-N and free amino acids N than control. The FA treatment was lower in soluble N, but higher in peptide-N, than control. Silage pH was lowest in FA (4.25), followed by LP (4.28), and control (4.38). Ruminal in vitro gas production and VFA concentrations were not different among treatments (P>0.05). Compared to control, FA- and LP-treated silage yielded greater MNAN and MBY. These findings suggested that L. plantarum preserved more true protein during silage fermentation than control, which in turn increased in vitro ruminal microbial growth.     

Effects of dose and adaptation time of a specific blend of essential oil compounds on rumen fermentation

Essential oils can be used as natural additives in animal feeds. The present study evaluated the effects of three different doses and different adaptation times of a specific blend of essential oils (BEO) on rumen microbial fermentation. Eight dual flow continuous culture fermenters (1320 ml) were used in two periods of 9 days each to study the effects of increasing doses of BEO. Treatments were: CTR (no BEO), D5 (5 mg/l of BEO), D50 (50 mg/l of BEO) and D500 (500 mg/l of BEO). During the last 3 days, samples were taken at 0, 2, 4 and 6 h after the morning feeding and analyzed for large peptide (LPep), small peptides plus amino acid (SPep + AA) and ammonia N concentrations, and at 2 h after feeding for volatile fatty acids (VFA) concentration and profile. The D5 increased total VFA concentration, acetate proportion and acetate to propionate ratio, and decreased propionate and valerate proportion, compared with CTR. The concentration of LPep N tended (P=0.08) to be lower for D5 compared with CTR. In the second experiment, eight sheep were used to study the effects of long-term adaptation of rumen fluid to BEO on ruminal fermentation. Four sheep were assigned at random to the CTR treatment (no BEO) and four sheep were adapted to BEO (110 mg/day of BEO) for 4 weeks (ADBEO). After 4 weeks samples of ruminal fluid were obtained at 0 and 3 h after the morning feeding and in 2 consecutive days using an oro-ruminal probe. Samples were analyzed for LPep, SPep + AA and ammonia N concentrations, total and individual VFA, and pH. Treatment ADBEO tended (P<0.10) to increase acetate proportion and decrease valerate proportion, compared with CTR. Ruminal fluid collected from each of CTR and ADBEO sheep was used to study in vitro fermentation profile of soybean meal, corn meal, alfalfa hay and ryegrass hay. Treatments were: Control fluid (CTR without BEO), CTR fluid plus a single dose of BEO (11 mg/l; CTR + BEO) and ADBEO fluid plus a single dose of BEO (11 mg/l; ADBEO + BEO). Acetate proportion and acetate to propionate ratio was higher, and propionate and isovalerate proportion, and BCVFA and ammonia N concentration were lower in ADBEO + BEO fluid compared with CTR fluid. The addition of essential oils can shift the microbial fermentation in the rumen by increasing the acetate to propionate ratio and inhibiting deamination.     

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.     

Effects of dietary whole cottonseed and crude protein level on rumen protozoal population and fermentation parameters

In this investigation in vitro and in vivo trials were performed to determine the efficacy of a cottonseed to limit protozoal population and fermentation parameters. The composition of diets given to the different treatments were as follow: (1) control (without whole cottonseed), 16% crude protein (CP), 3.2% ether extract (E.E.); (2) 20% whole cottonseed, 16% CP, 6.5% E.E.; (3) 20% whole cottonseed, 13% CP, 6.4% E.E. and (4) 20% crushed whole cottonseed, 13% CP, 6.4% E.E. DM disappearance (DMD) and fermentation characteristics of the treatments were determined by in vitro incubation studies. In the in vivo trial, ruminal fluid was taken by rumenocentesis (3 h after feeding) on days 1, 3, 5, 7, 9, 11, 14, 21 and 28 from four sheep fed about treatment diets. The pH and protozoal counts were determined in each sample, while ammonia nitrogen and volatile fatty acid (VFA) were determined in samples taken on days 7, 14, 21 and 28. The in vitro DMD after 24 h incubation decreased (p < 0.01) with the addition of cottonseed in diets 3 and 4 and DMD after 72 h incubation was highest (p < 0.01) for the control diet. The fractional rate of gas production (c) for the control and diet 2 was higher (p < 0.05) than for the diets 3 and 4. Feeding crushed whole cottonseed decreased molar proportion of propionate (p < 0.05) and increased molar proportion of butyrate (p < 0.01). Low crude protein level increased the molar proportion of propionate (p < 0.05) and decreased molar proportion of butyrate (p < 0.05) and cellolytic protozoa population (p < 0.05). Feeding cottonseed decreased (p < 0.05) the total protozoa population from approximately 500,000 to 250,000 ml⁻¹ and Holotrich and cellulolytic protozoa disappeared from the rumen of sheep and only Entodinium sp., remained. This was associated with lower concentration of ammonia nitrogen in rumen fluid of sheep fed diets 4 (p < 0.05) and 2 (p < 0.01). It was concluded that cottonseed reduced rumen fauna and ammonia nitrogen, but had no effect on ruminal VFA while the crushed whole cottonseed decreased molar proportion of isovalerate only. In vivo molar proportion of propionate and butyrate and valerate were increase and decrease, respectively, by decreasing CP percentage in treatment diets.     

Batch culture evaluation of carbohydrase inhibitors to moderate rumen fermentation

While carbohydrase inhibitors have been widely investigated for regulating human carbohydrate assimilation, their potential application to animal nutrition has been largely ignored. Batch culture fermentations were conducted to determine how commercially available α-amylase and α-glucosidase inhibitors affect rumen fermentation. Fermentations were with 0.5 g of ground corn grain, and 40 mL of buffered rumen fluid inoculum. Rumen fluid donors were fed a 0.5 concentrate 0.5 forage diet. Incubations were conducted in duplicate and replicated on consecutive days with pH and volatile fatty acid (VFA) concentrations measured. The microbial-derived inhibitors, acarbose (ACB) and trestatin (TRE), prevented the decreases in pH and VFA production observed in the control tubes at doses of 1.2–9.5 and 0.1–1.1 mg, respectively. Miglitol, glipizide, and the plant-derived amylase inhibitors failed to affect pH or reduce VFA concentrations with the same apparent potency as did ACB and TRE, which both show the potential to reduce the amount of starch fermented in the rumen. These compounds may be potentially useful for reducing ruminal acid production and allowing more starch to pass to the small intestine from the forestomachs.     

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.     

Rumen enzyme profile and fermentation characteristics in sheep as affected by treatment with sodium lauryl sulfate as defaunating agent and presence of ciliate protozoa

The efficiency of sodium lauryl sulfate as a defaunating agent and effect of rumen protozoa on nutrient utilization, fermentation characteristics and enzyme profile were evaluated in adult sheep maintained on a mixed ration containing 65:35% Pala (Ziziphus numularia) leaf: concentrate. Twenty-one adult Malpura sheep divided into three equal groups (DF, RF and F) were either defaunated by oral administration of sodium lauryl sulfate at the rate of 8 g/100 kg body weight (DF), or defaunated and again refaunated (RF), or maintained faunated (F). Daily dry matter intake was similar in defaunated, refaunated and faunated sheep. However, digestibility of cell wall and cell wall contents (NDF, ADF and cellulose) were lower (P < 0.01) in defaunated than refaunated and faunated sheep. Irrespective of the presence or absence of rumen protozoa, daily intake of DCP and DE were similar in the three experimental groups. Even with similar DM, DCP and DE intake, N-retention, blood glucose level, ruminal concentration of total VFA and total-N were higher (P < 0.01), while rumen pH and NH₃-N concentration were lower (P < 0.01) in defaunated sheep. Ruminal activity of amylase, xylanase, protease and urease enzymes were not influenced by presence or absence of ciliate protozoa. However, carboxymethyl cellulase enzyme activity was lower (P < 0.01) in the rumen of defaunated sheep. The total and differential counts of rumen protozoa were similar in refaunated and faunated sheep indicating lack of residual toxic effect of sodium lauryl sulfate. It is concluded that absence of ciliate protozoa increased ruminal TVFA, total-N with lower NH₃-N concentration and fibre digestibility in sheep. Moreover, sodium lauryl sulfate was fully effective for complete removal of rumen ciliate protozoa and successfully defaunated the sheep.     

Effect of elemental nano-selenium on feed digestibility,rumen fermentation,and purine derivatives in sheep

The objective of this experiment was to study the effect of elemental nano-selenium (NS) on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Eight male ruminally cannulated sheep (42.5 ± 3.2 kg of body weight, BW) were used in a replicated 4×4 Latin square experiment in four 20 day periods. Depending on treatment designation, sheep were fed the basal diet supplemented with 0 (control), 0.3, 3 and 6 g of nano-Se/kg dry matter (DM). Ruminal pH (range of 6.68–6.80) and ammonia N concentration (range of 9.95–12.49 mg/100 mL) was decreased (P<0.01), and total VFA concentration (range of 73.63–77.72 mM) was increased linearly (P<0.01) and quadratically (P<0.01) with increasing nano-Se supplementation. The ratio of acetate to propionate was linearly (P<0.01) and quadratically (P<0.01) decreased due to the increasing of propionate concentration. In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis and crude protein (CP) of soybean meal were linearly (P<0.01) and quadratically (P<0.01) improved by feeding nano-Se. Similarly, nutrients digestibility in the total tract and urinary excretion of purine derivatives were also quadratically (P<0.01) changed by increasing nano-Se supplementation. The present results indicated that nano-Se supplementation in basal diet improved rumen fermentation and feed utilization. Nano-Se could also stimulate rumen microbial activity, digestive microorganisms or enzyme activity. The optimum dose of nano-Se was about 3.0 g/kg dietary DM in sheep.     

Ruminal large and small particle kinetics in dairy cows fed red clover and grass silages harvested at two stages of growth

Passage, comminution and digestion rates of large and small particles were estimated using a rumen evacuation technique and total faecal collection with five lactating dairy cows in a 5 × 5 Latin square experiment. Two grass and two red clover silages harvested at early and late primary growth stages and a 1:1 mixture of late harvest grass and early harvest red clover were the dietary treatments. Cows received 9.0 kg supplementary concentrate per day. Ruminal contents and faeces were divided into large (>1.25 mm) and small (1.25–0.038 mm) particles by wet sieving. Indigestible neutral detergent fibre (iNDF) was determined by 12 days ruminal in situ incubation followed by neutral detergent extraction. Plant species did not affect ruminal particle size distribution, whereas advancing forage maturity decreased the proportion of large particles for both grass and red clover silage diets. Ruminal pool size of iNDF was higher (P<0.001) with red clover compared to grass silage diets. Ruminal passage rates of iNDF and potentially digestible NDF (pdNDF) increased with decreasing particle size (P<0.01). Passage rate of iNDF for small particles was slower (P<0.01) when red clover compared to grass silage diets were fed. Particle comminution rate in the rumen was slower (P<0.001) with red clover compared to grass silage diets and it increased (P<0.01) with advancing forage maturity. The contribution of particle comminution to ruminal mean retention time of iNDF in the ruminal large particle pool was smaller (P<0.01) in red clover compared to grass silage diets and it increased (P<0.05) with the mixed silage compared to the separate silages. Passage rate of pdNDF for both large and small particles was not affected by dietary treatments. Digestion rate of pdNDF for large particles was faster (P<0.001) with red clover compared to grass silage diets. Differences in ruminal passage and digestion rates of the large and small particles, in addition to differences in the passage and digestion rates of red clover compared to grass silage diets, emphasize the need to consider particle size and forage type in metabolic models predicting feed intake and fibre digestibility in ruminants.     

Influences of flavomycin,ropadiar, and saponin on nutrient digestibility,rumen fermentation,and methane emission from sheep

This study focused on the effects of three additives given together with a hay/concentrate-based diet on nutrient digestibility, rumen fermentation, and methane emission from sheep. The basal diet consisted of 1.29 kg mixed hay and 0.43 kg concentrate mixture based on dry matter (DM). Treatments consisted of control (no additive), flavomycin⁴⁰ (250 mg/d), ropadiar from an oregano extract (250 mg/d), and saponin in the form of a yucca schidigera extract (170 mg/d). Results indicated that intake and digestibility were unaffected by treatments (P>0.05). The NH₃-N concentration of rumen liquor was lower (P<0.05) for additive treatments versus the control treatment. Higher concentrations of volatile fatty acid (VFA) were observed in the saponin (75.8 mmol/L) and ropadiar (73.1 mmol/L) treatments. The proportion of individual fatty acid of rumen liquor was unchanged, whereas lower ratio of acetate to propionate in the saponin treatment was observed (P<0.05). The average methane production expressed on digested organic matter (OM) and neutral detergent fiber (aNDFom) basis were decreased by approximately 3.3 and 12.0 g/kg, respectively in saponin, and 4.2 and 11.9 g/kg in ropadiar treatment compared to the control. Methane production was positively correlated with the concentrations of NH₃-N, and negatively correlated with total VFA and the proportion of propionate of rumen liquor (P<0.05). The study found that saponin and ropadiar could have the potential to reduce rumen methanogenesis in sheep.     

PEGylated chitosan complexes DNA while improving polyplex colloidal stability and gene transfection efficiency

Chitosan is widely explored as a gene delivery vehicle due to its ability to condense DNA, facilitate transport, and subsequent release allowing gene expression, as well as protecting the DNA. Here, we investigate the enhancement of chitosan–DNA dispersion stability while maintaining transfection efficacy by PEGylation of chitosan. Molecular properties of fully deacetylated chitosans and degree of PEGylation were investigated with respect to compaction of DNA, stability and transfection efficacy. Each of the three chitosan samples with varying chain lengths was PEGylated at three different degrees. The chitosans with degree of PEGylation from 0.6 to 1.9% made polyplexes with DNA. PBS induced colloidal aggregation of polyplexes with initial radius of about 100 nm observed for nonPEGylated chitosans was suppressed for 1.9% PEGylated chitosans. The observed increase in transfection efficacy coinciding with increased polyplex colloidal stability suggests that aggregation of gene-delivery packages may reduce the transfection efficacy.     

Assessment of the efficacy of varying experimental exogenous fibrolytic enzymes using in vitro fermentation characteristics

This study evaluated a series of recombinant, single activity experimental enzyme products including 13 endoglucanases (END) and 10 xylanases (XY), for their potential to improve in vitro ruminal degradation of alfalfa hay in two experiments. Based on the endoglucanase or xylanase enzymatic activities measured using complex substrates at the optimal conditions (pH 5.4, 37 °C) for the enzymes, a dose level (1 unit/g dry matter [DM]) was chosen for addition of enzymes to substrate. Enzyme products, re-suspended with water, were added to alfalfa hay (0.5 or 1.0 g DM) in culture vials in six replications. Anaerobic buffer medium (20 or 40 ml) adjusted to pH 6.0 and strained ruminal fluid (5 or 10 ml) were sequentially added to the vials and incubated for 18 h. Headspace gas production (GP) was measured throughout the incubation, and degradability of organic matter (OMD) and fibre and volatile fatty acid (VFA) concentrations were determined after 18 h of incubation. The enzyme products had a wide range of added endoglucanase or xylanase activities when determined using pure substrates and physiological conditions typical of the rumen (pH 6.0, 39 °C). In experiment 1, many END, and some XY, products increased GP and OMD. The correlation between added endoglucanase activity determined at ruminal conditions and OMD improvement was high (r = 0.71; P<0.01), whereas added activity of xylanase was not associated with OMD improvement. Two END and two XY products selected from experiment 1 were further assessed because they substantially improved GP and OMD. In experiment 2, all enzyme treatments, alone or in combination, increased total GP and DM and fibre degradabilities (P<0.05). However, the combinations of END and XY did not increase degradation of alfalfa beyond that of the component enzymes. Total VFA production was not affected by enzyme treatments although some products changed the acetate to propionate ratio. Experimental exogenous enzyme products with either endoglucanase or xylanase activity substantially improved in vitro ruminal degradation of alfalfa hay, but further improvement by combining these activities did not occur.     

Physicochemical characterization of chitin and chitosan from crab shells

Crab chitosan was prepared by alkaline N-deacetylation of crab chitin for 60, 90 and 120 min and the yields were 30.0-32.2% with that of chitosan C120 being the highest. The degree of N-deacetylation of chitosans (83.3–93.3%) increased but the average molecular weight (483–526 kDa) decreased with the prolonged reaction time. Crab chitosans showed lower lightness and WI values than purified chitin, chitosans CC and CS but higher than crude chitin. With the prolonged reaction time, the nitrogen (8.9–9.5%), carbon (42.2–45.2%) and hydrogen contents (7.9–8.6%) in chitosans prepared consistently increased whereas N/C ratios remained the same (0.21). Crab chitosans prepared showed a melting endothermic peak at 152.3–159.2 °C. Three chitosans showed similar microfibrillar crystalline structure and two crystalline reflections at 2θ = 8.8–9.0° and 18.9–19.1°. Overall, the characteristics of three crab chitosans were unique and differed from those of chitosan CC and CS as evidenced by the element analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction patterns.     

Effects of formic acid,molasses and inoculant additives on corn silage composition,organic matter digestibility and microbial protein synthesis in sheep

This study examined the production of com silages with low or high lactic acid concentrations, provided by the addition of formic acid (0.5%), molasses (5%) or microbial inoculant (homofermentative lactic acid bacteria, 10 g/tonne). After the fermentation period, sheep were fed the silages to determine true and apparent digestibility of the organic matter and microbial protein synthesis. The experiment were carried out with four KıvırcıkxMorkaraman sheep, 1.5 years old, fixed with cannula in their rumen and duodenum.Lactic acid concentrations were significantly higher in silages treated with enzyme or molasses compared to other specific treatments. Acetic acid concentration was highest in silage treated with formic acid, and lowest in silage treated with molasses (P < 0.05). The by-pass of crude protein was highest in silage treated with formic acid.     

In situ degradability of seven plant protein supplements in heifers fed high concentrate diets with different forage to concentrate ratio

Four Holstein heifers (297.5 ± 27.7 kg BW) fed high concentrate diets were used in a crossover experiment in order to characterize the rumen fermentation pattern, and to estimate by the in situ method rumen degradation kinetics of alfalfa hay and seven plant protein supplements: solvent-extracted soybean meal, solvent-extracted sunflower meal, peas (Pisum sativum L.), lupin seeds (Lupinus sp.), broadbean (Vicia faba L.), horsebean (Vicia faba L. var equina) and vetch (Vicia sativa L.), in high concentrate diets with different forage to concentrate ratio. Heifers were fitted with a ruminal cannula. The experiment was performed in two 30-day periods, 15 days of diet adaptation and 15 days of sampling. At each period, heifers were offered one of two total mixed rations (12:88 versus 30:70 forage to concentrate ratio), two heifers per diet, on ad libitum basis. After the first period, heifers switched treatments. Intake of dry matter (DM), organic matter, crude protein and neutral detergent fibre (NDF), expressed as kg/day, did not differ between treatments, but DM intake, expressed as g/kg metabolic body weight (BW), was higher in the 12:88 diet. Average rumen pH was 6.0 in both diets, and the time pH was below 5.8, which is considered as a critical threshold for fibre degradation, was the same for both treatments (10.4 ± 1.6 h). Average ammonia nitrogen and volatile fatty acid (VFA) concentrations did not differ between treatments and individual VFA proportions were typical of high concentrate diets. Average effective degradability of DM (0.62 ± 0.02) and NDF (0.25 ± 0.03) of alfalfa hay were low and no differences were detected between treatments. The same extent of NDF degradation, together with the same proportions of VFA would indicate that both diets had the same fibrolytic activity. Forage to concentrate ratio did not affect rumen nitrogen degradability of any protein supplements incubated in situ. Corrected effective degradability for small particle losses of sunflower meal (0.78) was higher than legume seeds, which were not statistically different between each other and ranged from 0.63 to 0.66. Soybean meal had the lowest degradability value (0.61). These nitrogen degradation values must be considered more valid for beef cattle formulation of high concentrate diets than data obtained with forage diets.     

Influence of natural magnesium sources on the in vitro fermentation and protozoan population in the rumen fluid collected from sheep

The objective of this experiment was to determine the effect of two types of caustic calcinated magnesite (caustic magnesite (CM) and Agromag (AG)) upon the end products of in vitro fermentation (total gas, methane, total and individual fatty acids, and VFA) and protozoan population in the rumen fluid collected from sheep. Both magnesium additives (CM and AG) as natural products in the dose of 0.01 g were added to the fermentation bottles containing rumen inoculum from sheep and different substrates. Meadow hay (MH), wheat straw (WS), amorphous cellulose (AC) and barley grain (BG) were used as substrates and incubated with the buffered rumen fluid using an in vitro gas measuring technique during 72 h of incubation. The rumen protozoa, Entodinium spp., Trichostomatids and large Entodiniomorphids and the total protozoan concentration were counted after 24 h of incubation. The methane production was significantly decreased with CM or AG, respectively, by 58 or 62% (MH), by 65% (WS), by 52% (AC) and by 58% (BG). The total VFA concentration was significantly lower compared to control for CM plus MH, WS, AC, BG and AG plus WS. The total VFA concentration was significantly higher compared to control for AG plus AC. The effect of the both additives on ciliate population was not uniform and depended on the substrates used and protozoan type. Ciliate population was significantly increased in Entodinium spp. (AG plus BG) and Diploplastron affinae (CM or AG plus BG) compared to control. Tested additives significantly decreased population of Entodinium spp. (AG plus MH or AC), Dasytricha ruminantium (AG plus AC), Ophryoscolex c. tricoronatus, Eremoplastron dilobum and Polyplastron multivesiculatum (CM or AG plus BG). It can be concluded that both natural magnesium sources influenced rumen fermentation patterns and protozoan population in vitro depending on the type of the substrate used; therefore, the relative efficacy of individual tested additive cannot be determined from these experiments. In vivo experiments are required in future.     

Intake,digestibility and rumen characteristics in cattle offered whole-crop wheat or barley silages of contrasting grain to straw ratios

The effects of varying the grain (G) to straw (S) ratio (G:S) of whole-crop wheat and barley silages on intake and digestibility and whole-crop barley silage on rumen fermentation characteristics were examined in two parallel studies. For the intake and digestibility study, eight Aberdeen Angus cross-bred steers (mean bodyweight 407 kg (S.D. 24.2)) were used in two (barley and wheat) 4 × 4 Latin Square designed experiments. The dietary treatments were four G:S ratios: 0:100, 30:70, 60:40 and 90:10. Intake of grain linearly increased (P<0.001) while that of straw decreased (P<0.001) as the ratio of G:S increased for both cereals. No effect (P>0.05) was observed in total dry matter (DM) intake (DMI) or in DMI per kg liveweight. There was a positive linear (P<0.001) effect on the digestibility of the DM and organic matter (OM) and a negative linear effect on neutral detergent fibre (aNDFom) digestibility (P<0.01) as the G:S ratio increased for both cereals. Both a positive linear (P<0.05) and quadratic (P<0.01) effect were observed for the G:S ratio on nitrogen (N) digestibility of barley and a corresponding positive linear increase (P<0.01) for wheat. A negative linear effect was found for digestibility of starch (P<0.01) and a positive linear effect for faecal grain content (P<0.01) with increasing G:S ratio. Four Holstein–Friesian steers (mean bodyweight 659 kg (S.D. 56.9)) fitted with rumen cannulae were used in the rumen study. A negative linear effect of G:S ratio was found on rumen pH (P<0.001) while a positive linear effect was found on rumen ammonia (P<0.001) and total volatile fatty acid (VFA) concentration (P<0.01) with increasing G:S ratio. A negative linear effect (P<0.01) was found on the molar proportion of acetic acid. However, this decrease was offset by linear increases in the molar proportions of iso- and n-butyric acid, iso- (P<0.01) and n- (P<0.05) valeric acid, and to a lesser extent in propionic acid (P<0.01). No effect of treatment was found on rumen pool sizes of DM or its constituents. A positive linear effect (P<0.01) was found on the effective degradability (ED) of the DM, OM, N and starch while it was found to be negative in aNDFom (P<0.05). No effect (P>0.05) was found on the fractional clearance rates of DM, OM, aNDFom or starch or on liquid passage rate. It is concluded that increasing the G:S ratio in whole-crop wheat or barley silage linearly increased the intake of digestible nutrients for both wheat and barley and increasing the G:S ratio for whole-crop barley increased the concentration of fermentation products (total VFA, ammonia and the molar proportions of the VFAs, except acetic acid) in the rumen.