Spawning Quality Research Articles

Evaluation of Vocational Training Programmes on Mushroom Cultivation

To address the livelihood security of the small and marginal farmers, adoption of subsidiary occupations have been constantly advocated by the extension scientists. Mushroom cultivation, having no requirement of arable land, can be an important subsidiary enterprise for small and marginal farmers. The present study was conducted to evaluate the training programmes on mushroom cultivation organized by KVK, Moga (Punjab). Study revealed that majority of the trainees were found to be satisfied with respect to various aspects of training programmes like subject matter content, training duration, practical exercises, provision of literature. More than 90 per cent trainees found their training programme effective in meeting their expectations. Study further reveals that most of the trainees scored medium to high knowledge scores after attending the training programme on mushroom cultivation. There was significant gain in knowledge of trainees after participating in mushroom cultivation training programmes. It was also observed that 37.24 percent of the trainees had adopted mushroom cultivation enterprise after training whereas 29.79 percent of the trainees discontinued the enterprise over time. Lack of proper infrastructure, discouragement by fellow farmers, lack of assured market, non-remunerative prices, and poor quality of spawn were found to be the main reasons for non-adoption and discontinuance of the mushroom cultivation enterprise.

Nutritional programming through broodstock diets to improve utilization of very low fishmeal and fish oil diets in gilthead sea bream

The complete removal of fishmeal (FM) and fish oil (FO) is required to promote the sustainable development of aquaculture and for that, fast growing high quality fish that are fed without FM and FO are necessary. Early nutritional programming may allow the production of fish better adapted to utilize diets with vegetable meals (VM) and oils (VO). The main objective of this study was to research in the potential value of fatty acids as modulators of early nutritional programming in marine fish for a better utilization of VO/VM. For that purpose gilthead sea bream (Sparus aurata) broodstock were fed four different replacement levels of FO by linseed oil (LO) and their effect on fecundity and spawn quality, egg composition, Δ-6-desaturase (Δ6D) gene expression, progeny growth performance and their growth response to a challenge with diets low in FO and FM, but high in VO and VM. The results showed that feeding gilthead sea bream broodstock with high LO diets had very long-term effects on the progeny. Thus, FO replacement by LO up to 80–100% in broodstock diets for gilthead sea bream not only reduced fecundity and spawn quality, but also growth of 45 dah and 4-month-old juveniles, as well as Δ6D gene expression. However, when the 4month-old juveniles were fed with a low FM and FO diet, even those from broodstock fed only 60% replacement of FO by LO showed a higher growth and feed utilization than juveniles from parents fed FO. These results demonstrate the interesting potential of early nutritional programming of marine fish by broodstock feeding to improve long-term performance of the progeny. Further studies are being conducted to determine optimum nutrient levels in the broodstock diets and the molecular mechanisms implied to develop effective nutritional intervention strategies for this species. Statement of relevanceThis study demonstrates for the first time in fish the potential of broodstock nutrition to conduct early nutritional programming of culture fish for a better utilization of low fish meal and fish oil diets by the progeny, showing its effect not only during reproduction and larval development but also during on-growing.

Relationships between spawn quality and biochemical composition of eggs and hatchlings of Octopus vulgaris under different parental diets

Abstract Three frozen mono-diets (sardine, crab and squid) were supplied to Octopus vulgaris broodstocks, and their effects on the spawn quality and biochemical composition of eggs and hatchlings were studied. Squid and crab diets achieved superior spawn quality, producing in general significantly larger eggs, as compared to sardine diet. Similar differences were also observed in the biometric parameters of hatchlings (ventral and dorsal mantle lengths and dry weight) as well as in the survival of fasted hatchling which were greater in the squid and crab groups with respect to sardine treatment. On the other side, a strong and significant relationship between the mentioned biometrical measures and hatchlings survival was found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. Statistical techniques as multivariate and correlation analyses were used to distinguish dietary groups based on protein content and lipid and fatty acid composition of achieved eggs and hatchlings as well as to relate this composition with spawn quality parameters. The analyses allowed to discriminate the nutrient composition of the early stages which was also found to be significantly correlated to the differences in the spawn quality of the different dietary groups, thereby underlining the importance of the protein content, and lipid classes like phosphatidylethanolamine, phosphatidylcholine, cholesterol and triacylglycerol, as well as docosahexaenoic (22:6n-3) and eicosapentaenoic (20:5n-3) fatty acids in the reproduction of O. vulgaris . Statement of Relevance It has been demonstrated that biochemical composition of the broodstock diet is a major determinant of successful reproduction and offspring survival in teleost fish (Watanabe & Vasallo-Agius, 2003; Bobe and Labbe, 2009). For Octopus vulgaris , our data suggest that the broodstock diet influenced the protein content and lipid composition of eggs and hatchlings, and these nutrients are related to the differences found in the spawn quality. A strong and significant relationship between the measured biometrical parameters and hatchlings survival was also found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. On the other side, the utilization of nutrients during the embryo development can also be seen as an indicator of the nutritional requirements during the early stages of development and be useful for a future advance in the formulation of paralarvae artificial diets. Our results pointed to an embryo catabolism mainly based on proteins, as previously suggested (Lee, 1994; Villanueva and Norman, 2008). Data also suggest that triacylglycerol, sterol ester and phosphatidylcholine were specifically catabolized for energy and/or used to de novo synthesize lipid classes such as PS or PE. Within fatty acids, we found that arachidonic acid was strongly reduced (50–51%) during embryonic development. Further studies on the particular role of AA and the n–3 HUFA (mainly EPA and DHA) for early stages of O. vulgaris are needed, specially taking into account that these FAs are essential for this species (Monroig et al., 2012a,b).

Spawn quality and GnRHa induction efficiency in longfin yellowtail (Seriola rivoliana) broodstock kept in captivity

Abstract The longfin yellowtail ( Seriola rivoliana ) is a preferred species for aquaculture diversification in the Canary Islands. The aim of the present study was obtain a large number of spawns whit hormonal induction, which would provide reliable numbers of juveniles for the sustainable development of longfin yellowtail culture. Two females with oocytes bigger than 500 μ, and four males, previously captured from the wild were used for this study. Females and males of 10.7 ± 1.4 and 8.5 ± 0.9 kg body weight and 86.2 ± 5.3 and 78.9 ± 1.9 cm total length, respectively, were acclimated in 10 m 3 tanks. Fish were injected three times per month between June and November with 20 μg kg − 1 of GnRHa. During the experimental period, temperature ranged from 21.9 ± 0.2 °C in June to 23.5 ± 0.4 °C in November. Broodstock feeding consisted in Atlantic mackerel ( Scomber scombrus ) at 2% BW, three times per week. A total of 20,189,700 eggs (944,326 eggs female kg − 1 ) were obtained with fifteen injections and 33 spawns (2.2 ± 0.7 spawns per injection). A significant positive was found, between the numbers of eggs obtained each month and the average monthly temperature. Latency period was approximately of 28 h and 30 min. A highly significant negative statistical relation ( P − 1 of GnRHa every 10 days in fluent males and 500 μm oocytes bearing females of longfin yellowtail broodstock were successful to obtain a high induction efficiency and excellent spawn quality.

Influence of hormonal induction and broodstock feeding on longfin yellowtailSeriola rivolianamaturation, spawning quality and egg biochemical composition

To optimize broodstock management for Seriola rivoliana, a survey over 5 years was performed to evaluate the effects of successive hormonal inductions with GnRHa or dietary regime on spawning quality. Running males and females with an oocyte diameter > 500 μm were injected with GnRHa. The spawning quality was compared among consecutive years and different moments along the spawning season. Besides, three different feeding regimes were tested. Spawning quality parameters were not significantly affected by time along the spawning season, whereas they were clearly influenced by diet. Particularly, broodfish fed the mackerel regime (M) showed a significantly higher number of eggs than other treatments. Besides, dietary protein content significantly improved broodstock fecundity of S. rivoliana. Moreover, hatching rates were also higher in broodfish fed mackerel and the dietary docosahexaenoic acid (DHA) levels significantly increased this parameter. Despite polar lipids were not significantly affected, neutral lipids fatty acid composition of S. rivoliana eggs showed higher 18:2n-6 in eggs, whereas ARA content was not affected. The results of this study denoted the high fecundity and good spawning quality of S. rivoliana broodfish and suggested the importance of high protein, energy and DHA levels in broodstock diets.

Genetic diversity within sea trout population from an intensively stocked southern Baltic river, based on microsatellite DNA analysis

AbstractSea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small‐scale differentiation in sea trout populations from one basin with a strong emphasis on the relationship between wild and hatchery origin fish. A total of 216 sea trout were genotyped at 10 microsatellite loci. Global FST obtained by amova was low at 0.0165. Pairwise FST were significant for all tests except wild and stocked adults. The highest pairwise difference was found between the hatchery sample and Kwacza (FST = 0.038). Analysis of the genetic structure revealed micro‐geographical differentiation with four subpopulations. The quality of the artificial spawning was found not to be adequate with a high risk of adverse effects to the whole population. All future stocking actions in the basin should consider the existing population structures.

Comparison of temperature shock timing to induced artificial mitotic gynogenesis and androgenesis in common tench

The aim of the study was to determine the optimum temperature shock timing to induce androgenetic and gynogenetic growth in common tench (Tinca tinca L.). UV radiation at the dose of 3,456 J m−2 was used to inactivate the genome of oocytes (androgenesis) and sperm (gynogenesis). In each case, the optimum timing was sought (between 20 and 60 min) before the beginning of diploidization of genetic material with a temperature shock (40 °C, duration 2 min). Eggs were incubated under laboratory conditions at 21 °C. The highest survival rate for androgenotes was observed after the temperature shock was applied for 30 min and for gynogenotes 40 min after the activation. The survival rate for embryos did not exceed 2 % in the best variants, either in andro- or gynogenesis. A negative correlation was found to exist between the quality of spawn and the occurrence of spontaneous andro- and gyno-genotes.

Different suitability of improved irrigation channels as reproductive sites for Cyprininae and Silurus asotus

Irrigation channels around paddy fields have been drastically improved over the past several decades in Japan. This has been accomplished exclusively by covering all the sides of channels with concrete. Although it is conventionally accepted that channel improvement has deteriorated quality of spawning and nursery sites for fish, to date, there is little evidence to support this claim. We examined the degree to which an improved irrigation channel with pools functioned as a spawning and nursery site for Silurus asotus and Cyprininae species within the Ezuragawa creek system that pours into Lake Biwa, Hikone, Shiga Prefecture, Japan. More eggs were observed for S. asotus than for Cyprininae species, but the opposite tendency was observed for the larvae and juveniles. Moreover, S. asotus juveniles were extremely rare. Therefore, our data suggest that improved irrigation channels are not suitable spawning and nursery sites for some species.

Marketing scenario and problems of mushroom growing in Punjab

Punjab state is known for its contribution to central pool in the production of rice and wheat grains. Various studies show the stagnation in productivity of these crops resulting decline in the returns. To augment their income some of the farmers adopted mushroom growing as subsidiary occupation of farming. The present study was undertaken in Amritsar and Gurdaspur districts of Punjab by taking a sample of 80 mushroom growers. The analysis brought out that Also, to examine the marketing structure of mushrooms, equal number of wholesalers and retailers were randomly selected from Amritsar and Gurdaspur markets. Mushroom growers were divided into three categories on the basis of bed area spawned using cumulative cube root frequency method. Marketed surplus of mushroom was about 99 per cent with meager family consumption, quantity given to labour as kind payment and to relatives. Marketing pattern revealed that the net price received by the growers was highest in producer → consumer channel while the marketing agency through which major chunk of produce transected was wholesaler. The production and marketing problems faced by mushroom growers were inadequate and poor quality of spawn, lack of assured market, price fluctuation, lack of canning and processing units and refrigerated storage. The study emphasized the need of canning and refrigeration facility for mushroom growers in case of higher production to stop distress sale and creating awareness among masses about nutritional importance of mushrooms to increase its consumption.

Effect of different grain spawns and substrate sterilization methods on yield of oyster mushroom in Botswana.

The effect of three different grain spawns and two substrate sterilization methods on the spawn quality and yield of a hybrid of Pleurotus ostreatus x P. florida (Po x Pf) was studied on maize cobs supplemented with 20% wheat bran and 2% gram flour in a low technological mushroom house at Botswana College of Agriculture, Sebele. Sorghum grains proved to be better mycelium carriers (5.25, 7 days, 12 days and 75.4%) over wheat (2.45, 17 days, 16 days and 53.55%) and barley grains (3.46, 14 days, 13 days and 55.24%) in terms of mycelium growth vigor, colonization time, spawn running time of the substrate and yield of the oyster mushroom. Hot water treatment and steaming of substrate significantly reduced substrate contamination and improved mushroom yield as compared to the untreated control. Mushrooms grown on steamed substrates had significantly higher yield (BE: 69.4%) than those grown on substrates treated with hot water (BE: 53.3%).

Effects of different photoperiods and handling stress on spawning and reproductive performance of pikeperch Sander lucioperca

The objective of this study was to control the reproductive cycle of pikeperch (Sander lucioperca) through determining the effects of different photoperiods and handling stress on the reproduction quality, timing and quality of spawning, fertilization, sex steroids, and cortisol concentrations. In this study, 72 pikeperch broodstocks with an average weight of 1367±55.3g were exposed to different photoperiods including constant light (24L:0D), constant darkness (0L:24D), and 12h of light, 12h of darkness (12L:12D) for 40days. Half of the broodstocks of each photoperiod treatment were exposed to handling stress at a specific time of the day. Applying different photoperiods caused changes in the timing of broodstocks’ spawning, so that fish under 24L:0D spawned earlier than those of other photoperiods, and stressed fish of the 0L:24D photoperiod had a delayed spawning compared to others. Also, the spawning of the broodstocks at different photoperiods which were exposed to handling stress was either delayed or did not occur at all. The highest and lowest spawnings were observed in the morning and at night, respectively. Fertilization percentage, number of eggs per gram, sex steroids including estradiol, progesterone, and testosterone, as well as cortisol and calcium concentrations did not show any significant difference in different photoperiods and handling stress. In stressed males of the 24L:0D photoperiod, there only was a significant decrease of testosterone concentration compared to the beginning of the experiment. Results indicated that the spawning performance of pikeperch broodstocks could be considerably stimulated using an effective photoperiod. Similarly, pikeperch broodstocks in culture systems are usually affected by handling stress, and this stress could lead to a poor reproductive performance and inhibition of spawning.

Effect of Different Live Prey on Spawning Quality of Short‐Snouted Seahorse, Hippocampus hippocampus (Linnaeus, 1758)

The importance of a suitable diet for reproduction has been recognized as one of the major factors in ornamental aquaculture. In seahorses, mysids have been described as preys in the wild. Also, Artemia has been usually employed for rearing fish, including syngnathids. Therefore, the aim of this work was to evaluate the effect of these live preys on the spawning quality of Hippocampus hippocampus. After 108 d, no differences were found in adults concerning all biological parameters evaluated, but broodstock fed on mysids showed better results than Artemia regarding number of spawning events (12 vs. 3), brood sizes (233.50 ± 59.04 vs. 68.00 ± 57.97 juveniles), and newborn seahorses standard length (10.61 ± 0.64 vs. 8.75 ± 1.32 mm). The better nutritional quality of mysids, overall in Docosahexanoic acid, could be one of the main responsible factors. However, mysids stock is conditioned by natural catches and rearing techniques are little known. Another alternative would be to combine them with Artemia in mixed diet. Further research must be done concerning mysids breeding techniques to delineate their employment as a sustainable prey for seahorse aquaculture. This trial showed for the first time the effect of mysids to enhance reproduction efficiency in H. hippocampus.

SUBSTRATE EFFECTS OF GRAIN SPAWN PRODUCTION ON MYCELIUM GROWTH OF OYSTER MUSHROOM

Spawn is pure culture of mycelium growing on a solid substrate such as cereal grain. Mushroom spawn has a fundamental role in global agricultural productivity. Its production has not been adopted by many farmers due to insufficient knowledge of scientific techniques needed for spawn production and mushroom cultivation. Just as seed quality is important to crop production, so is spawn quality to mushroom production. The most frequently used substrate for spawn production in Kenya is wheat and there is need to use the more widely available maize grain as substrate for grain mother spawn production of oyster mushrooms. Maize, wheat and millet grains were used as substrates in four replicates for production of grain mother spawns of Pleurotus ostreatus. Linear mycelium extension was measured, and recorded after every three days. Compost for planting the spawns was prepared and sterilized in an autoclave. The best grain mother spawns from the three grain substrates were planted in four replicates. Mycelia growth in the different bags was compared and recorded. The experimental design used was the completely random design and the data collected were compiled and subjected to analysis of variance (ANOVA) using SAS. Separation of the means obtained was done through LSD. The results revealed that linear mycelium growth was significantly (p<0.05) affected by the substrates of spawn production. There was a clear difference in mycelia growth in the grain substrates with maize substrate being the best, followed by wheat, then millet respectively.

Arachidonic Acid Effects on Reproductive Performance, Fry Quality and PGE 2 Level in Silverside Chirostoma estor

Introduction: Arachidonic acid (ARA, 20:4n-6) is the precursor of prostaglandins type 2, such as PGE2 and PGF2α, which modulate reproduction, ovulation and spawning in vertebrates [1]. In a previous study we proposed that low ARA levels in spawns of cultured silverside Chirostoma estor (2% vs 8% in wild, total fatty acids) could be associated to poor spawn quality [2]. The silverside (C. estor) is a freshwater endemic fish from Patzcuaro Lake in Michoacan, Mexico. Aquaculture development has been implemented partially to replenish wildstock; however, there is limited knowledge about its reproductive physiology. In the present study, silverside broodstock was fed with adult artemia (Artemia franciscana) enriched with ARA (3%, 4% and 7%, total fatty acids) during 10 weeks in order to evaluate dietary ARA effects upon reproductive performance, spawn quality, PGE2 level and fatty acid composition in gonads

Effect of substrates of spawn production on mycelial growth of Oyster mushroom species

Spawn quality is the most important factor in the production of edible mushroom (which is fast gaining prominence in Nigeria and Africa at large). In order to determine the effects of substrates spawn preparation on mycelial growth of oyster mushroom species, the experiment was conducted in a factorial experiment design at randomized completely with three replications. In this experiment, first and second factors respectively were substrates (Wheat, yellow maize, Guinea Corn, Millet, Red Sorghum and White Maize (Bende local)) and oyster mushroom species (Pleurotus tuber-regium and pelurotus pulmonarius). The results clearly demonstrated that between various substrates used, maximum and minimum growth rate were recorded for white maize (Bende Local) and least mycelial extension and fresh weight on wheat.The second best grain for both species used was Red Sorghum.

Effect of tributyltin oxide exposure on the F0 and F1 generations of a marine teleost, the mummichog Fundulus heteroclitus

The effects of organotin compounds on marine organisms, especially on their reproduction, are a continuing source of concern. We performed full-life-cycle exposure tests of tributyltin oxide (TBTO) at sub-lethal concentrations (0.13, 0.25, 0.5 and 1.0 μg/l) using a marine fish, the mummichog Fundulus heteroclitus, and studied the toxic effects of exposure to TBTO at various life-cycle stages of the fish. The effect of TBTO was initially studied on sex differentiation and then on spermatogenesis in maturing fish. A mating experiment was performed to determine the effects of exposure on the fecundity of female fish, fertilization success, and the hatch of the F1 generation. In all experimental groups, TBTO exposure resulted in a tendency toward a male-biased sex ratio and caused a significant increase in the frequency at which apoptotic cells appeared in the testes. Exposure to 1.0 μg/l TBTO resulted in a significant decrease in fecundity, but no significant effect was found on the fertilization ratio. Time to hatch and hatchability of the F1 generation were markedly affected in some exposure groups. These results indicate that long-term exposure of the mummichog to TBTO affects not only gonadal sex differentiation and spermatogenesis but also spawning and egg quality.

Habitat suitability analysis for lacustrine brown trout (Salmo trutta) in Lake Walchensee, Germany: implications for the conservation of an endangered flagship species

Abstract The lacustrine brown trout (Salmo trutta) is endangered and of high conservation importance. In the only spawning habitat of the population in the Bavarian Lake Walchensee, the River Obernach, a substantial decrease in spawning runs has been reported. In this study, the present ecological state of the spawning stream was analysed with the objective of identifying life‐stage specific limitations to successful recruitment attributable to deficiencies in (i) spawning migration, (ii) spawning habitat quality, and (iii) habitat quality for juveniles. Structural stream analysis showed that discharge and several migration barriers — particularly near the river outlet into the lake — prevent successful spawning migrations at normal water levels. Migration barriers are probably the main limiting factor for reproduction of lacustrine brown trout, whereas structural variability of the Obernach meets the habitat requirements of both spawners and juveniles. Spawning site quality was suitable for trout, as indicated by stream substratum texture and high exchange rates between free‐flowing water and the interstitial zone in physico‐chemical parameters (redox potential, dissolved oxygen, pH, temperature and conductivity). Analyses of fish community structure revealed dominance of lithophilic species, in particular of riverine brown trout (Salmo trutta). Its density and intact demographic population structure suggest that spawning and juvenile habitat quality for salmonids is not limiting. Recapture of stocked lacustrine trout juveniles also indicates habitat suitability for the juvenile stage. In conclusion, the results show that the methodology used in this study is suitable for the identification of life‐stage specific habitat deficiencies in lacustrine brown trout and other fish species. Availability of habitat data throughout the species' distribution range is a first crucial step for the development of an effective recovery plan. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Factors affecting recruitment dynamics of Great Lakes sea lamprey ( Petromyzon marinus) populations

Knowledge of stock–recruitment dynamics is as important for control of pest species such as the sea lamprey ( Petromyzon marinus) as it is for sustainable harvest management of exploited fish species. A better understanding of spatial and temporal variation in recruitment of pest populations may inform managers on where and when to effectively apply different control methods. Sea lamprey stock–recruitment data combined from streams across the Great Lakes basin into a Ricker stock–recruitment model indicated both compensation (density-dependent survival) and a large amount of density-independent recruitment variation. We evaluated the use of a mixed-effects model to look at common year effects and stream-level variables that could affect productivity and growing season length, with the objective of identifying factors that may explain this density-independent variation in recruitment. After selecting the “best model”, we tested factors that might affect recruitment variation, using a Great Lakes dataset comprising 97 stream–years. Lake Superior tributaries, streams with larger numbers of lamprey competitors, and streams regularly requiring lampricide treatment showed significantly higher recruitment. Alkalinity and thermal regulation did not affect the observed recruitment pattern among streams. In four long-term study streams we observed significant variation among streams, tested as a fixed effect, but no evidence suggested a common pattern of variation among years. Differences in recruitment among streams were consistent with evidence of quality of spawning and larval habitat among streams. Our findings suggest that management models should account for differences in recruitment dynamics among sea lamprey-producing streams, but not common year effects.

Ichthyoplankton Assemblages of Coastal West-Central Lake Erie and Associated Habitat Characteristics

Early life stage survival often determines fish cohort strength and that survival is affected by habitat conditions. The structure and dynamics of ichthyoplankton assemblages can tell us much about biodiversity and fish population dynamics, but are poorly understood in nearshore areas of the Great Lakes, where most spawning and nursery habitats exist. Ichthyoplankton samples were collected with a neuston net in waters 2–13 m deep weekly or biweekly from mid-April through August, during 3 years (2000–2002) as part of a study of fish assemblages in west-central Lake Erie. A suite of abiotic variables was simultaneously measured to characterize habitat. Cluster and ordination analyses revealed several distinct ichthyoplankton assemblages that changed seasonally. A lake whitefish (Coregonus clupeaformis) dominated assemblage appeared first in April. In May, assemblages were dominated by several percid species. Summer assemblages were overwhelmingly dominated by emerald shiner (Notropis atherinoides), with large gizzard shad (Dorosoma cepedianum) and alewife (Alosa pseudoharengus) components. This seasonal trend in species assemblages was also associated with increasing temperature and water clarity. Water depth and drift processes may also play a role in structuring these assemblages. The most common and widely distributed assemblages were not associated with substratum type, which we characterized as either hard or soft. The timing of hatch and larval growth separated the major groups in time and may have adaptive significance for the members of each major assemblage. The quality and locations (with reference to lake circulation) of spawning and nursery grounds may determine larval success and affect year class strength.

Yield Of Edible Pleurotus Mushrooms Grown On Rice Straw With And Without Chicken Manure Supplementation In Morogoro, Tanzania

An experiment was conducted to determine the performance of different species of edible Pleurotus mushrooms grown on rice straw substrate with and without chicken manure supplementation. The Pleurotus species /varieties tested were P. flabellatus of Tanzania, India and Thailand origin, and P. sajor caju from Tanzania. Rice straw with and without chicken manure were used as substrates. The results showed that the duration of time from spawning to pin formation and from pin formation to first harvest was not significantly different for both treatments (p=0.05). The yields of the Indian and Thai P. flabellatus varieties were significantly higher than yields of P. flabellatus and P. sajor caju from Tanzania (p=0.05). The yields of the substrate amended with manure and un-amended were not significantly different. These results suggest that yields of the studied varieties of Pleurotus mushrooms are not influenced by substrate amendments rather other factors like spawn quality. This implies that use of high quality spawn can be a good determinant of high yields. On the other hand local varieties had lower yields than exotic varieties under the same treatments showing that research and breeding to screen and select for good quality local edible varieties can adequately improve yields and utilization of local breeds/varieties. Keywords : Pleurotus flabellatus - Pleuotus sajor caju – yield – amendmended, un-amended substrates Tanzania Journal of Forestry and Nature Conservation Vol. 77 2008: pp. 46-53