植酸酶的激活及其催化植酸钠水解提取肌醇

以脱脂米糠为原料提取肌醇,用离子交换树脂吸附植酸,再用NaOH洗脱,得到植酸钠溶液,采用植酸酶阳离子激活提高酶活后催化植酸钠水解,水解液最后用CaCO3溶液破坏水解平衡的原理辅助水解,从而制得得率高达11.5％的肌醇.     

Effect of grain source and exogenous phytase on phosphorus digestibility in dairy cows

Two experiments were conducted to determine P digestibility in lactating dairy cows fed corn or barley as grain sources. The first experiment utilized a replicated incomplete 5 × 4 Latin square design with 8 lactating Holstein cows fed diets containing either corn alone or corn in combination with one of 4 barley varieties that differed in chemical composition. Total tract digestibility of P ranged from 11 to 29% for diets containing the barley varieties and was approximately 35% for the corn diet. A second experiment compared P digestibility in cows fed diets containing corn or barley when exogenous phytase was added to the diets. Lactating Holstein cows (n = 16) were arranged in 4 replications of a Latin square with 2 grains (barley or corn), fed separately or with added exogenous phytase (427 phytase units/kg of total mixed ration and 4 periods of 21 d. Phytate P comprised about 50% of the total P (0.46% P) in the total mixed ration. The concentration of serum inorganic P was higher in cows fed diets with exogenous phytase (5.8 vs. 6.5 mg/dL in cows fed barley diets and 5.5 vs 6.0 mg/dL in cows fed corn diets). Using acid detergent lignin as an internal marker, hydrolysis of phytate P was increased by the exogenous phytase, and total P digestibility tended to be increased. In contrast to Experiment 1, in Experiment 2 there was no effect of grain source on P digestibility and total fecal P. Dry matter intake and efficiency of milk production were not affected by exogenous phytase or grain type. Although phytase activity occurs in the rumen, physical properties of the diet and ruminal passage rates may prevent total hydrolysis of phytate in the rumen of lactating cows. Thus, exogenous dietary phytase might improve P digestibility in dairy cows in some dietary situations.     

The analysis for inositol phosphate forms in feed ingredients

Limited data are available on the content of inositol phosphates in feed ingredients. The doubtfulness over the identity and literature values of the inositol hexaphosphate (phytate) analysed in feed ingredients by the classical iron precipitation method prompted the analysis for inositol phosphates in some feed ingredients using a modified high-performance liquid chromatography method. The inositol phosphates analysed were inositol triphosphate (IP3), inositol tetraphosphate (IP4), inositol pentaphosphate (IP5) and inositol hexaphosphate (IP6). At least 97% of the inositol phosphates in grains occurred as IP6 and the remainder as IP5. In milled products the relative percentage of IP5 was higher (up to 14·5% in wheat bran) but the overall IP6 relative percentage was still high (more than 82%). IP3 and IP4 were not present in grains, and their amounts were very low when present in their milling or processed fractions. The absolute IP6 content was highest in rice bran and wheat bran at 68·31 and 47·63 g kg⁻¹, respectively. The results indicate that processed plant products may contain hydrolysis products of IP5 and IP6. These products contain greater percentages of IP3, IP4 and IP5 than in grains or milling products. © 1998 SCI.     

Degradation of starch in feed concentrates by enzymes,rumen fluid and rumen enzymes

The degradation of starch from various feedstuffs was investigated with rumen fluid, α-amylase, pancreatin and a freeze-dried, cell-free preparation of rumen fluid. Rumen fluid was taken from either a hay-fed cow or a concentrate-fed cow. It was shown that incubations with rumen fluid at a constant pH of 6·5 gave a higher degradation of starch than those with a decreasing pH. The degree of starch degradation varied widely for the 21 feedstuffs investigated. Sorghum, maize and millet degraded slowly whereas tapioca showed fast degradation. Processed feedstuffs showed a higher level of degradation than unprocessed ones. The use of enzymes did not allow an accurate prediction of starch degradation by rumen fluid. However, this was made possible by the use of a freeze-dried, cell-free preparation of rumen fluid. Scanning electron microscopic observations showed that for the degradation of starch granules additional enzymes, present in rumen fluid, are necessary.     

Determination of in vitro isoflavone degradation in rumen fluid

The aim of this study was to determine the degradation of dietary isoflavones in rumen fluid under 2 feeding regimens. The experiments were performed in vitro using a rumen fluid buffer system. The rumen fluid was taken from cows fed either a hay diet or a concentrate-rich diet (the diet consisted of 34.6% maize silage, 17.6% haylage, 12.8% alfalfa hay, and 35.0% supplemental mixture on a dry matter basis). As a source of isoflavones, 40% soybean extract (Biomedica, Prague, Czech Republic) at levels of 5, 25, 50, and 75 mg per 40 mL of rumen fluid was used. Samples of soybean extract were incubated in triplicate at 39°C for 0, 3.0, 6.0, 12.0, and 24.0 h in incubation solution. The metabolism of daidzein and genistein was faster under concentrate-rich diet conditions. In general, production of equol started after 3 to 6 h of incubation and reached the highest rate after approximately 12 h of incubation regardless of the type of diet or concentration of extract. In most of the experiments, production of equol continued after 24 h of incubation. Generally, equol production was greater under the hay diet conditions. Furthermore, experiments with higher amounts of added soybean extract revealed possible inhibitory effects of high levels of isoflavones on the rumen microflora.     

不同储藏条件下小麦粉植酸酶活性变化规律研究

在不同储藏条件下,对小麦粉中植酸酶活性变化规律进行研究。采用储藏条件为:相对湿度分别是55%和70%,温度分别为10℃、15℃、20℃、25℃、30℃、35℃,以此进行小麦粉模拟储藏试验。结果表明,小麦粉植酸酶活性为先快速上升,而后趋于平稳,继而下降;温度、时间对酶活性影响极其显著;小麦粉中植酸酶作用有限,大多数磷都以有机磷形式存在。     

植酸酶对鲫鱼养殖中磷、粗蛋白质和粗脂肪的影响

通过设置5组不同水平无机磷和植酸酶添加量的饲料来喂养鲫鱼,探索鲫鱼饲料中植酸酶和无机磷之间的最佳配比。结果表明:用植酸酶替代无机磷能明显减少养殖水体中磷的排放,同时能满足鱼体对磷的需求,对鱼体粗蛋白质含量影响较小,并能降低鱼体粗脂肪的含量。最佳的无机磷盐和植酸酶配比是1 kg饲料中加9 g的Ca(H2PO4)2和1500 U的植酸酶,其磷的排放量减少了66.9%,粗脂肪含量降低17.65%。     

Variations in mass and enzyme activity of rumen microorganisms: Effect of barley and buffer supplements

Four ruminally cannulated cows were used to investigate effect of barley with or without buffer on modifications of mass and enzyme activity in rumen microorganisms. Animals were given restricted feed (80% of ad libitum intake) of 7 kg DM day^?1 and with three successive diets. The diet H consisted of 100% Cocksfoot hay. The diet HB was 65% hay with 35% pelleted ground barley with infusion of bicarbonate salt for the diet HBB. The rumen was sampled before (-1 h) and after feeding (+ 5 h) to isolate liquid-and solid-associated microbial population. ¹⁵(NH₄)₂SO₄ was continuously infused into the rumen as a microbial marker. For all diets microorganisms associated with particles constituted a mean of 74% of the total rumen microbial mass. The density of microorganisms adherent to particles was similar (P > 0.05) for the different diets and the two sampling times, but fibrolytic enzymes activities (xylanase, CMCase, glycosidases) in this microbial population were maximal (P < 0.001) 23 h after feed intake. Xylanase (P < 0.05) and CMCase (P < 0.01) activities just before feeding varied according to diet; they were highest with diet H and similar between barley supplemented diets. Higher glycosidase activities were measured with diet H and HBB than with diet HB 5 h after feeding.     

外源性植酸酶在大豆乳中的应用

植物性食物中的植酸不能被单胃动物吸收,但是植酸酶能够水解植酸最终释放出肌醇和无机磷,供单胃动物吸收利用。本实验在研究温度、pH等因素对植酸酶活性影响的基础上,确定植酸酶催化植酸的水解条件为温度45℃、pH4.5、时间2h、酶添加量300FTU/kg。将植酸酶添加到大豆乳中,对大豆乳中植酸/植酸盐进行水解,分析发现大豆乳中有机磷的水解率高达82.9%;植酸酶对大豆乳中植酸/植酸盐的水解作用,对提高大豆乳的营养价值具有重要意义。     

The effects of forage particle length and exogenous phytase inclusion on phosphorus digestion and absorption in lactating cows

Accurate estimates of phosphorus (P) availability from feed are needed to allow P requirements to be met with reduced P intake, thus reducing P excretion by livestock. Exogenous phytase supplementation in poultry and swine diets improves bioavailability of P, and limited research suggests that this strategy may have some application in dairy cattle rations. The effects of exogenous phytase and forage particle length on site and extent of P digestion were evaluated with 5 ruminally and ileally cannulated lactating cows (188 ± 35 d in milk). Cows were assigned in a 2 × 2 factorial arrangement of treatments in 2 incomplete Latin squares with four 21-d periods. Diets contained P slightly in excess of National Research Council requirements with all P from feed sources. During the last 4 d of each period, total mixed ration, refusals, omasal, ileal, and fecal samples were collected and analyzed for total P, inorganic P (Pi), and phytate (Pp). Total P intake was not influenced by dietary treatments but Pp intake decreased and Pi intake increased with supplemental phytase, suggesting rapid action of the enzyme in the total mixed ration after mixing. Omasal flow of Pi decreased with phytase supplementation, but we observed no effect of diet in ileal flow or small intestinal digestibility of any P fraction. Fecal excretion of total P was slightly higher and Pp excretion was lower for cows receiving diets supplemented with phytase. Milk yield and composition were unaffected by diets. When phytase was added to the mixed ration, dietary Pp was rapidly degraded before intake and total-tract Pp digestion was increased. The lack of effect of phytase supplementation on dietary P utilization was probably because these late-lactation cows had a low P requirement and were fed P-adequate diets.     

The passage of lactic acid bacteria from silage into rumen fluid, in vitro studies

Inoculated silages sometimes improve cattle performance, possibly because of probiotic effects of lactic acid bacteria (LAB) silage inoculants. The cause of improved animal performance following feeding with inoculated silage is unclear. One issue in studying this phenomenon is to find out whether LAB pass from silage into the rumen fluid and survive in it. The purpose of the present study was to determine whether LAB from inoculated and uninoculated silages pass into the rumen fluid in vitro. Wheat and corn silages, uninoculated or inoculated with 1 of 10 commercial silage inoculant LAB, were prepared in glass jars. After ensiling, a 2.5-g silage sample was added to 25 mL of heat-sterilized or strained rumen fluid together with 5 g/L glucose, and incubated for 48 h at 39 degrees C. Analysis of the incubated rumen fluid included pH measurement, enumeration of LAB, and determination of lactic acid and volatile fatty acids (VFA). The pH of the rumen fluid decreased during incubation; both heat-sterilized and strained rumen fluid contained large numbers of LAB. The heat-sterilized rumen fluid contained lactic acid in addition to VFA, whereas the strained rumen fluid contained only VFA. The results indicate that LAB pass from silage samples into the rumen fluid in vitro and survive there. Their interactions with rumen microorganisms should be studied further to understand how some silage inoculant LAB exhibit probiotic effects in dairy cattle.     

The effect of steam-flaked or dry ground corn and supplemental phytic acid on phosphorus partitioning and ruminal phytase activity in lactating cows

The effect of starch source and phytic acid (PA) supplementation on phosphorus (P) partitioning and ruminal phytase activity was evaluated in eight midlactation cows (four ruminally cannulated). Cows were randomly assigned to treatments in replicated 4 x 4 Latin squares with four 18-d periods. Diets included dry ground corn (DG) or steam-flaked corn (SF), with no supplemental P (L; 0.33% P) or supplemental purified PA (0.44% P) to provide additional P from a nonmineral source. Total collection of milk, urine, and feces was conducted on d 16 to 18 of each period. Ruminal fluid was sampled and ruminal pH measured every 8 h on d 17 and 18. Milk yield was unaffected by starch source, despite lower DMI by cows fed SF. Cows fed SF had increased DM digestibility compared with those fed DG, and tended to have higher efficiency of milk yield (1.40 vs. 1.35 kg of milk/kg of DMI). Intake and fecal excretion of P was lower in cows fed SF than in cows fed DG. In cows fed SF, milk P as a percentage of P intake increased compared with cows fed DG. Ruminal pH was unaffected by diet, but milk fat content was lower for cows fed SF. Milk yield, DMI, and feed to milk ratio were not affected by supplementation with PA. Although cows fed PA had increased P intake compared with cows fed low P diet, increased P excretion resulted in no differences in apparent P digestibility. Phosphorus balance tended to be higher in cows fed PA, but milk P as a percentage of intake was reduced. The interaction of starch source and PA affected ruminal phytase activity. Altering starch source to improve efficiency of milk yield in lactating dairy cows may help reduce P losses from dairy farms.     

Effect of essential oil active compounds on rumen microbial fermentation and nutrient flow in in vitro systems

Two experiments were conducted to determine the effects of several essential oil active compounds on rumen microbial fermentation. In the first experiment, 4 doses (5, 50, 500, and 5,000 mg/L) of 5 essential oil compounds were evaluated using in vitro 24-h batch culture of rumen fluid with a 60:40 forage:concentrate diet (18% crude protein; 30% neutral detergent fiber). Treatments were control (CON), eugenol (EUG), guaiacol, limonene, thymol (THY), and vanillin. After 24 h, the pH was determined, and samples were collected to analyze ammonia N and volatile fatty acids (VFA). The highest dose of all compounds decreased total VFA concentration and increased the final pH. Eugenol at 5 mg/L tended to reduce the proportion of acetate and the acetate to propionate ratio, at 50 and 500 mg/L tended to reduce ammonia N concentration, and at 500 mg/L reduced the proportion of propionate and branched-chain VFA concentration, without affecting total VFA concentration. All other treatments had minor effects or changes occurred only after total VFA concentration decreased. In the second experiment, 8 dual-flow continuous culture fermenters (1,320 mL) were used in 3 replicated periods (6 d of adaptation and 3 d of sampling) to study the effects of THY and EUG on rumen microbial fermentation. Fermenters were fed 95 g/d of DM of a 60:40 forage:concentrate diet (18% crude protein; 30% neutral detergent fiber). Treatments were CON, 10 mg/L of monensin (positive control), and 5, 50, or 500 mg/L of THY and EUG, and were randomly assigned to fermenters within periods. During the last 3 d of each period, samples were taken at 0, 2, 4, and 6 h after the morning feeding and analyzed for peptides, amino acids, and ammonia N concentrations, and total and individual VFA concentrations. Monensin changed the VFA profile as expected, but inhibited nutrient digestion. Eugenol and THY decreased total VFA concentration and changed the VFA profile, and only 5 mg/L of THY tended to reduce the proportion of acetate, increased the proportion of butyrate, and increased the large peptides N concentration without decreasing total VFA concentration. Most of these essential oil compounds demonstrated their antimicrobial activity by decreasing total VFA concentration at high doses. However, EUG in batch fermentation and 5 mg/L of THY in continuous culture modified the VFA profile without decreasing total VFA concentration, and EUG in batch fermentation decreased ammonia N concentration.     

植酸酶替代日粮中磷酸氢钙对肉鸡饲养效应的研究

通过两次试验，探讨了微生物植酸酶替代日粮中磷酸氢钙对肉鸡的饲养效应，表明添加植酸酶可减少肉鸡日粮中的磷酸氢钙的用量。     

Uptake of small neutral peptides by mixed rumen microorganisms in vitro

The metabolism of a range of neutral di- and oligopeptides and peptide p-nitroanilides was investigated in strained ruminal fluid diluted with anaerobic buffer. Peptide uptake was assayed by decrease in fluorescamine-reactive material in extracellular fluid, and peptide p-nitroanilide hydrolysis by diazotisation of the released p-nitroaniline. Addition of glucose and dithiothreitol did not alter uptake of di- or trialanine. Calculated V_max for di- and trialanine uptake were 1.4 and 1.9 nmol min^?1 mg DM^?1, corresponding K_m were 0.30 and 0.14 mmol litre^?1. Dipeptide uptake was 0.72 to 0.90 nmol min^?1 mg DM^?1, except for glycylproline, which was taken up at 0.43 nmol min^?1 mg DM^?1. There was a wider range for tripeptide uptake (0.5 to 1.6 nmol min^?1 mg DM^?1), with trialanine being taken up most rapidly. Tetra- and pentaalanine were removed at 0.93 and 0.71 nmol min^?1 mg DM^?1. Uptake of amino acid residues as alanine oligopeptides was two to three times more rapid than uptake as dialanine. These data suggest that peptides would accumulate in rumen fluid during hydrolysis of rapidly degraded proteins, but peptide uptake would exceed rate of release from more slowly degraded proteins. Rates of hydrolysis of eight peptide p-nitroanilides were 0.56 to 1.53 nmol min^?1 mg DM^?1, and were of similar magnitude to uptake of di- and tripeptides; proline-containing p-nitroanilides were also more slowly metabolised.     

Effect of dietary mineral phosphorus and phytate on in situ ruminal phytate disappearance from different concentrates in dairy cows

The first objective of this study was to determine the influence of dietary composition on the in situ disappearance of phytate (InsP₆) from wheat, corn, soybean meal, and rapeseed meal [solvent-extracted, without (RSM) or with (hRSM) heat treatment] in the rumen of dairy cows. The second objective was to assess the primary degradation products of InsP₆ in the rumen. Three diets differing in phosphorus and InsP₆ concentration (basal diet = 0.38% P in dry matter; high-P diet = 0.56% P; high-InsP₆ diet = 0.39% P) were fed to 3 ruminally fistulated lactating Jersey cows in a 3 × 3 Latin square. Ground concentrates (sieve size = 2 mm) were incubated in polyester bags in the rumen for 2, 4, 8, 16, and 24 h. The bag residues were analyzed for P, InsP₆, isomers of lower inositol phosphates (InsP₅, InsP₄, InsP₃), and crude protein. The InsP₆ disappeared more rapidly from cereal grains than from oilseed meals; however, after 24 h of incubation ≥95% InsP₆ had disappeared from all concentrates except hRSM (57%; diet average). Feeding the high-InsP₆ diet increased InsP₆ disappearance for oilseed meals, but not for corn and wheat. The predominant InsP₅ isomer in all bag residues was Ins(1,2,4,5,6)P₅ followed by Ins(1,2,3,4,5)P₅ and Ins(1,2,3,4,6)P₅. A further InsP₅ isomer [Ins(1,3,4,5,6)P₅] was detected in both rapeseed meal bag residues. Feeding the high-InsP₆ diet led to lower concentrations of Ins(1,2,4,5,6)P₅ and Ins(1,2,3,4,5)P₅, whereas an interaction between diet, concentrate, and time occurred for Ins(1,2,3,4,6)P₅ and Ins(1,3,4,5,6)P₅. The results confirm the high potential of rumen microorganisms to hydrolyze InsP₆; however, increasing the amount of InsP₆ in the diet can further enhance InsP₆ hydrolysis, which may be relevant when concentrates with slowly degradable InsP_6, such as RSM or heat-treated concentrates, are fed to dairy cows. Based on the concentrations of InsP₅ isomers, 3 and 6 phytases appear to play a major role in the rumen. Conversely, intrinsic plant phytase activity appears to be less relevant as the percentage of its primary hydrolysis product, Ins(1,2,3,4,5)P₅, changed only slightly upon using wheat known for high intrinsic phytase activity instead of the other concentrates. Additional information regarding the factors influencing the extent of ruminal InsP₆ disappearance will require further studies to determine the phytase activity of rumen microorganisms and the characteristics of their respective phytases.     

Effect of phytase inclusion and calcium/phosphorus ratio on the performance and nutrient retention of grower–finisher pigs fed barley/wheat/soya bean meal‐based diets

Two experiments were conducted to evaluate the effects of phosphorus (P) level and calcium (Ca)/total P (tP) ratio on the efficacy of microbial phytase. Experiment 1 examined the effects of P concentration and microbial phytase inclusion on mineral excretion and pig performance, while experiment 2 examined the effects of Ca/tP ratio and microbial phytase inclusion on mineral excretion and pig performance. In experiment 1, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (T1) 5.5 g kg^?1 tP, 2.3 g kg^?1 available P (aP) and 8.0 g kg^?1 Ca, (T2) 5.5 g kg^?1 tP, 2.3 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 Peniophora lycii phytase, (T3) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP and 8.0 g kg^?1 Ca and (T4) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. In experiment 2, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (TT1) 4.3 g kg^?1 tP and 8.0 g kg^?1 Ca, (TT2) 4.3 g kg^?1 tP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase, (TT3) 4.3 g kg^?1 tP and 5.0 g kg^?1 Ca and (TT4) 4.3 g kg^?1 tP, 5.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. All diets were formulated, using standard feeding values for the ingredients, to have similar concentrations of digestible energy (DE) and lysine. In experiment 1, pigs offered the low‐P diets had significantly lower P intake (P < 0.001), faecal P excretion (P < 0.05), Ca intake (P < 0.05) and faecal Ca excretion (P < 0.05) compared with pigs given the adequate‐P diets. These pigs also had significantly lower daily gain (P < 0.01), feed intake (P < 0.05) and feed conversion ratio (FCR) (P < 0.05). The inclusion of phytase in both the adequate‐ and low‐P diets increased the digestibility of energy (P < 0.05) and Ca (P < 0.01) but had no effect on pig performance. In experiment 2, lowering the Ca/tP ratio from 1.85:1 to 1.15:1 increased the DE content of the diet (P < 0.05). The inclusion of phytase increased (P < 0.05) the digestibility of protein (0.874 versus 0.840, SEM 0.009) and Ca (0.427 versus 0.380, SEM 0.019) as well as the DE content of the diet (14.47 versus 14.26 MJ kg^?1, SEM 0.073). There was a significant ratio × phytase interaction (P < 0.5) for P digestibility. Microbial phytase significantly increased P digestibility when added to the 1.15:1 ratio diet but had no effect when added to the 1.85:1 ratio diet. The inclusion of microbial phytase increased feed intake (2.16 versus 2.00 kg day^?1, SEM 0.05; P < 0.05) and weight gain (0.893 versus 0.818 kg day^?1, SEM 0.022; P < 0.05). Lowering the Ca/tP ratio resulted in a significant improvement in FCR (2.32 versus 2.40 kg kg^?1, SEM 0.03; P < 0.05). In conclusion, the beneficial effects of microbial phytase supplementation of pig diets are adversely affected by a wide Ca/tP ratio. © 2002 Society of Chemical Industry     

Effect of in vitro docosahexaenoic acid supplementation to marine algae-adapted and unadapted rumen inoculum on the biohydrogenation of unsaturated fatty acids in freeze-dried grass

The objective of this study was to examine the ruminal biohydrogenation of linoleic (18:2n-6) and linolenic (18:3n-3) acid during in vitro incubations with rumen inoculum from dairy cattle adapted or not to marine algae and with or without additional in vitro docosahexaenoic acid (DHA, 22:6n-3) supplementation. Treatments were incubated in 100-mL flasks containing 400 mg of freeze-dried grass, 5 mL of strained ruminal fluid, and 20 mL of phosphate buffer. Ruminal fluid was collected just before the morning feeding from 3 cows receiving a control diet (49% ryegrass silage, 39% corn silage, 1% straw, and 11% concentrate, fresh-weight basis) supplemented with marine algae for 21 d (adapted rumen fluid, aRF) or from the same cows receiving the control diet only for 14 d after marine algae supplementation was stopped (unadapted rumen fluid, uRF). In half of the incubation flasks, pure DHA (5 mg) was added as an oil-ethanol solution (100 mL). Incubations were carried out during 0, 0.5, 1, 2, 4, 6, and 24 h. After 24 h, in vitro addition of DHA resulted in greater amounts (mg/incubation) of 18:3n-3 (0.23, 0.43, 0.26, and 0.34 for aRF, aRF+DHA, uRF, and uRF+DHA), 18:2n-6 (0.14, 0.22, 0.15, and 0.20 for aRF, aRF+DHA, uRF, and uRF+DHA) and trans-11, cis-15-18:2 (0.27, 2.40, 0.06, and 2.21 for aRF, aRF+DHA, uRF, and uRF+DHA), whereas no effect of inoculum source was observed. Trans-11-18:1 accumulated after 24 h when aRF was incubated irrespective of in vitro DHA supplementation, whereas in incubations with uRF, accumulation of trans-11-18:1 only occurred when DHA was added (6.40, 4.35, 1.06, and 3.91 for aRF, aRF+DHA, uRF, and uRF+DHA). The increased amounts of trans-11-18:1 were due to the strong inhibition of the reduction to 18:0 because no 18:0 was formed when trans-11-18:1 accumulated after 24 h. The results of the current experiment shows hydrogenation of trans-11, cis-15-18:2 occurred in the absence of in vitro DHA only, whereas substantial hydrogenation of trans-11-18:1 to 18:0 only took place in incubations without DHA and with unadapted rumen inoculum, confirming the higher sensitivity of the latter process to DHA.     

Effects of time at suboptimal pH on rumen fermentation in a dual-flow continuous culture system

Ruminal pH varies considerably during the day, achieving values below 6.0 when cows consume large amounts of concentrates. Low ruminal pH has negative effects on ruminal fermentation. However, previous studies have indicated that rumen bacteria may resist short periods of low ruminal pH, and it is not clear how long this period may be before rumen microbial fermentation is negatively affected. Seven dual-flow continuous culture fermenters (1,320 mL) were used in 3 replicated periods with the same diet (97 g of dry matter/d of a 60:40 forage-to-concentrate diet, 18.3% crude protein, 35.9% neutral detergent fiber), temperature (39°C), and solid (5%/h) and liquid (10%/h) dilution rates to study the effects of increasing time at suboptimal pH on rumen microbial fermentation and nutrient flow. Treatments were a constant pH of 6.4 and 6 different intervals of time during the day (4, 8, 12, 16, 20, 24 h) at suboptimal pH (5.5), with the rest of the day being at pH 6.4. Polynomial equations were derived using the Mixed procedure of SAS, and linear, quadratic and cubic terms were left in the equation if P < 0.10. True organic matter digestion decreased with increasing time at suboptimal pH and was best described by a cubic regression (TOMD = 58.5 − 2.15x + 0.16x² −0.0037x³; R² = 0.74). Digestion of NDF (DNDF = 55.1 − 1.00x; R² = 0.75) and digestion of ADF (DADF = 56.2 − 1.33x; R² = 0.78) decreased linearly with increasing time at suboptimal pH. Total VFA had a cubic response (VFA = 112.7 − 2.09x + 0.17x² − 0.0054x³; R² = 0.82). The proportion of acetate decreased linearly (acetate = 58.7 − 0.61x; R² = 0.79). The propionate proportion increased (propionate = 17.6 + 2.09 × −0.044x²; R² = 0.85) and branched-chain VFA decreased (BCVFA = 4.45 −0.51x + 0.014x²; R² = 0.75) quadratically. The ammonia N concentration (NH₃-N = 5.85 − 0.13x; R² = 0.46) and flow (NH₃-N flow = 0.18 − 0.0039x; R² = 0.43) decreased linearly as the time at suboptimal pH increased. Crude protein degradation (CPd = 41.9 − 1.60x + 0.060x²; R² = 0.71), efficiency of microbial protein synthesis (EMPS = 26.6 − 0.33x + 0.021x²; R² = 0.77), microbial N flow (MN flow = 1.38 − 0.036x + 0.0015x²; R² = 0.77), and dietary N flow (DN flow = 1.49 + 0.041x − 0.0015x²; R² = 0.65) had a quadratic response. The flow of essential, nonessential, and most individual AA increased linearly with increasing time at suboptimal pH. The effects of pH on rumen fermentation appear to start as soon as pH drops to suboptimal pH.     

Effect of inositol and its derivatives on diabetes: a systematic review

A growing body of research has investigated the association between inositol and diabetes. The purpose of this review is to report through a systematic way the current scientific evidence relating potential benefits of inositol isomers on diabetes/gestational diabetes. The screening of the studies published last decade was performed in 4 databases (Pubmed-Web of Science-The Cochrane Library-Lilacs). Among the 1640 studies identified in the search, only 26 studies had sufficient data to be included in the systematic review. The available literature suggests that inositol seems to be provide improvements in fasting blood glucose and other biochemical results, which are among the most important parameters in diabetic individuals. Although there are some studies demonstrating that inositol may be effective in prevention and treatment of diabetes/gestational diabetes, conduction of studies with larger sample and longer follow-up duration is required for it to be represented as an effective strategy in management of diabetes.