Diel patterns of leaf and root growth: endogenous rhythmicity or environmental response?

Plants are sessile organisms forced to adjust to their surrounding environment. In a single plant the photoautotrophic shoot is exposed to pronounced environmental variations recurring in a day-night 24?h (diel) cycle, whereas the heterotrophic root grows in a temporally less fluctuating environment. The contrasting habitats of shoots and roots are reflected in different diel growth patterns and their responsiveness to environmental stimuli. Differences between diel leaf growth patterns of mono- and dicotyledonous plants correspond to their different organization and placement of growth zones. In monocots, heterotrophic growth zones are organized linearly and protected from the environment by sheaths of older leaves. In contrast, photosynthetically active growth zones of dicot leaves are exposed directly to the environment and show characteristic, species-specific diel growth patterns. It is hypothesized that the different exposure to environmental constraints and simultaneously the sink/source status of the growing organs may have induced distinct endogenous control of diel growth patterns in roots and leaves of monocot and dicot plants. Confronted by strong temporal fluctuations in environment, the circadian clock may facilitate robust intrinsic control of leaf growth in dicot plants.     

Do tropical forest leaves suffer more insect herbivory? A comparison of tropical versus temperate herbivory,estimated from leaf litter

It is generally believed that tropical forests suffer more herbivory, as a proportion of leaf area, than do temperate forests. Reviews so far have compared studies performed by different authors using very different methodologies. Here we carried out studies on 125 samples at 86 localities in eastern North America and on 75 samples taken at five localities in Malaysia and Singapore, including both mature secondary and primary forest. Samples in North America were spread over 3 years. In tropical Asia, the samples were taken at four time slices at least 8 months apart, scattered over a 4-year period. Total herbivore damage during the lifetime of tree leaves was estimated from the percentage area damaged in recently fallen, undecayed leaves from the forest floor, using scanner-linked software. In terms of percentage damage per leaf, the results suggest that lowland tropical forest has significantly higher leaf herbivory (5.82%) than temperate forest (5.48%). This is in accord with the general expectation that aseasonal tropical forests should have more herbivory damage. However, when percentage damage ‘per unit time of growing season’ is calculated based on an estimate of leaf lifetime in the tropics, tropical lowland herbivory damage turns out to be a fraction (about one half) of that in the temperate zone. Thus, these results tend to put in question the widely held view that herbivore damage is markedly more intense in the tropics. Over total leaf lifetime, the intensity of damage in the tropical area is only slightly higher than temperate regions. In terms of intensity of herbivory on leaves per unit of time, the opposite seems to be the case. It is uncertain which index should be taken as more significant in interpreting the selection pressure for anti-herbivore defenses in the tropics.     

Are differences in root growth of nitrogen catch crops important for their ability to reduce soil nitrate-N content,and how can this be measured?

An experiment was made to measure root growth of nitrogen catch crops, to investigate whether differences in root growth among plant species are related to their ability to deplete the soil nitrate-N pool. Large differences were observed in root growth parameters. Monocot species had rooting depth penetration rates in the range of 1.0 to 1.2 mm d^–1 °C^–1, whereas the non-legume dicot species had rates between 1.5 and 2.3 mm d^–1 °C^–1. Substantial differences were also found in the lag time from sowing until significant root growth was observed. The estimated temperature sum needed for the crops to reach a rooting depth of 1.0 m varied from 750 d °C for fodder radish to 1375 d °C for Italian ryegrass. The depth distribution of the root system varied strongly, and at a depth of 1.0 m the non-legume dicot species generally had root intensities (number of root intersections m^–1 line on the minirhizotrons) 12 times as high as the monocot species.The amount of nitrate left in the topsoil (0–0.5 m) was only weakly correlated to a few of the measured plant and root parameters, whereas nitrate left in the subsoil (0.5–1.0 m) was clearly correlated to several root parameters. Subsoil nitrate residues were well correlated to root intensity, but showed even stronger correlations to more simple estimates of rooting depth. In the deepest soil layer measured (1.0–1.5 m), the soil water nitrate concentration was reduced from 119 g L^–1 without a catch crop to 61 g L^–1 under Italian ryegrass and to only 1.5 g L^–1 under fodder radish.The results show that to identify the important differences in root growth among catch crops, root growth must be measured in deep soil layers. In this study, none of the measurements made aboveground or in the upper soil layers were well related to subsoil nitrate depletion.     

Exploring patterns of fine root morphological,chemical, and anatomical traits of 12 tree species from visible–near-infrared spectral reflectance

Plant and Soil - Root morphological response to localised phosphorus (P) application plays a crucial role in P acquisition. However, detailed knowledge of when and where roots respond to P patch...     

Effect of pH, light intensity, salt and nitrogen concentrations on growth and β-carotene accumulation by a new isolate of Dunaliella sp

Summary In the present study Dunaliella sp. that could grow in the Johnson medium was isolated from hypersaline Lake Tuz and its β-carotene production was studied in a batch system, in order to determine the optimal conditions required for the highest β-carotene accumulation. In the experiments with light intensity, the cell numbers and β-carotene content were maximum at pH 9, with 20% of NaCl concentration and 48 kerg cm⁻² s⁻¹ light intensity. At this light intensity, the β-carotene content of Dunaliella sp. ranged between 0.177 and 1.095 mg/ml for the culture broth and 0.119 to 0.261 ng/cell on a per cell basis under the nitrogen limitation. At the end of the experiments, the maximum β-carotene accumulation and the cell number were obtained at pH 7, 5 mM NaNO₃ and 20% NaCl concentrations as 0.261 ng/cell, 4.2×10⁶ cell/ml, respectively.     

Do <Emphasis Type="Italic">Polylepis australis</Emphasis> trees tolerate herbivory? Seasonal patterns of shoot growth and its consumption by livestock

Browsing is one of the main factors determining survival, growth rate, woodland structure, and distribution of the high mountain tree Polylepis australis. This species has a substantial regrowth capacity, which may function as a mechanism to tolerate herbivory, but it is unknown to what extent it may compensate for the impact of herbivory. In 15 low-density tree stands subject to exclusion, moderate, and heavy livestock pressure, we selected 12 P. australis individuals <2 m tall, tagged four new shoots per tree and measured shoot length every month during a year. At the stand and at the tree level, we analyzed monthly dynamics of growth and browsing, and the annual output in terms of total browsing and total gross and net growth (not discounting and discounting consumption, respectively). In addition, we assessed the influence of stand, tree and microsite characteristics on growth and browsing patterns. Polylepis australis fully compensated for herbivory in terms of shoot gross growth at moderate, but not at heavy livestock pressure. In terms of net growth, this species did not fully compensate for herbivory at any stocking rate. We found a strong coupling between browsing and growth along the year, suggesting that regrowth attracts browsing, and browsing promotes regrowth. At the stand level, annual gross growth was not affected by habitat characteristics, while at the tree level, annual gross growth decreased on more rocky microsites for browsed but not for unbrowsed trees. We concluded that stocking densities should be limited to allow for a reasonable annual net growth, as its nitrogen rich leaves are a valuable food resource and P. australis forests provide important ecosystem services.     

Phenolic content and growth of wetland macrophytes: Is the allocation to secondary compounds driven by nutrient availability?

This study compares soluble phenolics and lignin content in two wetland macrophytes with contrasting life strategies grown under a varying nutrient supply in the field and in a greenhouse experiment. The differences are explained in terms of the protein competition model (PCM) hypothesis relating changes in secondary metabolites to changing nutrient limitation. The two study species, Eleocharis cellulosa (EC) and Typha domingensis (TD), are both widespread in tropical and subtropical freshwater and brackish marshes of the New World, and are often found in P-limited rather than N-limited conditions. TD is a fast-growing competitor with large nutrient requirements. EC is a stress tolerator, quite well adapted to growth in nutrient-limiting environments. In both species, the concentration of phenolics was negatively correlated with increasing growth (due to increasing nutrient levels). This is in agreement with the PCM hypothesis, which predicts an increase in phenolic synthesis when protein synthesis (and consequently growth) is low due to limited resource availability. An interesting difference was found in the correlation between tissue nutrients and phenolics. TD from both the field and the greenhouse showed a negative correlation between tissue P and phenolics, while EC displayed a significant negative correlation between tissue N and phenolics. EC is adapted to low P, and increased tissue P content represents luxury consumption (uptake of P for storage) which is not reflected in increased growth and thus is not correlated with phenolics. These are the first steps in elucidating the relationship among nutrient availability, growth and phenolic content in two important primary producers of tropical and subtropical marshes.     

What explains patterns of species richness? The relative importance of climatic‐niche evolution,morphological evolution,and ecological limits in salamanders

A major goal of evolutionary biology and ecology is to understand why species richness varies among clades. Previous studies have suggested that variation in richness among clades might be related to variation in rates of morphological evolution among clades (e.g., body size and shape). Other studies have suggested that richness patterns might be related to variation in rates of climatic‐niche evolution. However, few studies, if any, have tested the relative importance of these variables in explaining patterns of richness among clades. Here, we test their relative importance among major clades of Plethodontidae, the most species‐rich family of salamanders. Earlier studies have suggested that climatic‐niche evolution explains patterns of diversification among plethodontid clades, whereas rates of morphological evolution do not. A subsequent study stated that rates of morphological evolution instead explained patterns of species richness among plethodontid clades (along with “ecological limits” on richness of clades, leading to saturation of clades with species, given limited resources). However, they did not consider climatic‐niche evolution. Using phylogenetic multiple regression, we show that rates of climatic‐niche evolution explain most variation in richness among plethodontid clades, whereas rates of morphological evolution do not. We find little evidence that ecological limits explain patterns of richness among plethodontid clades. We also test whether rates of morphological and climatic‐niche evolution are correlated, and find that they are not. Overall, our results help explain richness patterns in a major amphibian group and provide possibly the first test of the relative importance of climatic niches and morphological evolution in explaining diversity patterns.     

Can the growth factors PTHrP,Ihh and VEGF,together regulate the development of a long bone?

Endochondral ossification is the process of differentiation of cartilaginous into osseous tissue. Parathyroid hormone related protein (PTHrP), Indian hedgehog (Ihh) and vascular endothelial growth factor (VEGF), which are synthesized in different zones of the growth plate, were found to have crucial roles in regulating endochondral ossification. The aim of this study was to evaluate whether the three growth factors PTHrP, Ihh and VEGF, together, could regulate longitudinal growth in a normal human, fetal femur. For this purpose, a one-dimensional finite element (FE) model, incorporating growth factor signaling, was developed of the human, distal, femoral growth plate. It included growth factor synthesis in the relevant zones, their transport and degradation and their effects. Simulations ran from initial hypertrophy in the center of the bone until secondary ossification starts at approximately 3.5 months postnatal. For clarity, we emphasize that no mechanical stresses were considered. The FE model showed a stable growth plate in which the bone growth rate was constant and the number of cells per zone oscillated around an equilibrium. Simulations incorporating increased and decreased PTHrP and Ihh synthesis rates resulted, respectively, in more and less cells per zone and in increased and decreased bone growth rates. The FE model correctly reflected the development of a growth plate and the rate of bone growth in the femur. Simulations incorporating increased and decreased PTHrP and Ihh synthesis rates reflected growth plate pathologies and growth plates in PTHrP-/- and Ihh-/- mice. The three growth factors, PTHrP, Ihh and VEGF, could potentially together regulate tissue differentiation.     

Mum, why do you keep on growing?Impacts of environmental variability on optimal growth and reproduction allocation strategies of annual plants

In their 1990 paper Optimal reproductive efforts and the timing of reproduction of annual plants in randomly varying environments, Amir and Cohen considered stochastic environments consisting of i.i.d. sequences in an optimal allocation discrete-time model. We suppose here that the sequence of environmental factors is more generally described by a Markov chain. Moreover, we discuss the connection between the time interval of the discrete-time dynamic model and the ability of the plant to rebuild completely its vegetative body (from reserves). We formulate a stochastic optimization problem covering the so-called linear and logarithmic fitness (corresponding to variation within and between years), which yields optimal strategies. For ``linear maximizers', we analyse how optimal strategies depend upon the environmental variability type: constant, random stationary, random i.i.d., random monotonous. We provide general patterns in terms of targets and thresholds, including both determinate and indeterminate growth. We also provide a partial result on the comparison between ``linear maximizers' and ``log maximizers'. Numerical simulations are provided, allowing to give a hint at the effect of different mathematical assumptions.     

Are contents of Rubisco, soluble protein and nitrogen in flag leaves of rice controlled by the same genetics?

Genetic relations among the contents of Rubisco, soluble protein and total leaf nitrogen (N) in leaves of rice (Oryza sativa L.) were studied by quantitative trait loci (QTL) analysis with a population of backcross inbred lines (BILs) of japonica Nipponbarexindica Kasalath. The ratio of Rubisco to total leaf N in leaves is the main target in improving photosynthetic N-use efficiency in plants. QTLs controlling Rubisco content were not detected near QTLs for total leaf N content. These results indicate that contents of Rubisco and total leaf N are controlled by different genetics. QTLs that controlled the ratio of Rubisco to total leaf N (CORNs) were detected. These results suggest that some mechanism(s) may be involved in determining this ratio, while the contents of Rubisco and total leaf N are controlled in other ways. In elite BILs, the ratios of Rubisco to total leaf N were higher than those of both parents. These results suggest a good possibility of improving N-use efficiency by CORNs in cultivated rice. A QTL controlling Rubisco content was mapped near a QTL for soluble protein content on chromosome 8 at 5 d after heading and on chromosome 9 at 25 d. In each chromosome region, the peaks of both QTLs overlapped accurately, giving a high possibility of pleiotropic effects by the same genes. Different QTLs controlling soluble protein or Rubisco were detected from those detected at 5 d or 25 d after heading. This suggests that these traits are genetically controlled depending on the growth stages of leaves.     

Methylation of ribonucleic acid by the carcinogens dimethyl sulphate, N-methyl-N-nitrosourea and N-methyl-N′-nitro-N-nitrosoguanidine. Comparisons of chemical analyses at the nucleoside and base levels

1. The following methods for hydrolysis of methyl-(14)C-labelled RNA, and for chromatographic isolation and determination of the products, were investigated: enzymic digestion to nucleosides at pH6 or 8; alkaline hydrolysis and conversion into nucleosides; hydrolysis by acid to pyrimidine nucleotides and purine bases, or completely to bases; chromatography on Dowex 50 (NH(4) (+) form) at pH6 or 8.9, or on Dowex 50 (H(+) form), or on Sephadex G-10. 2. The suitability of the various methods for determination of methylation products was assessed. The principal product, 7-methylguanosine, was unstable under the conditions used for determinations of nucleosides. 3- and 7-Methyladenine and 3- and 7-methylguanine are best determined as bases; 1-methyladenine and 3-methylcytosine can be isolated as either nucleosides or bases; O(6)-methylguanine is unstable under the acid hydrolysis conditions used and can be determined as the nucleoside; 3-methyluracil was detected, but may be derived from methylation of the ionized form of uracil. 3. Differences between the patterns of methylation of RNA and homopolyribonucleotides by the N-methyl-N-nitroso compounds and dimethyl sulphate were found: the nitroso compounds were able to methylate O-6 of guanine, were relatively more reactive at N-7 of adenine and probably at N-3 of guanine, but less reactive at N-1 of adenine, N-3 of cytosine and probably at N-3 of uridine. They probably reacted more with the ribose-phosphate chain, but no products from this were identified. 4. The possible influences of these differences on biological action of the methylating agents is discussed. Nitroso compounds may differ principally in their ability to induce miscoding in the Watson-Crick sense by reaction at O-6 of guanine. Both types of agent may induce miscoding to a lesser extent through methylation at N-3 of guanine; both can methylate N atoms, presumably preventing Watson-Crick hydrogen-bonding. N-Methyl-N-nitrosourea can degrade RNA, possibly through phosphotriester formation, but this mechanism is not proven.     

Three diurnal patterns of anthesis in Ipomoea carnea subsp. fistulosa (Convolvulaceae): Implications for temporal,behavioral and morphological characteristics of pollinators?

Flowers of Ipomoea are characterized mainly by being ephemeral and showy. They attract many floral visitors of different taxonomic groups, whose activity is generally synchronized with opening and closing times of flowers. In this study we tested whether flowering, morphology and floral biology of Ipomoea carnea subsp. fistulosa were related to pollinator dynamics and environmental factors, emphasizing temporal and behavioral aspects in different months of the year, in an area shaped by human activities of the semi-arid region of Bahia, northeastern Brazil. Observations were made for three days each month, from October 2009 to August 2010 in the campus of the State University of Feira de Santana. We investigated morphology, floral biology, reproductive system, and flowering of I. carnea, and collected floral visitors. Flowering occurred in all months. Flowers opened during three periods of the day: morning, afternoon and night, with life-time of the respective flowers being 11, 19, and 16 h in each period, respectively. The study species is self-incompatible. Flowers were visited predominantly by bees and moths, and exhibit morphological traits related to the syndromes of melittophily and phalaenophily. The conspicuous pink flowers attracted bees and the strong sweet scent produced during the night attracted moths. The bees Apis mellifera, Melitomella murihirta, Melitoma aff. segmentaria and Pseudaugochlora pandora were considered as potential diurnal pollinators, and the hawkmoth Agrius cingulata as a potential nocturnal pollinator. The 24 h flower display increases the chance of pollination, especially for ruderal and weedy species such as I. carnea subsp. fistulosa^© 2013 Elsevier GmbH.     

Can ecosystem functional recovery be traced to decomposition and nitrogen dynamics in estuaries of the Lower Laguna Madre,Texas?

The biggest incentive to attempt the restoration and protection of estuaries is their widely acknowledged ecological and economic importance. Assessing estuary health and recovery can most accurately come from examining ecosystem processes. The purpose of this study was to explore the potential of mass loss and nitrogen (N) dynamics during leaf litter decomposition, to detect signs of functional recovery in two estuarine systems in south Texas. Submerged litterbags with black mangrove (Avicennia germinans) leaves were retrieved at various dates over 320 days. Decomposition was about 50% slower in one of the recovering systems compared to a reference site. Nitrogen immobilization and release from decaying leaf litter also discriminated among sites. Nitrogen immobilization potentials ranged from 4.15 to 6.89 mgN/g leaf litter, with the reference site exhibiting the highest value and thus the highest potential to conserve N during litter decomposition. The reference site also had a N immobilization time twice as long as the recovering sites, and a slower net release after the immobilization, appearing again as the most conservative in this part of the N cycling, possibly pointing to a less disturbed, or more stable ecosystem. Overall, the N dynamics during decomposition of mangrove leaf litter were similar in both recovering sites, whereas the reference site had a more conservative nutrient dynamics with more N being retained for longer in decomposing litter, coupled with a slower net release. Metrics derived from N dynamics may provide a finer resolution assessment of functional recovery, than only decomposition metrics.     

Net uptake of dissolved free amino acids by the giant clam, Tridacna maxima: alternative sources of energy and nitrogen?

 The role of dissolved free amino acids (DFAA) in nitrogen and energy budgets was investigated for the giant clam, Tridacna maxima, growing under field conditions at One Tree Island, at the southern end of the Great Barrier Reef, Australia. Giant clams (121.5–143.7 mm in shell length) took up neutral, acidic and basic amino acids. The rates of net uptake of DFAA did not differ between light and dark, nor for clams growing under normal or slightly enriched ammonium concentrations. Calculations based on the net uptake concentrations typical of the maximum concentrations of DFAA found in coral reef waters (∼0.1 μM ) revealed that DFAA could only contribute 0.1% and 1% of the energy and nitrogen demands of giant clams, respectively. These results suggest that DFAA does not supply significant amounts of energy or nitrogen for giant clams or their symbionts. Accepted: 7 October 1998     

Can acclimation of thermal tolerance,in adults and across generations,act as a buffer against climate change in tropical marine ectotherms?

Thermal acclimation capacity was investigated in adults of three tropical marine invertebrates, the subtidal barnacle Striatobalanus amaryllis, the intertidal gastropod Volegalea cochlidium and the intertidal barnacle Amphibalanus amphitrite. To test the relative importance of transgenerational acclimation, the developmental acclimation capacity of A. amphitrite was investigated in F₁ and F₂ generations reared at a subset of the same incubation temperatures. The increase in CT_max (measured through loss of key behavioural metrics) of F₀ adults across the incubation temperature range 25.4–33.4 °C was low: 0.00 °C (V. cochlidium), 0.05 °C (S. amaryllis) and 0.06 °C (A. amphitrite) per 1 °C increase in incubation temperature (the acclimation response ratio; ARR). Although the effect of generation was not significant, across the incubation temperature range of 29.4–33.4 °C, the increase in CT_max in the F₁ (0.30 °C) and F₂ (0.15 °C) generations of A. amphitrite was greater than in the F₀ (0.10 °C). These correspond to ARR's of 0.03 °C (F₀), 0.08 °C (F₁) and 0.04 °C (F₂), respectively. The variability in CT_max between individuals in each treatment was maintained across generations, despite the high mortality of progeny. Further research is required to investigate the potential for transgenerational acclimation to provide an extra buffer for tropical marine species facing climate warming.     

Do the maximum sizes,ages and patterns of growth of three reef‐dwelling labrid species at two latitudes differ in a manner conforming to the metabolic theory of ecology?

The size and age data and patterns of growth of three abundant, reef‐dwelling and protogynous labrid species (Coris auricularis, Notolabrus parilus and Ophthalmolepis lineolata) in waters off Perth at c. 32° S and in the warmer waters of the Jurien Bay Marine Park (JBMP) at c. 30° S on the lower west coast of Australia are compared. Using data for the top 10% of values and a randomization procedure, the maximum total length (L_T) and mass of each species and the maximum age of the first two species were estimated to be significantly greater off Perth than in the JBMP (all P < 0·001) and the maximum ages of O. lineolata in the two localities did not differ significantly (P > 0·05). These latitudinal trends, thus, typically conform to those frequently exhibited by fish species and the predictions of the metabolic theory of ecology (MTE). While, in terms of mass, the instantaneous growth rates of each species were similar at both latitudes during early life, they were greater at the higher latitude throughout the remainder and thus much of life, which is broadly consistent with the MTE. When expressed in terms of L_T, however, instantaneous growth rates did not exhibit consistent latitudinal trends across all three species. The above trends with mass, together with those for reproductive variables, demonstrate that a greater amount of energy is directed into somatic growth and gonadal development by each of these species at the higher latitude. The consistency of the direction of the latitudinal trends for maximum body size and age and pattern of growth across all three species implies that each species is responding in a similar manner to differences between the environmental characteristics, such as temperature, at those two latitudes. The individual maximum L_T, mass and age and pattern of growth of O. lineolata at a higher and thus cooler latitude on the eastern Australian coast are consistent with the latitudinal trends exhibited by those characteristics for this species in the two western Australian localities. The implications of using mass rather than length as the indicator variable when comparing the maximum sizes of the three species and the trends exhibited by the instantaneous growth rates of those species at different latitudes are explored. Although growth curves fitted to both the L_T and masses at age for the males of each species lay above those for their females, this would not have influenced the conclusions drawn from common curves for both sexes.     

Inhibition of bacterial growth and galactosyltransferase activity of WbwC by α, ω-bis(3-alkyl-1H-imidazolium)alkane salts: Effect of varying carbon content

A series of compounds was designed and synthesized having two imidazolium rings separated by a polymethylene spacer and having alkyl substituents on each of the imidazolium rings. The compounds were assayed for their effects on the activity of galactosyltransferase WbwC, and also on the growth of Gram-negative and Gram-positive bacteria, as well as human cells. The inhibition observed on enzyme activities and cell growth was dependent on the total number of carbons in the spacer and the alkyl substituents on the imidazolium rings. These readily synthesized, achiral compounds have potential as antimicrobial and antiseptic agents.     

Efficacy of β-mannanase supplementation to corn–soya bean meal-based diets on growth performance,nutrient digestibility,blood urea nitrogen,faecal coliform and lactic acid bacteria and faecal noxious gas emission in growing pigs

A study was conducted to determine the efficacy of β-mannanase supplementation to a diet based on corn and soya bean meal (SBM) on growth performance, nutrient digestibility, blood urea nitrogen (BUN), faecal coliforms and lactic acid bacteria, and noxious gas emission in growing pigs. A total of 140 pigs [(Landrace × Yorkshire) × Duroc; average body weight 25 ± 3 kg] were randomly allotted to a 2 × 2 factorial arrangement with dietary treatments consisting of hulled or dehulled SBM without or with supplementation of 400 U β-mannanase/kg. During the 6 weeks of experimental feeding, β-mannanase supplementation had no effect on body weight gain, feed intake and gain:feed (G:F) ratio. Compared with dehulled SBM, feeding hulled SBM caused an increased feed intake of pigs in the entire trial (p = 0.05). The G:F ratio was improved in pigs receiving dehulled SBM (p < 0.05). Dietary treatments did not influence the total tract digestibility of dry matter, nitrogen and gross energy. Enzyme supplementation reduced (p < 0.05) the population of faecal coliforms and tended to reduce the NH₃ concentration after 24 h of fermentation in a closed box containing faecal slurry. Feeding hulled SBM tended to reduce NH₃ emission on days 3 and 5 of fermentation. In conclusion, mannanase supplementation had no influence on growth performance and nutrient digestibility but showed a positive effect on reducing coliform population and tended to reduce NH₃ emission. Dehulled SBM increased G:F ratio and hulled SBM tended to reduce NH₃ emission.