Effects of mannan level and β-mannanase supplementation on growth performance,apparent total tract digestibility and blood metabolites of growing pigs

The exogenous enzymes are less consistent in their effects as their beneficial effects depend upon the types and level non-starch polysaccharides (NSP) present in the diets. Therefore, exogenous enzymes should be selected on the basis of types and amount of the NSP in the pig diets. The objectives of the present experiments were to investigate the effects of dietary level of mannan and β-mannanase supplementation on growth performance, apparent total tract digestibility (ATTD) of energy and nutrients, and blood metabolites of growing pigs. In Exp. 1, 96 barrows were randomly allotted to four treatments on the basis of BW. There were four replicates in each treatment with six pigs per replicate. The dietary treatments were a corn–soybean meal (SBM)-based control diet and three other diets consisted of the control diet supplemented with 400, 800 or 1600 U of β-mannanase/kg diet. The final BW, average daily gain (ADG) and blood glucose increased (linear, P<0.05) with increasing concentrations of dietary β-mannanase. The ATTD of dry matter (DM), gross energy (GE) and β-mannan was higher (linear, P<0.05) with increase in dietary β-mannanase concentrations. In Exp. 2, 288 barrows were allotted to six treatments in a 2×3 factorial arrangement of mannan level (high v. low) and addition of β-mannanase (0, 400 or 800 U/kg diet). There were four replicates in each treatment with 12 pigs/replicate. Pigs were fed corn–SBM-based low-mannan diet (6.1 g/kg) or high-mannan (25.2 g/kg) diet in which corn and SBM were partially replaced with 50 g/kg diet palm kernel meal. All diets were fed in meal form for 42 days. Pigs fed diets supplemented with β-mannanase had greater (P<0.05) final BW, ADG, feed to gain (F : G), the ATTD of DM, GE, and β-mannan and blood glucose concentration compared with pigs fed diets without β-mannanase. In addition, the final BW, ADG, F : G and the ATTD of GE and β-mannan were reduced (P<0.05) in low mannan level. The dietary level of mannan and the β-mannanase supplementation had no effects (P>0.05) on the concentrations of blood total cholesterol, triacylglycerides and blood urea nitrogen. These results indicate that supplementation of β-mannanase to low- or high-mannan diets have potential to improve the performance of growing pigs. In addition, palm kernel meal may partially replace corn and SBM without reducing pig performance if β-mannanase is added to diet.     

Effects of combined α-galactosidase and xylanase supplementation on nutrient digestibility and growth performance in growing pigs

Two experiments were conducted to investigate the effect of combined supplementation of α-galactosidase and xylanase on nutrient digestibility and growth performance in growing pigs. Experiment 1 had a 2 × 2 Latin square design, where eight barrows (45.0 ± 0.52 kg body weight [BW]) were fitted with a simple T-cannula in the distal ileum and received a basal diet without or with supplementation of α-galactosidase (12 U/kg diet) and xylanase (15 AXC/kg diet) within two periods of 10 d. The apparent ileal digestibility (AID) and apparent total tract digestibility of nutrients, pH, viscosity of digesta and digestive enzyme activities were assessed. In Experiment 2, a total of 432 growing pigs (initial BW 44.7 ± 0.66 kg) were allocated to four treatments. Diets were based on corn and soybean meal and had a normal or reduced nutrient level (reduced by 0.42 kJ digestible energy [DE] per kg and 0.8% crude protein). Both diets were offered without or with supplementation of α-galactosidase and xylanase. The growth performance was assessed within a 43-d feeding period, where at the end, biochemical serum indices were estimated. In Experiment 1, the enzyme-supplemented diet had a greater contents of DE and DE/gross energy ratio (p < 0.05), and a higher AID of Arg, raffinose, stachyose and arabinoxylan (p < 0.05). In Experiment 2, the low nutrient level caused lower daily gain (p < 0.05), which was partially compensated by enzyme addition. Enzyme addition also increased the serum concentration of Lys (p < 0.05). Moreover, it appears that the tested enzyme supplementation could increase dietary DE, serum total amino acid concentrations and decrease serum urea nitrogen.     

Effects of supplementation with corn distillers’ dried grains on animal performance,nitrogen balance,and enteric CH4 emissions of young Nellore bulls fed a high-tropical forage diet

The inclusion of corn-dried distillers’ grains (DDG) could be an alternative supplement to increase animal performance, nitrogen efficiency usage (NEU), and decrease enteric methane (CH₄) emissions. Our goal was to determine whether DDG could replace a traditional supplement (cottonseed meal) without affecting animal performance, N balance, and CH₄ emissions. The experiment was conducted during the forage growing season (December to April), with 15 d adaptation, and a 112 d experimental period. The experimental design was completely randomized with four treatments: a mineral supplement (MS), cottonseed meal supplement (CS), 50% replacement of CS by DDG (50DDG), and 100% replacement of CS by DDG (100DDG). Cottonseed meal and DDG were used as protein supplement. A total of 12 paddocks, 3 per treatment, were used to measure forage mass: morphological and chemical composition of forage, forage allowance, and animal performance. Six animals per treatment were used to evaluate DM intake, digestibility, CH₄ emissions, microbial protein production (MCP), and NEU of each treatment. Eighty-one Young Nellore bulls (48 testers, 12 per treatments and 33 adjusters) with initial BW of 255 ± 5 kg (10–12 months old) were supplemented with each supplement type at a level of 0.3% of BW. Pasture management was continuous stocking with a variable stocking rate (put-and-take). Enteric CH₄ was measured using the gas tracer technique. The MCP was quantified using purine derivatives and the NEU mass balance. No differences were found in nutrient intake (P > 0.228). Individual animal performance and gain per area were higher in the treatments with concentrates compared with that of MS; however, there was no difference among treatments CS, 50DDG, and 100DDG. The ADG was 0.83 for MS and 1.08 kg/animal/d when supplemented (P < 0.05). Gain per hectare was 709 kg/ha for MS and 915 kg/ha when supplemented with concentrates (P < 0.05). There was no difference in CH₄ production among treatments that average 180 g/animal/d; however, CH₄ per kg of gain was reduced with CS. The CH₄ conversion factor averaged 5.91%. There was no difference in the synthesis of MCP and NEU. Corn DDG can replace 100% of cottonseed meal as a protein source for supplementation of young Nellore bulls grazing in tropical pastures without affecting animal performance, NEU, MCP, and CH₄ emissions.     

In situ ruminal degradation of amino acids and in vitro protein digestibility of undegraded CP of dried distillers’ grains with solubles from European ethanol plants

The objectives of this study were to compare the in situ ruminal degradation of CP and amino acids (AAs) of dried distillers’ grains with solubles (DDGS), and to estimate intestinal digestibility (ID) of undegradable crude protein (UDP) with the in vitro pepsin–pancreatin solubility of CP (PPS), using either DDGS samples (DDGS-s) or DDGS residues (DDGS-r) obtained after 16 h ruminal incubation. Thirteen samples originating from wheat, corn, barley and blends were studied. Lysine and methionine content of DDGS-s varied from 1.4 to 4.0 and 1.3 to 2.0 g/16 g N, respectively. The milk protein score (MPS) of DDGS-s was low and ranged from 0.36 to 0.51, and lysine and isoleucine were estimated to be the most limiting AAs in DDGS-s and DDGS-r. DDGS-r contained slightly more essential AAs (EAAs) than did the DDGS-s. Rumen degradation after 16 h varied from 44% to 94% for CP, from 39% to 90% for lysine and from 35% to 92% for methionine. Linear regressions showed that the ruminal degradation of individual AAs can be predicted from CP degradation. The PPS of DDGS-s was higher than that of DDGS-r and it varied from 70% to 89% and from 47% to 81%, respectively. There was no significant correlation between the PPS of DDGS-s and PPS of DDGS-r (R²=0.31). The estimated intestinally absorbable dietary protein (IADP) averaged 21%. Moderate correlation was found between the crude fibre (CF) content and PPS of DDGS-r (R²=0.43). This study suggests an overestimation of the contribution of UDP of DDGS to digestible protein supply in the duodenum in some currently used protein evaluation systems. More research is required and recommended to assess the intestinal digestibility of AAs from DDGS.     

Effect of dietary cation–anion difference on ruminal metabolism,total apparent digestibility,blood and renal acid–base regulation in lactating dairy cows

The present study aimed to evaluate the effect of dietary cation–anion difference (DCAD) on ruminal fermentation, total apparent digestibility, blood and renal metabolism of lactating dairy cows. Sixteen Holstein cows were distributed in four contemporary 4×4 Latin Square designs, which consisted of four periods of 21 days and four treatments according to DCAD: +290; +192; +98 and −71 milliequivalent (mEq)/kg dry matter (DM). Ruminal pH and concentrations of acetic and butyric acid increased linearly according to the increase of DCAD. Similarly, NDF total apparent digestibility linearly increased by 6.38% when DCAD increased from −71 to 290 mEq/kg DM [Y=65.90 (SE=2.37)+0.0167 (SE=0.0068)×DCAD (mEq/kg DM)]. Blood pH was also increased according to DCAD, which resulted in reduction of serum concentrations of Na, K and ionic calcium (iCa). To maintain the blood acid–base homeostasis, renal metabolism played an important role in controlling serum concentrations of Na and K, since the Na and K urinary excretion increased linearly by 89.69% and 46.06%, respectively, from −71 to 290 mEq/kg DM. Changes in acid–base balance of biological fluids may directly affect the mineral composition of milk, as milk concentrations of Na, K, iCa and chlorides were reduced according to blood pH increased. Thus, it can be concluded that the increase of DCAD raises the pH of ruminal fluid, NDF total apparent digestibility, and blood pH, and decreases the milk concentration of cationic minerals, as well as the efficiency of Na utilization to milk production.     

Effects of Yucca schidigera and Quillaja saponaria with or without β 1–4 galacto-oligosaccharides on ruminal fermentation,methane production and nitrogen utilization in sheep

Effects of Quillaja saponaria extract (QSE) and Yucca schidigera extract (YSE) with or without β 1–4 galacto-oligosaccharides (GOS) on ruminal fermentation, methane production and N utilization in wether sheep were evaluated. Four wethers fitted with permanent ruminal fistulae were assigned in a 4 × 6 Youden square design experiment and fed a basal diet comprised of concentrate and Italian ryegrass hay (2:3, on a DM basis) at 55 g/kg metabolic body weight. Treatments were: (1) control (no addition of supplement); (2) 14 ml of QSE; (3) 14 ml of YSE; (4) 20 g of GOS; (5) 14 ml QSE + 20 g GOS; (6) 14 ml YSE + 20 GOS per day. Digestibility of NDFom increased (P<0.05) in sheep treated with QSE, QSE + GOS, and YSE + GOS, but was not affected by YSE or GOS. Ruminal fluid pH increased (P<0.05) in sheep administered with YSE compared with other treatments. Ammonia N and total VFA concentrations declined (P<0.001) with administration of QSE and YSE compared with the control. Propionate and acetate molar proportions were not affected, while butyrate molar proportion declined (P<0.001) with QSE alone or in combination with GOS. Digestible energy increased (P<0.05) with all treatments, except YSE. Results suggest that administration of QSE and YSE reduced ruminal ammonia N and total VFA concentration, and numerically decreased methane emissions, without having adverse effects on fiber digestion. In addition, administration of YSE, with or without GOS, numerically reduced protozoal numbers. QSE, YSE and YSE + GOS may have potential as beneficial manipulators of ruminal fermentation.     

Effects of light quality,CO2 tensions and NO 3 +− concentrations on the inorganic nitrogen metabolism of Chlamydomonas reinhardii

The blue light dependent utilization of nitrate by green algae under common air and high irradiances, besides its assimilatory nature, is associated with the release of NO₂ ^– and NH₄ ⁺ to the culture medium. If the CO₂ content of the sparging air was increased up to 2%, previously excreted NO₂ ^– and NH₄ ⁺ were rapidly assimilated. When under air and high irradiances the cell density in the culture reached values corresponding to 25 g Ch 1.ml^-1, no further growth was observed and the highest values of NO₃ ^– consumption and NO₂ ^– and NH₄ ⁺ release were attained. Besides low CO₂ tensions, increasing NO₃ ^– concentrations in the medium stimulated the release of NO₃ ^– and NH₄ ⁺. Under CO₂-free air the consumption of NO₃ ^– and the release of NO₂ ^– and NH₄ ⁺ on a total N bases were almost stoichiometric and their rates saturated at much lower irradiances than under air. Under CO₂-free air high rates of NO₂ ^– release were only observed under the blue radiations that were effectively absorbed by photosynthetically active pigments, i.e. 460 nm, but not under 404 and 630 nm radiations. However, the simultaneous illumination of the cells with 404 and 630 nm monochromatic light showed a remarkable synergistic effect on NO₂ ^– release.The results are discussed in terms of the close relationship between C and N metabolism, the photosynthetic reducing power required to convert NO _inf3 ^sup± -N into R – NH₂-N and the blue light activation of nitrate reductase.     

Effects of β-alanine supplementation on the onset of neuromuscular fatigue and ventilatory threshold in women

Summary. This study examined the effects of 28 days of β-alanine supplementation on the physical working capacity at fatigue threshold (PWC_FT), ventilatory threshold (VT), maximal oxygen consumption ( O_2-MAX), and time-to-exhaustion (TTE) in women. Twenty-two women (age ± SD 27.4 ± 6.1 yrs) participated and were randomly assigned to either the β-alanine (CarnoSyn™) or Placebo (PL) group. Before (pre) and after (post) the supplementation period, participants performed a continuous, incremental cycle ergometry test to exhaustion to determine the PWC_FT, VT, O_2-MAX, and TTE. There was a 13.9, 12.6 and 2.5% increase (p < 0.05) in VT, PWC_FT, and TTE, respectively, for the β-alanine group, with no changes in the PL (p > 0.05). There were no changes for O_2-MAX (p > 0.05) in either group. Results of this study indicate that β-alanine supplementation delays the onset of neuromuscular fatigue (PWC_FT) and the ventilatory threshold (VT) at submaximal workloads, and increase in TTE during maximal cycle ergometry performance. However, β-alanine supplementation did not affect maximal aerobic power ( O_2-MAX). In conclusion, β-alanine supplementation appears to improve submaximal cycle ergometry performance and TTE in young women, perhaps as a result of an increased buffering capacity due to elevated muscle carnosine concentrations.     

Effects of high irradiances on photosynthesis,growth and crassulacean acid metabolism in the epiphyteKalanchoö uniflora

Summary Kalancho? uniflora was grown in the glasshouse with and without shading. Chlorophyll content, area/FW ratio and specific leaf area were higher in leaves of shaded as compared to unshaded plants. Light saturation curves and continuous gas exchange measurements showed that the apparent quantum yield and the light-saturated photosynthetic rate were higher in shaded plants. Shaded plants had lower “mesophyll resistances” than unshaded plants, indicating that the different photosynthetic capacities reflected different contents of ribulose biphosphate carboxylase-oxygenase. Highlight treatment of plants grown in the shade resulted in a decreased photosynthetic efficiency, showing that these plants were sensitive to photoinhibition. However, dry matter production was higher in unshaded than in shaded plants. Obviously the difference in irradiance between the two growth regimes did more than offset the differences in photosynthetic efficiency. Applying additional nutrients did not alter the effects of high PFDs. The results are discussed in respect to photosynthetic performence and plant distribution in the epiphytic habitat.     

Variations in chemical composition and in vitro and in situ ruminal degradation characteristics of dried distillers’ grains with solubles from European ethanol plants

The objective of this study was to characterise variations in the composition and nutritive value of dried distillers’ grains with solubles (DDGS) for ruminants, and to estimate the undegradable crude protein (UDP) in DDGS. Thirteen samples originating from wheat, corn, barley and blends of different substrates were studied. The rumen degradation of crude protein (CP) was determined using the nylon bag technique. Samples were incubated for 0, 1, 2, 4, 8, 16, 32 and 72 h, and in situ degradation kinetics were determined. The UDP was estimated using a passage rate of 8%/h. In vitro gas production was measured to estimate the metabolisable energy (ME), net energy for lactation (NE_L) and in vitro digestibility of organic matter (IVDOM). Chemical profiles varied among samples [in g/kg dry matter (DM) ± standard deviation]; the values were 310 ± 33 CP, 86 ± 37 ether extract, 89 ± 18 crude fibre, 408 ± 39 neutral detergent fibre, 151 ± 39 acid detergent fibre and 62 ± 31 acid detergent lignin, as well as in protein fractions according to the Cornell Net Carbohydrate and Protein System [in g/kg CP]; the values were for fractions A, 161 ± 82; B1, 24 ± 11; B2, 404 ± 105; B3, 242 ± 61; and C, 170 ± 87. The ME, NE_L [MJ/kg DM] and IVDOM [%] also varied among samples: 12.1 ± 0.59, 7.3 ± 0.39 and 72.5 ± 4.30, respectively. The in situ rapidly degradable CP fraction (a) varied from 10.2% to 30.6%, and the potentially degradable fraction (b) averaged to 66.8%. The UDP varied from 8.6% to 62.6% of CP. The present study suggests significant variations in composition and nutritive value among different sources of DDGS. The UDP could be predicted on the basis of analysed CP fractions, but the accuracy of UDP prediction improved upon the inclusion of neutral-detergent insoluble nitrogen, explaining 94% of the variation in the UDP values. We conclude that chemical protein fractions may be used to predict the UDP values of DDGS and that the variability in the protein fractions of DDGS should be considered when formulating diets for dairy cows.     

Effects of wild-type and α-tocopherol-enriched transgenic Brassica juncea on the components of xenobiotic metabolism, antioxidant status, and oxidative stress in the liver of mice

Alpha (α)-tocopherol is the most biologically active and preferentially retained form of vitamin E in the human body and is known for its antioxidant and gene regulatory functions. Its increased intake is implicated in protection against diseases that involve an oxidative stress component. We have evaluated the chemopreventive potential of a diet supplemented with natural α-tocopherol-enriched transgenic (TR) Brassica juncea seeds. The modulation of phase I and phase II xenobiotic metabolism and of antioxidative enzymes was compared in the livers of mice fed on a control diet or on a diet supplemented with 2, 4, and 6 % (w/w) of wild-type (WT) or TR seeds. A dose-dependent increase in the specific activities of these enzymes was observed in those animals fed on diet supplemented with TR seeds. In comparison, an increase in the specific activities of antioxidative enzymes was substantial only at higher doses of WT seeds. Consequently, oxidative stress measured in terms of lipid peroxidation and lactate dehydrogenase activity was found to be lower in the case of mice fed with the supplemented diet. However, the chemopreventive potential of TR seeds was more pronounced than that of WT seeds. This study demonstrates the feasibility of fortifying diets with natural α-tocopherol for chemopreventive benefits by means of transgenic manipulation of a commonly used oilseed crop.     

Effects of testosterone and 17, β– estradiol on the polyamine metabolism in cultivated normal rat kidney epithelial cells

Summary. Ornithine decarboxylase (ODC) and diamine oxidase (DAO) are important enzymes involved in the metabolism of polyamines (putrescine, spermidine and spermine). The influence of testosterone (T) and 17, β– estradiol (E₂) on the activity of ODC and DAO was examined in cultivated normal rat kidney (NRK) epithelial cells. The results showed an increase in enzyme activities 4 hours or 12 hours after hormonal treatment. Both T and E₂ led to a significant increase (1.6-fold) in ODC protein level as compared to the controls. Cellular concentration of spermidine and spermine increased (2.2- and 2.6-fold respectively) 4 hours after T addition. A higher levels in concentrations of putrescine (1.4-fold) and spermine (1.5-fold) 12 hours after E₂ treatment were observed. These results suggest that the biosynthesis and terminal oxidation of the polyamines in NRK epithelial cells are androgen- and estrogen-mediated and depend on the hormonal sensitivity of the cells. Received April 5, 1999, Accepted December 20, 1999     

Influence of supplemental high molecular weight pullulan or γ-cyclodextrin on ileal and total tract nutrient digestibility,fecal characteristics,and microbial populations in the dog

Abstract

This study was conducted to determine if supplemental pullulan and γ-cyclodextrin affect canine nutrient digestibility, microbial populations, and fecal characteristics. Ileal cannulated dogs were fed a commercial diet, and treatments were administered daily in a 5×5 Latin square design: (i) no supplement; (ii) 2 g pullulan; (iii) 4 g pullulan; (iv) 2 g γ-cyclodextrin; (v) 4 g γ-cyclodextrin. Ileal and fecal samples were collected the last 4 d of each 14-d period. Increasing pullulan tended (p < 0.10) to linearly increase ileal bifidobacteria and lactobacilli and quadratically increase fecal lactobacilli. A similar response was noted in ileal bifidobacteria and lactobacilli with γ-cyclodextrin. γ-Cyclodextrin resulted in a quadratic decrease (p < 0.05) in fecal Clostridium perfringens. Increasing pullulan linearly increased (p < 0.05) fecal score, while γ-cyclodextrin resulted in a linear decrease (p < 0.05). Pullulan and γ-cyclodextrin supplementation may have beneficial effects on the microbial ecology of dogs.     

Effects of cereal β-glucans and enzyme inclusion on the porcine gastrointestinal tract microbiota

This study was designed to evaluate the effect barley-based diets vs. oats based diets on levels of Lactobacillus, Bifidobacterium and Enterobacterium in the porcine gastrointestinal tract (GIT). In addition the effect of enzyme supplementation in both diets was explored. Twenty-eight boars were used in a 2 × 2 factorial arrangement and were assigned to 1 of 4 dietary treatments: barley-based (B) diet; barley-based diet plus an enzyme supplement (B + ES); oat-based (O) diet or oat-based diet plus an enzyme supplement (O + ES). The enzyme supplement contained endo-1,3-β-glucanase and endo-1,4-β-xylanase. Faecal samples were collected from the pigs prior to initiations of the experiment and at slaughter. At slaughter digesta samples were collected from the stomach, ileum, caecum, proximal and distal colon. Alterations in Lactobacillus species composition in the gastrointestinal tract (GIT) were analysed by genus-specific PCR – denaturing gradient gel electrophoresis (DGGE). DGGE profiles indicated that cereal source provoked shifts in Lactobacillus population. The most diverse populations of lactobacilli emerged after feeding the O diets. Enzymes inclusion altered the composition of Lactobacillus species prevalent throughout the GIT in animals fed the B diet, causing a shift in the dominant lactobacilli present in the caecum and proximal colon. No such effect was evident in animals fed the enzyme supplemented O + ES diet. Microbial plate counts revealed that the O diets gave rise to higher counts of Lactobacillus in the caecum and colon and Bifidobacterium counts in the ileum, caecum and colon than the B diets. The O diet caused a 2 log increase in Enterobacterium counts in the proximal colon, no such effects were observed in animals fed the B, the B + ES or the O + ES diets. Overall both O diets had a more positive influence on the counts of the beneficial microorganisms and richness of the Lactobacillus population in the porcine GIT.     

Effects of microorganism on carbon,nitrogen and phosphorus of Dodonaea viscosa and the soils from different elevations in Yuanmou,Yunnan, China北大核心CSCD

Aims Understanding the effects of soil microorganism at different elevations on plant C:N:P stoichiometry can help us to understand the plant-soil interactions in the context of climate change. Our aim was to quantify the independent and interactive effects of soil microbial communities and temperatures on the C, N, and P in the leaves of Dodonaea viscosa-a global widespread species. Methods Rhizosphere soils of D. viscosa were collected from two elevation zones in Yuanmou County, Yunnan Province. A 2 × 3 factorial experiment with six replications was conducted using climate chambers. The leaf C, N and P contents and the soil properties were measured after three months of the treatments. Important findings Compared with the autoclaved treatment, inoculated rhizosphere soils from both high and low elevations had higher nutrient absorption, especially P uptake. Temperature produced no significant effect on leaf C:N:P stoichiometry, but the interactive effect of temperature and microbial treatment appeared significant. For inoculated rhizosphere soils from high elevation, temperature had no significant effect on leaf C:N:P stoichiometry. For inoculated rhizosphere soils from low elevation, leaf N and P contents under low temperature were significantly lower than those with warmer soils. The promoting effect of soil microorganisms on nutrient uptake may be due to the direct effect of beneficial microorganisms (e.g., mycorrhizal fungi), but not through the alteration of nutrient cycling process. Because D. viscosa in the inoculated rhizosphere soils absorbed more N and P from the soil than those in autoclaved soil, the available N and P in inoculated rhizosphere soils were lower than those in autoclaved soils. As predicted future temperature will be lower in the studied region, the growth of D. viscosa may be negatively affected through plant-microbe feedbacks.     

Effects of β-alanine supplementation on performance and body composition in collegiate wrestlers and football players

The purpose of this study was to examine the effectiveness of β-alanine as an ergogenic aid in tests of anaerobic power output after 8 weeks of high-intensity interval, repeated sprint, and resistance training in previously trained collegiate wrestlers (WR) and football (FB) players. Twenty-two college WRs (19.9 ± 1.9 years, age ± SD) and 15 college FB players (18.6 ± 1.5 years) participated in this double-blind, placebo-controlled study. Each subject ingested either 4 g·d β-alanine or placebo in powdered capsule form. Subjects were tested pre and posttreatment in timed 300-yd shuttle, 90° flexed-arm hang (FAH), body composition, and blood lactate after 300-yd shuttle. Although not statistically significant (p > 0.05) subjects taking β-alanine achieved more desirable results on all tests compared to those on placebo. Performance improvements were greatest in the FB supplement group, decreasing 300 shuttle time by 1.1 seconds (vs. 0.4-second placebo) and increasing FAH (3.0 vs. 0.39 seconds). The wrestlers, both placebo and supplement, lost weight (as was the goal, i.e., weight bracket allowance); however, the supplement group increased lean mass by 1.1 lb, whereas the placebo group lost lean mass (-0.98 lb). Both FB groups gained weight; however, the supplement group gained an average 2.1-lb lean mass compared to 1.1 lb for placebo. β-Alanine appears to have the ability to augment performance and stimulate lean mass accrual in a short amount of time (8 weeks) in previously trained athletes. Training regimen may have an effect on the degree of benefit from β-alanine supplementation.     

Effects of drought stress on the osmotic adjustment and active oxygen metabolism of Phoebe zhennan seedlings and its alleviation by nitrogen application北大核心CSCD

Aims Two-year-old seedlings of Phoebe zhennan were used in this study to explore the responses of osmotic adjustment and active oxygen metabolism to drought stress and the mitigation effect of nitrogen application. Methods The soil water content was firstly adjusted to four treatment levels, i.e. 80% of field water holding capacity (80% FC), 50% FC, 30% FC and 15% FC, respectively. The physiological variables of plants were measured after one week, and then three nitrogen application rates, control (N0), medium nitrogen (MN) and high nitrogen (HN) were performed at an interval of 7 days for four times (7 d, 14 d, 21 d and 28 d, respectively). The same physiological variables were determined again one month after the accomplishment of nitrogen application. Important findings 1) The free proline (Pro) and soluble sugar (SS) contents in the leaves increased significantly with the aggravation of drought stress after 7 days of drought, but the content of soluble protein (SP) was firstly increased and then declined. The increase of Pro content was especially obvious under severe drought (15% FC). After nitrogen application, the content of Pro raise further, but the values varied in drought treatment. The SS contents under sufficient water supply (80% FC) and mild drought (50% FC) were decreased by MN, but it did not change significantly when supplied with HN despite the soil water content. After nitrogen application, the SP contents under 80% FC and 50% FC were lower than those of no exogenous N, while they were opposite response under 30% FC and 15% FC. 2) Before nitrogen application, with the aggravation of drought stress, the hydrogen peroxide (H2O2) content, superoxide dismutase (SOD) activity, catalase (CAT) activity increased significantly, and the peroxidase (POD) activity showed an up-down trend. After nitrogen application, the content of H2O2 was generally deceased at each water condition, with the maximum decrease at MN, while the HN treatment was not conducive to reduce the content of H2O2. The activities of three kinds of enzymes responded differently to the severity of drought and the level of nitrogen application. 3) Before nitrogen application, the content of malondial-dehyde (MDA) in leaves increased significantly when the soil water content declined to and below 50% FC. The relative electrical conductivity (REC) was decreased at first, and followed by significant increase. Except severe drought (15% FC) stress, the MDA content showed a decreasing trend at MN, but a rebound at HN. As regards severe drought stress, however, the content of MDA increased at both MN and HN, indicating that nitrogen application is not a good choice to alleviate the damage caused by severe drought stress. 4)Two-factor ANOVA revealed an obvious interaction between nitrogen application and drought stress. In conclusion, a proper amount of nitrogen (1.35 g·a–1 for each sapling) could somewhat alleviate drought stress no severer than 15% FC on seedlings of Phoebe zhennan, but excessive nitrogen at rate of or more than 2.70 g·a–1 per sapling is not recommended. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

Effects of increasing the intake of dietary β-glucans by exchanging wheat for barley on nutrient digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid concentration and manure ammonia emissions in finishing pigs

An experiment (complete randomised design) was conducted to investigate the linear and quadratic effects of barley β-glucan inclusion level on total tract nutrient apparent digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid (VFA) profile and manure ammonia emissions in pigs. Twenty-four boars (66 kg) were assigned to one of four treatments: (T1) 0 g/kg barley (control diet) (5.6 g/kg β-glucan), (T2) 222 g/kg barley (12.1 g/kg β-glucan), (T3) 444 g/kg barley (18.9 g/kg β-glucan) and (T4) 666 g/kg barley (25 g/kg β-glucan). Barley was substituted for wheat in the diet. The diets were formulated to contain similar concentrations of digestible energy and digestible lysine. There was a linear decrease (P < 0.001) in the total tract apparent digestibility of dry matter, organic matter, gross energy and neutral-detergent fibre with increasing β-glucan concentration. Faecal nitrogen excretion was affected by dietary β-glucan concentration (quadratic P < 0.05). There was a linear decrease in Enterobacteria concentrations (P < 0.05) with increasing dietary β-glucan concentration. Increasing dietary barley levels caused a linear decrease in colonic (P < 0.01) and caecal pH (P < 0.001). Total caecal VFA and propionic acid were affected by dietary β-glucan concentration (quadratic, P < 0.05). There was a linear decrease in the proportion of acetic acid (P < 0.001), isobutyric acid (P < 0.01) and isovaleric acid (P < 0.05) with increasing levels of dietary barley in both the caecum and colon. There was a linear increase in the proportion of propionic acid (P < 0.001) and butyric acid (P < 0.05) with increasing barley in the colon. In conclusion, high level of dietary β-glucan (25 g/kg) is required to reduce offensive odour forming branched-chain VFAs; however, diet digestibility is compromised at such levels.     

Amino acid digestibility in corn distillers’ dried grains with solubles in pigs at different dietary levels of casein and test ingredient

Digestibility of amino acids (AA) in feed ingredients for pigs has been generally determined by feeding experimental diets containing test feedstuffs as a sole source of N, which may lead to the deficiency or imbalance of AA and hinder an accurate determination of digestibility values. Therefore, the addition of casein in experimental diets may ameliorate the potential negative effects of deficiency or imbalance of AA. In addition, the concentration of test feedstuffs in experimental diets may affect the digestibility of AA in test feedstuffs. Two experiments were conducted with corn distillers’ dried grains with solubles (DDGS) as the test feedstuff to determine the effects of increasing concentrations of casein in experimental diets on standardized ileal digestibility (SID) of AA in DDGS (experiment 1) and to investigate the effects of two concentrations of DDGS in experimental diets with or without the addition of casein on SID of AA in DDGS (experiment 2). In experiment 1, 20 barrows (initial BW = 45.3 ± 1.80 kg) surgically fitted with T-cannulas at the distal ileum were allocated to a quadruplicate 5 × 2 incomplete Latin square design with five diets and two periods. Four isonitrogenous diets containing increasing concentrations of casein from 0 to 165 g/kg with decreasing concentrations of DDGS from 466.8 to 0 g/kg and a N-free diet were prepared. The SID of AA, except for arginine, cysteine, and glycine, in DDGS linearly decreased (P < 0.05) with increasing concentrations of casein in experimental diets. Quadratic response (P = 0.023) was observed in the SID of lysine in DDGS when the concentration of casein in experimental diets increased. In experiment 2, the same 20 barrows (initial BW = 52.8 ± 2.99 kg) and experimental design as experiment 1 were used with different diets, which were prepared as a 2 × 2 factorial arrangement with the concentration of DDGS at 466.8 or 155.6 g/kg and that of casein at 0 or 110 g/kg. Regardless of the addition of casein, pigs fed experimental diets containing 466.8 g/kg DDGS had greater (P < 0.01) SID of indispensable AA, except for tryptophan, in DDGS than those fed diets containing 155.6 g/kg DDGS. In conclusion, the addition of casein in experimental diets did not affect the SID of AA in DDGS, whereas the SID of AA in DDGS decreased as the concentration of DDGS in diets decreased.